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post #31 of 204 Old 12-28-2013, 06:30 AM
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I am not sure what you hear, but the lossless copy i have, that also sound funny, don't seem to clip the bass. I believe its the center channel. It contains very little bass but has a few flat spots that could indicate clipped content. I got it from demo-world.eu.
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post #32 of 204 Old 12-28-2013, 07:55 AM - Thread Starter
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Quote:
Originally Posted by splotten View Post

I am not sure what you hear, but the lossless copy i have, that also sound funny, don't seem to clip the bass. I believe its the center channel. It contains very little bass but has a few flat spots that could indicate clipped content. I got it from demo-world.eu.

I analyzed the lossless version from demoworld and an AC-3 version that I was using. It is interesting to see that only the lossless version suffer from clipping in LFE and center channel. The AC-3 version don't. But still sounds a bit like clipping. Maybe this is intended by the creator.

Here is the LFE channel when the mushrooms come in.

AC-3:


DTS-Master:

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post #33 of 204 Old 12-28-2013, 11:49 AM
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Funny. My loss less version doesn't look like that in Audacity. Have you converted the file to analyze it. Mine was converted in TaudioConverter to open it in Audacity.



This screen shot is 26 seconds in.
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post #34 of 204 Old 12-28-2013, 12:06 PM - Thread Starter
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Originally Posted by splotten View Post

Funny. My loss less version doesn't look like that in Audacity. Have you converted the file to analyze it. Mine was converted in TaudioConverter to open it in Audacity.

I used eac3to with Sonic decoder. Maybe this part produces the clipping...

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post #35 of 204 Old 12-28-2013, 12:12 PM
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Yes. In a computer there is a lot of possibilities for something to wrong. In might be worth looking into if you use it for actual playback. Maybe you should try to capture the actual analog output from the soundcard if that is the case.

TaudioConverter uses FFMpeg to convert to Wav so that i can open the file in Audacity.
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post #36 of 204 Old 12-28-2013, 12:27 PM
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Here is a shot 17 seconds in to compare with.



I think this is actually the part your screenshot is from.
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post #37 of 204 Old 12-28-2013, 12:47 PM
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Beautiful system. Thanks for sharing. I thought your mains were Genelecs as well. I've don't a few waveguide speakers using dome tweeters. But never a dome mid. I got a friend in the US who has CNCed a few dome mid waveguides. About 14" wide. I haven't had the chance to try them though. I haven't talked to him in to long. You're making me dream. smile.gif

Enjoy your amazing creation.
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post #38 of 204 Old 12-28-2013, 01:55 PM
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Another inspirational build. Thank you for sharing.


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post #39 of 204 Old 12-29-2013, 12:19 AM - Thread Starter
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Quote:
Originally Posted by splotten View Post

Yes. In a computer there is a lot of possibilities for something to wrong. In might be worth looking into if you use it for actual playback. Maybe you should try to capture the actual analog output from the soundcard if that is the case.

Actually I use an Onkyo PR-SC5507 to decode the signal. But maybe I check this trailer when I have time. smile.gif


@all
I want to show how good the absorber on the back wall works and how it absorbs the length modes. The measurements are nearly unsmoothed (1/48 oct).

Frequency response:


Linearity changed from about +/- 30 dB to about +/- 7 dB. With equalizer +/- 2.5 dB is achieved in the range 4 - 200 Hz. This equals nearly 6 octaves.

Decay (empty room):


Decay (with absorber, without equalizer):


There is nothing left of the length modes. The concept works! smile.gif

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post #40 of 204 Old 12-29-2013, 02:34 AM
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Quote:
Originally Posted by splotten View Post

Funny. My loss less version doesn't look like that in Audacity. Have you converted the file to analyze it. Mine was converted in TaudioConverter to open it in Audacity.



This screen shot is 26 seconds in.

Sorry to be OT, but...

What channel is this, and what decoder are you using to decode the DTS-HDMA to wav? I have looked at both the trailer available at demo-world and the one on StarWars BD and found them to be very close. Using ArcSoft DTS decoder, the LFE channel clips on both versions, wither while looking at the DTS core or the DTSHD stream. Of course, place a 120Hz Lowpass and the clipping turns into a much nicer waveform.

JSS
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post #41 of 204 Old 12-29-2013, 03:35 AM
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It is the LFE channel. As stated, I have used Taudioconverter. It uses FFmpeg to convert to multi channel wav. I looked into to the issue a bit since posting that screenshot and it appears that it might only be the core portion that is actually converted. If any filtering is applied, it is done "behind the curtain" in the sense that I haven't applied anything on purpose or am aware that it happens. If FFmepeg applies filtering as a default setting that might be the reson. I have no other explanation for the discrepancy between my conversion and follgotts, but I have listened via headphones to that particular track as a solo track and i cant detect any artifacts or weird sounds. If I play all tracks at once, as a stereo mix, audacity clips it and it will sound bad.

Here is the encoding summary if that helps:

[29-12-2013 13:55:14] ----Encoding Summary----
[29-12-2013 13:55:14] -Number of processes: 2
[29-12-2013 13:55:14] -Copy tags: True
[29-12-2013 13:55:14] -Use custom tags: False
[29-12-2013 13:55:14] -Enable artwork: False
[29-12-2013 13:55:14] -Copy artwork to output: True
[29-12-2013 13:55:14] -Copy external artwork: False
[29-12-2013 13:55:14] -Download lyric: False
[29-12-2013 13:55:14] -Add encoder suffix: True
[29-12-2013 13:55:14] +Audio
[29-12-2013 13:55:14] -Encoder: Wav
[29-12-2013 13:55:14] -Bit Depth: Original
[29-12-2013 13:55:14] +Effects
[29-12-2013 13:55:14] -Disabled
[29-12-2013 13:55:14] Temp: C:\Users\'''\AppData\Local\Temp\TAudioConverter\
[29-12-2013 13:55:14] Output: C:\Users\Downloads\hd_thx_amazing_life_lossless.part2\hd_thx_amazing_life_lossless2
[29-12-2013 13:55:14] ----Encoding Summary----

As far as i can tell there is no clipping protection when Effects is disabled.

Its the loss less version found here:

http://www.demo-world.eu/trailers/high-definition-trailers.php

... And sorry for even more OT :-)

BTW. Amazing results FollGott. smile.gif
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post #42 of 204 Old 12-29-2013, 09:00 AM
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Your absorber results are nearly unbelievable.

You're 2m from the back wall? Fairly text book if you are. I wonder how a nearfield sub would manage that 42hz null and if it wouldn't be as good. That much absorbent is a lot for most people.
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post #43 of 204 Old 12-29-2013, 09:19 AM
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Quote:
Originally Posted by FoLLgoTT View Post



@all
I want to show how good the absorber on the back wall works and how it absorbs the length modes. The measurements are nearly unsmoothed (1/48 oct).

Frequency response:


Linearity changed from about +/- 30 dB to about +/- 7 dB. With equalizer +/- 2.5 dB is achieved in the range 4 - 200 Hz. This equals nearly 6 octaves.

Decay (empty room):


There is nothing left of the length modes. The concept works! smile.gif

Hey F, great stuff.

In the amp thread, you posted a link to your amp loopback measurement. I pasted that onto your in-room measurement and wanted to get your comments. Since we assume room gain effects continue to DC, the difference between your loopback and the in-room is not trivial. It could be from a number of things; measurement rig calibration and signal chain being the top suspects. I'm pretty sure I read that you had investigated the entire chain with flat response in mind, but could you post what the signal chain was for the in-room measurement?

Don't get me wrong here, your in-room roll off is enviable. It really doesn't matter to me where the roll off begins, I've just been curious as to the in-room roll off vs the signal chain roll off and haven't gotten any traction with the subject in the past. Another piece of curious input is that when anyone posts a close-mic FR of their sub on a graph to 2 Hz, there never seems to be evidence of any signal chain roll off (see 2nd pic below).



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post #44 of 204 Old 12-29-2013, 09:46 AM
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Quote:
Originally Posted by FoLLgoTT View Post

@all
I want to show how good the absorber on the back wall works and how it absorbs the length modes. The measurements are nearly unsmoothed (1/48 oct).

Linearity changed from about +/- 30 dB to about +/- 7 dB. With equalizer +/- 2.5 dB is achieved in the range 4 - 200 Hz. This equals nearly 6 octaves.

There is nothing left of the length modes. The concept works! smile.gif

Nice

You can clearly see the first and second axial length modes 1, 0, 0 and 2, 0, 0, and they correspond to the 28.7hz and 54.7hz textbook numbers based upon your 6m 4.8m 2.2m dimensions.

The decay is nice, but equally as impressive is the absence of the destructive null from the returning energy off the rear wall. The sharp Q somewhat rigid boundaries are in evidence too, pre treatment.

Curious, to what do you attribute the low 70s behavior?

Also, thanks for the link on the mains, very nice even in German. Really put my skills to the test, my German is rusty despite living in Kassel, West Germany, as an exchange student in high school.

Alles Gute!

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Flat, Deep, Clean, Linear, and Loud
------------------------------------
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(3)Seaton Cat12C up front, (4)QSC K8 sides/rears
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post #45 of 204 Old 12-29-2013, 10:11 AM - Thread Starter
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Quote:
Originally Posted by bossobass View Post

In the amp thread, you posted a link to your amp loopback measurement. I pasted that onto your in-room measurement and wanted to get your comments. Since we assume room gain effects continue to DC, the difference between your loopback and the in-room is not trivial. It could be from a number of things; measurement rig calibration and signal chain being the top suspects. I'm pretty sure I read that you had investigated the entire chain with flat response in mind, but could you post what the signal chain was for the in-room measurement?

The chain was:

Onkyo PR-SC5507 -> K+H Pro C 28 -> Sanway FP14000



But I don't know how exactly the Onkyo behave with HDMI input (with which the in-room measurement was taken). I did early measurements where soundcard was directly connected to the Sanway and the rolloff was there, too. So I don't think it is the signal chain.

Maybe the microphone has a roll-off, too? I mean, I don't know anyone who calibrates mics to the single digits. I just assume that it is flat to nearly DC (Audix TM 1), but I don't know it. rolleyes.gif
Quote:
Another piece of curious input is that when anyone posts a close-mic FR of their sub on a graph to 2 Hz, there never seems to be evidence of any signal chain roll off (see 2nd pic below).

Yes, this is strange. It looks like room gain is not excluded from the measurement under a certain frequency. Maybe the relation between direct sound and constructive interferences change? I mean direct sound falls, but constructive interferences raise. I bet the measurement looks different under free air condition (e.g. in the garden).

I never did close mic measurements which were loud enough to yield correct data in the single digits (I never needed this data). And now that 3 drivers are wired in parallel close mic is nearly impossible, because the other two have a very strong influence on the result.

Quote:
Originally Posted by FOH 
Curious, to what do you attribute the low 70s behavior?

I absolutely have no clue. I placed absorbers here and there, but the best place was on the floor directly in front of the subwoofers. When looking at the waterfall diagram you can see 2-3 problems between 70 and 80 Hz. I hope that this gets better when I install more absorbers. But I see it only as a minor problem.
Quote:
Also, thanks for the link on the mains, very nice even in German. Really put my skills to the test, my German is rusty despite living in Kassel, West Germany, as an exchange student in high school.

Thank you. smile.gif
Years ago I had a girl friend near Kassel. She was a nymphomaniac, but I think this wasn't her worst quality... biggrin.gif
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Alles Gute!

Danke, dir auch! Viele Grüße nach Midwest!

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post #46 of 204 Old 12-29-2013, 04:02 PM
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Quote:
Originally Posted by splotten View Post

It is the LFE channel. As stated, I have used Taudioconverter. It uses FFmpeg to convert to multi channel wav. I looked into to the issue a bit since posting that screenshot and it appears that it might only be the core portion that is actually converted. If any filtering is applied, it is done "behind the curtain" in the sense that I haven't applied anything on purpose or am aware that it happens. If FFmepeg applies filtering as a default setting that might be the reson. I have no other explanation for the discrepancy between my conversion and follgotts, but I have listened via headphones to that particular track as a solo track and i cant detect any artifacts or weird sounds. If I play all tracks at once, as a stereo mix, audacity clips it and it will sound bad.

Here is the encoding summary if that helps:

[29-12-2013 13:55:14] ----Encoding Summary----
[29-12-2013 13:55:14] -Number of processes: 2
[29-12-2013 13:55:14] -Copy tags: True
[29-12-2013 13:55:14] -Use custom tags: False
[29-12-2013 13:55:14] -Enable artwork: False
[29-12-2013 13:55:14] -Copy artwork to output: True
[29-12-2013 13:55:14] -Copy external artwork: False
[29-12-2013 13:55:14] -Download lyric: False
[29-12-2013 13:55:14] -Add encoder suffix: True
[29-12-2013 13:55:14] +Audio
[29-12-2013 13:55:14] -Encoder: Wav
[29-12-2013 13:55:14] -Bit Depth: Original
[29-12-2013 13:55:14] +Effects
[29-12-2013 13:55:14] -Disabled
[29-12-2013 13:55:14] Temp: C:\Users\'''\AppData\Local\Temp\TAudioConverter\
[29-12-2013 13:55:14] Output: C:\Users\Downloads\hd_thx_amazing_life_lossless.part2\hd_thx_amazing_life_lossless2
[29-12-2013 13:55:14] ----Encoding Summary----

As far as i can tell there is no clipping protection when Effects is disabled.

Its the loss less version found here:

http://www.demo-world.eu/trailers/high-definition-trailers.php

... And sorry for even more OT :-)

BTW. Amazing results FollGott. smile.gif

AFAIK, FFMpeg's DTS and Dolby decoders are good, but not bit-perfect, and cannot decode the lossless info, only the core. I'll have to do somemore experimentation....to ensure the problem is not on my end.

JSS
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post #47 of 204 Old 12-30-2013, 12:40 PM - Thread Starter
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Here are more measurements. I calibrated everything to reference SPL (85 dB at the listening position with a -20 dB FS signal). The subs were still 5 dB hot.
When I played the end scene of "How to tame a Dragon" I got 130 dB on the SPL meter! And the light got darker when the single digits came into play! eek.gif

And with CEA bursts at 20 Hz I got 130 dB, too.



Here are the nonlinear distortions at 110 dB. K2 is <2.5 % and K3 <1.8 %. Room gain helps to get good results here.



I'm very happy with these results. I would never watch a full movie at reference SPL. It is just too loud for me. But demo scences and trailers are just pure fun. The door is moving so much that I'm afraid that something gets damaged on the house. Even the concrete ceiling is vibrating. My wife came down and she was really upset. She told me I should never do this again! biggrin.gif
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post #48 of 204 Old 12-30-2013, 02:39 PM
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Nice output eek.gif
Dont damage your house wink.gif
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post #49 of 204 Old 12-30-2013, 05:54 PM
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Quote:
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The polar map in the PDF] was done in Excel. I exported several frequency responses from ARTA and made my own diagram. ARTA's directivity patterns are a bit ugly. Excel has more possibilities to make it look good. wink.gif

Really? Very inventive! Are you willing to share the file? I've been looking for a way to get nice polar maps (FuzzMeasure doesn't do them at all) and I don't really know my way around spreadsheets.

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post #50 of 204 Old 12-30-2013, 07:26 PM
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Omnimic can do it as well. Just import the files from a measurement program you own (like fuzz measure). I've personally never done it. But others have. Not sure where it can be downloaded either.

I've done circle polars in excel. Very laborious. Even with a template already made up. Still requires a lot of manipulation.
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post #51 of 204 Old 12-30-2013, 08:30 PM
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Omnimic can do it as well. Just import the files from a measurement program you own (like fuzz measure). I've personally never done it. But others have. Not sure where it can be downloaded either..

Hmm. Never thought about finding Omnimic software, firing up Parallels, and importing FuzzMeasure data. Assuming a license for the OM software can be legitimately acquired, for free or fee, without purchasing the whole get-up.

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post #52 of 204 Old 12-31-2013, 12:53 AM
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Hi Nils,

great work. Thanks for documenting all this madness smile.gif

Did you also measure how the damped SBA performs at different locations?
Quote:
Originally Posted by FoLLgoTT View Post

When I played the end scene of "How to tame a Dragon" I got 130 dB on the SPL meter! And the light got darker when the single digits came into play! eek.gif

Where're the "extra" dBs coming from?

Markus

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post #53 of 204 Old 12-31-2013, 01:54 AM - Thread Starter
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Really? Very inventive! Are you willing to share the file?

I don't have it here. I did the measurement with a friend and he has it on his computer.
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Did you also measure how the damped SBA performs at different locations?

Yes, here we go. The colors of the picture with the two seat rows correspond to the graph. Of course I measured only one side, because the room is symmetrical.





The first seat row looks very good. I already knew from my experiments that the second row is worse. But guests usually don't notice that. wink.gif
Quote:
Where're the "extra" dBs coming from?

The subwoofer was running hot. And all three main channels are very active in this scene.
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post #54 of 204 Old 01-03-2014, 04:48 AM
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I don't have it here. I did the measurement with a friend and he has it on his computer.
Yes, here we go. The colors of the picture with the two seat rows correspond to the graph. Of course I measured only one side, because the room is symmetrical.





The first seat row looks very good. I already knew from my experiments that the second row is worse. But guests usually don't notice that. wink.gif
The subwoofer was running hot. And all three main channels are very active in this scene.

Very nice seat-seat response!

JSS
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post #55 of 204 Old 01-04-2014, 03:07 AM
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.

Yep, nice result.
I remain curious about your overall impressions of the sound in the room when you're done, and what you're going to cover that back wall of insulation with.

My biggest experiment with covering an entire wall was with a front wall, 4" of insulation with a 4" air gap, and I didn't enjoy the reduction in ambiance.



Yours reminded me of Philip Newell's Non-Environment Room (13' tall room, with 5' of insulation in the ceiling, 3' of insulation on the back wall, 2' on left and right walls, and the front wall and floor reflective).

and a little of that pile of insulation in RoyalDevice's room:
http://www.bobgolds.com/royaldevice_SubwooferHorn_FiberglassCurtain_34a.jpg
http://www.royaldevice.com/custom.htm

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post #56 of 204 Old 01-04-2014, 07:11 AM
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Originally Posted by BasementBob View Post

Yep, nice result.
I remain curious about your overall impressions of the sound in the room when you're done, and what you're going to cover that back wall of insulation with.

My biggest experiment with covering an entire wall was with a front wall, 4" of insulation with a 4" air gap, and I didn't enjoy the reduction in ambiance.



Yours reminded me of Philip Newell's Non-Environment Room (13' tall room, with 5' of insulation in the ceiling, 3' of insulation on the back wall, 2' on left and right walls, and the front wall and floor reflective).

and a little of that pile of insulation in RoyalDevice's room:
http://www.bobgolds.com/royaldevice_SubwooferHorn_FiberglassCurtain_34a.jpg
http://www.royaldevice.com/custom.htm

Would using a diffuser that is transparent to the lower frequencies maintain the ambience?
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post #57 of 204 Old 01-04-2014, 07:30 AM - Thread Starter
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Originally Posted by BasementBob View Post

Yours reminded me of Philip Newell's Non-Environment Room (13' tall room, with 5' of insulation in the ceiling, 3' of insulation on the back wall, 2' on left and right walls, and the front wall and floor reflective).

At the moment my RT60 is > 0.5 s in the mids and highs. The recommendation is about 0.25 s. So I don't see any problem. And if RT60 is going to low, I will install slats or additional diffusers in front of the absorber.

When all this is finished I will write my impressions. smile.gif

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post #58 of 204 Old 01-04-2014, 02:14 PM
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Originally Posted by mikela View Post

Would using a diffuser that is transparent to the lower frequencies maintain the ambience?

My rear wall works that way & I'm satisfied with it. (No actual absorber, it is transparent near DC.)

Paul W

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post #59 of 204 Old 01-05-2014, 06:06 AM
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Originally Posted by FoLLgoTT View Post

At the moment my RT60 is > 0.5 s in the mids and highs. The recommendation is about 0.25 s. So I don't see any problem. And if RT60 is going to low, I will install slats or additional diffusers in front of the absorber.

When all this is finished I will write my impressions. smile.gif

What is RT60? Is this a measure of the time domain? What does RT60 tell you about the subwoofer setup, and how can the RT60 be adjusted?
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post #60 of 204 Old 01-05-2014, 06:36 AM - Thread Starter
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What is RT60? Is this a measure of the time domain? What does RT60 tell you about the subwoofer setup, and how can the RT60 be adjusted?

Yes, RT60 is a metric to quantify reverberation time. It is only valid with a statistical diffuse field (above Schröder frequency). This means >x00 Hz the RT60 value represents the time for which SPL is down to -60 dB of the original signal. Every absorber in the room lowers RT60. It is recommended to aim for a value of about 0.25 s.

In modal region RT60 metric does not apply. The bass region is a strong modal region.
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