Dayton OmniMic Precision Measurement System - Page 13 - AVS Forum
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post #361 of 2090 Old 01-06-2011, 09:05 PM
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Quote:
Originally Posted by noah katz View Post

Are you measuring in the same location(s) you had the Audyssey mike?

Because it would never give you a nice downsloping response like that (-10 dB from low freq to high).

And which version of Audyssey? It doesn't seem to be doing so great at smoothing the response except in the bass.

Do you have Audyssey Pro?

It'd be interesting to see how its graphs compare to OmniMic's.


Close to the same position. It's Audyssey XT32 in a Denon 4311. I did the quick manual calibration so I had an idea of how things would look like without EQ and to compare. I have an Audyssey Pro kit coming, but it's been on order for weeks...
What are your thoughts on the manual calibration graph?



Quote:
Originally Posted by soho54 View Post

In the dual graph which color is Audyssey, blue? Not much amplitude correction there.

Yes, Audyssey is blue. Not so great, right?

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post #362 of 2090 Old 01-06-2011, 09:18 PM
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The SPL reading of the channel levels after the Audyssey calibration is 68 dbSPL. A little low, wouldn't you say? For some reason the SPL graph is not the same as the meter reading?? The meter on the page was reading 68dB. My RS meter is reading 70-71 dB when Omni mic is reading 67-68 dB side-by-side.
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post #363 of 2090 Old 01-06-2011, 11:30 PM
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Quote:
Originally Posted by Gooddoc View Post

What are your thoughts on the manual calibration graph?

I said to myself "That might sound pretty darn good". Not sure whether the rise in upper mids would be strident; could be fine with the rising bass though.

How does that response sound to you?

How do you manually calibrate?

Re the SPL, I was reading through the manual and it said not to use the RTA and/or spectrum analyzer for SPL; I didn't really understand the explanation.

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post #364 of 2090 Old 01-06-2011, 11:45 PM
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Quote:
Originally Posted by ltd02 View Post

5 seconds of 50hz.

Not sure if they are distortions or not, but the wideband effects at the start and stop are clear.


LTD02,

I was curious about what you were observing, so I made a recording of a 50 Hz sine wave to see what was going on. Those start and stop effects are not distortion; they are the attack and decay of the sound as the woofer starts and stops moving. It's easier to see in the time domain instead of the frequency domain:



It's also interesting to see the attack and decay are longer at a lower frequency:

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post #365 of 2090 Old 01-07-2011, 05:24 AM
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Quote:
Originally Posted by Gooddoc View Post

Close to the same position. It's Audyssey XT32 in a Denon 4311. I did the quick manual calibration so I had an idea of how things would look like without EQ and to compare. I have an Audyssey Pro kit coming, but it's been on order for weeks...
What are your thoughts on the manual calibration graph?





Yes, Audyssey is blue. Not so great, right?

How much was the Audyssey Pro kit? Did you buy it directly from Audyssey?

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post #366 of 2090 Old 01-07-2011, 06:18 AM
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Originally Posted by t6902wf View Post

How much was the Audyssey Pro kit? Did you buy it directly from Audyssey?

I bought a pro kit from a local dealer. I don't think you can get the pro kit outside of dealer channels (as far as I know there are no direct sales from Audyssey). The street price for the kit is generally $500-550 and I have found a web seller. The price for the kit is about what you would probably pay for a single visit from an "installer". You also have to buy a one time license for each pre-pro or reciever from Audyssey for $150, which can be done through the installer section of the Audyssey website after you have registered your pro kit. You then get a license key/code which lasts 30 days, but can be renewed as many times as needed (new key/code is generated). The Audyssey sub eq (same hardware as the SVS sub eq, but uses the better mic from the pro kit and Audyssey software on your pc) does not require purchase of a license.

Hope this helps. PM me if you have other questions.

Also, I just ordered the Omnimic. I hope it is still actually in stock...

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post #367 of 2090 Old 01-07-2011, 08:06 AM
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Quote:
Originally Posted by noah katz View Post


I said to myself "That might sound pretty darn good". Not sure whether the rise in upper mids would be strident; could be fine with the rising bass though.

How does that response sound to you?

How do you manually calibrate?

It did sound pretty good. I did the manual calibration quickly, so I didn't move the subs or adjust the sub gain/phase as I normally would and that explains the rising bass. I used the "short sine waves" track to optimize the position of the mains(full range, no subs), then I add the subs and adjust the xo up or down until I get the flattest response. I used to do the same thing with REW using RTA and a looping 20Hz - 400 Hz sweep.


Quote:
Originally Posted by noah katz View Post

Re the SPL, I was reading through the manual and it said not to use the RTA and/or spectrum analyzer for SPL; I didn't really understand the explanation.

Well, that explains that. But as I said, the Omnimic meter itself read 68 dBspl and my RS meter right next to it read 71 dBspl. Audyssey has said that you can't use the channel level on the receiver to accurately set levels, but 71 is a long ways from 75.

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post #368 of 2090 Old 01-07-2011, 03:29 PM
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Quote:
Originally Posted by JohnPM View Post
The mic cal is likely a mic-specific sensitivity figure coded into the value you enter (required for the SPL meter which needs to know overall sensitivity) and a generic response cal file built into the software.

A USB mic looks just like any other soundcard but only has inputs. Should be useable with anything.
The user manual implies the cal file is unique to each mic, at least to some degree. The frequency response cal code and SPL sensitivity adjustments are separate controls.

Given the wording of the calibration section, I would guess part of the calibration is handled in the form of QC tolerances and then the code identifies the appropriate embedded cal settings to use based on the QC findings. Just realized P-E doesn't actually list a spec for the OmniMic's accuracy.

-Brent
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post #369 of 2090 Old 01-07-2011, 04:35 PM
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Here are some measurements I just took.

Room size is about 15' wide x 28' long x 8' high. There are some strange angles that can be seen in the pictures. Acoustic panels can also be seen in the pictures of the room layout.

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post #370 of 2090 Old 01-07-2011, 04:35 PM
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Other graphs. I am going to try and re-run some decay graph’s for the subs and try to use that cut feature of Windows 7. When I just tried using the snapshot of the program it only grabbed the lower section, so it did not show the bass response in the picture.

I also have to agree with Warp when he states about the program size itself; it has to be tweaked to allow a bigger window.

James
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post #371 of 2090 Old 01-07-2011, 06:37 PM
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Exojam, were you using REW prior to this?

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post #372 of 2090 Old 01-07-2011, 07:39 PM
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I had ran REW before but it has been awhile since I have.

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post #373 of 2090 Old 01-07-2011, 08:37 PM
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Quote:
Originally Posted by soho54 View Post

In the dual graph which color is Audyssey, blue? Not much amplitude correction there.

I have to disagree. After stretching the traces to a graph I'm more used to seeing, he goes from +/-8.5dB to +/-3dB from 30-100 Hz. But, look at the boost Audessey applies; +8dB from 25-30 Hz!



Doc,

If you get a chance, what room size, how far is the mic from the sub and what sub? Can you do a close mic of the sub to see the room influences?

Bosso
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post #374 of 2090 Old 01-07-2011, 09:47 PM
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Quote:
Originally Posted by bossobass View Post


I have to disagree. After stretching the traces to a graph I'm more used to seeing, he goes from +/-8.5dB to +/-3dB from 30-100 Hz. But, look at the boost Audessey applies; +8dB from 25-30 Hz!

Doc,

If you get a chance, what room size, how far is the mic from the sub and what sub? Can you do a close mic of the sub to see the room influences?

Bosso

My room is 13.5x28.5 ft. and I have two CHT 18.1's. One sub is about 14 ft. and the other is about 12 ft. from the MLP. I can tell you I had to move one of my subs to make a spot for the Christmas tree . So my subs are not in the place they should be and also realize my house is rarely quiet, and wasn't when these shots were taken.

I think they are fairly accurate though....close enough for horseshoes and hand grenades

That is one hellava boost though! I have to say it sounds pretty good, even though I know I can make it considerably better once I get my subs where I want them.

I've been waiting to put any considerable time into optimizing the system because I have the audyssey pro kit being delivered early next week. I'm gonna get the christmas tree down so I can move the subs, and I'm gonna see what I can accomplish with Audyssey Pro.

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post #375 of 2090 Old 01-07-2011, 10:05 PM
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Quote:
Originally Posted by bossobass View Post

I have to disagree. After stretching the traces to a graph I'm more used to seeing, he goes from +/-8.5dB to +/-3dB from 30-100 Hz. But, look at the boost Audessey applies; +8dB from 25-30 Hz!

Disagree? You need to stretch that graph on out. It wasn't an LFE measurement. Noah caught it.

His low end is ~13dB higher than his treble. What is really scary, is that exojam's looks the same.

Never been a big Audyssey fan myself.
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post #376 of 2090 Old 01-08-2011, 03:12 AM
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Quote:
Originally Posted by soho54 View Post

Disagree? You need to stretch that graph on out. It wasn't an LFE measurement. Noah caught it.

His low end is ~13dB higher than his treble. What is really scary, is that exojam's looks the same.

Never been a big Audyssey fan myself.

Sorry, I never look at the top side. IMO, treatments and placement are everything. I don't believe auto EQ can do much up there (or anywhere for that matter)

It did the same to mine. It boosted the sub to stupid. It seems that Audessey leaves the peaks and boosts everything around them to flatten. The opposite of what most have said is preferred.

Bosso
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post #377 of 2090 Old 01-08-2011, 07:27 AM
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I am sooo PO'd.

My OmniMic has been backordered. I placed the order as soon as I got the e-mail saying it was in stock. The site confirmed the order, but yet no OmniMic.

Of course they sent the other stuff I ordered along with the Red Fury Pocket Speaker.
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post #378 of 2090 Old 01-08-2011, 12:12 PM
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Quote:
Originally Posted by soho54 View Post

His low end is ~13dB higher than his treble

I wish Audyssey would do that to my bass; I have to boost it 10 dB.

Hopefully I'll finish some more bass traps today and a Pro setup will fix it.

Noah
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post #379 of 2090 Old 01-08-2011, 12:54 PM
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Originally Posted by noah katz View Post

I wish Audyssey would do that to my bass; I have to boost it 10 dB.

What's the difference?

Bosso
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post #380 of 2090 Old 01-08-2011, 02:53 PM
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Quote:
Originally Posted by bosso View Post

BTW, it doesn't take the kind of overkill many here engage in to get full BW replay at normal (-10dBRL with the sub running a bit hot) levels and the subsonic reproduction is simply a consequence of using the 2nd order roll off sealed alignment

Quote:


Just build a sealed L/T'd system and stick the box in a corner and there you go. If you prefer higher SPL, add more. Pretty simple if you ask me. Never saw what the fuss was about.

Quote:


4-18" IB drivers and a budget amp will cover reference level LFE for any room I've been in for $1500.

Aside from the fact that this all doesn't really work, it's a great story

Ilkka's measurements (which are still posted on the internet at a different forum) of a sealed Adire Tumult 15" show 100% or greater THD at 10hz at 2m GP at 90db. Corner load the sub to gain more output sensitivity, but the distortion comes with it. You're looking at about 60db 2m GP before the distortion becomes reasonable at 10hz. How little amplitude before it becomes reasonable at 5hz, 20db? Sure, don't forget your room gain of about 6-8db per octave starting around 25hz, but the distortion comes with it. You're going to need a ton of drivers to accomplish what you speak of without >100% THD my friend, a ton.

He then went on to measure the LMS-5400 18", what many would consider the most capable low distortion subwoofer driver available. 93db at 2m GP at 10hz with about 25% THD. 83-84db to get to a level where the THD is reasonable. How much amplitude to make that reasonable at 5hz, maybe 30db? Thats a lot of drivers to get to 118db, as spl grows by 6db when you double displacement, so driver count gets out of hand really quick. Don't forget the amps!

Now don't get me wrong, going for full subwoofer bandwidth is something I am in favor of. Using drivers - especially sealed - is just too inefficient though, especially if you want less than 100% THD. If we get this rotary subwoofer going as a diy project, then 0.1-120hz capability at reference with far less than 100% THD may be available for the masses.....or at least the <1% of the masses who are interested.

Didn't mean to interrupt discussion about the new Dayton mic, but I couldn't let that go unchallenged.
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post #381 of 2090 Old 01-08-2011, 03:02 PM
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Holy Crap! A time warp! We are in 2007 again!

I knew I shouldn't have started watching Star Trek DS9 again. Frigging chromatons.

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post #382 of 2090 Old 01-08-2011, 03:45 PM
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Here are two bass decay graphs from last night. I have not had the chance to run anymore today, other stuff going on. These are at different volume levels and are subs only.

James
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post #383 of 2090 Old 01-08-2011, 04:24 PM
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Quote:
Originally Posted by SteveCallas View Post

Aside from the fact that this all doesn't really work, it's a great story

Ilkka's measurements (which are still posted on the internet at a different forum) of a sealed Adire Tumult 15" show 100% or greater THD at 10hz at 2m GP at 90db. Corner load the sub to gain more output sensitivity, but the distortion comes with it. You're looking at about 60db 2m GP before the distortion becomes reasonable at 10hz. How little amplitude before it becomes reasonable at 5hz, 20db? Sure, don't forget your room gain of about 6-8db per octave starting around 25hz, but the distortion comes with it. You're going to need a ton of drivers to accomplish what you speak of without >100% THD my friend, a ton.

He then went on to measure the LMS-5400 18", what many would consider the most capable low distortion subwoofer driver available. 93db at 2m GP at 10hz with about 25% THD. 83-84db to get to a level where the THD is reasonable. How much amplitude to make that reasonable at 5hz, maybe 30db? Thats a lot of drivers to get to 118db, as spl grows by 6db when you double displacement, so driver count gets out of hand really quick. Don't forget the amps!

Now don't get me wrong, going for full subwoofer bandwidth is something I am in favor of. Using drivers - especially sealed - is just too inefficient though, especially if you want less than 100% THD. If we get this rotary subwoofer going as a diy project, then 0.1-120hz capability at reference with far less than 100% THD may be available for the masses.....or at least the <1% of the masses who are interested.

Didn't mean to interrupt discussion about the new Dayton mic, but I couldn't let that go unchallenged.

This post is at the top of the list of reasons why I'll be moving on. Some folks go along for the ride and not only glean nothing, but post post against what there is to learn.

Ilkka's CEA 2010 RMS chart lists 87dB at 12.5 Hz. Add +9dB to that for peak at 1M, within which distance room gain occurs. That's 96dB within the CEA peak test criteria. A pair with 2400W (roughly a Raven) gives you 102dB. Plus 9dB room gain gives you 111dB, more than enough for reference playback of any source.

Room gain will also reduce THD significantly as there is none at the harmonics of 12 Hz. 30% @ 12 Hz then becomes 10%. Stack 2 Blackbirds and you have a very economical system that sits 43" tall and on 2.7 square feet and takes you to 117dB at 12 Hz, 105dB at 6 Hz.

That is, if you set MVL at reference levels when you watch a movie.

Play F'in' Irene at reference level and you "see" virtually no THD. Jack the SW level up to +10dB and you still have completely inaudible harmonics at less than 10% (you're welcome to come and try to dispute that anytime you wish).

Please take 1/2 the time to study this graph that you have taken to see the bad in every other test result you cite. It's the real deal at my seat, not a sine wave sweep in some parking lot of a poorly executed subwoofer.

Look for inaccuracies, artifacts, harmonics or whatever. If they existed, especially at "over 100%" they would be on there and easily spotted vs the digital version.



I only use this one because it is the easiest to study. I have dozens from many movies and I've pored over them looking for your cited boogeymen and shortcomings with no success.

Bosso
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post #384 of 2090 Old 01-08-2011, 04:38 PM
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Quote:


This post is at the top of the list of reasons why I'll be moving on.


But, but.....we have missed the Callas vs Bosso debates

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post #385 of 2090 Old 01-08-2011, 07:28 PM
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But, but.....we have missed the Callas vs Bosso debates

Coming soon...

The same graphs using a ported sub.

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post #386 of 2090 Old 01-09-2011, 09:37 AM
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Steve, I've read quite a lot of your posts, however this statement here;

Quote:
going for full subwoofer bandwidth is something I am in favor of. Using drivers - especially sealed - is just too inefficient though, especially if you want less than 100% THD

really needs some added context, or outright explanation in more terms other than citing one isolated example. This painting with such a broad brush seems as gross oversimplification at best. Obviously, I'm missing something.

For my DIY attempt at addressing the LF in my room, I looked at all the alignments and went sealed (IB) due to many factors, however higher THD wasn't one of them.

Thank you

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post #387 of 2090 Old 01-09-2011, 09:39 AM
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Quote:
Originally Posted by FOH View Post

Steve, I've read quite a lot of your posts, however this statement here;



really needs some added context, or outright explanation in more terms other than citing one isolated example. This painting with such a broad brush seems as gross oversimplification at best. Obviously, I'm missing something.

For my DIY attempt at addressing the LF in my room, I looked at all the alignments and went sealed (IB) due to many factors, however higher THD wasn't one of them.

Thank you

Is infinite baffle considered sealed?

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post #388 of 2090 Old 01-09-2011, 10:39 AM
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I have been following this thread from the beginning, did some one actually review the system? All I see now is discussion of measurement results and audio theory.
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post #389 of 2090 Old 01-09-2011, 11:35 AM
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Quote:
Originally Posted by bossobass View Post

Sorry, I never look at the top side. IMO, treatments and placement are everything. I don't believe auto EQ can do much up there (or anywhere for that matter)

It did the same to mine. It boosted the sub to stupid. It seems that Audessey leaves the peaks and boosts everything around them to flatten. The opposite of what most have said is preferred.

Bosso

Close.....Audyssey provides an inadvertent boost to material below 20Hz, it is a known fault.

These are line outputs from the subwoofer out of a Denon Receiver with MultEQ XT.....

First up, Audyssey off:



Next, Audyssey on:



Note that Audyssey has raised the entire level of the signal and applied cuts.

Now, both traces together:



To see that Audyssey just applies cuts then raises the entire signal level, move the Audyssey 'on' trace down:



This is the inadvertent 'boost' Audyssey provides. I had a message dialogue with Chris Kyriakis about it, and my solution was to implement a high-pass filter. Not many sub systems can take an 8-10dB boost below 20Hz....

The other reason Audyssey can make the low end too robust is if Dynamic EQ is engaged, as it boosts both low and high end to account for ELC as you turn MVL down from reference.

Another factor is the target curve used. Audyssey has several target curves, flat and the 'audyssey curve', which rolls off the highs somewhat, just like they are in a theatre due to the screen losses and distance propagated, as the air preferentially attenuates high freqs....to better simulate the 'theater experience', and just in case you are getting the master on the disc from the mixing stage, and not a near-field mix that would compensate for the in-theatre hi freq losses.....

JSS
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post #390 of 2090 Old 01-09-2011, 02:11 PM
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Quote:
Originally Posted by maxmercy View Post


Close.....Audyssey provides an inadvertent boost to material below 20Hz, it is a known fault.

These are line outputs from the subwoofer out of a Denon Receiver with MultEQ XT.....

First up, Audyssey off:

Next, Audyssey on:

Note that Audyssey has raised the entire level of the signal and applied cuts.

Now, both traces together:

To see that Audyssey just applies cuts then raises the entire signal level, move the Audyssey 'on' trace down:

This is the inadvertent 'boost' Audyssey provides. I had a message dialogue with Chris Kyriakis about it, and my solution was to implement a high-pass filter. Not many sub systems can take an 8-10dB boost below 20Hz....

The other reason Audyssey can make the low end too robust is if Dynamic EQ is engaged, as it boosts both low and high end to account for ELC as you turn MVL down from reference.

Another factor is the target curve used. Audyssey has several target curves, flat and the 'audyssey curve', which rolls off the highs somewhat, just like they are in a theatre due to the screen losses and distance propagated, as the air preferentially attenuates high freqs....to better simulate the 'theater experience', and just in case you are getting the master on the disc from the mixing stage, and not a near-field mix that would compensate for the in-theatre hi freq losses.....

JSS

Max I am glad you brought this up. I have done a b comparisons with Audyssey and I want to use it, it improves most of the sound. If I measure with REW I get results like you posted. Nice smooth line turned into a not smooth line.
It always makes me wonder, if we are measuring frequency only and ignoring time is it a valid measurement? Is there anyone with the knowledge to comment of the frequency time relationship? I am seriously considering adding a mini dsp to put in a hi pass filter for my DTS 10 and adding a Adyssey SVS unit to do the bass. What bothers me is that I want to be able to validate what the SVS unit is doing but I don't think that can be done with a simple frequency response graph. It would take a leap of faith to do this. I am not good at leaps of faith.

I'd love to hear opinions.

T6

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