How does room EQ affect noise and distortion?

[Dj7675]

We are starting to get a nice sampling of AVRs and Processors. SINAD measurements range from 53-103. All measurements are done in direct mode. The AVRs/Processors will almost always be used with some sort of room EQ engaged. Couple of basic questions:
-What affect does running Audyssey or Dirac for example have on noise/distortion?
-Would it vary depending on the amount of boosts/cuts applied by the eq system?
-Is it possible to measure SINAD with room eq engaged and if so would these measurements be meaningful?

It seems like an important question. For example if using eq degrades SINAD by 10, there could be some advantages for having a higher SINAD device to allow for the effects of using automated eq.

 

[DonH56]

Boosts and cuts will impact the level of noise and distortion but it depends upon how much boost and cut, what frequencies, etc. It could help or hurt noise and/or distortion. Since the amounts depend upon the room and system I don't think a comparison would be meaningful. And note all the correction is done in the digital domain so unless they mess up and do something really dumb in the processing the correction itself is benign until it hits something in the analog chain.

 

[RayDunzl]

My practical experience with manipulating digits in a Behringer DEQ2496 and a miniDSP OpenDRC-DI is that no audible degradations are noticed.

I could measure and post, but the measurements I have taken in the normal course of my activities with and without DRC active have shown no anomalous or otherwise deleterious behavior.

I don't remember any threads here where someone posts that their DRC is noisy or causes distortion. Maybe some have disappointing results for other reasons.

 

[Dj7675]

Thanks both for your reply. I have always been curious if it has any affect if so how much. Sounds like not much of a concern.

 

[RayDunzl]

An old measurement of distortion from the speakers

Red - no DRC
Black - with DRC

 

[Hipper]

I agree with Ray. I have used a Behringer DEQ2496 for some fourteen years and was often told on other forums that equalisers generally, and in one case the Behringer specifically, were noisy but I have never heard this myself nor have I seen any relevant measurements. It's possible some of those people were referring to analogue equalisers of old and not today's digital models.

The effect of using EQ is such an improvement that if there was any noise it has so far been hidden.

How would one measure SINAD in a normal domestic listening set up?

 

[RayDunzl]

Here's a preamp output of distortion.

Red - no DRC
Black - DRC for JBL speakers
Green - DRC for MArtin Logan speakers

Three years ago, so using a noisy cable across the room to the PC 's ADC

But, the point is there wasn't a lot of difference between no DSP and two different settings with DSP