Upgrading the Definitive Technology BP2000 Speakers

[Big Daddy]

I recently performed surgery on my Definitive Technology BP2000 speakers and replaced all their drivers with completely different (in my opinion better) drivers. The BP2000 speakers are bipolar and use very sophisticated design. Their wiring is not very easy to follow. Every inch of my body hurts from carrying these massive speakers. It would probably be useful to start with some introduction.

The Definitive Technology BP2000 speakers were introduced in 1995. They were among the first speakers that had built-in powered subwoofers. The built-in subwoofers were not LFE subwoofers. They were meant to provide the speakers with low frequency extension. The 15 inch subwoofers are not the typical subwoofers with an upper bass frequency limit of around 150Hz - 200Hz. They extend way beyond that to have a seamless . The subwoofers are meant to be fed with full-range signal. You can use speaker wires or an RCA cable to feed full-range signal to the subwoofers. A sophisticated Linkwitz Riley crossover system takes care of the frequencies between the subwoofers and the midrange/tweeter drivers. They have a level control and a low frequency equalization control. The level control works in conjunction with a gain sensitivity button to vary the overall level of the subwoofer section in relation to the rest of the system. The gain sensitivity button varies the input sensitivity to give you a greater range of levels.

The BP2000 speakers are bipolar. They have two 6.5 inch midrange drivers and a one inch aluminum driver on the front and exactly the same drivers on the back of the speakers. They use MTM (D’Appolito) driver arrangement with the tweeter placed slightly to the side of the front and rear baffles so that the two woofers are closer to each other. The cabinets of the speakers are very solid with plenty of braces. Plenty of foam and polyfill are used inside the cabinet to provide enough sound dampening. The drivers on the front and back are separated from each other and the subwoofer has its own dedicated chamber.

Specifications

Dimmensions: 50"H, 9"W, 16 7/8 /8 "D
Weight: 120 lbs each
Frequency Response: 15Hz - 30kHz
Efficiency: 90 dB
Impedance: Compatible with 4-8 ohm outputs
Built-in Subwoofer Amplifier: 300 watts RMS
Tweeters: Two 1" (25 mm) aluminum dome tweeter (one in the front and one in the back)
Midrange: Four 6 ½" (17 cm) high definition cast-magnesium basket polymer drivers (two on the front and two on the back)
Subwoofer: One 15" (38.1 cm) subwoofer on the side


Some Images and Detailed Information:

Reviews:

The reviews of BP2000 speakers were excellent. I myself found out that the speakers are extremely well made. The cabinets are very rigid with lots of bracing and dampening material. Their performance was far better than speakers that cost several times more. Although the price of $3,000 a pair in 1995 sounds like a lot, these were among a few high-end speakers that were worth every penny. There are plenty of outrageously-priced speakers around with absolutely nothing significant in their design or performance that can justify their price. A lot of credit should be given to the Definitive Technology founder/designer, Sandy Gross.

The following reviews of BP2000 speakers were by the late Julian Hirsch in Stereo Magazine (September 1995) and Brent Butterworth in Home Theater Technology magazine (November 1995):

[Big Daddy]

I have owned these speakers since 1996. They have served me extremely well. Recently, I was subjected to a severe case of speakers upgrade-itis. Most people in my position would think about selling their previous speakers and buying new ones. Being a bit crazy, I am not like most people. I prefer to upgrade my equipment myself and suffer the countless sleepless nights of planning, researching, purchasing, modifying, and dealing with all the frustrations. When you do the upgrade work yourself, the most often problem that you are faced with is dealing with parts that don’t fit or work.

I decided to replace all the drivers for the following reasons:

• Craziness.
• Enhanced performance.
• The drivers are getting around 18 years old and may be a good idea to replace them.
• Perhaps, there have been some technological advancements in driver material and manufacturing.
• Preferred to have silk dome tweeters instead of aluminum dome tweeters.
• Wanted to try midrange drivers with phase guides and higher efficiency. My intention was to replace the front midrange drivers and not the rear ones so that the sound coming from the front of the speakers is a few dBs higher than the sound from the rear of the speakers. This is along the line of the new Definitive Technology Super Tower speakers. According to Definitive Technology, the new approach to bipolar speaker design called Forward Focused Bipolar Array, combines the benefits of bipolar designs with the pinpoint localization of images typical of traditional forward-radiating speakers.
• Replace the 15" subwoofers with a new driver with enhanced frequency response and higher sensitivity.
• Adding external super tweeters to enhance the upper frequency range.

The two BP2000 speakers are mirror image of one another. One has the front tweeter and the subwoofer on the right side and the other one has the front tweeter and the subwoofer on the left side.

The Left Speaker With Original Mid-Woofers and New Tweeter




The Right Speaker With Original Drivers

REPLACING THE TWEETERS

Each BP2000 speaker has two identical tweeters, one in the front and one in the back. Their location are between the two midrange drivers in an MTM type arrangements. One tweeter is placed toward the left edge of the baffle and the other tweeter is placed toward the right edge of the baffle on opposite side of the speaker. The tweeters are placed closer to the edges of the baffles in order to decrease the distance between the two midrange drivers. This has the effect of reducing lobing errors and improving the off-axis response of the speaker.

Tweeter Requirements:

• Driver Diameter: Exactly 3 inches.
• Impedance of the driver must be 6 Ohms.
• Sensitivity: >= 90dB
• Maximum Mounting Depth: 3 inches.
• Frequency Response: The upper limit should preferably be beyond 20,000 Hz.
• Power Tolerance: Sufficient power tolerance.
• Optional Requirement: The stock tweeters are aluminum tweeter. I preferred to replace them with silk-dome tweeters.

After an exhausting search on the Internet, I finally found the Vifa D27TG-35-06 1" Silk Dome Tweeter to meet almost all of the above conditions.

Vifa D27TG-35-06 Tweeter Specifications:
Power handling: 25 watts RMS / 50 watts max
VCdia: 1"
Impedance: 6 ohms
Re: 4.7 ohms
Frequency response: 880-30,000 Hz
Fs: 880 Hz
SPL: 92.6 dB 2.83V/1m
Overall diameter: 4.10"
Cutout diameter: 3"
Depth: 1.25"

The Stock Tweeter (Left) and the New Wifa Tweeter (Right)

ADDING LCY-100K SUPER TWEETERS

Craziness did not stop with replacing the tweeters. I had to do something else and that something else cost me a lot of money. The final step was to add a pair of ribbon super tweeters. Let’s hope this is the final step. Super tweeters cost from a couple of hundred dollars to a couple of thousand dollars. I bought a pair of LCY 100K super tweeters for about $580, including tax and shipping. Their frequency response is rated up to 100kHz with two built-in crossover settings. They also have a beautiful metallic case with locks.

LCY-100K Super Tweeter Specifications:
Frequency Response: 7KHz-100KHz (-18dB/oct built-in HP filter)
Sensitivity (2.83V / 1M) : 10KHz, 96dB (Switching right when viewed from the rear), 13KHz, 92dB (Switching left when viewed from the rear)
Nominal Impedance : 8O
Magnet Type: Neodymium magnet
Ribbon Effective Area: 375mm2
Ribbon Thickness : 0.006mm
Nominal Power Handling: 300W
Price per Pair : USD 598 / HKD 4580

Attaching them is very easy. You simply connect them to the binding posts of the main speakers and place them on top of your speakers. You can tweak their position and direction a little bit until you get the desired sound.


REPLACING THE MIDRANGE DRIVERS

Each BP2000 speaker has a total of four midrange drivers. Two of them are in the front and two are in the rear of the speakers. They are identical and are wired together in a bipolar configuration. The impedance of each driver is 4 Ohms. The front and rear drivers are isolated from each other by a solid bracket between them. As a result, the mounting depth of each midrange driver could not exceed 3 inches.

Requirements:

• Driver Diameter: Exactly 6.5 inches.
• Impedance of the driver must be 4 Ohms.
• Sensitivity: >= 90dB
• Maximum Mounting Depth: 3 inches.
• Frequency Response: As wide as possible.
• Power Tolerance: Sufficient power tolerance.
• Optional Requirement: A driver with Phase Plugs would be preferred.

After an exhausting search on the Internet, I finally found the PowerBass 4XL-65-92 4XL-6592 6.5" Midrange Speaker Driver to meet almost all of the above conditions.

PowerBass 4XL-65-92 6.5" Mid Range Specifications:

• Paper/Laminated cone
• Aluminum phase plug
• Accordion style cloth surround
• Chrome push input terminals
• Diameter Size: 6.5 in
• Power Handling (RMS): 100 watts
• Power Handling (Peak): 200 watts
• Nominal Impedance: 4 ohm
• Voice Coil Size: 2 in KSV Voice Coil
• Frequency Response: 100 Hz - 10000 Hz
• Sensitivity: 92 dB
• Motor Structure: 35 oz.
• Mounting Depth: 2.8 in

Nomex paper (NSV), Kapton (KSV), Aluminium (ASV, AL), Til (TSV), Kraft Paper (PSV).
AL (Aluminium Lock)
KSV (Kapton, Polyimide Film)
PSV (Kraft Paper SV)
NSV (Nomex SV)
BASV (Black Aluminium SV)

Phase Plug Technology

http://www.preference-audio.com/phaseplug.htm

In any conventional loudspeaker, the highest frequencies of audio emanate from the area around the center of the cone and the lower frequencies are produced by the area of the cone that is farther from the center. In fact, the distance from the center at which a sound wave will come off a loudspeaker cone is directly related to its frequency. This helps explain why larger cone loudspeakers are usually capable of producing more bass.

Due to the shape of the conventional loudspeaker cone, the higher frequency sound waves tend to collide at a focal point. This causes phase distortion and a loss in clarity. As a result, accuracy and transparency suffer. This also has detrimental effects on the realism of the sound environments created by today's high fidelity digital audio and surround sound systems.

The phase plug pole piece extension improves driver performance and clarity by deflecting delicate midrange audio out into the sound space and minimizing distortion producing collisions.

A while ago, I sent the Fostex 206E drivers in my DIY super tower speakers for an upgrade. A new Phase Plug was added to the driver to improve its performance. Read all about it in THIS POST.

Additional References on Phase Guides:

http://www.decware.com/paper79.htm
http://www.decware.com/paper46.htm
http://www.uaudio.com/blog/understanding-audio-phase/

The Two Midrange Openings




The Front Side of the Stock Midrange Driver (Left) and the New PowerBass Driver (Right)




The Back Side Stock the Midrange Driver (Left) and the New PowerBass Driver (Right)

REPLACING THE 15 INCH SUBWOOFER DRIVERS

Requirements:

• Driver Diameter: Exactly 15 inches.
• Impedance of the driver must be 4 Ohms.
• Sensitivity: >= 90dB
• Maximum Mounting Depth: 8 inches.
• Frequency Response: From around 20Hz to the around 2,000Hz. The typical 15" subwoofer driver extends up to around 200Hz and has a mounting depth exceeding 10 inches. The built-in 15" subwoofers in the Definitive Technology BP2000 are not LFE subwoofers. They are added to extend the low frequency perfomance of the speakers. In that respect, they are different than the Definitive Technology BP7000 series speakers. Although the 15-inch drivers of the BP2000s have their own dedicated 300 watts amplifiers, they have to be given a full-range signal and not an LFE signal. This can be done either with speaker wires or separately with RCA cables. The RCA cables must be connected to the pre-outs for the main (front channels) on the back of the receiver/processor.
• Power Tolerance: Sufficient power tolerance.

After an exhausting search on the Internet, I finally found the Mavin Model EM-TL3806Y-4 15 Inch woofers to meet almost all of the above conditions.

Mavin Model EM-TL3806Y Specifications:
Rubber Surround
Minimum SPL of 92 dB from 23 Hz. to 3kHz. 89.5 dB @ 20 Hz.
Magnet: 9 pounds
Impedance: 4 ohm
Power Rating: 500 Watt
Vented Voice Coil to help displace heat and improve performance
Size: 15.125"
Cutout Diameter: 13.8125"
Depth: 6"

The 15" Subwoofer Opening




The Stock Subwoofer (Left) and the New Mavin Subwoofer (Right)

This is the picture of the right BP2000 speaker after all the drivers are installed.

[Big Daddy]

Performance and Evaluation

Preliminary grade: A+++

I believe I have created the best sounding Definitive Technology speakers ever. This includes the BP7000 Super Towers and all Mythos speakers. I will also include all the speakers from Golden Ear Technology. I am willing to put my money where my mouth is. It appears that Sandy Gross is in trouble.

These are without a doubt among the best sounding speakers that I have heard. I have heard many speakers costing over $50,000 and a few over $100,000. They can easily compete with the best speakers ever produced.


To be continued.

.
.
.

[prerich]

Originally Posted by Big Daddy

Performance and Evaluation

Preliminary grade: A+++

I believe I have created the best sounding Definitive Technology speakers ever. This includes the BP7000 Super Towers and all Mythos speakers. I will also include all the speakers from Golden Ear Technology. I am willing to put my money where my mouth is. It appears that Sandy Gross is in trouble.

These are without a doubt among the best sounding speakers that I have heard. I have heard many speakers costing over $50,000 and a few over $100,000. They can easily compete with the best speakers ever produced.


To be continued.

.
.
.

You're a mad, mod man!!!!

[Big Daddy]

Originally Posted by prerich

You're a mad, mod man!!!!

Thanks. It was a lot of work. I am going to change my name to Mad Mod Big Daddy.

I am now stuck with a lot of midrange drivers and tweeters. I also have several subwoofers from this project and a few other past Mad Mod projects. They are all in working conditions. I should start selling them at bargain prices to make room for additional crazy upgrades.

[prerich]

Originally Posted by Big Daddy

Thanks. It was a lot of work. I am going to change my name to Mad Mod Big Daddy.

I am now stuck with a lot of midrange drivers and tweeters. I also have several subwoofers from this project and a few other past Mad Mod projects. They are all in working conditions. I should start selling them at bargain prices to make room for additional crazy upgrades.

I'm listening ....pm me with what ya got...I might be interested

[prerich]

Originally Posted by Big Daddy

Thanks. It was a lot of work. I am going to change my name to Mad Mod Big Daddy.

I am now stuck with a lot of midrange drivers and tweeters. I also have several subwoofers from this project and a few other past Mad Mod projects. They are all in working conditions. I should start selling them at bargain prices to make room for additional crazy upgrades.

Bd, where do you buy your super-tweeters from?

[josh6113]

Sounds great!...I am a big fan of definitive and own the new 8060-st's...I'd love to see pics of the final build...congrats on your endeavor...

[Big Daddy]

Originally Posted by prerich

I'm listening ....pm me with what ya got...I might be interested

I believe I have about eight 61/2 inch brand new midrange drivers in their original packaging. They are made by Polk Audio. I also have two or three new tweeters and several crossovers. I had ambitions to upgrade my Polk RTA15 speakers or build an entire home theater speaker systems, but the possibility of sleeping in the doghouse for eternity was not very appealing.

I also have four 61/2 inch midrange drivers, four tweeters, and two 15 inch subwoofer drivers that I recovered from upgrading the BP2000 speakers.

Additionally, I have two 12 inch subwoofer drivers (one made by Dayton and one by Pioneer). The Pioneer one is a car subwoofer and I used it in briefly in my HT room. Surprisingly it was very good.

I also have a couple of AVRs, several DVD players (including an Oppo, a Denon, a Carver tube CD, and a Rotel), an Epson 1080UB projector, two Carver stereo preamps (one of them is Sonic Holography), a Carver amplifier, a Sony 200 disc CD changer, a brand new and unopened Sony 200 disc DVD changer, a Klipsch center channel speaker, a Yamaha center channel speaker, two Pioneer bookshelf speakers, two Laser Disc players (one Sony and one Pioneer), one Beta VCR, several VHS VCRs, several high-end equalizers, etc., etc, etc. I am sure I missed a few important items.

I just remembered. I have a whole bunch of capacitors, inductors, and long HDMI, component, and RCA cables. You can probably find a whole bunch of car speakers and amplifiers in the garage.

To summarize, I am better stocked than Amazon, Best Buy, Parts Express, and Ebay put together.

[Big Daddy]

Originally Posted by prerich

Bd, where do you buy your super-tweeters from?

I bought the LCY super tweeter a while ago from E-Speakers.com. It costs me $580 plus shipping. I don't believe they carry it anymore.

http://www.e-speakers.com/

I also have a Fostex super tweeter. I bought it from Madisound. They carry the internal LCY super tweeter, but not the external one.

http://www.madisoundspeakerstore.com...super-tweeter/
http://www.madisoundspeakerstore.com...=super+tweeter

The LCY super tweeter has a built-in crossover. You can set it to 8,000Hz or 13,000Hz. The Fostex super tweeter does not have a crossover and you have to attach a capacitor to it to block the lower frequencies. The internal LCY super tweeter does not have a crossover. You have to build one for it.

I found out that I do not need the super tweeters with the BP2000 speakers. The new Vifa tweeters that I installed in them extend all the way up to 30,000Hz. I should probably sell both super tweeters. You can add them to the list above.

[Big Daddy]

Originally Posted by josh6113

Sounds great!...I am a big fan of definitive and own the new 8060-st's...I'd love to see pics of the final build...congrats on your endeavor...

Thank you. I have been a fan of Def Tech bipolar speakers since the early 1990s. I owned a pair of BP20s before the BP2000s.

[josh6113]

Originally Posted by Big Daddy

Thank you. I have been a fan of Def Tech bipolar speakers since the early 1990s. I owned a pair of BP20s before the BP2000s.

Anytime......and these are my first deftech's and I really enjoy them....can't wait too see what they cook up next...

[WiWavelength]

Big Daddy, I both applaud and admire your reengineering endeavor. But I have to question your methodology.

You do not seem to have any ability to conduct anechoic (or quasi anechoic) measurements. Is that correct? If not, you are selecting new drive units based purely on their published specs, not on how they interact with your preexisting crossovers and cabinets.

AJ

[Big Daddy]

Originally Posted by WiWavelength

Big Daddy, I both applaud and admire your reengineering endeavor. But I have to question your methodology.

You do not seem to have any ability to conduct anechoic (or quasi anechoic) measurements. Is that correct? If not, you are selecting new drive units based purely on their published specs, not on how they interact with your preexisting crossovers and cabinets.

AJ

I am not surprised that you ask this question. However, I believe you are missing the point. My intention was never to replace the drivers because they were malfunctioning or damaged. From day one, I realized that there was some risk involved. I was willing to take that chance and create something different and hopefully better. Let me explain my reasoning for doing this project:

• I have been thinking about replacing my speakers for a while and doing a lot of research.
• Most people start thinking about replacing or upgrading their speakers and other equipment after a couple of years. I have done that with my electronic equipment such as receiver, amplifier, equalizer, TV, projector, BD/DVD players, and even subwoofers. Although I have replaced (built) new speakers and modified the previous speakers a few times in my two-channel room, the main speakers in my HT room have remained the same for a long time.
• I bought a pair of Definitive Technology BP20s in early 1990s to use in my basic HT room. I was very happy with them until I heard that Definitive Technology has introduced super tower speakers with built-in subwoofers. Of course, the upgrade bug gave me a few sleepless nights and I finally yielded and traded in the BP20s with the BP2000s in early 1996.
• I have been very happy with the BP2000 speakers and that is the reason why I have kept them for so long. However, they were getting old and I was getting bored.

Here are my answers and comments to your specific questions:

1. Although my HT room is pretty well treated (over treated), it is not an anechoic chamber and I do not have access to an anechoic chamber.
2. I rely mostly on:
   1. Driver/speaker specifications.
   2. Measuring the frequency response of the speakers. I do own some professional equipment for this purpose.
   3. Close miking measurements of the drivers, particularly the subwoofers.
   4. And the most important of all, extensive listening and comparison testing by myself and others. As part of the listening test, I strongly believe in trial and error by using different drivers and measuring and evaluating their performance.

After I made the final decision that I will not buy new speakers and instead do something more exciting, it was much easier to focus. What I had in mind could have enhanced or destroyed the wonderful and old speakers. Most people would not take a chance on speakers that they had paid $3,000 for, but I had done crazier things in my life.

After doing some thinking, I decided to use the cabinets and the crossovers plus all the wiring of the BP2000 speakers and build custom speakers based on them. In fact, brand new empty BP2000 cabinets are sold on Ebay for custom projects. I believe they are excess cabinets that Definitive Technology no longer needs and sells them through Ebay dealers.

Initially, my intention was to enhance the cabinets with additional bracing and dampening material. As I removed the drivers and peaked inside the cabinets, I was pleasantly surprised at how well these cabinets were built. They had plenty of bracing and filled with foam and polyfill.

The next step was to find appropriate drivers. The main factors in selecting drivers in order of importance were:

1. Driver size. The diameters of the cutouts of the cabinets pretty much made that decision for me. Finding 1" tweeters, 6 ½" midrange drivers, and 15" subwoofers is pretty easy. However, what made the job of searching very difficult was the mounting depth of the drivers. Because of the bracing used inside the cabinets, I was limited to finding tweeters with a mounting depth of 3", midrange drivers with mounting depth of 3", and subwoofers with a mounting depth of 8". That made my job much more difficult and I had to spend several days to find appropriate drivers.
   
   Finding tweeters with a mounting depth of 3" or less is not too difficult, but finding midrange drivers with a mounting depth of 3" or subwoofers with a mounting depth of 8" is next to impossible.
   
   
2. Impedance. The BP2000 speakers are bipolar, the drivers (three drivers in the front, three in the back, one subwoofer on the side, and one sub amplifier in the back) are connected to each other with combination of series and parallel connections and multiple wires. Since there is limited access to the inside of the cabinets, following the wiring is very difficult. It is perhaps easiest and best to match the impedances of the old drivers.
   
   Finding midrange drivers with an impedance of 4 ohms, and subwoofer drivers with an impedance of 4 ohms is relatively easy. However, finding tweeters with an impedance of 6 ohms is not as easy and you will be limited with only a couple of brands.
   
   
3. Frequency response. The existing crossover of the BP2000 speakers is the highly rated Linkwitz-Rilely crossover. Matching driver with crossovers is not a very difficult job. Because I made the decision to use the existing crossover, I had to make sure that the new drivers have an extremely wide frequency range so that the interaction between the tweeters, midrange drivers, and subwoofers are as seamless as possible.
   
   Finding tweeters and midrange drivers with a wide range of frequency response is not very difficult. However, finding a subwoofer with a mounting depth of 8" that extends from around 20Hz to over a 1000Hz limits you to one or two subwoofers.
   
   
4. Sensitivity. I was looking for high sensitivity drivers above 90dB. The stock BP2000 speakers have a sensitivity of 90dB.
   
   
5. Power Tolerance. The drivers had to have enough power tolerance as I hook up my speakers to strong amplifiers and I crank up the speakers occasionally.

The search for the drivers:

• Tweeters. It was important that I find a silk dome tweeter with an impedance of 6 ohms. The search immediately showed the Vifa tweeters sold by Parts Express. I found out that the existing tweeters in the BP2000 speakers are also made by Vifa. The only difference is that they are aluminum dome tweeters. The silk dome tweeters are used in some of the current Definitive Technology speakers. If you call Def Tech and ask for replacement tweeters, they will refer you to Parts Express. One point of interest is that on the old tweeters, it says “Made in Norway.” On the new tweeters, it says “Designed in Denmark.” Most probably, they are made in China. It is amazing how things have changed in less than 20 years.
  
  The replacement of the aluminum dome tweeters with silk dome tweeters is not quite strange. A couple of years ago, I did replace the tweeters of my old Polk RTA15TL speakers with silk dome tweeters. I called Polk and bought the tweeters from them. They specifically recommend using the silk dome tweeters on the old vintage RTA and SDA speakers. Because of the new soft dome tweeters, the upper range performance of the speakers were vastly improved.
  
  
• Midrange Drivers. The search for midrange drivers was not so easy. It was very difficult to find 6 ½" midrange drivers with sufficient frequency response range and a mounting depth of 3". Additionally, I preferred drivers with phase guides. I experimented with three drivers. I used a set of 6 ½" driver made by Polk Audio. I was not happy with them because they had a slightly higher mounting depth and their sound was not right. I also used a 6 ½" Dayton midrange driver. Although it had the proper mounting depth, I found out it did not have the upper range frequency response and the sound was not pleasing to my ears. I finally chose the PowerBass midrange drivers. They had the proper size and specifications and their sound was pleasing to my ears.
  
  
• Subwoofer Drivers. The search for appropriate subwoofer drivers was by far the most difficult and took me several days to find what I had in mind. There were several problems. Most subwoofers had a mounting depth higher than 8". Although the low frequency extension of many HT subwoofer drivers can go down to 20Hz, the upper frequency extension of most of them do not go beyond 150Hz. Pro subwoofer drivers can go beyond 1000 Hz, but most of them do not have very good ultra low frequency extension and almost all of them have a mounting depth higher than 8". I was looking for a subwoofer driver that had good low frequency extension, could go above 1000Hz, and had a mounting dept 8" or less. When I found the Mavin subwoofer driver, I was ecstatic.

After each step of the project, I used extensive listening tests by myself and others. Not only did I test the performance of the individual drivers after I replaced each one, I also replaced all the drivers of the right speaker and did extensive comparison testing with the left speaker that had all the original drivers. I was finally satisfied that the new drivers sound significantly different and in my opinion better.

I did additional measurements and equalization. I may tweak them again in the future. I may even decide to experiment with other drivers.

By and large, I believe I have succeeded in creating speakers have very good performance and can easily compete with other speakers. Most importantly, they received the seal of approval from the most important authority, my wife. She has given the new speakers two enthusiastic thumbs up. Over the years, she has attended many audio shows with me and has become quite an amateur audiophile. She has much better ears than I do.

As long as Mrs. Big Daddy is satisfied, Thiele, Small, and Sandy Gross will have to sit this one out.

Next Project: Replacing the drivers of the matching center channel speaker that uses the same drivers.

[WiWavelength]

Originally Posted by Big Daddy

I am not surprised that you ask this question. However, I believe you are missing the point. My intention was never to replace the drivers because they were malfunctioning or damaged. From day one, I realized that there was some risk involved. I was willing to take that chance and create something different and hopefully better. Let me explain my reasoning for doing this project:

I appreciate your well thought out reasoning, and my intent is not to be a buzzkill. Rather, I just want to offer up a few caveats in the interest of information. And I suspect that you can appreciate that, as your posts are almost universally very informative.

The two issues that immediately come to my mind are individual driver directivity and sensitivity:

First, the individual driver directivity of the stock drivers and replacement drivers is almost certainly not identical. Thus, the radiation pattern and spatial power response among the drivers and of the speaker as a whole has changed. This could be for the better or for the worse. Now, since these are bipolar towers, this is of less concern because the radiation pattern and spatial power response are going to be complex, regardless, due to the delayed fill in from the rear facing drivers.

Second, the existing crossover network is geared toward the stock drivers and their individual sensitivity specs. Since your replacement drivers differ in sensitivity from the stock drivers, I practically guarantee that the level match among the new drivers is worse than that among the stock drivers. Now, if you are using a digital room correction system of some sort, any mismatch could be ameliorated.

If the goal is your own pleasure, then it sounds as if you have accomplished that in both the project and its results. But if the goal is fidelity, I am not sure. I do not put too much credence in listening tests. Those are too easily influenced by other factors.

AJ

[Big Daddy]

Originally Posted by WiWavelength

I appreciate your well thought out reasoning, and my intent is not to be a buzzkill. Rather, I just want to offer up a few caveats in the interest of information. And I suspect that you can appreciate that, as your posts are almost universally very informative.

The two issues that immediately come to my mind are individual driver directivity and sensitivity:

First, the individual driver directivity of the stock drivers and replacement drivers is almost certainly not identical. Thus, the radiation pattern and spatial power response among the drivers and of the speaker as a whole has changed. This could be for the better or for the worse. Now, since these are bipolar towers, this is of less concern because the radiation pattern and spatial power response are going to be complex, regardless, due to the delayed fill in from the rear facing drivers.

Second, the existing crossover network is geared toward the stock drivers and their individual sensitivity specs. Since your replacement drivers differ in sensitivity from the stock drivers, I practically guarantee that the level match among the new drivers is worse than that among the stock drivers. Now, if you are using a digital room correction system of some sort, any mismatch could be ameliorated.

If the goal is your own pleasure, then it sounds as if you have accomplished that in both the project and its results. But if the goal is fidelity, I am not sure. I do not put too much credence in listening tests. Those are too easily influenced by other factors.

AJ

Thank you for your thoughtful comments.

I would like to emphasize that I do not rely exclusively on listening tests. I also do measure the frequency response of the speakers in the room. I own a $500 Phonic PAA3 Audio Analyzer. It is the size of a very thick cell phone and has the capability of displaying the frequency response of the speakers on its screen almost instantaneously.

I also have a Behringer calibrated pro microphone, an M Audio MobilePre USB Powered Preamp, and the REW software program as described in THIS POST to do extensive frequency response mesurements.

Additionally, I do extensive automatic and manual speaker/subwoofer equalization to perform frequency correction.

Ultimately, home theater is about enjoyment and not a science class. As I explained before, I was getting a bit bored with my speakers and not using my HT room as much as I used to in the past. After this crazy endeavor, I have become more excited with the new sound and can't wait to go to the HT room and play some movies or music. It is as if I have bought two new sets of high-end speakers. The greatest part is that I bought champagne for the price of beer.

[josh6113]

Originally Posted by Big Daddy

Thank you for your thoughtful comments.

I would like to emphasize that I do not rely exclusively on listening tests. I also do measure the frequency response of the speakers in the room. I own a $500 Phonic PAA3 Audio Analyzer. It is the size of a very thick cell phone and has the capability of displaying the frequency response of the speakers on its screen almost instantaneously.

I also have a Behringer calibrated pro microphone, an M Audio MobilePre USB Powered Preamp, and the REW software program as described in THIS POST to do extensive frequency response mesurements.

Additionally, I do extensive automatic and manual speaker/subwoofer equalization to perform frequency correction.

Ultimately, home theater is about enjoyment and not a science class. As I explained before, I was getting a bit bored with my speakers and not using my HT room as much as I used to in the past. After this crazy endeavor, I have become more excited with the new sound and can't wait to go to the HT room and play some movies or music. It is as if I have bought two new sets of high-end speakers. The greatest part is that I bought champagne for the price of beer.

Now that's thinking outside the box big daddy...

[v_squared123]

Two thumbs up. And I couldnt view some pictures, especially the comparison pics of the drivers! Some loaded, some didn't so I didn't think it was on my end. Anyway you can fix it?

[Blu-Dog]

Originally Posted by Big Daddy

Performance and Evaluation

Preliminary grade: A+++

I believe I have created the best sounding Definitive Technology speakers ever. This includes the BP7000 Super Towers and all Mythos speakers. I will also include all the speakers from Golden Ear Technology. I am willing to put my money where my mouth is. It appears that Sandy Gross is in trouble.

I've seen some serious trash talk before, but that was Lakers vs. Celtics, 1985. I pretty much called that the gold standard for hard-ass woofing.

I've got to rank this right up there with that. No question. Trust my judgement, I grew up in Compton and Watts.

I know world-class woofing when I hear it. And frankly, I am impressed.

Originally Posted by Big Daddy

These are without a doubt among the best sounding speakers that I have heard. I have heard many speakers costing over $50,000 and a few over $100,000. They can easily compete with the best speakers ever produced.

Now, I would class this as bluster, save for one fact: the man is ready to back it up. That's what separates the foghorn from the howitzer, if you know what I mean.

I think Big Daddy is serious, and from the quality of gear he shoved in those things, he may be right.

[Big Daddy]

Originally Posted by josh6113

Now that's thinking outside the box big daddy...

Actually, it is thinking outside two boxes of 120 pounds each.

Originally Posted by v_squared123

Two thumbs up. And I couldnt view some pictures, especially the comparison pics of the drivers! Some loaded, some didn't so I didn't think it was on my end. Anyway you can fix it?

Thank you. There is nothing wrong with the comparison pictures. You have to fix your end.

Originally Posted by Blu-Dog

I've seen some serious trash talk before, but that was Lakers vs. Celtics, 1985. I pretty much called that the gold standard for hard-ass woofing.

I've got to rank this right up there with that. No question. Trust my judgement, I grew up in Compton and Watts.

I know world-class woofing when I hear it. And frankly, I am impressed.



Now, I would class this as bluster, save for one fact: the man is ready to back it up. That's what separates the foghorn from the howitzer, if you know what I mean.

I think Big Daddy is serious, and from the quality of gear he shoved in those things, he may be right.

I am just having fun. Don't take anything I write too seriously.