Article: Dirac Live 2 Digital Room Correction Software Walkthrough

[mitchco]

Hello @cpdk welcome to Audiophile Style and thanks for your comment.

 

Yes, the answer is in the 5th paragraph of the conclusion. 

 

Kind regards,

Mitch

[hulkss]

Hi Mitch,

Another great article. Thanks.

 

I gave the new Dirac VST plug-in a try. I found some bugs and it does not yet support multi-channel home theater. I'm now on their beta-tester list and will try it again in the future.

 

I like the Dirac VST plug-in because I can insert it in JRiver DSP with other audio processing.

 

I'm now a big fan of the Multi-Sub Optimizer (MSO) software. It's the best ever for low frequency correction assuming you have multiple subwoofer channels. I posted my experience here: Optimization of a Subwoofer Line Array with MSO

 

I hope to try Dirac with my MSO subwoofers in the future.

[mitchco]

Hi @hulkss good to hear from you! Thanks for your comments. I have used MSO as well. Excellent software!  Would be curious to see the corresponding phase response that goes with the frequency response plots in your MSO post...

Hope you are well.

Kind regards,

Mitch

[hulkss]

2 hours ago, mitchco said:

Hi @hulkss good to hear from you! Thanks for your comments. I have used MSO as well. Excellent software!  Would be curious to see the corresponding phase response that goes with the frequency response plots in your MSO post...

Hope you are well.

Kind regards,

Mitch

 

Sure, I'll add a couple more charts in a post to the thread I started.

[wgb113]

Great article Mitch!  I’d love to jump down this rabbit hole but I can’t wrap my head around how to implement it in my system:

Sources:

Mac running iTunes/Roon

Cambridge Audio CXC

Technics SL-1200GR

 

All run into a pair of KEF LS50W.  I’m not sure if an additional piece of hardware like something from miniDSP is the way to go or if I just need to look at other options.

 

Bill

 

[mitchco]

Bill, great to hear from you! I hope all is well.

Dirac suggests: http://diracdocs.com/Roon_&_Dirac_Live_2.0.pdf to work with Roon. 

I don't know how your other sources are hooked up, but the idea is that the input signal would be routed through Audio Hijack to Dirac Live Processor and then out to your LS50W.

Don't have a Mac or LS50W, so could not say for say for sure...

Hope that helps.

Mitch

 

[wgb113]

19 hours ago, mitchco said:

Bill, great to hear from you! I hope all is well.

Dirac suggests: http://diracdocs.com/Roon_&_Dirac_Live_2.0.pdf to work with Roon. 

I don't know how your other sources are hooked up, but the idea is that the input signal would be routed through Audio Hijack to Dirac Live Processor and then out to your LS50W.

Don't have a Mac or LS50W, so could not say for say for sure...

Hope that helps.

Mitch

 

Mitch,

 

Thanks for the response!  In order to get all of my sources to benefit from Dirac would a hardware solution like the miniDSP DDRC-24: https://www.minidsp.com/products/dirac-series/ddrc-24  be better?  Signal path would be:  Sources->miniDSP & Dirac->KEF LS50W

 

As an aside I made a first attempt at measuring using a UMIK-1/REW to come up with filters for Roon to use and it seemed to take away bass.  Is it safe to assume those are just room modes I've become accustomed to?  My room is small 12L x 10W x 9H so it's an acoustical challenge to say the least.

 

Bill

[mitchco]

Bill,

 

The miniDSP DDRC-24 should work no doubt. I have never used one, but I know it has a limited amount of filter taps as compared to the processing on a PC. Less taps generally means less low frequency resolution. However, I can't speak about how Dirac 2 is implemented in the miniDSP unit and may or may not be an issue. Perhaps @flak can comment or a post on the miniDSP forum or maybe another member has experience with this combo and can comment...

 

Wrt 2nd question, hard to say without seeing any before and after graphs. It could be room modes, but could also be the target is a bit too bright that makes the bass sound thin. If you could post some charts that would assist. Also, feel free to add a bit of bass boost like in this target from the miniDSP Dirac 2 user manual: https://www.minidsp.com/images/documents/miniDSP Dirac Live 2.0 User Manual.pdf  See page 36.

 

Kind regards,

Mitch 

[wgb113]

4 hours ago, mitchco said:

Wrt 2nd question, hard to say without seeing any before and after graphs. It could be room modes, but could also be the target is a bit too bright that makes the bass sound thin. If you could post some charts that would assist.

 

 

Mitch,

I’ll have to try and attach some charts but I was thinking back to some the Hartman white papers I’ve read and if Dirac is trying to fill some of the dips in the bass and those dips are due to room modes isn’t any boost it applies going to make that dip worse?  Shouldn’t it instead focus on bringing down the peaks?

What charts would help and what smoothing/windows would you want to see them in?  Would you want FR using REW’s sweep or using pink noise?  What time window would you want to see on a waterfall plot?

[mitchco]

Hi Bill, Dirac I believe is cut only filters, so if you lower the peaks to be even with the majority and not worry about the narrow dips. Narrows dips we don't hear.

 

Sure. just use REW's default settings and sweep 10 Hz to 24 kHz using a 48 kHz sample rate of the left and right speakers at the listening position. Just PM me the .mdat or send to [email protected] and once we sort it out, you can post the results here if you wish.

 

Mitch

 

 

[Iansr]

This sounds like something most “audiophiles” would want, however, am I correct in understanding that you need a computer based audio player to implement it? How would you use it if you just use a discrete streaming device like an Aries mini?

Also, same question if you have a turntable?

[Kal Rubinson]

6 hours ago, Iansr said:

This sounds like something most “audiophiles” would want, however, am I correct in understanding that you need a computer based audio player to implement it?

Yup although some hardware players are now implementing it.  See NAD M10 https://www.stereophile.com/content/nad-masters-series-m10-streaming-integrated-amplifier

6 hours ago, Iansr said:

How would you use it if you just use a discrete streaming device like an Aries mini?

Pipe it through such a player or, as I do, using Jriver on my PC-based audio player, pipe it through JRiver.

6 hours ago, Iansr said:

Also, same question if you have a turntable?

The M10 has line-level inputs which would support the output of your phono preamp and, AFAIK, digitize the output from the TT.

[wgb113]

2 hours ago, Kal Rubinson said:

Yup although some hardware players are now implementing it.  See NAD M10 https://www.stereophile.com/content/nad-masters-series-m10-streaming-integrated-amplifier

Pipe it through such a player or, as I do, using Jriver on my PC-based audio player, pipe it through JRiver.

The M10 has line-level inputs which would support the output of your phono preamp and, AFAIK, digitize the output from the TT.

 

Similarly Kal, miniDSP offers hardware capable of implementing Dirac Live's filters to analog and digital sources.  I'm considering the DDRC-24 which is very reasonable considering you get a full Dirac Live license with it.

 

Just sent my REW measurements off to @mitchco to get his thoughts as my small 12x10x9 room suffers from room modes which I've attempted to alleviate through a combination of a near field setup and DIY acoustic treatments.

 

This article has me very interested in getting as much of the room out of my sound as possible to hear that level of detail I experience with my headphone setup.

 

Bill 

 

P.S. Very sorry to hear about Art.  His voice will be missed in this pursuit of ours.

[Kal Rubinson]

5 hours ago, wgb113 said:

Similarly Kal, miniDSP offers hardware capable of implementing Dirac Live's filters to analog and digital sources.  I'm considering the DDRC-24 which is very reasonable considering you get a full Dirac Live license with it.

I have great respect for miniDSP products but they often have i/o or processing constraints that deter me from doing more than experimenting with them.  

[mitchco]

I agree with @Kal Rubinson. My concern for any hardware DSP is the limited processing power available. Typically they are limited to 4096 FIR filter taps, which is not enough for low frequency control. For example, the miniDSP 2x4 HD in the datasheet talks about 4096 taps. But this is the total number. For 4 channels you have 1024 taps each channel available. The frequency resolution of a 1024 taps filter @ 48 kHz samplerate is 48000/1024 = 46.875 Hz. So below 100 Hz there are just 2 frequency bins at 46.875 and 93.75 Hz. This clearly means that you have no control over the lower frequency range.

 

I don't know how Dirac is implemented in these h/w devices, but on a PC you typically use 65,536 taps per channel which gives full low frequency control. Remember the primary purpose of DRC is to correct the low frequencies below Schroeder. So my review of Dirac 2 is only in the context of using Dirac on a PC. I make no claims on how it works/effectiveness with miniDSP gear or any other hardware.

[Tp]

Hi,

 

great article with really useful information, Thank you for this!

 

i've read all comments as well, but i have a question:

 

should one remove, let say carpet of (7ft by 8ft) between the speakers and listening position as well as sofa before making measurements, or not.  what would be the best excercise?

 

Pictures on the wall, bookshelfs (with books) and maybe some room treatment stuff at the corners should stay where they are when making measurements, right?

 

thanks in advance,

Tp

[mlknez]

I enjoyed your article and want to try it myself.  What is the name of the DSP VST file?  I cant seem to find it anywhere?

[mitchco]

Hi @Tp no need to remove the carpet or other objects on walls, etc. What we are trying to avoid is anything in the direct path between the speakers and microphone like plants coffee table, etc. Also, anything around the microphone can cause odd sounding corrections, hence moving the chair or sofa from around the mic.

 

Hi @mlknez Do you mean DiracLiveProcessor.dll? On my Win10 computer it is located at: C:\Program Files\Common Files\VST2

[flak]

It's still possible to watch a recording of this Webinar by StormAudio about Dirac Live Bass Control... Jakob Agren explains and provides details about its inner workings:
https://register.gotowebinar.com/rt/8043050009869528846

 

Flavio

[Andyman]

 

Firstly I’d like to say thank you Mitch for this excellent article (which I’ve only got around to looking at now with “benefit” of UK Covid lockdown!) 

 

I do have a couple of questions further to both the article and following comments.

 

Firstly the measuring bit looks fairly straightforward - hopefully a case of just getting used to the interface and software.

 

Here, and further to your answer to Ted_b question; I get that moving tables, plants etc. whilst measuring makes sense, but I humbly suggest that (especially in smaller rooms - see final question below) the sofa is effectively part of the room and might best be left in situ; moving it could have quite a large impact?

 

[As an aside I believe the acoustics of auditoria are modelled even to account for the absorption of people in seats - or standing!]

 

What then is unclear to me (also having looked at Dirac’s website) is, having chosen target curve and generated filter, how to implement; in my case using Mac and Audirvana. I don’t see any mention of AU plugin but believe this would be the default for Dirac and A+?

 

But then, screen shots seem to show the filters as for a specific sample rate and bit depth (is this correct?) A+ will happily playback whatever rate file is chosen (without SRC unless chosen) so would I need separate filters per SR/depth or would one one filter “adapt” to the rate chosen? Or something else...

 

Back to your own adventure, once you have generated and implemented filters, I am slightly confused why you choose to use REW to verify? Is it not possible simply to measure again (Dirac) after you’ve applied your target eq so you’re looking at the changes in the same “format”? Or if this is possible, why then would you choose to use REW?

 

Finally, a further question on a practical level. A friend of mine has recently moved house and has a small room (similar in size to that of Bill - wgb113) which he intends to use solely for audio, and into which he has shoehorned his existing system. At the moment his B&W floorstanders are almost wedged into corners, necessitating port bungs in place. Even so, really not sounding all that great (don’t worry, the chances of him reading this are minuscule!) and seems like the perfect candidate for testing. Would it make more sense to remove bungs, allowing the speakers to breathe and letting Dirac take care of everything? Or leave them in so less work for eq?

 

Best wishes all. And Mitch, I for one would greatly enjoy a follow up article if you do have time.

 

Andy

[mitchco]

Cheers @Andyman

 

Wrt questions about Audirvana, AU plugin and sample rates, are product questions that perhaps Flavio @flak can answer as I don't have a Mac.

 

While one could use Dirac to measure the correction result, it is typical to use a 3rd party application for verification measurements. In my case, I have been using REW for +ten years and as a general acoustic measurement software, it has several additional acoustical analysis displays that Dirac does not have. For example, one typically uses a Step response as one of the verification measurements to view the timing response of the loudspeaker, which I show in the article. Also REW allows us to share measurements in a portable format and compare measurements in overlays.

 

I usually put "ideally" in front of moving objects out of the path between the speakers the measurement mic. Of course, it may not be possible. The issue with the couch depends on how close the back of the couch is to the microphone and how reflective the couch surface is. For example, if the mic is 6" or 12" away from a reflective surface is right in the midrange and upper midrange frequency range, where our ears are the most sensitive. Further, because of the close proximity and how reflective the couch is, the reflected sound may be as high in amplitude as the direct sound. Producing a correction in this situation will not sound very good. If there is no choice, try and throw thick wool blankets over the couch area that the mic is moving around which will limit the comb filtering in the analysis and produce a much better sounding correction filter.  I encourage folks to try it for themselves and hear what I am talking about.

 

Re: B&W floorstanders. Take a measurement with the bungs in, then take another measurement with the bungs out Which one produces the flattest response? Go with that. As a general guide, we want to try and get the best sound possible before room correction. It is not so much about less work for the room correction software but the better the setup before hand the better the correction, meaning better sound quality.

 

Thanks Andy, I am looking forward to putting Dirac Live Bass Management through its paces!

 

Kind regards,

Mitch

[asdf1000]

On 4/17/2020 at 12:35 AM, mitchco said:

I don't know how Dirac is implemented in these h/w devices, but on a PC you typically use 65,536 taps per channel which gives full low frequency control. Remember the primary purpose of DRC is to correct the low frequencies below Schroeder. So my review of Dirac 2 is only in the context of using Dirac on a PC. I make no claims on how it works/effectiveness with miniDSP gear or any other hardware.

 

Hi @mitchco (maybe also @flak)

 

Does Dirac Live 2.0 (or later) + Dirac Live Plugin on PC use 65k taps ?

 

Has this been confirmed specifically for Dirac?

 

I know Audiolense and Acourate do (and even higher number of taps)

 

[Cazzesman]

https://live.dirac.com/download/

 

DL 3.0 I see is out.

 

Time to start again Mitchco 😀

 

Thanks for a great article.   I run my DL 2.0 within Minidsp 22D and into Kii 3's.   Very happy with the result.

 

Regards Cazzesman

[wanta911]

A great post as always Mitch.

 

I have been using Dirac with a MiniDSP DDRC-22D for years now with my B&W 803D speakers and with Dirac V3.0 now out I finally decided to update from V2.3 and run my measurements again using your recommendation of removing furniture. In the past I have removed objects between the LP and speakers (if any) but have left the L shaped leather couch in place. I would describe my room as tending to be more on the dead side with carpeted floors and absorption on the wall approx. 1.5m behind the listening position. I guess the couch would have been a major point of reflections?

 

One slight bugbear in the past was that whilst Dirac did a great job as far as frequency correction was concerned, the sound always seemed to lack the "openness" of the uncorrected playback and that is now back without losing any imaging focus. Historically I never liked recommended target curves of more than 6dB maximum tilt, as they invariably sounded dull. I am listening now with a straight 8dB tilt from 20Hz to 20kHz and it sounds great.

 

I don't know if the improvement I'm hearing is due to the new software or the couch removal during measurement or a combination of both....and I really don't care 😀  Interestingly my first impression with the new measurements apart from the increased openness is that everything sounds just a touch slower and coherent. 

[R1200CL]

On 4/16/2020 at 6:35 PM, mitchco said:

I don't know how Dirac is implemented in these h/w devices, but on a PC you typically use 65,536 taps per channel which gives full low frequency control. Remember the primary purpose of DRC is to correct the low frequencies below Schroeder. So my review of Dirac 2 is only in the context of using Dirac on a PC

Could one (Dirac) limit the frequency band below a certain frequency ? Like you concentrate the frequency taps in restricted area, and then achieve a more narrow frequency bin. 
 

I think no, cause this is about frequency resolution, so you can’t shrink somehow. 
 

Also some HW manufacturers is using 96 kHz, and then you actually need double the number  of taps in in order to achieve same resolution. Correct ?

 

What would be an acceptable frequency bin or resolution ?

I probably don’t ask the correct question, but I hope you somehow understand what I’m thinking about 😀

Like adjusting more taps to lover frequencies. And less to the higher ones. Don’t think this make sense. 

96000/65536 = 1.46 Hz. Would you like to see a lower number, or what is acceptable In your opinion ?

I notice Dirac now have a basic version below 500 Hz for 3.x, and then you pay extra in order to get access to adjust frequency above that. 
I still would think Dirac requires some sort of available processing power from the HW manufacturers. Unless Dirac supplies the board to the manufacturers. Do you happen to know anything about how this works ?