A Guide to Amplifiers

[crazyBLUE]

Originally Posted by Big Daddy

You guys are slave drivers and sadists. You don't want to give me a break.

I added some simplified information to post #2 on amplifier classes.

Thank you for the second post . I read some of it & will read again after dinner Thanks Bd & sorry for working you so hard

[D]

I just wanted to include a very important item for anyone who might be considering getting into tube amplifiers. Especially those considering any type of DIY kit. The procedure of tube bias should ONLY be done by an experienced DEALER, because it can be quite dangerous if not done PROPERLY! D.

[Fors*]

Incredible sticky BD! I haven't read the whole thing yet....but it is FULL of info......this will be a reliable asset to have when I finally get my first amp! Thanks again BD!

[jomari]

-id also consider the different types of amp classes (and ive seen them already added), but more or less how our speakers work with them (in regards to impendance as well as resistance)...

-power consumption by amplifiers and how it can definitely be a factor in deciding which one to choose...(yes, there are some that are definitely power hungry, and finicky about their diet).

as others have mentioned, compliments as always BD, clarity is definitely one of your strong points in writing this sumnation.

[Rob J in WNY]

As always, excellent information and presentation, BD!

The Pioneer Elite SC class receivers currently (no pun intended) use Class D multichannel amplifiers. Their chief advantage is power efficiency, resulting in cooler operation and reduced power consumption. They can be more prone to electrical interference which can 'color' pure input audio, and they depend greatly on hyperaccurate switch timing, but good logic board/component layout and design can overcome these deficiencies greatly.

Class D amplifiers are sometimes incorrectly designated as "digital" amplifiers.

On a different note, it is impressive how well signal-to-noise ratios have improved over the last 20 years. I remember open reel S/N ratios, without any type of noise reduction, hovering around 55 to 65dB. Dolby B type noise reduction brought 60dB S/N ratios to cassette recordings, and C type noise reduction increased it to 70dB. I remember how impressive these were, not to mention dbx and Dolby S type NR.

To see amplifiers consistently able to produce S/N ratios in excess of 100dB is a testament to the quality of audio we enjoy in the home. Like deep black-levels on our flatscreen displays, we enjoy awesome dynamic range in our theater audio systems, in part due to the excellent S/N ratios of our digital sources/components, processors and, of course, amplifiers.

[Big Daddy]

Originally Posted by Rob J in WNY

As always, excellent information and presentation, BD!

The Pioneer Elite SC class receivers currently (no pun intended) use Class D multichannel amplifiers. Their chief advantage is power efficiency, resulting in cooler operation and reduced power consumption. They can be more prone to electrical interference which can 'color' pure input audio, and they depend greatly on hyperaccurate switch timing, but good logic board/component layout and design can overcome these deficiencies greatly.

Class D amplifiers are sometimes incorrectly designated as "digital" amplifiers.

On a different note, it is impressive how well signal-to-noise ratios have improved over the last 20 years. I remember open reel S/N ratios, without any type of noise reduction, hovering around 55 to 65dB. Dolby B type noise reduction brought 60dB S/N ratios to cassette recordings, and C type noise reduction increased it to 70dB. I remember how impressive these were, not to mention dbx and Dolby S type NR.

To see amplifiers consistently able to produce S/N ratios in excess of 100dB is a testament to the quality of audio we enjoy in the home. Like deep black-levels on our flatscreen displays, we enjoy awesome dynamic range in our theater audio systems, in part due to the excellent S/N ratios of our digital sources/components, processors and, of course, amplifiers.

Thank you and +1 on Signal to Noise ratio. I have a Sony ES cassette player with Dolby S. I was so proud of it when I purchased it.

[Rob J in WNY]

Originally Posted by Big Daddy

Thank you and +1 on Signal to Noise ratio. I have a Sony ES cassette player with Dolby S. I was so proud of it when I purchased it.

Very cool, BD. I, too, have a Sony cassette deck with Dolby S NR. It is a model TC-WE605S, equipped with dual-well decks and logic-controlled operation. It also had a function where it would sample the tape to precisely adjust recording bias on a "tape-by-tape" basis. I'm sure yours does the same, as mine wasn't an ES machine. It was actually an impressive unit when powered on and in operation, with its fluorescent display components.

Here's a photo of one I found online. Mine is packed away in its original factory carton and packaging.



Before long, this thread will go the way of mostly-on-topic Polk thread. Sure is fun talking about all this stuff, though, especially the enjoyment of past audio technology.

[MADNOD]

as usual excelent, thanks for the sticky.

i believe u didn't mention the amplifier input sensitivity, this is an important issue since most of the AVRs can't deliver more than 1V on their pre-out thus limiting the choice or decreasing the efficency/rating of amplifiers.

[Big Daddy]

Originally Posted by MADNOD

as usual excelent, thanks for the sticky.

i believe u didn't mention the amplifier input sensitivity, this is an important issue since most of the AVRs can't deliver more than 1V on their pre-out thus limiting the choice or decreasing the efficency/rating of amplifiers.

I added a few paragraphs on input sensitivity of an amplifier to the original post. It is toward the end, right before Damping Factor.

You guys are making me work too hard.

[Intamin]

Quick question about S/N ratio. Just looking at the specs of two unnamed amplifiers, one has a S/N of:

Signal to Noise Ratio
1 watt: >89db
Full Power: >117db

The other has a S/N of:
S/N ratio (relative to 1kHz sine wave full level output into 8Ω) 112dB

Why do manufacturers list at full power? Wouldn't 1 watt be a better measuring stick since most amplifiers are rarely at full power? Also, for comparisons sake, since amp 1 has a higher S/N at full power, is it safe to also assume it has a higher S/N at 1 watt compared to amp 2, even though amp 2's spec isn't mentioned?

[Big Daddy]

Originally Posted by Intamin

Quick question about S/N ratio. Just looking at the specs of two unnamed amplifiers, one has a S/N of:

Signal to Noise Ratio
1 watt: >89db
Full Power: >117db

The other has a S/N of:
S/N ratio (relative to 1kHz sine wave full level output into 8Ω) 112dB

Why do manufacturers list at full power? Wouldn't 1 watt be a better measuring stick since most amplifiers are rarely at full power? Also, for comparisons sake, since amp 1 has a higher S/N at full power, is it safe to also assume it has a higher S/N at 1 watt compared to amp 2, even though amp 2's spec isn't mentioned?

Unfortunately, we do not have common standards for measuring different characteristics of amplifiers and manufacturers pretty much do what they want. If an amplifier has good S/N at full power, that is a good thing. However, there are far too many variables and we can't simply say that amplifier 1 is better than amplifier 2.

The signal to noise ratio is the last thing you want to worry about. Thechnology has improved so much that even the most basic amplifiers more than meet the requirements for S/N.

This is from post #1:

All amplifiers and all electrical circuits generate a certain amount of electrical noise. Amplifiers that are designed better minimize the amount of noise. However, no matter how good the design, there will always be some noise. Generally, the more powerful the amplifier, the more noise it will produce. An amplifier with a poorly regulated power supply can create additional noise.

The Signal-To-Noise Ratio (S/N) measures the ratio of sound to background noise. It is expressed in decibels. S/N is calculated by measuring a unit's output noise, with no signal present, and all controls set to a predetermined level. A higher number is desirable.

[comcats]

Last year I purchased a Marantz 5002 for my home theater system. It came with a very difficult and technical manual. I still don't understand it. Due to Hurricane Charly, I am using two Bose 301 front speakers, a Bose center speaker, and the Bose Acoustimass passive subwoofer. For the rear speakers I have a pair of 100 watt JBL Control ONe's. I am using the Brighthouse Scientific Atlanta DVR. I am disabled and had a fried hook up the speakers and equipment using the HDMI connections. All heck broke loose. I had crackling and squeaking noises from the rear JBL's and the 5002 shut down. After a few unsuccessful tries, I called Marantz and their technician had me go through some various permutations and told me it needed to be repaired. I sent the 5002 to Atlanta for repairs. I live in Tampa, FL and Atlanta was the nearest authorized repair shop. While I was waiting, I went back to my old Sony receiver and had no problems. When the Marantz 5002 came back, we set it all up and had the same problems. As long as the volume was set low, I had no crackling from the rear jbl's but I started having problems with the sound going off and on. I had the Brighthouse technicians come over and they tried many, many, different connections from using the red, green, & blue cables, to the red and white cables, and many various permutations. I have had over 11 techs from Brighthouse try to fix the situation.

I now, after 15 month, learned that the Marantz 5002 is probably incompatable with the Bose Acoustimass Passive subwoofer system. Can anyone out there verify this and help with a solution. I'll be glad to try and answer any technical questions. Please know first hand that I am an idiot when it comes to electronics and it takes me a bit of time to crawl around and change cables. But right now I'd piss on a spark plug if someone can help me figure this all out. Thanks and have a great day!

[Sousa86]

if i take a speaker such as the polk tsi500, which recommends 20-275 watts of power and bi-amp it to a 5ch amp, such as an emotiva xpa5, that has 200 wpc, would that give me 400 watts total, surpassing the recommended wattage, or is it just 275 watts max recommended for each connection on the speaker (2 pairs of banana plugs) sorry about the run-on sentences lol

or would an amp such as the emotiva upa5 with 125 wpc be better bi-amped to a tsi500 since the total is 250, falling under the rec 275max for the polk

(sorry that my question is all over the place )

[Driver_King]

When you bi-amplify speakers, you simply divide the amplification duties into two different sections of a speaker, meaning both parts of the speaker get identical amounts of power(if you use multiple channels on a single amplifier). You would not add the wattage together since you are equally powering two different sections of a speaker.

[stcurell]

Is it true that class D amplifiers are more efficient at low impedance loads, and AB at higher loads?

I am looking at the following two amps:

http://www.sonicelectronix.com/item_...C1500.1D-.html

http://www.woofersetc.com/p6835/DSC1...-Amplifier.htm

They're a good comparison being of the same manufacturer and product line. As you can see they have similar output ratings at 4 ohms but at 1 ohm the class D is about 150% the class A/B. (That's one way to look at it.)

[LP Scream]

Hey there,

I'm planning on buying this Paradigm set:

Fronts - Studio 100
Center - Studio CC-690
Surrounds - ADP-590
Subwoofer - SUB12

and I'm confused should I go with the Onkyo TX-NR3008 or the TX-NR1008
and how many Emotiva I should get? I wanna get the fullest power this set can give me

The Onkyo TX-NR3008 says 140W

and from the Paradigm Studio 100 catalogue:
Suitable Amplifier Power range: 15 – 350 watts
Maximum Input Power†: 90 Watt

This thread is so advance for me. and I was trying to do some of the calculations but numbers and I .. are not friends.

[Big Daddy]

Originally Posted by LP Scream

Hey there,

I'm planning on buying this Paradigm set:

Fronts - Studio 100
Center - Studio CC-690
Surrounds - ADP-590
Subwoofer - SUB12

and I'm confused should I go with the Onkyo TX-NR3008 or the TX-NR1008
and how many Emotiva I should get? I wanna get the fullest power this set can give me

The Onkyo TX-NR3008 says 140W

and from the Paradigm Studio 100 catalogue:
Suitable Amplifier Power range: 15 – 350 watts
Maximum Input Power†: 90 Watt

This thread is so advance for me. and I was trying to do some of the calculations but numbers and I .. are not friends.

The thread is too advanced for me too. I must have been intoxicated when I wrote it. Read post #2 of the Amplifier Manufacturers thread. It is much easier to understand.

http://forum.blu-ray.com/1457088-post2.html

Under normal circumstances, you are only using a few watts for an average movie. However, it is a good idea to have as much headroom as possible for the peaks. My recommendation is to buy the best and most powerful amplifier you can afford. The amplifier will have enough power to satisfy your needs and at the same time you will not have the urge to upgrade in the future.

According to JBL Pro:

Ideally you should pick an amplifier that can deliver power equal to twice the speaker's continuous power rating. This means that a speaker with a "nominal impedance" of 8 ohms and a continuous power rating of 350 watts will require an amplifier that can produce 700 watts into an 8 ohm load. For a stereo pair of speakers, the amplifier should be rated at 700 watts per channel into 8 ohms.

A quality professional loudspeaker can handle transient peaks in excess of its rated power if the amplifier can deliver those peaks without distortion. Using an amp with some extra "headroom" will help assure that only clean, undistorted power gets to your speakers.

http://www.jblpro.com/pages/general_faq.htm
http://www.jblpro.com/pub/technote/lowpower.pdf

If you plan to buy an external amplifier to power your speakers, don't waste too much money on a receiver. Just buy one that has pre-outs for all the channels and spend the rest of the money on a 3-channel or 5-channel Emotiva amplifier. If you don't plan to buy an amplifier, then buy the Onkyo TX-NR3008.

[crazyBLUE]

Originally Posted by Big Daddy

The thread is too advanced for me too. I must have been intoxicated when I wrote it. .

[Big Daddy]

Originally Posted by crazyBLUE

I am sober now.

[crazyBLUE]

Originally Posted by Big Daddy

I am sober now.

Thanks ~ The beginning of that post gave me a good laugh