THD , SNR , and more crucial specs :) - AVS Forum
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post #1 of 10 Old 01-02-2013, 09:32 AM - Thread Starter
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How important is what so called the THD+N ( total harmonic distortion ) of a receiver or a power amplifier ?
Does it matter a lot if one receiver is rated at 0.008 % , while the other rates at 0.012 % , both at 1 Khz ?

Would this carry a noticeable difference in sound or amplification quality ?

Also , what about the S.N.R ( Signal To Noise Ratio) ? My old yammie (Rxv-2500) is measured at –99.50 dBrA , while the new Onkyo Nr-1009 is measured at –108.22 dBrA both at 10Hz -24Khz ? Would this also offer a profound step-up in any terms of exported sound or power quality ?

Please explain and discuss , Audiophiles .. smile.gif

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post #2 of 10 Old 01-02-2013, 10:53 AM
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Depends. It's widely accepted, I think, that 1% THD is essentially inaudible. Generally, those specs are given at a particular output power, and in the end it's just a choice of deciding where in the increasing-THD curve you choose to specify power. Look at a few Stereophile.com amp review measurement sections and you'll see the basic behavior is almost always the same - - a low level of THD+N (which will be noise) throughout the lower-power parts of the test, then you hit a "knee" where THD+N takes off - - with harmonic distortion ramping up fairly quicly compared to the below-the-knee behavior.

In the end, I'd much rather see power specified with 1% or less THD+N from 20Hz to 20 KHz rather than at 1 Khz, because some amps have trouble meeting the same output power cleanly at low or very high frequencies. Especially true with the amp sections in receivers (for lower frequency power) because their power supplies tend not to have nough oomph to service high power at low frequencies with multiple channels running. (Although this may never matter in practice, since if you use a sub and bass management, the receiver's power amps never have to amplify lower frequencies (below the crossover) and AFAIK, real world movies or multichannel music never come close to stressing all amps equally. If the surrounds are even 3 dB belos the mains (and 3 dB is typically considered "one notch" quieter) they need half the power of the mains . . .)
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post #3 of 10 Old 01-02-2013, 12:45 PM - Thread Starter
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Quote:
Originally Posted by JHAz View Post

It's widely accepted, I think, that 1% THD is essentially inaudible.

So , I've read that the THD is a much less important value in determining the performance power of an audio receiver than the SNR ..

They say that the hight the SNR , the more pure and clean the receiver would be ..

According to this , would a receiver of a SNR 100 dBrA sound much worse than another one with a SNR of 108 dBrA ?

Would this differ that much ?

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post #4 of 10 Old 01-02-2013, 12:52 PM
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For me what counts is if i put it on 0dB full blast pre-amp open and hit pause on a cd do i hear anything at the speakers with my ears at 3".

Having a silent starting point adds to the dynamic feel like blacklevels do for projectors imho.

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post #5 of 10 Old 01-02-2013, 12:59 PM - Thread Starter
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Originally Posted by danielo View Post

Having a silent starting point adds to the dynamic feel like blacklevels do for projectors imho.
Daniel.

This is a great golden rule . Nice words , Daniel . smile.gif

but I still need an answer for my basic simple question : would a receiver of a SNR 100 dBrA sound much worse than another one with a SNR of 108 dBrA ?

I shall be telling this with a sigh..
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I took the one less-travelled by..
And that has made all the difference..
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post #6 of 10 Old 01-02-2013, 01:57 PM
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Specifications such as THD, IM Distortion, Signal-to-Noise all have merit....
However when reviewing the higher quality brands the differences become very slight...
The primary issue are the lower-end brands which tend to hype the subject specifications as to try and impress the purchaser. Read the various forums and specialist publications and one can easily separate between the brands for electronics...


Just my $0.02... wink.gif
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post #7 of 10 Old 01-02-2013, 02:00 PM
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Quote:
Originally Posted by Dayter View Post

Quote:
Originally Posted by danielo View Post

Having a silent starting point adds to the dynamic feel like blacklevels do for projectors imho.
Daniel.

This is a great golden rule . Nice words , Daniel . smile.gif

but I still need an answer for my basic simple question : would a receiver of a SNR 100 dBrA sound much worse than another one with a SNR of 108 dBrA ?

There are many more parameters than SNR.

That said, I cannot imagine going from 100 to 108 dB SNR (A-weighted or not) matters for the vast majority of rooms, sources, and listeners.

"After silence, that which best expresses the inexpressible, is music" - Aldous Huxley
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post #8 of 10 Old 01-02-2013, 02:10 PM
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Quote:
Originally Posted by Dayter View Post

This is a great golden rule . Nice words , Daniel . smile.gif
but I still need an answer for my basic simple question : would a receiver of a SNR 100 dBrA sound much worse than another one with a SNR of 108 dBrA ?

My point was as MCode points out at some point they are just 'claims' mostly about 1 part of the audio chain. Like with contrast ratio higher is better nobody will disclaim that but in the end it is what do you notice. For example you could have the same ansi contrast ratio on 2 projectors but in one you clearly see gray instead of deep blacks in dark scenes. Bringing this back to sound on a good recording if the whole audio chain is silent when there is no content on the recording is a nice thing and if that 'works' for you depends on more than just a SNR on one of the devices in the chain.

The proof is in the listening to the end result and if it can fool you enough...

Daniel.

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post #9 of 10 Old 01-02-2013, 02:12 PM - Thread Starter
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Quote:
Originally Posted by M Code View Post

However when reviewing the higher quality brands the differences become very slight...
)

And that's what I really noticed wink.gif
Quote:
Originally Posted by DonH50 View Post

That said, I cannot imagine going from 100 to 108 dB SNR (A-weighted or not) matters for the vast majority of rooms, sources, and listeners.

I hope so . I also wonder if this is a measure of the preamp section of a receiver or the amp section !
My Yammie Rxv-2500 seems to have (according to reviews) more distortion produced from multichannel input to speakers , than that produced from dolby digital input to speakers .. !

Weird .

I shall be telling this with a sigh..
Somewhere ages and ages hence..
Two roads diverged in a wood and I..
I took the one less-travelled by..
And that has made all the difference..
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post #10 of 10 Old 01-02-2013, 02:14 PM - Thread Starter
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Quote:
Originally Posted by danielo View Post

The proof is in the listening to the end result and if it can fool you enough...
Daniel.

I don't have the ability to compare right now . i'm stuck with the components i've bought already . I didn't hook em up yet though .
But will . and wish to hear this black silence dynamics when listening at the reference levels' silence wink.gif

I shall be telling this with a sigh..
Somewhere ages and ages hence..
Two roads diverged in a wood and I..
I took the one less-travelled by..
And that has made all the difference..
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