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Understanding the State of the Art of Digital Room Correction

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mitchco

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A deep dive presentation on the fundamentals of "proper" Digital Room Correction (DRC). Includes hands-on DSP FIR Filter Designer demos using Acourate and Audiolense.

Having participated in many audio forum discussions, having watched online videos on Digital Room Correction (or DRC), and having reviewed over a dozen DRC products over the past 11 years, I have come to two conclusions. One is that there is considerable misunderstanding about DRC, how it works and even what problems DRC is trying to solve. And, just as important, understanding what is possible using the SOTA of DRC. I hope you find the content educational and practical.

 

Matias

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This speaks for itself! :oops:

print.jpg
 

jtwrace

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I wonder if more people would try it and like it if they said "the digital filters need 100 hours to burn in". Then, for some, it would be easier to get past the change in the sound.
I have a good story about that. :p
 

ta240

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I'm done buying audio stuff for quite some time so, maybe someday I'll find out if it would work for me.
 

spacevector

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@mitchco, might you be able to share the presentation so I can follow the links on various slides?
Very nice video btw!
 

dougi

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I understand that this is all possible to do now and well explained, but convince me it is all necessary! Isn't the jury still out whether time domain/FIR correction is really needed and has it proven to be audible? I suppose if you can do it practically and get an ideal response, you might as well! Speaking with vested interest of course being a RoomPerfect user, which is IIR only I believe and horrible step responses, in part I gather due to the split low/high filter banks and considerable low frequency added group delay.
 

jtwrace

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I understand that this is all possible to do now and well explained, but convince me it is all necessary!
Measure your system, do it, then measure and listen again. Boom.

Isn't the jury still out whether time domain/FIR correction is really needed and has it proven to be audible?

Nope, it is.
 

Another Bob

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I understand that this is all possible to do now and well explained, but convince me it is all necessary! Isn't the jury still out whether time domain/FIR correction is really needed and has it proven to be audible?
It's probably the biggest improvement you can make to your system short of replacing your speakers. I say this as a current Audiolense and former Dirac user.
 

ta240

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I wish there were more, good and somewhat affordable, non-PC, all digital options for those that don't use a PC as their source. Something like the PW-Link/Unison without the glitch.
 

JRS

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Long time believer here. Nearly 20 years ago, I had access to a DEQX, a pair of inexpensive JBL bookshelf loudspeakers, and the highly regarded 10K/pair Infinity Preludes. In spite of never having used DEQX before (which required several hours to sort out), it was only a matter of a few hours before it was difficult to tell the two apart at moderate volumes. Naturally as one increased the volume and/or LF material, the advantage of a dedicated integral 400W subwoofer was obvious.

Took the Preludes back to a Magnolia store and asked for a refund. I haven't bought a pair of high end speakers since--mind you prior to the Preludes, I had owned Thiel 3.5, Dunlavy SC-IV, Infinity IRS Gamma, Infinity Kappa 9's, and Newform ribbon/dynamic hybrids over a period of ten years.

Yes, it makes that big a difference!
 

dougi

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I wish there were more, good and somewhat affordable, non-PC, all digital options for those that don't use a PC as their source. Something like the PW-Link/Unison without the glitch.
Some of the mini-DSP with Dirac live are relatively affordable (eg DDRC-22D) or is DIRAC not as capable as these software solutions? If not, can someone explain why? When I get time, i might try one of the software solutions and c/w with my existing RoomPerfect. Can anyone recommend where to start to try it out, preferably something that will run OK on an i5 based small PC?
 

jtwrace

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Some of the mini-DSP with Dirac live are relatively affordable (eg DDRC-22D) or is DIRAC not as capable as these software solutions? If not, can someone explain why? When I get time, i might try one of the software solutions and c/w with my existing RoomPerfect. Can anyone recommend where to start to try it out, preferably something that will run OK on an i5 based small PC?
Dirac isn't close to these...watch the video as Mitch will explain it all.
 

Another Bob

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Can anyone recommend where to start to try it out, preferably something that will run OK on an i5 based small PC?
You can download Audiolense without buying it and it will run in demo mode. In demo mode you can do the full measurement and filter design process, and you can create a .WAV file of 30 seconds of one of your music files with the correction applied. It just won't let you save the filter for ongoing use.

I am using Audiolense on an i5-based NUC and it works just fine.
 

jtwrace

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My pet peeve in presentations - the presenter reading text off slides - and in an almost dead monotone. I'm not going to sit through nearly 2 hours of that.

Just put it in a document, and I can read it myself.
At least you're not critical of the mans first video. :p It's very informative so if you can watch it, you'll likely learn something. Perhaps @mitchco will publish the PowerPoint Presentation too.

If you want to learn more about Mitch, see this video with me here.
 

audio2design

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Isn't the jury still out whether time domain/FIR correction is really needed and has it proven to be audible?

Nope, it is.

Nope it is not, at least at the speaker level as discussed in the last few posts. It really depend on the frequency range of the drivers and whether you have a cross-over in the critical ITD frequency range. There is a reason why there is no preference advantage for so called time aligned speakers overall. We are not talking totally unaligned, but close enough.
 

jtwrace

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Nope it is not, at least at the speaker level as discussed in the last few posts. It really depend on the frequency range of the drivers and whether you have a cross-over in the critical ITD frequency range. There is a reason why there is no preference advantage for so called time aligned speakers overall. We are not talking totally unaligned, but close enough.
???
 

Morpheus

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Thanks a lot to whoever actually did this, it was a long time coming...Could have found a better Mitchco impersonator though, even without my glasses its a tough sell.. ;)
 
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