SINAD "penalty" by built in Room EQ?

[respice finem]

Disclaimer: No engineer here so the following may be just an idea of a halfwit

Every AVR or AV preamp has built-in room EQ these days, and so does an increasing number of stereo amps/preamps, even some active speakers and/or subs.
If an external room EQ device can decrease the SINAD of the system it's working in, as shown in the Antimode test

DSPeaker Anti-Mode 2.0 Dual Core Room EQ Review

This is a review and detailed measurements of the DSPeaker Anti-Mode 2.0 Dual Core Room Equalizer. It is on kind loan from a member and costs US $1,200. This review is only focused on electronic performance of the device. If I have time, I may test its correction ability later. There is not...

www.audiosciencereview.com

then it's likely similar with built-in DSP.

It seems to me, it might be worthwhile to measure SINAD for every device equipped with room EQ twice: with room EQ on vs. off.

 

[Sokel]

Have a look here where there was some problems but eventually most of it was fixed:

DSP Measurements and Rising Noise Floor

In several threads related to DSP platforms I've seen requests for measurements with filters engaged. I thought it unlikely that implementing filters in a DSP would have measurable effect on noise / distortion other than the obvious change in the fundamental, however @Sokel recently mentioned...

www.audiosciencereview.com

 

[respice finem]

Thank you, I've indeed read it before - but, what is probably interesting for potential buyers, whether the "SINAD penalty" of their intended purchase is negligible or not.
As I see from AVR tests especially, there are big differences between models, even without considering this, and all "sins" will add up in real use.

 

[Willem]

The equalization will inevitably eat up some of the headroom. This is apart from the fact the the additional electronics may be imperfect. However, I think it is more than worthwhile.

 

[respice finem]

Sure, mitigating the "sins" of nearly any listening room is worth losing a few dB SINAD - but the better has always been the enemy of the good. Probably anyone would prefer to lose 3 dB instead of 12 dB or more - but how much is this "penalty" really, with built-in room EQ?

 

[RayDunzl]

I would consider any losses, other than what you desire to be lost, to be at the end of the volume scale where you can't hear any of it anyway.

So, as far as I'm concerned, a little DSP under your control is a good thing, if you care to use it.

 

[respice finem]

We may hope so, but we don't know without measuring, do we?
If low SINAD matters for a DAC rating, why not also measure DSP?

 

[-Matt-]

SINAD for a DAC is measured electrically at the output of the device. Well designed modern DACs are able to reproduce the intended electrical signal with very high precision. (I.e. the noise and distortion on that signal would be inaudible even if the rest of your hifi chain was perfect).

When we discuss room EQ the signal goes through many more processes so there isn't a direct comparisson to DAC SINAD...

Digital Input > AVR Room EQ (DSP) > DAC > Amplification > Speaker (electrical to soundwave conversion) > Propogation & coupling to room modes > detection at listening position via microphone (conversion back to electrical signal) > amplification > ADC (conversion back to digital).

Even if the hifi system (amplifiers and speakers) were perfect, the sound propogation and coupling to room modes could easily introduce huge variations (+-12dB or more) in the frequency response. If you attempt to determine the SINAD at your ears (or at the measurement mic) after propogation through the air, you will get a very poor value without room EQ, which can be greatly improved by carefully calibrated DSP EQ.

Any decrease in SINAD, at the electrical output of the AVR, caused by the DSP, (a few dB?) is insignificant relative to the gross errors introduced by sound wave propogation in the room (10s of dB). Therefore, if applied correctly, the net effect of room EQ on SINAD (at the ears) is greatly beneficial.

 

[dlaloum]

Also worth considering that SINAD measurements include distortion, not just noise, and in "room" terms, one needs to consider speaker distortion.

A Speaker that achieves 0.5% THD is considered excellent (possibly even SOTA) - yet that would be a SINAD of 46db (!!)

Also some aspects of the measurement will be improved by EQ, as you reduce the level of certain frequencies, as part of the RoomEQ, the THD and Noise contribution at those frequencies will also be reduced, potentially improving the overall measurement...

There are some artificialities imposed by the requirements of measurement... with components, we typically run a flat un-equalised frequency response, even though we know, that the end result will be altered by the speakers and the room (and we will tune it in-room with acoustic treatments, and speaker positioning) - even in the absence of any EQ.

what is meaningful?

 

[MarkS]

If low SINAD matters for a DAC rating

Only the very worst performing DACs might have audible SINAD (and likely not even those).

IMO, ASR overemphasizes measurements beyond the level of audibility.

 

[respice finem]

...Any decrease in SINAD, at the electrical output of the AVR, caused by the DSP, (a few dB?) is insignificant relative to the gross errors introduced by sound wave propogation in the room (10s of dB). Therefore, if applied correctly, the net effect of room EQ on SINAD (at the ears) is greatly beneficial.

Thanks for the elaborate response, and yes, looking at the measured problems of pretty much any room, this seems obvious.
Probably even applicable for all home audio. Our hearing is far from perfect either. But, some rooms, some people's hearing and some devices will be better than others. Last but not least, imperfections in the audio chain add up.

But, why not measure the "electrical part", as is done in other cases, even if it's just for being able to have an objective result.
That's why I've mentioned DACs in this context. A DAC with 120 dB SINAD will probably hardly be audibly better than one with 100 dB - but everyone can decide for themselves after seeing the measurements. Then (maybe less with DACs) there is always a possibility, a device is simply botched "by design", so my line of thinking is rather "if you can measure, do it".

 

[respice finem]

IMO, ASR overemphasizes measurements beyond the level of audibility.

Maybe. Even probably, if we look at the old DIN 45500, which wasn't made by and for deaf people either.
But for me, it's still a better source of information for potential buyers, than audiophile lyric from manufacturers (I'm old enough to remember the 80s).

Well, maybe just a silly thought, as said in the OP. A "luxury problem" for sure. But we buy things that are more than the bare essentials all the time, don't we?

 

[respice finem]

what is meaningful?

That's... a very good question (not limited to audio).
Maybe I'm just spending too much time thinking about it? It's just a hobby after all...
Not a rhetorical remark, I'll seriously consider this.

 

[bodhi]

IMO, ASR overemphasizes measurements beyond the level of audibility.

I think it's only a minority of people reading too much into measurements when it concerns audibility. It can be still fun and interesting to discuss performance stuff even if it doesn't matter in real life: if we would only talk about stuff that is demonstrably audible in casual listening situations then it would be a quiet forum indeed.

Being too nitpicky about SINAD or other measurements and trying to get experience somehow matching the results while listening, when there really shouldn't be any, is just another flavor of subjectivism.

 

[-Matt-]

But, why not measure the "electrical part", as is done in other cases, even if it's just for being able to have an objective result.

For the record, I'm not against such testing, I even suggested something similar discussed here...

https://www.audiosciencereview.com/...s/room-correction-software-measurements.42841

 

[FrantzM]

Hi

Engineer here but have taught myself not to overthink things..

Let's suppose a good ASR, approvable DAC, in the "Excellent Range" SINAD around 110 dB?
Now we know that a SINAD of 70 dB is supposed more than sufficient.. Let's be generous let's go to 80 dB.
If the DSP eats out 30 dB ... quite a bit but ..
you are left with 80 dB.. which, for 99.99% of audiophiles on the planet, is transparent, Yes!

Peace.

 

[respice finem]

Yes, as I already said, but, even not being an engineer, before (hypothetically) buying a device, I would prefer to know instead of suppose...

 

[Sokel]

Measuring stuff here turned out to improve things as it's evident in the thread I posted above.
Yes,filters will always give a hit in SINAD,even the improved "after" version shows that clearly.

Adding more filters,reducing level,interlink with other components will further reduce SINAD.
BUT,if noise is not audible and all the above addresses far worst room issues is a risk worth taking.