Does adding high SINAD amp to AVR make sense?

[Flash]

Am I wrong to wonder what the benefit of adding a high-SINAD external amp to an AVR is?

I mean, yes, having more power to handle dynamic loads is the main reason. But am I well into diminishing returns when the external AMP SINAD ratings eclipse that of the AVR's pre-outs? ie. In the following OVERSIMPLIFIED example: Is there anything to gain from buying a -100db SINAD amp over a -90db amp when the AVR itself is capable of -80db?

 

[voodooless]

The real question is: do you need a high-SINAD amp at all?

 

[HarmonicTHD]

Am I wrong to wonder what the benefit of adding a high-SINAD external amp to an AVR is?

I mean, yes, having more power to handle dynamic loads is the main reason. But am I well into diminishing returns when the external AMP SINAD ratings eclipse that of the AVR's pre-outs? ie. In the following OVERSIMPLIFIED example: Is there anything to gain from buying a -100db SINAD amp over a -90db amp when the AVR itself is capable of -80db?

In the end only you can decide. To help you along a bit:

There is a thread somewhere here which explains the propagation of noise and distortion in an audio chain which might be helpful.

Some AVRs eg the Denons perform better SINAD wise when their internal power amps are switched off and if they only operate in pre-amp mode.

Power is the main reason for separate power amps as in any of the above mentioned cases you might still be in the range where SINAD is not audible regardless with or without separate power amps.

 

[Aerith Gainsborough]

Am I wrong to wonder what the benefit of adding a high-SINAD external amp to an AVR is?

The only thing would be "peace of mind" that the power amp's THD would not "degrade" the signal further.

Realistically speaking: it makes no sense to shell out extra cash for a high SINAD when the source is already "medium SINAD".
You can grab a cheaper amp that does the job just as well and never notice any difference.

There is a thread somewhere here which explains the propagation of noise and distortion in an audio chain which might be helpful.

As a rule of thumb: the SINAD of the most distorted component is the SINAD of the entire system.

EG:
AVR Preamp: 80dB
Power AMP: 100dB
DAC: 120dB

SINAD of the entire system: ~80dB

Compared to the 80dB of the AVR Preamp, the 100dB or 120dB of the other components are so small, that they are of no consequence.
Even if it's a worst case scenario and the distortion products are of the same frequency and add up.

 

[GaryH]

You forgot the SINAD of the speaker, which will invariably be even lower than the lowest SINAD of your electronics chain, rendering the latter even more irrelevant.

 

[Flash]

You forgot the SINAD of the speaker, which will invariably be even lower than the lowest SINAD of your electronics chain, rendering the latter even more irrelevant.

Didn’t realize the speaker has a SINAD.

In my case, I have a new X8500HA (likely non AKM DAC’s) with the internal amps turned off and feeding the external power amps. All things considered, I am starting with a pretty good source as I understand it. The speakers are NHT C4’s.

The consideration for the external power amp is whether or not it is audibly noticeable, and thus worth the extra investment, between a hypex and purifi based unit. You guys answered the question based on the weak link in the chain dictating it. I guess it’s more about peice of mind.

 

[Aerith Gainsborough]

You forgot the SINAD of the speaker, which will invariably be even lower than the lowest SINAD of your electronics chain, rendering the latter even more irrelevant.

Left it out on purpose.
Good speakers have a THD in the range of -40 to -60dB.
In the sub bass, THD can be way worse, but human hearing is bad in that area, so it doesn't matter.

 

[GaryH]

That's precisely my point. A speaker THD of -60 dB will combine (worst-case, in-phase) with an electronics THD of -80 dB to produce a total THD of -59.96 dB i.e. the electronics adds an inaudible 0.04 dB THD to the speaker's and so is irrelevant.

 

[Flash]

That's precisely my point. A speaker THD of -60 dB will combine (worst-case, in-phase) with an electronics THD of -80 dB to produce a total THD of -59.96 dB i.e. the electronics adds an inaudible 0.04 dB THD to the speaker's and so is irrelevant.

Interesting. I didn't think that the electronics would degrade an already degraded speaker THD. What math did you use to arrive at the above -59.96 dB?

 

[GaryH]

You can use the calculator at the bottom of this page.

 

[Aerith Gainsborough]

Interesting. I didn't think that the electronics would degrade an already degraded speaker THD. What math did you use to arrive at the above -59.96 dB?

To put it simply: THD is basically a second frequency that is MUCH more quiet than the primary frequency we want to amplify.
If you output, say 1KHz as your desired tone, pretty much any equipment we have (transducer or electronics) will output something at higher harmonics, e.g.: 2000Hz but e.g.: 1000 times quieter.

If amp AND speaker output the same undesired frequency at 2000Hz, the amplitudes can add up and it gets louder. If the amps 2KHz is 1000x quieter than the speakers 2KHz, which is already 1000x quieter than the 1K you are listening to, you can imagine that the contribution of the amp (now a million times quieter than the desired signal) is completely irrelevant.

Overall: Instead of being 1000x quieter, your added 2KHz signal will then be 999x quieter.

That is only in the worst case, when the frequencies add up.

Numbers are just examples, not accurate math.

I think, unless you need to amp extremely weak signals and have to watch the noise floor of the electronics, modern amps/DAC are a complete non-issue. Yes, even the "lousy" measuring AVRs, as long as they can cope with the speaker load and operate within linearity.

Unless... some BS "audiophile" boutique brand designs their equipment to have a colored sound on purpose.

 

[restorer-john]

Speakers have inherent THD (which is frequency and level dependent), but they do not have a SINAD number.

a) they don't have residual noise and
b) SINAD figures are always with respect to a specific level. Loudspeakers do not produce an output, they sink it.

 

[abdo123]

your question can be answered with two follow up questions:

1) Does the AVR on its own provides me with enough continuous and peak power for my use? (Check online calculators and Amir's measurements).

2) Are the speakers hissing when they're driven by the amplifiers of the AVR (at any volume that you use, 24/7).

Everything else is more or less irrelevant.

 

[3125b]

One theoretical concern might be the reduction of the AVRs DAC/preamp performance with active vs. inactive power amps, we've seen that to varying degrees in reviews, most of the time it's probably not noteworthy.
As far as noise is concerned, just see if the hiss is audible at reasonable listening distances.
Most AVRs don't perform all that well in terms of signal quality, but that doesn't mean it's a problem in actual use.
My Denon X2700 for example has a higher noise floor than my SMSL chipamp, however that only means the noise is ever so slightly audible at 20cm rather than 10cm, inconsequential in reality.

 

[Flash]

makes sense. Can Hiss be initiated by simply turning up the volume with no source playing, or do i have to have a source playing in silence to experience it? I couldn't hear even a hint of hiss with the amps on and turned up to the normal volume I listen to with my ear <5cm from the tweeter, but that was with nothing playing.

 

[fpitas]

Speakers have inherent THD (which is frequency and level dependent), but they do not have a SINAD number.

a) they don't have residual noise and
b) SINAD figures are always with respect to a specific level. Loudspeakers do not produce an output, they sink it.

Oh, but they do produce many outputs in the form of harmonics and intermod.

 

[Flash]

makes sense. Can Hiss be initiated by simply turning up the volume with no source playing, or do i have to have a source playing in silence to experience it? I couldn't hear even a hint of hiss with the amps on and turned up to the normal volume I listen to with my ear <5cm from the tweeter, but that was with nothing playing.

I tested by pausing the music and then turning the volume up to the loudest I would likely ever listen and still enjoy the sound and the hiss was so faint that you would have to be less than 10cm from the tweeter. So I am going to assume I am in great shape.

 

[Aerith Gainsborough]

makes sense. Can Hiss be initiated by simply turning up the volume with no source playing, or do i have to have a source playing in silence to experience it?

On my lil' Yammy AVR, it is audible w/o any active source once I push volume past -15dB on the display. It's only an issue if I try to amp up very faint digital signals.
Nearfield setup though.