The Subjective and Objective Evaluation of Room Correction Products - Page 20 - AVS Forum
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post #571 of 582 Old 03-25-2010, 06:01 PM
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Maybe this thread is dead and I'm late to the party, but did anyone mention the Filipetti interviews on the Audyssey website (linked on the right in Archives)? Good stuff that pertains to much of the on-topic (non-hockey) debate here as to room correction in the mixing room.

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post #572 of 582 Old 03-25-2010, 07:28 PM
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Quote:
Originally Posted by SoundofMind View Post

Maybe this thread is dead and I'm late to the party, but did anyone mention the Filipetti interviews on the Audyssey website (linked on the right in Archives)? Good stuff that pertains to much of the on-topic (non-hockey) debate here as to room correction in the mixing room.

Since you've woken the thread up, I might as well opine that somehow I don't think that news will be welcomed at this party.
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post #573 of 582 Old 03-29-2010, 07:36 PM
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Why not? What's objectionable in that review? The guy's subjective opinion of Audyssey Pro correction?
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post #574 of 582 Old 10-03-2010, 06:06 AM
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I did want to attempt to revive this topic, particularly to discuss the issue of using Room Correction software to EQ above the transition frequency.

Also, is using Room EQ to attempt to correct a deficiency in power response a good idea? What is the software actually doing? Is it boosting on-axis output to make up for a deficiency in off-axis response? Is this desirable?
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post #575 of 582 Old 10-06-2010, 09:54 PM
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Originally Posted by dweltman View Post

I did want to attempt to revive this topic, particularly to discuss the issue of using Room Correction software to EQ above the transition frequency.

Also, is using Room EQ to attempt to correct a deficiency in power response a good idea? What is the software actually doing? Is it boosting on-axis output to make up for a deficiency in off-axis response? Is this desirable?

I'm probably a bit out my league with the company of guys posting here, but I do have a strong interest in acoustics and sound analysis, and since no one else has stepped up to answer this, I'll take a shot.

In my experience, the answer is, "it depends". I've owned speakers with power response problems that responded very well to Room EQ, and others that haven't. The problems tend to occur with attempting to correct the in-room response of speakers that show a dip at the mid / tweet crossover. If the EQ flattens the response through this region, sometimes the sound can become aggressive and harsh.

I think it is inevitable that if you correct a deficiency in the power response there will be a corresponding boost to that region in the direct sound. I don't know how much weight something like Audyssey gives to the direct vs. reflected sound, but I've often wondered if more weight should be given to the direct sound so that it doesn't "overcorrect" a dip in the power response.
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post #576 of 582 Old 10-07-2010, 04:45 AM
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Originally Posted by hifisponge View Post

I don't know how much weight something like Audyssey gives to the direct vs. reflected sound

How does it know which is which?
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post #577 of 582 Old 10-07-2010, 10:15 AM
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Quote:
Originally Posted by Gary J View Post

How does it know which is which?

Direct vs reflected sound can be distinguished by the arrival time of the test tone to the mic.

Two things come to mind that could help place more weight on the direct sound from the speaker.

A. Mic tip orientation: Point the tip of the mic towards the speaker.

B. Time-gated measurements: narrow the time window of the measurement so that the later-arriving reflected sounds contribute less to the reading.
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post #578 of 582 Old 07-26-2011, 03:08 AM
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I believe this topic is still of interest and would encourage others to post here, ignoring the old thread warning, if that will resuscitate the thread. Otherwise we should start a new one.

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post #579 of 582 Old 02-09-2012, 11:44 PM
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Originally Posted by Tonmeister2008 View Post


There has been a lot of research on this. If you look at pages 283 -287 of "Perceptual Audio Evaluation" by Soren Bech and Nick Zacharov you will find a summary of research on preferred listening levels or "most comfortable listening" levels (MCL) for different signals including the recommended levels from various standards. MLC for music varies from 69 to 85 dB depending on background noise. Mathers suggested an average level for music of 83.5 dB (A) which is close to what we used, and which our listening panel found comfortable and acceptable.

The MCL depends on many factors such as signal bandwidth, signal type, background noise, listening context (conversation versus entertainment), and age of listener (older people prefer higher levels for speech due to age-related hearing loss known as prebycusis: increasing the level improves speech intelligibility).

As far as standards go there are different recommended reference playback levels between SMPTE and ITU. ITU-R BS 1116-1 recommends a reference SPL of 85 dB(A) slow, which the authors claim is typically 5-10 dB too loud for subjects with most programs. I would tend to agree.

Wow I had to read a long way in this thread to get this nugget.

The Audyssey system used assumed 0dbfs on a recording is played back in the room at 105db, film industry standard.

But since the recordings used were pop records, where average levels were within 5db of 0dbfs, and the in room spl was about 80db, they had the system set more than 20db too low for Audyssey.... And the bass sounded anemic. Fletcher Munson, your dynamic loudness correction curve is calling and ready to assist.... If you want to use the system as intended, he says, turn me, dynamic EQ, on, or turn up the volume to theater reference levels....

Which I guess means that a room correction system without dynamic compensation for different mastering levels and playback volumes needs to assume compressed brick walled recordings played back at approx 80db?


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post #580 of 582 Old 02-10-2012, 01:50 AM
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Quote:
Originally Posted by nathan_h View Post

The Audyssey system used assumed 0dbfs on a recording is played back in the room at 105db, film industry standard.

Ok

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But since the recordings used were pop records, where average levels were within 5db of 0dbfs,

I doubt that the average level of the pop recordings were -5 dBFS. But yes, they are indeed recorded at higher average levels than movies, typically 10-15 dB higher. In any case, it does not matter what modulation index is used on the delivery medium, as that is irrelevant to how loud we play music.

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and the in room spl was about 80db, they had the system set more than 20db too low for Audyssey....

While the peak level of a movie channel is theoretically 105 dB (in one channel with a 0 dBFS sine wave), the average level of dialog is -27 dBFS, or 78 dB. That seems close enough to the 80 dB level of the music test.

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And the bass sounded anemic. Fletcher Munson, your dynamic loudness correction curve is calling and ready to assist....

Not needed in this case.
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post #581 of 582 Old 02-10-2012, 01:52 PM
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Interesting. I cannot account for all the results of the listening test, but I have found the same anemic bass result with the older version of Audyssey when listening to music versus listening to movies. I guess I'm not explaining it well, but since it works when listening to a movie at reference level but not when listening to music, when I have to turn down the volume by 15 on the prepro to have e same impression of volume in the room, I surmise it has something to do with the program content.


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post #582 of 582 Old 02-10-2012, 07:09 PM
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Quote:
Originally Posted by nathan_h View Post

Interesting. I cannot account for all the results of the listening test, but I have found the same anemic bass result with the older version of Audyssey when listening to music versus listening to movies. I guess I'm not explaining it well, but since it works when listening to a movie at reference level but not when listening to music, when I have to turn down the volume by 15 on the prepro to have e same impression of volume in the room, I surmise it has something to do with the program content.

Yes, I also find that movies generally have more bass than music, particularly those from the last decade. So I set up my processor's movie config with less bass than the music config to compensate.
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