A Guide to Audyssey Auto Calibration & Other Technologies

[Big Daddy]

A GUIDE TO AUDYSSEY AUTO CALIBRATION & OTHER TECHNOLOGIES

Although this guide is written for Audyssey AUTO calibration program, many of its suggestions can be used by people who are using other receivers/processors and auto calibration programs.

Audyssey is used by Creston, Denon, Integra, Marantz, NAD, Onkyo, Phase Technology, and Wisdom. It does not stand for anything with respect to audio. Audyssey is a name that is used by the founders of the company, Chris Kyriakakis (a Professor at USC) and Tomlinson Holman of THX.

Anthem: ARC = Anthem Room Correction
Emotiva XMC-1: TACT = Tuned Aperture Computed Tomography
Pioneer: MCACC = Multi Channel Acoustic Calibration and Control
Sherwood: Room Acoustic Calibration with EQ
Sherwood Newcastle R-972: Trinnov Optimizer
Sony: DCAC = Digital Cinema Auto Calibration
Yamaha: YPAO = Yamaha Parametric Room Acoustic Optimizer

Before you run any auto calibration program, it is highly recommended that you read the following threads:

A Guide to Bass Management (Part I)
A Guide to Bass Management (Part II)

The importance and necessity of equalization is discussed in the following thread:

Why Do We Need Equalization and Room Correction?

PRELIMINARY PREPARATION

It is important that you follow the following steps before you attempt to run the auto calibration program:

1. Place your front speakers about 6 feet (1.8 m) to 10 feet (3 m) apart. Make sure the rear of the speakers are a couple of feet away from the front wall.
2. Do not toe in your front speakers too much. If you want to do this, make sure the speakers are pointing to your shoulders and not your head.
3. Place your main listening chair/sofa in a location between the two front speakers so that they make approximately an equilateral triangle.
4. The low frequency sound waves interact with the room boundaries and create standing waves and room modes. Because of these modes, there will be many peaks and valleys of low frequency waves. You should not sit exactly in the middle of a typical rectangular room because that location falls in the valley of many of these room resonances and you will have a hard time hearing any bass. At the same time, you should not sit against the wall as the bass will be too heavy, boomy, and tiring.
5. Do not place the center speaker inside a cabinet as the cabinet can interfere with the speaker and distort the sound. If you are placing the center speaker under the TV/Screen, put something like door stops under the front of the speaker to point it upward towad your head. If you are attaching the center speaker to the wall above the TV/projector screen, make sure it is pointing downward toward your head.
6. As far as surround speakers are concerned, follow the guidelines recommended in A Guide to Bipolar, Dipolar, and Monopole Surround Speakers (Part I).
7. I highly recommend using room treatments to improve the sound in your HT room. At the minimum, buy absorption panels/foams and place them in the locations to reduce early reflections from the boundaries into the listening area.
8. Connect all speakers and pay attention to polarity of the seaker wires (positive to positive and negative to negative).
9. It is highly recommended that you use a subwoofer as the auto calibration programs work best with a subwoofer present. Make sure you connect the subwoofer to the subwoofer output (LFE output) on the back of the processor. If you do not have a subwoofer, it is important that you use front speakers that are capable of reproducing the lower frequencies with ease. In such a case, you must set the front speakers to LARGE. Many receivers/processors will automatically set the front speakers to LARGE when a subwoofer is not present.
10. The phase control on the back the subwoofers is a usually a simplistic analog control that only changes the phase at one frequency. Proper phase alignment requires that the phase change is different at every frequency. Unfortunately, that is not possible with an analog control. As a result, Audyssey recommends that you leave the phase control at zero.
11. After all the speakers/subwoofer(s) are connected, go to the processor’s menu and set the subwoofer to YES or NO depending on whether you have or do no have a subwoofer. Make sure all other speakers are recognized properly.
12. Many receivers/processors may have an option to set the Subwoofer to DOUBLE BASS, LFE+MAIN, or BOTH. Turn that off and set the subwoofer to LFE only. There is a complete explanation of this in the two guides mentioned at the beginning of this post.

USING THE AUDYSSEY AUTO CALIBRATION PROGRAM

The Audyssey room correction program comes in four different flavors: MultEQ XT32, MultEQ XT, MultEQ and 2EQ. Although they are all built on the same basic fundamentals, each receiver/processor may use a different version depending on its DSP processing power. Furthermore, it is possible that some lower end processors may have to turn Audyssey off if you set them to process the bitstream HD audio. Check the owner’s manual for further information.

MultEQ XT32: Our newest and most accurate room correction solution with more than ten thousand individual control points allowing finer details of the room’s problems to be captured and corrected. The ultra high resolution filters are applied to all channels including the subwoofers, with the most obvious benefit being heard in the low frequency range where correction is needed the most.

MultEQ XT: Our advanced resolution room correction solution with high resolution equalization filters for satellites and subwoofers. Most products with MultEQ XT are installer-ready and can be calibrated by an Audyssey Registered Installer to provide even higher performance for even the most demanding large or odd-shaped rooms.

MultEQ: Our standard resolution room correction solution that uses mid-level resolution filters for satellites and subwoofers.

2EQ: Our basic resolution room correction solution that uses basic resolution filters for the satellites, but does not apply a filter to the subwoofers.

* Up to 32 measurement positions with MultEQ Pro. Most AVRs with MultEQ XT32 and
MultEQ XT are installer-ready and can be calibrated by an Audyssey Registered Installer to
provide even higher performance for even the most demanding large or odd-shaped rooms.

This page on Audyssey's website gives you all the information about the version of the MultEQ that is available on any particular AVR.

http://www.audyssey.com/products?ins...d=44&ptype=All


How to Run MultEQ:

1. Before you run Audyssey auto calibration program, it is not necessary to turn off Dynamic EQ, Dynamic Volume, or any other options. All internal settings are ignored when the calibration is running, including the volume, level trims, delays, and speaker settings. They are set after you are finished and saved the results of the auto calibration program
2. After calibration, if you plan to use Dynamic EQ and Dynamic volume, it is a good idea to turn off the Night Mode, Dynamic Range Compression (DRC), and Dynamic Compression (D. Comp) in the receiver/processor as well as the player. In addition, if your receiver/processor has the THX Loudness Plus or Dolby Volume, you should turn them off as these may possibly have an adverse effect on Audyssey Dynamic EQ and Dynamic Volume.
3. If you have a Bass Shaker, Buttkicker, or Tactile Transducer under the listening sofa/seat, turn it off. The vibrations from them may fool the calibration microphone into measuring and setting a much shorter distance than the actual distance from the subwoofer to the listening seat. It may also result in incorrect equalization for the subwoofer.
4. Connect the included microphone to the receiver/processor and set it at ear level in the primary listening location. Always start the measurements from the primary listening location and spread out from there. Approximate distance from the first measurement position to any other position is 2 feet (0.6 m), no more than 3 feet (≈ 1m). The first measurement must be taken in the middle of the listening area. After that, the exact location of each measurement is not critical, but be sure to follow the following diagram for proper microphone positioning:
   
   
   
   
   
   
   
5. Depending on the version of MultEQ included in your AVR, you will have 3, 6 or 8 measurement locations. With MultEQ Pro software, you can take up to 32 measurements (12 positions are shown in the diagram). Make sure you use all positions for the MultEQ included in your AVR.
   
   You will notice that positions 1, 2, and 3 are located on the seats of the couch. Use a small tripod (see Post #31 for links to a few options) and place it on the couch. If the couch back is slightly higher than ear level, raise the tripod a few inches as reflections from the back of the sofa may interfere with the sound if the microphone is placed too close to it. Since it is recommended that the microphone should be placed as close as possible to ear height, instead of raising it, you can keep it at ear height and move it forward so that it is not too close to the back of the seat. You may also use a boom arm (Post #31 has links to microphone stands and boom arms), but make sure the arm is not in the path of the speakers and also the tripod head should be as small as possible so that is does not interfere with the microphone.
   
   
6. Focus on the central listening area and avoid extreme positions such as the back wall or too far beyond the left and right speakers. The delays and levels for each of your speakers are calculated from the first microphone position. The center position is usually defined as the tip of the triangle with the base of that triangle running through the two front speakers. In an ideal setup, the triangle is equilateral (60° angles). But, in most home theater rooms that cannot always be the case. Even if the seat is off to the side, it is still recommended taking the first measurement location to be in the center of the listening area and then following the pattern in the diagram. The measurements are designed to collect information about the response of your speakers in the room. It's best to avoid placing the microphone in extreme off axis positions because that can give it misleading information about the off axis response of your speakers.
7. Place the microphone on a tripod for better stability. Make sure the microphone is facing upward toward the ceiling.
8. Do not place the microphone on the back cushions or the arms of a sofa.
9. Use only the microphone that was included with your AVR. If the microphone is damaged or lost, contact the manufacturer and purchase a new one. It is possible that some microphones may be compatible. For example, Denon and Marantz share the same parent company and it is more than likely that they use identical microphones.
10. Unplug any headphones that may be connected to the AV receiver.
11. Do not stand or sit next or in front of the microphone. Make sure nothing else is blocking the path between the speakers and the microphone. Any changes that you make to the room will require that you run Audyssey again.
12. Make the room as quiet as possible. Background/ambient noise may distort the measurements. Close all doors and windows, turn off cell phones, radios, air conditioners/heaters, fluorescent lights, light dimmers, or other devices. Radio Frequency Interference (RFI) may cause measurement disruptions.
13. Do not disconnect the microphone during the setup.
14. Do not connect or disconnect any speakers during the setup.
15. Start Audyssey MultEQ as instructed in the manual.
16. You will hear the pink noise from each loudspeaker until the cycle is finished.
17. After the measurements for the main position are finished, the following will occur:
    • Audyssey will report all the speakers it has recognized. If some of the speakers are missing in the list, check the connections and go back and repeat the measurements for position one.
    • Another very common problem is that Audyssey may report that your speakers are out of phase. Again, do not be alarmed. Always interpret the phase warning by Audyssey with a grain of salt. Complexity of room dynamics and/or some loudspeakers unique crossover/driver arrangements, can trick the auto calibration programs into reporting speakers as being wired out of phase when in fact they are not. Some drivers are intentionally wired out phase. Moreover, it is possible that some amplifiers may invert the signal. If the calibration program reports any of your speakers are out of phase, first check the wiring manually and then use calibration discs such as Avia, DVE, or AIX to audibly confirm the proper phase of each channel. If you checked all your wiring and everything seems ok, just ignore the out-of-phase message.
      
      
      
      
      
      In Phase Speakers
      
      
      
      
      Out of Phase Speakers
      
      
      It is important not to confuse phase with polarity. Polarity change is switching the positive and negative speaker wires. A change in polarity only reverses the direction of the frequency wave. Phase shift is a timing difference in frequencies as exhibited in the following diagram. Many factors such as the crossovers, equipment, and the room can affect that.
      
      
      
      
      Animation courtesy of Dr. Dan Russell, Kettering University
      
      
      The weakest link in a loudspeaker is its crossover network. All crossovers create a phase shift of varying degree between the frequencies at the crossover point. Drivers within a speaker are wired out of phase to compensate for that. Also, the interaction inside a subwoofer between the woofer and port can cause polarity reversal warnings. Many auto calibration programs inside the receivers/processors detect the absolute phase and cannot really tell you for sure if the polarity of the speakers are correct.
    
    
18. After you are finished with checking the polarity of the speakers and all speakers are properly recognized, move the microphone to a new position around the listening area and take measurements.
19. Once you have finished the measurements for all the listening positions, Audyssey will do some calculations for a few minutes and will ask you to double check the settings. You can adjust them later after the calibration for all the speakers is finished. In general, several things may occur:
    • You may notice that your front speakers are set to LARGE (FULL BAND) or SMALL. Audyssey does not make this decision. Audyssey simply takes some measurements and reports them to the AVR. The AVR manufacturer has complete control over how the speakers should be set. Many of them use inappropriate or archaic rules to set the speakers to LARGE as long as the speakers show some response below 80Hz. You can adjust this later and set your speakers to SMALL. For further information, read the two Bass Management Guides mentioned at beginning of this post.
    • It is important that you understand that Audyssey measures the performance of the speakers in your room. The frequency response of your speakers in the room as measured by Audyssey may be significantly different than the frequency responses as measured by the manufacturer in an anechoic chamber. Don’t be alarmed. All speakers react with the room boundaries, furniture, and with each other. They exhibit different frequency response in real rooms. Audyssey measures what your speakers are doing in your room and recommends a setting based on their placement. Its results are based on the placement of the speakers and the microphone.
      
    • You may notice that Audyssey has reported a much longer distance between your subwoofer and the listening position or a significantly shorter distance between the two. This problem arises because Audyssey MultEQ does not actually measure distance between the subwoofer and the listening area. It measures signal delay. This delay consist of:
      1. The time it takes for sound to travel in the air to the microphone.
      2. The electrical delay in the signal inside the subwoofer:
      • Any type of filter in the sub introduces delay.
      • Any type of DSP processing in the subwoofer introduces delay.
      • The interaction of the woofer and the port in in a subwoofer can also cause problems. This interaction can also cause polarity reversal warnings.
      Because of these delays, it is quite normal to see longer distances reported for the subwoofer. You should leave it as MultEQ found it.
      
      When the reported distance is much shorter than the physical distance, then you should worry. Something else has caused that. The most likely cause is vibrations that travel to the microphone through a solid surface such as the floor or the sofa/seat. Sound travels faster in solids than it does in air and this can cause the short readings. The only alternative you have is to try is to make sure that the microphone is isolated from any vibrating surfaces. Avoid placing it on the edge of the listening sofa. Also, move the subwoofer to a different location or isolate it from the vibrations by using a riser.
20. Once you have finished with the calibration and confirmation, save the measurements to your AVR.
21. Every time, you move the speakers, furniture, add new curtains or room treatment, you should run the Auto Calibration program again. The crossover recommendations made by Audyssey are based on the measurements in your room. It is not surprising that the roll off frequencies change when you do the above. For example, if the distance from the wall is changed, then it is expected to see a change in the roll off frequency. That is the whole point of measuring and not depending on the the theoretical specifications as reported by the manufacturers.

WHAT YOU SHOULD DO AND WHAT YOU SHOULD NOT DO

1. It is ok to increase the crossover frequencies of the speakers as set by Audyssey. It is generally not recommended to lower the crossover frequencies below the numbers set by Audyssey. If you do that, Audyssey will not apply correction filters to the frequencies below the numbers that are set by the auto calibration program.
   
   Many people are hung up on the 80Hz crossover frequency that is suggested by most experts. Although 80Hz crossover frequency works for many speakers, it is not a number that is etched in stone. That number was originally recommended by THX and applies to THX certified speakers that have certain frequency characteristics.
   
   Audyssey does not measure the frequency response of a speaker as it was reported by the manufacturer and supposedly measured in an anechoic chamber. Audyssey measures the performance of the speakers in the room and based on that, it recommends some crossover numbers. Depending on their location, proximity to room boundaries, furniture, wall coverings, position of the microphone, etc., even identical speakers may have different performances in the room.
   
   
2. It is ok to change a speaker from Large to Small. For the reason mentioned above, you should not change a speaker that has been set to Small and set it to Large. Always remember that if you have a subwoofer, all your speakers become Small by default.
3. Do not use Double Bass, LFE+Main, or Both for your subwoofers. Those options will engage Bass Management for speakers that has been set to Large. To understand this, go back and read the two Guides mentioned at the beginning of this post.
4. Speakers/Subwoofer Distances: Audyssey MultEQ does not measure speaker/subwoofer distances. It actually measures the signal delay. For the main speakers this delay calculation usually results in actual physical distances. But, subwoofers have filters in them that delay the signal more. So, this is equivalent to the subwoofer being further away. It is quite normal to see longer distances reported for the subwoofer.
   
   To summarize, the subwoofer distance calculation is more complex than simply using a measuring tape. Subwoofers have filters in them that add delay to the signal and the auto calibration program compensates for that. That is why you should leave the distances as the auto calibration program found them.
   
5. It is ok to double check the speaker levels with an SPL meter after Audyssey calibration is finished. If you are going to do that, make sure you use an external test tone disc such as AIX, Avia, or DVE as the internal test tones of the AVRs bypass all post processing done by the calibration program and will not reflect the true level of the speakers when you play a movie with all the post processing engaged. Furthermore, it is possible that the player and/or cables may affect the actual level of a speaker during playback of a movie. Therefore, it is more appropriate to run the test tones through the same player and cables.
   
   It is important to remember that if you adjust the speaker levels with an SPL meter, you may change the reference level. This means that when you set the master volume to zero level, it may no longer represent the reference level.
   
   After running a MultEQ calibration and turning on Dynamic EQ, if you find the surround speakers to be much louder than the front and center speakers, that is done on purpose. The researchers at Audyssey have found out that human perception of loudness falls off faster behind us than it does in front. So, Dynamic EQ compensates for that using a human loudness spatial model that looks at the master volume setting and makes the appropriate adjustment to the level of the surrounds. This is designed for content where the overall surround impression should remain the same at all volume levels: i.e. surround movies and music.
   
   
6. It is ok to increase the level of the center channel speaker by a few dB's if you feel you are having a difficult time hearing the dialog. Poor response from the center channel speaker is caused due to room acoustics and placement. If a center speaker is placed inside a cabinet or too close to the floor, it can have less than ideal sound.
7. If the you notice the level of the subwoofer is set to -10dB or a higher negative number in the receiver, it probably means that the level on the back of the subwoofer is set too high. If the level control on the back of the subwoofer is set too high, this can cause the AV Receiver to run out of level correction range when MultEQ tries to set the subwoofer to reference level. Lower the sub level on its back and run the auto calibration again.
8. If you notice the subwoofer’s level is set too high (e.g., 5dB or more), before you increase the level of the subwoofer on its back and increase the chance of clipping or bottoming, move the subwoofer to a better location. A subwoofer in a corner uses all room resonance modes and will be the loudest. Alternatively, you can use the sub crawl technique. Make sure you run the auto calibration again.
9. Audyssey applies more correction filters to the subwoofer than the other speakers. It is not a good idea to use a muti-channel speaker setup without a subwoofer or intentionally set the subwoofer channel to NO in the AVR. The filters in the subwoofer channel are designed to only operate in that channel and so they will remain unused if there is no subwoofer in the system.
10. If you are using a subwoofer equalizer such as the Velodyne SMS-1, REW/BFD, etc., you should equalize your subwoofer(s) before you run the Audyssey auto calibration program. In addition, some of these equalizers have a subsonic filter. If you are using a ported subwoofer, it is a good idea to use this feature to protect the subwoofer from over extension and damage. You should set this filter to 15Hz to 20Hz, depending on the low frequency extension of your subwoofer.
11. Manual Equalization: After Audyssey calibration, if you decide to perform manual equalization by copying the Audyssey base curve into the manual EQ, this does not copy all the thousands of adjuments points that Audyssey makes. It does not copy the Audyssey filters. In fact, Audyssey is tuned off when you switch to Manual EQ. All you get is a simple graphic equalizer that roughly has the shape of the Audyssey filter in the frequency domain. The time domain benefits of Audyssey filtering are lost.

REFERENCE LEVEL

Reference level is defined for film mixing and movie theaters. Every studio and movie theater is calibrated according to this level. It represents an average of 85dB for the regular speakers on the SPL meter (set on C weighting and Slow) using a band limited (500Hz to 2,000Hz) pink noise at the listening position. The peak level is set 20dB higher at 105db and the LFE peak level is set +10dB higher to a maximum of 115dB. The purpose of the +10 dB gain for the LFE channel is to increase the dynamic range of bass sound such as explosions and crashes. This means when the receiver master volume is set to 0dB, the regular speakers are expected to play a peak level of 105dB and the subwoofer is expected to produce a peak output level of 115dB. This is louder than most people can tolerate, so people normally set the master volume much lower than 0 when watching movies or listening to music. Furthermore, such loud bass level places a heavy burden on the subwoofer and requires multiple high-end subwoofers to produce it accurately.

Because 85dBC test tones can be very loud in a small home theater room and can damage hearing, receiver manufacturers through the encouragement by Dolby and THX decided that a reasonable test-tone level is 75dB and that is the level that most receivers use.

To summarize,

• Reference Level is 1.85v line level = 0dB VU meter = 85db playback level.
• 105dB Peak level = 0dB (Full Scale).
• 85dB Average Level = -20dB (Full Scale).
• 75dB Average Reference Level = -30dB (Full Scale).
• dBFS (Full Scale) = unit of measure for the amplitude of digital audio signals.
• The reference level is "0" dBFS, which is also the maximum signal amplitude that can be stored digitally in a typical digital audio recording system.
• Signals louder than 0dBFS just produce clipping (truncation of the waveform, hence distortion).

When calibrating your audio system, the receiver plays pink noise that is recorded at 75dB (-30dB FS). When the individual speaker levels are set to 75dB at the listening position, as measured by an SPL meter, the effects of speaker sensitivity and room acoustics are accounted for and the speakers are all level-matched against the Reference Level.

You can use either the internal test tones of a receiver or an external disc. The internal test tones of most receivers are band limited and recorded at 75dB level (-30 dB FS). External calibration signals on most discs are typically full-range pink noise and recorded at 85dB (-20dB FS). It really doesn't make a lot of difference which method you use as long as all the speakers are balanced. However, it is important to remember that when you play the internal test tones inside a receiver/processor, they normally bypass all post processing, including equalization.

[Big Daddy]

AUDYSSEY AND MUSIC

Movies are mixed in studio rooms calibrated for the film reference level (see the last section below for explanation of the Reference Level). Home theater systems that are calibrated by Audyssey MultEQ will play at home reference level when the Master Volume is set to 0 dB position. To achieve this reference level, the levels of all the speakers/subwoofer(s) are adjusted so that the system plays at the reference level when the master volume is set to 0dB position. This is normally done by playing the internal pink noise generated by the receiver/processor so that it produces 75 dB sound pressure level at the main listening position. The pink noise inside most receivers/processors are band-limited (500Hz – 2000Hz) and recorded at -30dBFS. This is done so that we hear the sound at the same level that was intended by the mixers.

Most people do not listen at reference level and turn the master volume down to -10dB - 15dB. When you turn the master volume down, some of the frequencies, particularly the lower frequencie, will suffer. Audyssey Dynamic EQ was created to make adjustments to maintain the reference response and surround envelopment when the volume is turned down from 0dB. It is referenced to the standard film mix level.

Unfortunately, music recordings do not have a well defined reference level like movies and are recorded at many different levels. In order to alleviate this problem, the Audyssey Dynamic EQ has Reference Level Offset to set for content that does not follow the standard movie refence level. These are the Reference Level Offsets that are suggested by Audyssey:

0 dB (Film Reference): This is the default setting and should be used when listening to movies.

15 dB (Pop/Rock Music): Select this setting for pop/rock music or other program material that is mixed at very high listening levels and has a compressed dynamic range.

10 dB (Jazz & TV Content)): Select this setting for jazz or other music that has a wider dynamic range. This setting should also be selected for TV content as that is usually mixed at 10 dB below film reference.

5 dB (Classical Music): Select this setting for content that has a very wide dynamic range, such as classical music.

Please note that the Audyssey Dynamic EQ Offsets are not available for all receivers. For example, for the Denon receivers, it was introduced with XX10 models. You can achieve the same thing by going into the setup menu of the receiver and turning down the Input Level for your selected source by 5, 10 or 15dB. You should then turn the master volume up tby the same amount from wherever you had it set before so that you can listen at the same volume level as before. Turning the volume up tells Dynamic EQ to make smaller adjustments. The 10dB adjustment may work for most music content.

INVERSE CORRECTION FILTER

Let's fully understand what the Audyssey Auto Calibration does. Although Audyssey measures and sets the levels of the speakers/subwoofer(s), I limit my discussion to equalization only.

1. It measures and sets the levels of the speakers/subwoofer(s).
2. It tries to determine the frequency roll-off of the speakers/subwoofer. To do that, it uses sophisticated algorithms to distinguish between the normal peaks and troughs in the frequency response and the roll-off frequencies (low and high).
3. It then selects hundreds of correction points on the frequency response curve (mostly in the lower frequencies). This is far more advanced than most parametric equalizers do.
4. The final step is that it applies an Inverse Correction Filter to the measured frequency response curve. Everywhere that there is a dip, the filter applies a peak with the same shape. Similarly, every peak is corrected by a dip.

Note: Audyssey does not apply correction filters to frequencies below and above the rolloff frequencies.

The steps above are summarized in the following graphs:


http://www.audyssey.com/audio-technology/multeq/tour

http://www.audyssey.com/node/545

SUBWOOFER CORRECTION

MultEQ corrects the subwoofer in every seat providing precise bass reproduction.

http://ask.audyssey.com/entries/7724...c-equalization

Q. Can you explain a little about how MultEQ deals with the time domain? Is it in the measurement or the correction you apply?

A. MultEQ measurements are taken in the time domain. That means that the test signal is captured after playing from each speaker and is analyzed to see how it evolves in time. The first burst comes from the direct path, then from various room reflections. This gives MultEQ a pattern of how sound from that speaker was influenced by the room and nearby surfaces. Methods that use pink noise (or similar) do not have the ability to see the time domain and only look at the frequency response.

Once all the measurements have been taken, MultEQ performs an analysis of all the time domain patterns and groups them according the similarity of the problems it finds. Then it creates a representative time domain response for each group. These representative time domain responses are then combined to give a single time domain representation of the speaker behavior in the room. The MultEQ filter is then created by inverting that final time domain response. A filter is created for each measured speaker and sub and is then applied to the signal in the time domain via a process called convolution.

http://ask.audyssey.com/entries/9416...-target-curves

Contrary to popular belief, a target curve that is flat from 20 Hz to 20 kHz is not always the one that will produce the correct sound. There are several reasons for this. One has to do with the translation required from a large movie theater to a smaller home listening room. The other reason has to do with the fact that loudspeakers are much more directional at high frequencies than they are at low frequencies. This means that the balance of direct and room sound is very different at the high and low ends of the frequency spectrum.

The Audyssey Reference target curve setting makes the appropriate correction at high frequencies to alleviate this problem. A slight roll-off is introduced that restores the balance between direct and reflected sound.

The Audyssey Flat setting uses the MultEQ filters in the same way as the Audyssey curve, but it does not apply a high frequency roll-off. This setting is appropriate for very small or highly treated rooms in which the listener is seated quite close to the loudspeakers. It is also recommended for all rooms when the receiver is in THX processing mode. This allows THX re-equalization to operate exactly as it was intended.

Some manufacturers have decided to implement a Bypass L/R (or Front) setting. This uses the MultEQ filters that were calculated for the entire listening area, but it does not apply any filtering to the front left and right loudspeakers. The average measured response from the front left and right loudspeakers is used as the target curve for the remaining loudspeakers in the system. The subwoofer in this case is equalized to flat as is the case for all the settings described above. This is not a setting recommended by Audyssey.

In some products, there is a Manual EQ setting. This is a traditional parametric equalizer that does not use the MultEQ filters or the Audyssey measurement process at all.

http://ask.audyssey.com/entries/4101...e-compensation

Midrange compensation is an intentional dip in the 2 kHz region where the vast majority of tweeter-to-midrange crossovers are. In that region the tweeter is at the low end of its range and the midrange at the high end of its range and the directivity of the speaker goes through major changes. We found that if that region is equalized to flat, the change in direct to reflected ratio that happens because of the directivity variations causes voices to sound harsh (among other things). So, we have this implemented in the Audyssey target curve. With MultEQ Pro you can choose to turn it off, but we don't recommend it. This notion was observed 40 years ago by BBC speaker designers in their studio monitors. They designed their speakers with this "BBC dip" intentionally in the speaker response.

http://ask.audyssey.com/entries/9346...re-interaction

Audyssey MultEQ creates room correction filters to two specific target curves. One is the Audyssey Reference curve that has a slight roll off in the high frequencies above 10 kHz that has to do with the translation required from a large movie theater to a smaller home listening room. The other is Flat that has no roll off. Some AVR makers decide to give the user a manual choice and others, like Onkyo, make the switch automatically.

Re-EQ is not an Onkyo function, it is part of THX. We recommend using the Flat room correction curve so that the intent of THX Re-EQ is preserved. Onkyo allows you to switch Re-EQ on and off separately from the other THX functions and so you could listen to Audyssey Flat if you turn off Re-EQ.

There is no interaction between the Re-EQ button and Audyssey. If you are in THX mode then you are listening to Audyssey Flat regardless of whether you have Re-EQ engaged. Of course, if you do have it engaged it applies a high frequency adjustment that takes you away from Flat. I recommend using Re-EQ with Audyssey Flat for movie listening.

There is no way to have Audyssey Flat in Onkyo products without having the THX mode engaged.

In Onkyo receivers with THX, if you turn on Re-EQ and you are not in THX mode, then you will be using the Audyssey Reference curve plus Re-EQ.


http://www.audyssey.com/blog/2009/05...vs-preference/

Reference vs. Preference
By Chris Kyriakakis

Here is a trick question: “What if I correct the acoustical problems in my room, but I don’t like the resulting sound?” If you find yourself asking this question you have stumbled on the line between Reference and Preference.

Let’s look at what room correction aims to do. You start with a good (or not so good) set of speakers, you place them in a room and what you have is problems: acoustical problems. Sound from the speakers comes to you from many different directions. Some of it directly, but most of it after interacting with the floor, ceiling, walls, and furniture. Because each of these elements is at different distances from where you sit, the combined sounds arrive at slightly different times and what you hear is a form of distortion. Voices can sound unnatural, the low frequencies are muddy or boomy, and the high frequencies lack air and sparkle (yes, these are all technical terms).

A well-designed room correction system captures information throughout the listening area and analyzes it in the time domain. It then creates an equalization solution for each speaker and applies it so that the response matches a certain target sound. And here is where we first catch a glimpse of the Reference vs Preference line: What should this target sound be?

The answer lies earlier in the chain, where the content is made. The film industry adheres to a set of strict standards that are used in the creation of the content and in the reproduction of the content in movie theaters. These standards define the location, level, and frequency response (target sound) of the speakers in the audio system. They are in place so that content created in one location can translate perfectly to thousands of movie theaters. The same translation should apply when the content is played back in a home theater.

So, calibrating your home theater system “to reference” means that: (i) the levels of each speaker and subwoofer are matched to each other; (ii) the playback level of the system reaches a certain sound pressure level when the volume control on your AVR is set to “0”; (iii) the time delays for each speaker and subwoofer are adjusted so that sound from all of them arrives at the same time to the central point of the listening area; and (iv) the frequency response of each speaker and subwoofer is such that the perceived octave-to-octave balance is the same at home as it is in the dubbing stage or the movie theater.

Reference is a good thing because it gives us a way to reproduce the art the way it was made. But, you might say: “I like more (or less) bass.” OK, I’ve never heard anyone ask for “less bass,” but I suppose it’s possible. As soon as the word “like” is uttered we have crossed into the uncharted waters of the Preference abyss. It can be a fun place to be and there is nothing wrong with applying personal touches to your sound, especially if you are the one enjoying it. But know this: It’s not the job of a room correction system to determine your preference. That is entirely up to you. What room correction gives you when it delivers reference is a known baseline and the ability to apply preference consistently. Without it, boosting the bass for some content would not sound the way you want it for other content because you are not starting from a known condition. If you want to apply your preference, I have some words of advice: “Start with reference.”

http://www.audyssey.com/technology/bassxt-abx.html

What is BassXT and ABX?
Audyssey BassXT enables low frequency drivers to produce deeper bass by intelligently monitoring incoming audio signals and extending driver performance to its maximum safe limits at all volume levels. With a BassXT-enabled system, small woofers sound big, and big woofers sound bigger. Audyssey ABX is specifically created for very small drivers such as those found in televisions. It combines adaptive equalization, principles of human perception and monitors the content to provide an extension to the frequency response.

Deeper bass
Small subwoofers are desirable because of their small footprint, but this also makes it difficult to reproduce very low bass sounds. Traditionally, the only way to extend the bass response to lower frequencies would be to invest in a subwoofer with a bigger driver in a bigger enclosure. BassXT enables smaller drivers and enclosures to reproduce very low bass sounds by dynamically monitoring the low frequency signals and constantly pushing the speaker to its maximum capability. ABX applies the same principles along with psychoacoustic algorithms to small drivers in televisions and other audio systems.

Before a speaker system comes to market, Audyssey works closely with the manufacturer to create a precise model for the driver and the enclosure of the subwoofer or full-range speaker. Based on this model, BassXT and ABX are able to accurately monitor the level and frequency content of the signal. The content is continuously monitored so that both soft and loud passages extend the driver to near maximum excursion. This enables the system to produce lower frequencies than would be possible with a traditional system of the same size.

Optimized to work with other Audyssey technologies
Many of the bass methods available today simply provide a bass boost, but do not offer any perceivable extension of the response to lower frequencies. Furthermore, they are not customized for your exact driver, but are generic for any speaker system. BassXT and ABX are specifically calibrated to enhance the bass response of your individual system.

Audyssey BassXT and ABX are designed to work in conjunction with our loudness compensation technology, Audyssey Dynamic EQ, and our core room equalization technology, Audyssey MultEQ. MultEQ first determines the proper equalization curve for your system. Dynamic EQ then determines the proper loudness compensation based on the sound pressure level information MultEQ provides. BassXT and ABX then utilize the real-time loudness compensation data from Dynamic EQ to extend the maximum capability of your system's low end.

Can BassXT push my system too far and damage it?
BassXT and ABX are designed to avoid that exact problem while extending bass performance to its safe limits. Because Audyssey engineers are able to analyze specific driver models from manufacturers, they fully characterize the capabilities and limits of each driver. BassXT and ABX will never push your system beyond what it can do, but will make sure your drivers are doing all they can to deliver the deepest possible bass response.

BassXT highlights

1. Not a bass boost. Audyssey BassXT actually extends your subwoofer’s driver response to reproduce lower frequencies.
2. Deeper bass. With BassXT you will get deeper bass than any other subwoofer of the same size.
3. Custom performance. Every implementation of Audyssey BassXT is specifically calibrated to enhance the bass response of your individual woofer – from an audio system to a sound bar.

And this from Audyssey's FAQ page:

http://www.audyssey.com/technology/faq.html#overdriving

Is there a danger of overdriving the loudspeakers by using MultEQ?
No, MultEQ filters are calculated by taking into account the capability of the loudspeaker and the overall gain structure of the system. Limits in correction are imposed at each frequency to prevent the loudspeakers from being overdriven.

This is from the Q & A of Audyssey's Bass Management blog.

http://www.audyssey.com/blog/2009/05/small-vs-large/
Question: My main speakers are full range actives that go down to 15Hz at reference levels, so they’re set to large. Needless to say, I don’t have a separate sub connected to the LFE channel of my Denon AVR-3808. You stated that “the MultEQ subwoofer filters have 8x higher resolution than the filters in the other channels.” What happens to those filters in my setup? Do they just sit idle, or are they re-assigned to help manage the bass spectrum of my full range main speakers?

Answer by Chris Kyriakakis:
June 10th, 2009 at 10:31 pm
The filters in the subwoofer channel are designed to only operate in that channel and so they will remain unused if there is no subwoofer in the system.

Q: Is it true that if you change the crossover settings (for any of the 5 channels) to a lower point than Audyssey found for the -3db down point then the corrections will no longer be applied? If so, is it just for the channel you adjusted or is the effect global?

More to the point, is there any way you are aware of to “dummy” a lower crossover and still keep the Audyssey correction for that channel?

A: Hi Bryan,

Yes it’s true. MultEQ creates correction filters down to the in-room measured –3 dB point of each speaker. It won’t try to correct below that as that could end up boosting below the capability of the speaker. This is done for each speaker individually. So, if you manually set the crossover below the calculated –3 dB point you will not be getting correction from MultEQ below that point.

I am not sure I understand your second question. Why would you want to do that? There are many reasons that a measured roll-off is higher than the manufacturer specs in an anechoic measurement. That’s the whole point of measuring in your room! I hear from many users who feel “insulted” when their “big towers” didn’t measure as low as the spec sheet. Placement in the room and the room itself are the cause of that. There is no performance hit to set your crossover higher than the spec. On the contrary, the blend with the subwoofer will be optimized for your room and the bass going to the sub will benefit from the 8x higher resolution that the MultEQ filters provide in the sub channel.

Some final thoughts by Chris Kyriakakis of Audyssey:

1) The frequency response of your speakers in your room is different than what was used to make the content. This is what Audyssey MultEQ tries to solve by measuring the room and creating a set of filters that correct acoustical problems. This is also an area where proper bass management is needed. Content is made to extend to a certain low frequency and at a certain sound pressure level. The amplifier power needed to reproduce the required SPL levels at low frequencies is quite high and so, using a separate subwoofer amp for that purpose is beneficial to the playback quality of the entire system. Furthermore, the MultEQ room correction filters in the subwoofer channel have 8x more resolution and so redirecting content to that channel for reproduction greatly improves the bass response in your listening room.

2) Most people at home typically listen at levels 10-20 dB below what the mixers listen. Because human hearing perceives octave-to-octave balance differently at lower volumes we developed Dynamic EQ to adjust for that so that the balance is restored even at low volumes. Our perception of surround impression also changes at lower volumes so Dynamic EQ makes an adjustment to the surround speaker level to maintain constant surround impression.

REFERENCES AND ADDITIONAL INFORMATION

Audyssey Technologies:
http://www.audyssey.com/technology.html

Different Flavors of Audyssey MultEq:
http://www.audyssey.com/technology/multeq.html

MutEQ Steps:
http://www.audyssey.com/technology/m...to-multeq.html

Microphone Placement:
http://ask.audyssey.com/entries/7328...hone-placement

Audyssey Calibration Guide on AVS Forum:
http://www.avsforum.com/avs-vb/showp...postcount=5701

Surround Sound:
http://www.amsky.com/~cirkuit/media/surround.html

Dynamic EQ and Reference Level:
http://ask.audyssey.com/entries/7328...eference-level

Audyssey and Subwoofer Distance:
http://ask.audyssey.com/entries/2275...oofer-distance

[Big Daddy]

INFORMATION ABOUT AUDYSSEY TECHNOLOGIES

FAQ Questions About Audyssey MultEQ, Dynamic EQ, Dynamic Volume, and DSX:
http://www.audyssey.com/technology/faq.html#faq_multeq

Audyssey MultEQ, Dynamic Volume and Dynamic EQ
http://ask.audyssey.com/entries/9204...and-dynamic-eq

All of the Audyssey technologies are designed to solve specific problems.

MultEQ: solves the problem of room acoustics. Sound from speakers interacts with the room, furniture, etc. and by the time it arrives at your ears it has been distorted by the room. MultEQ measures these interactions and creates a filter that runs in each channel to "undo" them and allow you to listen to the intended sound.

Dynamic EQ: solves the problem of differences in human hearing at various listening levels. Content is created by mixers who listen at very high levels. They make decisions about the balance of low and high frequencies at that listening level. At home, we listen well below that and so our hearing changes. For example, we are less sensitive to low frequencies as we turn the volume down. Dynamic EQ restores the balance of the mix at lower listening levels. It also restores the surround impression that diminishes at lower volumes.

Dynamic Volume: solves the problem of constant variations in the volume level of the content. From dialog, to explosions, to dialog, to commercial you have to constantly adjust the remote. Dynamic Volume allows you to set the volume for the dialog level you prefer and then monitors the content and makes automatic adjustments to the volume so you never have things get too loud (or too soft) around the dialog level you have selected.

http://www.audyssey.com/audio-technology/sub-eq-ht

SUB EQ HT: Bass in small rooms is notoriously difficult to get right. Bass lovers will try almost anything to enhance bass output. Many believe adding a second subwoofer will solve the problem – this is true in part, but only if the second subwoofer is properly integrated, not simply added on to an existing set-up. Audyssey Sub EQ HT ensures that the level and delay for each subwoofer is correct before integrating them into the equalization solution.

This new technology is a huge leap forward from the days when adding an additional subwoofer was accomplished by adding a y-chord to the subwoofer output of an AVR. Now, the process is automated and produces better results because it is fully integrated with MultEQ. The process takes only a few minutes and results in rich, full bass for everyone in the room.

Audyssey Dynamic Volume: More than just volume spikes
http://www.audyssey.com/blog/2010/04...volume-spikes/

Volume spikes are getting a lot of press these days. An Adweek Media/Harris Poll released today finds 93% of people say they are bothered by commercials that are louder than TV shows. The latest stories refer to the Commercial Advertisement Loudness Mitigation (CALM) Act and move quickly into discussions of technologies, such as Audyssey Dynamic Volume, which already solve the problem. If the Senate passes the legislation, would the post-CALM age mean the end of Dynamic Volume?

If spikes were the only problem then the answer would be, “Yes.” But, volume spikes are just one problem for TV viewers and Dynamic Volume solves many problems.
When Audyssey developed Dynamic Volume, we tracked how people use the volume control. Of course they turned down the volume quickly during loud commercials. But they changed the volume in other ways, too. At times, our test subjects would slowly turn down the volume during parts that would gradually grow loud. We also observed that people crank the volume to hear soft dialogue. Remote controls get quite a workout!

It is no easy task to get all of this right, as anyone with a remote can testify. It seems, just when you turn up the volume to hear two people whispering to each other, a bomb goes off and you need to turn it down again. Before Dynamic Volume, automated systems would go crazy turning things up and down. This is called pumping and is almost as annoying as the spikes. In fact, our partners tell us of TVs with pumping problems being returned because the customers thought they were broken—not a problem with Audyssey Dynamic Volume.

On the other hand, if you have a system that only focuses on turning down the spikes so it cannot get itself into a pumping state, it may turn down the overall soundtrack.

It is really about dynamic range

Dynamic range is the difference between the loudest and softest passages of a program. Controlling the dynamic range means that no matter the environment, no matter the material, you will always be able to hear everything at a level you enjoy.

Dynamic Volume allows users to control the dynamic range of any program (television show, movie or music) and that’s much more powerful than merely cutting out spikes.

To get the right dynamic range, Audyssey uses dialogue as the midpoint target. Set your volume at a level where regular speaking is comfortable to hear, and Dynamic Volume will make sure nothing gets too loud or too soft from that target. It anticipates level changes so there is never any pumping. Problem solved, right? Well, things are a little more complicated.

Take classical music. It is often said to cover the widest range of loudness, from silence (0 dB) to the full orchestra playing at its loudest (100 dB). In order to hear this dynamic range, you must listen in a carefully constructed and designed concert hall.

Now, go to a bar where people are ordering drinks, talking to each other and having fun and you will find the noise level is about 70 dB already. There will be no chance for anyone to enjoy anything approaching classical music’s dynamic range, but rock and roll fits the bill just fine. If the quiet parts are just equal to the background noise, they will seem pretty quiet and when the band cranks it, they may go over 100 dB for a dynamic range of 30-40 dB.

So what does this have to do with Dynamic Volume? Think of a romantic movie night with your significant other watching movies; this is your classical music night. You will enjoy it more if the dynamic range is pretty wide (around 80 dB). If, on the other hand, you have friends over to watch the Super Bowl, it will be similar to your night at a bar. In this case, you will enjoy the game more if you can limit the dynamic range to 40 dB and keep the volume above the noise of everyone talking.

Get the most out of Audyssey Dynamic Volume

Dynamic Volume has a number of settings you can control. Although our partners use different names, there are three settings: Heavy (Midnight), Medium (Evening) and Light (Day). These control the dynamic range.

Heavy (Midnight): This is the narrowest range. If you want to watch an action movie late at night and not wake anyone, use this setting. Use it, too, for Super Bowl Sunday.

Medium (Evening): This is the most common setting and is the default we recommend. This is perfect for daily television use, especially in a living room setting.

Light (Day): This setting offers the widest dynamic range. Use this when you pop in your latest movie from Netflix after dinner. You won’t miss a thing.

There are many other situations for using wide and narrow dynamic ranges for your listening enjoyment, but you get the idea. If you have any questions, submit a request on Ask Audyssey. If you want to make sure your next TV, AVR or HTiB has Dynamic Volume, just check our product catalog. Also, be sure to check the manual that came with your equipment, so you can exercise full mastery over your volume.

Best way to set up Dynamic Volume
http://ask.audyssey.com/entries/1198...dynamic-volume

Unlike the other Audyssey technologies that are used to provide you with a reference experience, Dynamic Volume is a purely personal choice. The technology is designed to let you set the dialog level to where you prefer it and then not have to worry about the loud parts getting too loud and the soft parts getting too soft.

So, that's my recommendation: simply decide what level you want the dialog and then leave it there. I recommend starting with the middle (Evening) setting for Dynamic Volume. For late night watching (with others sleeping) you can switch to Midnight so that the range between softest and loudest is reduced even more and nobody is disturbed.

Audyssey Dynamic EQ:
http://ask.audyssey.com/entries/7328...eference-level

Movies are mixed in rooms calibrated for film reference. To achieve the same reference level in a home theater system each speaker level must be adjusted so that –30 dBFS band-limited (500 Hz – 2000 Hz) pink noise produces 75 dB sound pressure level at the listening position. A home theater system automatically calibrated by Audyssey MultEQ will play at reference level when the master volume control is set to the 0 dB position. At that level you can hear the mix at the same level the mixers heard it.

Audyssey Dynamic EQ is referenced to the standard film mix level. It makes adjustments to maintain the reference response and surround envelopment when the volume is turned down from 0 dB. However, film reference level is not always used in music or other non-film content. The Dynamic EQ Reference Level Offset provides three offsets from the film level reference (5 dB, 10 dB, and 15 dB) that can be selected when the mix level of the content is not within the standard.

0 dB (Film Ref): This is the default setting and should be used when listening to movies.

15 dB: Select this setting for pop/rock music or other program material that is mixed at very high listening levels and has a compressed dynamic range.

10 dB: Select this setting for jazz or other music that has a wider dynamic range. This setting should also be selected for TV content as that is usually mixed at 10 dB below film reference.

5 dB: Select this setting for content that has a very wide dynamic range, such as classical music.

MultEQ vs other equalization methods?
http://ask.audyssey.com/entries/2155...zation-methods

There are two fundamental differences from every other method available in AV receivers today. The first is that MultEQ is not based on parametric equalization. Parametric equalization relies on a few bands that are centered at certain frequencies. These bands do not provide sufficient resolution to address many room acoustical problems. Also, parametric bands tend to interact so that changes at one frequency have undesirable results at nearby frequencies. Moreover, parametric equalization methods use a particular type of digital filter called Infinite Impulse Response (IIR) that only attempts to correct the magnitude response in the frequency domain. These filters can cause unwanted effects, such as ringing or smearing, in the time domain particularly as the bands get narrower. MultEQ uses Finite Impulse Response (FIR) filters for equalization that use several hundred coefficients to achieve much higher resolution in the frequency domain than parametric bands. Furthermore, by their nature, FIR filters simultaneously provide correction in the frequency and time domains. FIR filters had been considered to require too many computational resources. But Audyssey solved this problem by using a special frequency scale that allocates more power to the lower frequencies where it is needed the most.

The second major difference is that MultEQ combines multiple measurements to create equalization filters that better represent the acoustical problems in the room. Most other methods only perform a single point measurement and this can result in making other locations in the room sound worse than before equalization. There are some methods that use spatial averaging to combine multiple room measurements. Although this is a step above single-point correction, it does not provide optimum correction when discussing spatial averaging. For example, it is common to find a peak at a certain frequency in one location and a dip at the same frequency at another nearby location. The averaging methods will add the peak and the dip and this will result in an apparent flat response at that frequency, thus causing the equalization filter to take no action. MultEQ uses a clustering method to combine measurements so that acoustical problems are better represented, thus allowing the equalization filter to perform the appropriate correction at each location.

How does MultEQ apply room correction?
http://ask.audyssey.com/entries/7328...oom-correction

The technology is a result of a multi-year university research effort to understand the key factors that influence sound reproduction. From this research came two key findings:

1. Acoustical problems in the room are more accurately measured in the time domain. This type of analysis provides information about the direct sound and the effects of reflections from room surfaces. This was a departure from traditional EQ methods that only looked at data in the frequency domain.
2. Measuring in a single location does not capture sufficient information and often results in equalization artifacts. Multiple measurements are required to capture the spatial distribution of acoustical problems, particularly in the low frequencies where the problems are more serious.

MultEQ captures multiple measurements in the time domain and then groups them in clusters based on similarities in the data. Using Fuzzy Logic mathematics, the clusters are allowed to overlap so that each measured response belongs to each cluster with a certain probability. In each cluster a representative response is then created that is weighted by the acoustical problems in that cluster, but also by those in the other clusters. MultEQ then re-combines these representative responses to create a final room representation and then inverts that to create the correction filter for each loudspeaker. The type of filter used by MultEQ simultaneously corrects the time and frequency domain problems to produce a smooth response.

MultEQ also measures the time it takes for the signal to arrive from each speaker to the first microphone position. Delays are then applied to the speakers that are closer to match the timing of the signals coming from the speakers that are farther away. Finally, the sound pressure level produced by each speaker is adjusted with the trim controls so that they match each other.

[Big Daddy]

AUDYSSEY DSX

Audyssey DSX can be used either to add a pair of horizontal-plane front width speakers to expand the width of the front soundstage or a pair of front-height channels. For example, Denon 4310CI’s DSX implementation doesn’t support simultaneous height and width channels, but Denon 4810CI receiver can do both simultaneously.

Important Facts About Audyssey DSX

1. DSX requires a 5.1 input in order to create the additional wide and height channels.
2. If the original sound is in 2- channel stereo, you must use an available mode in your AVR such as Dolby PLIIx or DTS Neo to upmix that content into 5.1 channels.
3. If you are not using a center or surround channels, you cannot turn on Audyssey DSX.
4. The content for the DSX Wides and Heights is derived using a proprietary method. It looks at the front left, right, and surround content as well as the center content to make this determination and the output is content dependent. However, there is no content from the Center channel that is sent to the Wides or Heights.
5. Although Audyssey DSX requires a 5.1 input (discrete or matrixed), it does not need the .1 information. It only needs the surround and center channels.
6. For 7.1 content (matrixed or discrete), Audyssey DSX will look at the Back Surround content when determining what to send to the Wides and Heights. It also applies a blending algorithm to the Surrounds and Back Surrounds to create a more seamless surround stage.
7. After the information for the wide and height channels are extracted, the content for the front right, left, and center channels will stay exactly the same as before. However, the surround channels will be processed by Audyssey DSX to provide a better blend with the front soundstage.

Dolby IIz delivers multichannel surround with height channels from mono, two-channel and multichannel audio sources, but DSX adds width and height channels only to sources with 5.1 or more channels. Although Audyssey DSX does not work with stereo or mono sources, you can make it work with those sources through Dolby Pro Logic IIx (not PLIIz) and DTS Neo:6. Also, it is important to know that Pro Logic IIx Music mode includes a center width control on some receivers that lets you adjust the mix of vocals into the center channel and adjusting that can enhance the results of Audyssey DSX.

Audyssey DSX may be "sweet spot-centric" and may not give you good results for other seats in the room.

http://www.ultimateavmag.com/news/audyssey_dsx/

DSX stands for Dynamic Surround Expansion. In addition to the standard 5.1 channels of most home-theater systems, it will provide the option of adding up to six additional full-range channels. Ideally, these extra channels would be discrete—that is, separate, independent channels in the source content. But there's no such content available at this time, so DSX derives the added channels using advanced digital signal processing. No artificial "enhancements," such as delays or added reverb, are involved.

The extra channels are called Left and Right Wide, Height, and Back Surround, and each requires its own speaker. The Wide speakers should be located at ±60 degrees from the center—that is, well outside the main L/R speakers but still in front of the listener. The Height speakers should also be located outside the main L/Rs at an angle of ±45 degrees, and they should be raised above the plane of the other main speakers at a vertical angle of 45 degrees. The placement of the two Back Surround speakers is not well defined, but they should be directly behind the listeners.

Why add these channels? Audyssey's extensive research clearly indicates that human perception of directionality is much more precise in front of the listener than behind. Thus, expanding 5.1 to 7.1 by adding back-surround speakers is not nearly as effective as adding speakers in the front. According to Audyssey's findings, adding the Wide speakers is the most effective at increasing the sense of envelopment, followed by the Height speakers. Adding Back Surround speakers is the least effective because our sense of directionality is relatively poor to the rear—in fact, a single Back Surround speaker works perfectly well.

A demonstration this week at Audyssey's facilities in Los Angeles definitely showed the effectiveness of the system. Whether or not a significant number of consumers will want to set up 11 speakers in their system (plus one or more subs) remains to be seen. But the user can opt to use only part of the system's full capabilities, perhaps adding more channels at a later date. As indicated earlier, for a partial DSX setup, adding the Wide channels provides the single greatest enhancement, followed by the Height channels and, finally, Back Surround.

The following conclusions are based on an enormous amount of supporting data and some elegantly performed experiments:

http://www.audioholics.com/education...yssey-dsx-10.2

1) The front half of the room is more important than the back half!
What is perhaps the most repeated mantra I heard during my visit was how the decision to add 2 rear channels when 7 channel sound offered itself as an improvement over 5 channels is according to Audyssey, a serious error. IF these extra channels are available, they should be added to the front, NOT the rear. Why? Human hearing has far better spatial acuity in the front of us than we do behind us. According to Tom Holman, we can resolve auditory spatial information to about 1 degree in angle in front of us from right to left, (Horizontal plane) and about 3 degrees in height (Vertical plane). Both of these sensitivities are far greater than what we have for sounds coming from behind us. Hence Audyssey's preference of multiple channels in front and sides, and one required for rear channel sound.

2) Width is more important than height!
Width is crucially important in placing instruments and recreating acoustical space. Concert halls with side walls perpendicular to the stage are considered by experts on the subject to be acoustically superior spaces to fan shaped halls. One of the reasons here is the importance of the early reflections from the right and left side walls perpendicular to the stage. In the "fan shaped" concert halls, the splayed side walls did not support the same kind of early reflections and are one of the main reasons these halls are not judged as good by the experts. To quote Mr Holman, "it is known in concert hall acoustics that the first side wall reflection is the single most important reflection direction, it sets the auditory source width... Channels constrained to plus/minus 30 degrees are too narrow for that". For this reason, the DSX standards (7.1, 9.1 and 10.2) support a left wide and right wide channel at plus/minus 60 degrees to reproduce the kind of side wall reflection you would hear if you were seated in a great concert hall. (Note: Those who recall Audioholics' original article on 10.2 may note that the front widths were at 55 degrees, not 60 degrees. According to professor Chris, this small adjustment was made because the difference between the two angles was minimally audible, and "60 degrees is easier to eyeball").

3) If you pan front from the front to the surrounds, it is nearly impossible to get the sound source to appear to go behind you with only the two rear channels at 110 degrees. For this reason and others, 10.2 employs a center back channel, located 180 degrees relative to the listener.

4) Because height is also an important element in recreating acoustic space. (Not as important as width, but important nonetheless) a pair of channels are added at 45 degrees off the center front, and 45 degrees high relative to the listener. A sound source with height can best reproduce reflections from a high ceiling, adding an additional dimension of space to the recording. We were able to listen to some choral music during the hour or so spent in the USC multimedia room, and the high speakers made a dramatic difference in the source height and sense of space.

http://hometheatermag.com/receivers/...i_av_receiver/

Audyssey says that the most helpful enhancement is width, followed by height, followed by back-surround. In theory, all three can run simultaneously. If manufacturers follow through with 9.1-channel AVRs, which Denon has hinted at doing, you’d have a choice of two out of the three.

Why width? Audyssey says: “Research in human hearing shows that we can hear many more directions than what current systems provide. Experiments have shown that human localization is better in front than to the sides or behind. This means that for front-weighted content such as movies and most music, good engineering dictates that we employ more channels in the front hemisphere than the back. Imaging is also better horizontally than vertically, and so good engineering also dictates that channels must first be added in the same plane as our ears before going to higher elevations.”

http://www.avguide.com/blog/playback...sey-dsx-part-2

Tomlinson Holman said the greatest benefits come from adding DSX Wide channels first, and then DSX Height channels. Surround information can be well handled by two Side Surround channels, though there is some extra benefit that comes with adding one (or even two) Center Surround channels directly behind the listeners.

According to Chris Kyriakakis of Audyssey, the wide/height speakers for Audyssey DSX should be direct-radiating monopole (not dipole or bipole) speakers and timbre matched with the three front speakers. This also applies to Dolby PLIIz.

http://ask.audyssey.com/entries/98040-speakers-for-dsx

The general idea is to have the DSX Wide and Height speakers match the timbre of your front LCR speakers. Typically this is achieved by using speakers from the same family line as the fronts.

Audyssey DSX Wides and Heights should be direct radiators. Smaller speakers will be fine. Running MultEQ will help bring their response closer to that of the fronts.

http://www.audyssey.com/technology/dsx.html#techdetails

Why use more speakers?
Research in human hearing shows that we can hear many more directions than what current systems provide. We use the direct sound to localize the direction of sources and the reflected sound to perceive the size of the soundstage.

Experiments have shown that human localization is better in front than to the sides or behind. This means that for front-weighted content such as movies and most music, good engineering dictates that we employ more channels in the front hemisphere than the back. Imaging is also better horizontally than vertically and so good engineering also dictates that channels must first be added in the same plane as our ears before going to higher elevations.

Perception is not the only factor. The physics of room acoustics for music have been well studied, and their correlation with subjective impression increasingly understood over the last 30 years. This research has shown that we have strong built-in preferences for the direction, frequency response, and time of arrival of reflected sound. Additional channels and surround sound processing are needed to properly render these components.

Wides before Heights
One key finding from the research is that first side wall reflections play a great role in determining subjective impression. The most important direction of reflected sound was found to be ±60° relative to the front. Audyssey DSX provides a pair of Wide channels (LW and RW) at ±60° with appropriate frequency response and perceptual processing to match these requirements of human hearing. These Wide channels are much more critical in the presentation of a realistic soundstage than the Back Surround channels found in traditional 7.1 systems. Adding surround channels behind the listener has a very small impact compared to the increase in envelopment and soundstage width that the Wide channels provide.

The next most important acoustical and perceptual cues come from reflections above the front stage. Audyssey DSX provides a pair of Height channels (LH and RH) that should be ideally positioned at a 45° elevation angle.

Recommendation:

1. If your receiver supports Audyssey DSX and your room and budget allow it, you should go for all three width, height, and rear speakers.
2. If you have room, budget, or WAF limitations, then you should follow Audyssey's advice and go for the width speakers first.
3. If your room doesn't allow it or your receiver only supports Dolby PLIIz, then go for the height speakers.
4. If there are some other concerns, go for the rear speakers.
5. In many situations, you may be able to only use two of the above three options. For example, width and rear speakers or height and rear speakers. For most people, the front wall of their HT room may not be large enough to allow using both width and height speakers at the same time.

REFERENCES & ADDITIONAL INFORMATION

http://www.audyssey.com/technology/dsx.html
http://www.dolby.com/consumer/unders...z-details.html
http://www.audioholics.com/education...yssey-dsx-10.2
http://www.hemagazine.com/Dolby_Pro_...DSX?page=0%2C0
http://www.highdefjunkies.com/showth...sey-DSX-Report
http://hometheatermag.com/receivers/...i_av_receiver/
http://www.soundandvisionmag.com/tes...n-audyssey-dsx
http://www.ultimateavmag.com/news/audyssey_dsx/
http://www.avguide.com/blog/playback...sive-audio-lab
http://www.avguide.com/blog/playback...sey-dsx-part-2
http://www.avguide.com/blog/playback...-part-3?page=1

[LordoftheRings]

Fantastic work Big Daddy!

* With so many products now having embraced this great technology,
it will help a lot of folks around these quarters.

[Big Daddy]

Originally Posted by LordoftheRings

Fantastic work Big Daddy!

* With so many products now having embraced this great technology,
it will help a lot of folks around these quarters.

Thanks. I am sure you know how much work I had to do to prepare this thread.

[LordoftheRings]

Originally Posted by Big Daddy

Thanks. I am sure you know how much work I had to do to prepare this thread.

I'd bet you worked on that for more than a week, a month perhaps!

* Yes sir I know how much work is involved in that (some of my own graphs took me over 10 hours! Only for one graph!).

I can tell you did all the research for all the texts and links, and then you just post them after all were ready to be transfered.
It is simply amazing your dedication to this site and all its members!
We don't usually see that very often on the Internet!
But here it is, you are the real proof of the pudding!

At least your work is not in vain, as there are many people here that deeply appreciate. ...And I'm one of them, of course.
And this in the Ultimate Goal to perfect our Surround Sound Experience!
Chapeau! You truly rock!

[Johnny Vinyl]

Another great learning tool Frank!

John

[Tufelhundin]

Absolutely incredible, you definitely put in some over time to gather all the G2 and prepare it for "publishing". Thank you for your effort, like many of your sticky's, I will be using it as a reference for my system.


As a matter of fact, I played around with my ASEQ tonight.

[sptrout]

I agree with the other poster's; outstanding work and information!

May I make one suggestion? Could you add an explanation of Audyssey's Reference & Flat Curves? As I understand it, some AVRs allow the user to select one or the other, or is fixed to just one. The curve that is shown in your example below (post #2) is the Flat Curve, which can be difficult to find if it is available at all. The 805 as I understand it, for example, uses the Reference Curve and this can only be defeated (switched to the Flat Curve) by using specific listening modes none of which ever mention that the selected Curve is being switched.

I hope this was in your plans, but I think it would be helpful to explain these two Curves to make sure all understand what is happening. On another board many complain that Audyssey sounds like it is putting a blanket over the speaker and it was the general opinion that the AVR's in question was using the Reference Curve.

Thanks once again for great reference documents!

[MelloFellow13]

This is awesome, thanks a lot Big Daddy!

[Big Daddy]

Originally Posted by John72953

Another great learning tool Frank!

John

Originally Posted by Tufelhundin

Absolutely incredible, you definitely put in some over time to gather all the G2 and prepare it for "publishing". Thank you for your effort, like many of your sticky's, I will be using it as a reference for my system.


As a matter of fact, I played around with my ASEQ tonight.

Originally Posted by MelloFellow13

This is awesome, thanks a lot Big Daddy!

Originally Posted by sptrout

I agree with the other poster's; outstanding work and information!

May I make one suggestion? Could you add an explanation of Audyssey's Reference & Flat Curves? As I understand it, some AVRs allow the user to select one or the other, or is fixed to just one. The curve that is shown in your example below (post #2) is the Flat Curve, which can be difficult to find if it is available at all. The 805 as I understand it, for example, uses the Reference Curve and this can only be defeated (switched to the Flat Curve) by using specific listening modes none of which ever mention that the selected Curve is being switched.

I hope this was in your plans, but I think it would be helpful to explain these two Curves to make sure all understand what is happening. On another board many complain that Audyssey sounds like it is putting a blanket over the speaker and it was the general opinion that the AVR's in question was using the Reference Curve.

Thanks once again for great reference documents!

Thank you guys for your compliments.

Sprout,

I will try to do that. Unfortunately, I will be out of town most of today and will not return until very late. Perhaps I can add some more information to the thread later.

[LordoftheRings]

In most products there are three Audyssey target curves, but in Onkyo/Integra products, there is only one; the standard "Audyssey" curve; but two if you count the Audyssey "Flat" curve that is automatically engaged when in THX Cinema audio mode.

1. "Audyssey" target curve. This is the Reference Standard target curve; good with Movies.
[This curve has a gentle roll-off starting at about 4 kHz, and -2 dB at 10 Khz, and -6dB at 20 Khz.]

2. Audyssey "Flat" target curve.
[This curve tries to keep all your speakers flat and is the recommended one with Music audio modes.]

3. Audyssey "Front L/R Bypass" target curve. ...Used to be called simply "Front" curve..
[This curve turns Audyssey Off for the Front L & R channels and uses the Standard "Audyssey" correction curve for all the other channels.]

_____________________

* In NAD products, there is another "Audyssey" target curve, which is a custom "In-House" curve; which was developed by NAD with the help of Paul Barton from PSB speakers. This "Custom Audyssey" curve is similar to the standard "Audyssey" target curve as it too has a roll-off in the higher audio frequencies.

** In Onkyo/Integra products (pre/pros and receivers) which feature THX certification, there is only one Standard "Audyssey" curve, which of course is the #1 from above.
-> But, when you are using the THX post-processing Cinema audio mode, the Audyssey "Flat" curve is automatically selected as implemented by Onkyo/Integra products having the THX feature.
...This is good, because "Audyssey's" curve compounded with Re-EQ would result in a sound decidedly on the dryer side of things, with both the standard "Audyssey" target curve with its roll-off in the higher audio frequencies, and THX also with its roll-off in the very same higher audio frequencies (actually THX Re-EQ start the roll-off earlier than Audyssey, starting at 2 kHz).
So, even with Onkyo/Integra's omission in the choice of Audyssey full complement of the three target curves, they at least automatically revert to the Audyssey "Flat" curve when in THX Cinema mode.

~ And you cannot manually adjust those Audyssey target curves.
-> For some choice of adjustments and 'memory saved' Audyssey target curves, you'll need to invest in Audyssey MultEQ Pro with the software implemented and the help of your computer.
And you also need the Audyssey Pro kit with a specially calibrated microphone particular to your exact product model number. And up to 32 microphone positions are available with the Pro version.

*** I also should add that the Audyssey "Tower" type (Eiffel tower) microphone is calibrated
to better than +/-2 dB from 10 Hz to 24 kHz.
> This is much more accurate than the Radio Shack SPL meter.

_____________________

By the way, Audyssey MultEQ XT32 uses more than 10,000 FIR (Finite Impulse Response) filters all across the full spectrum of the audio range, from 10 Hz to 24 kHz! That is simply very sophisticated!

I am an Audyssey fan, can you tell?

P.S. Check this out: 32 mic positions (Pro version), MultEQ XT32 (highest Audyssey resolution), and 32-bit DACs (in flagship Onkyo/Integra pre/pros and receivers)! That is an interesting coincidence if you ask me.

[sptrout]

Originally Posted by LordoftheRings

In most products there are three Audyssey target curves......

Thanks LOTR, I think you just proved my point (vary well I might add) that Audyssey Curves can be confusing and a pain. I just want to easily pick flat. But, at least now I know how to get there......

[LordoftheRings]

Originally Posted by sptrout

Thanks LOTR, I think you just proved my point (vary well I might add) that Audyssey Curves can be confusing and a pain. I just want to easily pick flat. But, at least now I know how to get there......

Well my post was directly in response to your prior suggestion.
And I agree with you that it is a good point to make the difference and also to have a choice.

But I also wish that there was more; like more options to save lets say about six Audyssey target curves all together, and perhaps also with the choice to manually tweak them. ...But I know this is quite a tall order for now, but maybe in a near future when all cars will be flying!

...And with integrated REW into our pre/pros and receivers to see exactly (on-screen graphics) what is taking place in our room. So we can make the proper adjustments.

It'll come eventually with the DSP chip's advances in their increased computing power. ...Much much more memory will be possible and the number of MB, GB, TB, will reach the sky...

[Big Daddy]

Originally Posted by LordoftheRings

In most products there are three Audyssey target curves, but in Onkyo/Integra products, there is only one; the standard "Audyssey" curve; but two if you count the Audyssey "Flat" curve that is automatically engaged when in THX Cinema audio mode with Re-EQ engaged.

[B]1. "Audyssey" target curve. This is the Reference Standard target curve; good with Movies.
[This curve has a gentle roll-off starting at about 3 kHz.]

I am not sure if the 3 kHz roll-off is correct. According to Chris Kyriakakis of Audyssey, the roll-off starts after 10 kHz.

http://ask.audyssey.com/entries/9346...re-interaction

Audyssey MultEQ creates room correction filters to two specific target curves. One is the Audyssey Reference curve that has a slight roll off in the high frequencies above 10 kHz.

[Big Daddy]

Originally Posted by sptrout

Thanks LOTR, I think you just proved my point (vary well I might add) that Audyssey Curves can be confusing and a pain. I just want to easily pick flat. But, at least now I know how to get there......

Originally Posted by sptrout

I agree with the other poster's; outstanding work and information!

May I make one suggestion? Could you add an explanation of Audyssey's Reference & Flat Curves? As I understand it, some AVRs allow the user to select one or the other, or is fixed to just one. The curve that is shown in your example below (post #2) is the Flat Curve, which can be difficult to find if it is available at all. The 805 as I understand it, for example, uses the Reference Curve and this can only be defeated (switched to the Flat Curve) by using specific listening modes none of which ever mention that the selected Curve is being switched.

I hope this was in your plans, but I think it would be helpful to explain these two Curves to make sure all understand what is happening. On another board many complain that Audyssey sounds like it is putting a blanket over the speaker and it was the general opinion that the AVR's in question was using the Reference Curve.

Thanks once again for great reference documents!

I added significant amount of information to Post #2. Hopefully, this will help.

Originally Posted by sptrout

Thanks LOTR, I think you just proved my point (vary well I might add) that Audyssey Curves can be confusing and a pain. I just want to easily pick flat. But, at least now I know how to get there......

The confusion is not entirely the fault of Audyssey. It is mostly the fault of Onkyo and the way their receivers handle Audyssey Reference Target and Audyssey Flat curves. Go back to post #2 and find out how Onkyo handles the curves. In my Denon receiver, you can easily and manually choose whichever option you like.

[crazyBLUE]

I don't have audyssey But that's ok because my MCACC works great

Another great Sticky Big Daddy

[sptrout]

Originally Posted by Big Daddy

I added significant amount of information to Post #2. Hopefully, this will help.


The confusion is not entirely the fault of Audyssey. It is mostly the fault of Onkyo and the way their receivers handle Audyssey Reference Target and Audyssey Flat curves. Go back to post #2 and find out how Onkyo handles the curves. In my Denon receiver, you can easily and manually choose whichever option you like.

Thanks Bid Daddy for staying up all night to add the great new content! Post #2 is a big help and needs to be linked to any Onkyo discussion/thread. I knew that different manufacturers handled Audyssey differently, but I did not know that Onkyo was off in a field by themselves on the curves issues. (Naturally, their manuals never mention any of this (or much of anything else Audyssey-specific) so no wonder some are disappointed with the Onkyo's Audyssey results.)

Thanks again, and I hope you get some sleep!

[LordoftheRings]

Originally Posted by Big Daddy

I am not sure if the 3 kHz roll-off is correct. According to Chris Kyriakakis of Audyssey, the roll-off starts after 10 kHz.

http://ask.audyssey.com/entries/9346...re-interaction

Fixed! => But that roll-off actually starts at about 4 Khz, and it is already slightly down at 5 Khz,
and it is -2 dB by 10 Khz, and finally -6 dB at 20 Khz.
(So I was not very far off, only by one Khz.)

* What Chris called a slight roll-off at 10 Khz and above is already down by 2 dB at 10 Khz.
But that actual curve 'roll-off' starts really just above 4 Khz.
=> @ http://www.avsforum.com/avs-vb/showp...ostcount=34047

_____________________________________________

* THX with Re-EQ engaged starts its roll-off at 2 kHz?

________________________________________________

~ Also, you mentioned (from post #2 above) the Manual EQ on some products; but you said it was a traditional Parametric Equalizer. In your Denon receiver, do you have a separate "Q" adjustment?
Isn't it instead a Graphic Equalizer? In my Onkyo pre/pro and receivers it is in fact a Graphic Equalizer.
I also believe that the same applies for Denon and Marantz receivers and pre/pros as well.
...And Integra too.