Question to Dr. Toole about direct versus reflected sound

3db

3db

Audioholic Slumlord
I'm invovled in a discussion about the good/bad about AVR room correction facililty. It has been suggested by one individual that "The EQ doesn't change the loudspeaker radiation pattern. If it does change the ratio of direct to reflected sound, it's only an indirect effect of emphasizing or de-emphasizing different frequency ranges with different dispersion. What I'm saying is that full range auto-EQ can take a loudspeaker with excellent on-axis frequency response and mess it up. While the steady-state in-room response at the listening position is becoming flatter, the direct sound may be getting worse, and the direct sound is more important. The better the loudspeaker, the more likely that auto-EQ is degrading its performance rather than improving it. "

Other than bass (Above the Schroeder frequency (if I understand that term correctly) how would PEQ done by AVRs mess up the ratio of direct verses reflected sound?
 
P

PENG

Audioholic Slumlord
I'm invovled in a discussion about the good/bad about AVR room correction facililty. It has been suggested by one individual that "The EQ doesn't change the loudspeaker radiation pattern. If it does change the ratio of direct to reflected sound, it's only an indirect effect of emphasizing or de-emphasizing different frequency ranges with different dispersion. What I'm saying is that full range auto-EQ can take a loudspeaker with excellent on-axis frequency response and mess it up. While the steady-state in-room response at the listening position is becoming flatter, the direct sound may be getting worse, and the direct sound is more important. The better the loudspeaker, the more likely that auto-EQ is degrading its performance rather than improving it. "

Other than bass (Above the Schroeder frequency (if I understand that term correctly) how would PEQ done by AVRs mess up the ratio of direct verses reflected sound?
I highly doubt Dr. Toole has said such thing as "The better the loudspeaker, the more likely that auto-EQ is degrading its performance rather than improving it" explicitly, that would sound like someone's subjective interpretation..

On the other hand, don't we all already know Dr. Toole recommend DRC/Auto EQ be applied to the low frequency range below the specific room's "transition/Schroeder" frequency? I don't think he has ever said anything about the validity of doing it above the transition frequency, but he obviously suggested that doing so may do more harm than good and there's no need to do it if the speakers have good off-axis response. As you know, there are all kinds of self proclaim experts who, in my opinion should just quote/link the experts instead of trying to explain things away that they don't really understand enough.

One concern that I do know of is that, measurements taken above the Schroeder frequency may not be reliable, but it obviously depends on the software/hardware. If you talk to the Dr. Johansson of Dirac Live, Dr. Schuck of Anthem and Dr. Chriskakis of Audyssey Lab., you are going to get slight variations of their interpretations of the issues cited by various experts.

Anthem did offer a little bit of explanations:


"Nick Platsis: It is reliable up to 5 kHz. After that it starts becoming too directional with increasing frequency. Maximum correction range for MRX receivers is 5 kHz. This is the normally recommended setting, and the default, in all versions of ARC and is user adjustable down to 200 Hz. In AVM/D it can be set as high as 20 kHz, but effectiveness of correction at these upper frequencies often depends on whether the tweeters (and mic) are at ear level. A listening test is the best way to find out."

In case you may not know, Audioholics did interview the Doctors of Audyssey and Dirac Live as well:


With the introduction of the Editor App, all 3 of the major players in the AVR field provide the means to limit the affected frequency range.

I really don't see a short answer to your question but it is there if you spend time reading some of Dr. Toole's articles.

Below are what I would like to quote/link:


Or if you prefer to just read part of his conclusion below (no detailed explanation though..)

"Whatever solution(s) you choose, it is likely that some bass equalization will improve things. Just don't automatically extend the equalization above a few hundred Hz, because that is where the loudspeaker itself takes over and if you have good loudspeakers you might risk making them worse.

Make your choices, it is a free world."


Another great one to read:

 
Last edited:
everettT

everettT

Audioholic Spartan
Don't we all already know Dr. Toole recommend DRC/Auto EQ be applied to the low frequency range below the specific room's "transition/Schroeder" frequency? I don't think he has ever said anything about the validity of doing it above the transition frequency, but he obviously suggested that doing so may do more harm than good and there's no need to do it if the speakers have good off-axis response. As you know, there are all kinds of self proclaim experts who, in my opinion should just quote/link the experts instead of trying to explain things away that they don't really understand enough.

One concern that I do know of is that, measurements taken above the Schroeder frequency may not be reliable, but it obviously depends on the software/hardware. If you talk to the Dr. Johansson of Dirac Live, Dr. Schuck of Anthem and Dr. Chriskakis of Audyssey Lab., you are going to get slight variations of their interpretations of the issues cited by various experts.

Anthem did offer a little bit of explanations:


"Nick Platsis: It is reliable up to 5 kHz. After that it starts becoming too directional with increasing frequency. Maximum correction range for MRX receivers is 5 kHz. This is the normally recommended setting, and the default, in all versions of ARC and is user adjustable down to 200 Hz. In AVM/D it can be set as high as 20 kHz, but effectiveness of correction at these upper frequencies often depends on whether the tweeters (and mic) are at ear level. A listening test is the best way to find out."

In case you may not know, Audioholics did interview the Doctors of Audyssey and Dirac Live as well:


With the introduction of the Editor App, all 3 of the major players in the AVR field provide the means to limit the affected frequency range.

I really don't see a short answer to your question but it is there if you spend time reading some of Dr. Toole's articles.

Below are what I would like to quote/link:


Or if you prefer to just read part of his conclusion below (no detailed explanation though..)

"Whatever solution(s) you choose, it is likely that some bass equalization will improve things. Just don't automatically extend the equalization above a few hundred Hz, because that is where the loudspeaker itself takes over and if you have good loudspeakers you might risk making them worse.

Make your choices, it is a free world."


Another great one to read:

Correct that is where he applies it. I think I've linked this last week, but tons of great info in this thread.
 

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