Digital Room Correction (DRC) discussion

I was a staff member and reviewer at Home Theater Shack (the folks who wrote RoomEQWizard) for many years, and through necessity I had to become an expert at using it to measure gear and digitally correct my system.

As a home theater gear reviewer, I've also used Audyssey (MultEQ, XT, XT32) and am an Audyssey pro installer, Anthem Room Correction (ARC), Dirac Live and MiniDSP with custom filters extensively.

After countless hours spent calibrating my own system and review gear, I still love DRC, but I've learned that you can't take shortcuts to good sound. Proper acoustic treatment is necessary if you want excellent reproduction of sound, no matter how good you are with your EQ/DRC system. Here's what I've learned:

• DRC is fantastic for LFE/bass. if you have subs, you need to be using DRC, no question. Any product will work fine for subs as long as it has enough bands of EQ to correct the major issues.
• DRC can do a good job of taming bad room anomalies and is critical to a fully optimized system, but the quality of your DSP matters. If you are serious about quality, invest in a QSC Core110f and do it right - we spend crazy money on DACs and sources, why cheap out on the A->D->A step in your chain at the EQ and sacrifice that fidelity?
• Properly implemented acoustic treatments are far superior to DRC for major acoustic issues (SBIR,nulls,echo/slapback), and also enable DRC to more fully optimize a system. While it's possible to get a room close to perfect with acoustic treatments (I've got $3000 in acoustic treatments in my room), DRC will take it the final 10%.

 

Bonus on the acoustic treatments: maybe you won't need to worry about DRC for your vinyl playback if your room is acoustically sound.

I agree with SineDave about getting that last 10% in a properly treated room. However, it can also vastly improve the subsubsuboptimal rooms many of us must listen in for aesthetic or lifestyle reasons (i.e. living room to be shared with spouse and/or kids, giant bass traps not so sexy). Nothing will ever replace proper acoustics. But for the apartment living room I'm in, where I simply won't be placing acoustic treatments? Could be really good in at least getting the FR about right.

However, there is a reason my wife includes a listening room when she works on future house layouts. Gotta have it. Hate having great playback at work and coming home! Definitely a reason I rely heavily on headphone playback these days. Much easier to do that then sink $2k into treatments and buy a second set of speakers.

 

Great point - it's certainly a godsend when you can't treat at all, but these days no matter how choosy the spouse is, you can probably at least do something.

All sorts of decor appropriate acoustic products are starting to come out, and that is fantastic news. I love the fact that you can now buy GIK panels with printed artwork: http://www.gikacoustics.com/product/gik-artpanel-acoustic-panels/

Even bass traps can now be spouse appropriate: http://www.acoustimac.com/bass-traps/acousticart-bass-traps

Failing that, you can also hide cylindrical bass traps under tables and get really creative.

 

In the specific situation I was referencing, I am running an Xbox One S, OPPO UDP-203, OPPO DV-983H, and Windows HTPC. The solution that will take any of those HDMI audio signals in a convenient way and run Dirac over them is not a computer.

Also, as SineDave has mentioned, Dirac can only work with what it's given. Room treatments and your choice of gear still matters a lot. Dirac will not make everything sound the same.

 

Okay I finally managed to use the same measurement setup for both, Dirac and Sonarworks ("SW" henceforth). After a lot of A/Bing, here are my thoughts:

Measuring and making corrections: Well, SW is insanely easy to work with while making measurements. Being able to locate where your mic is direct you visually is a really cool feature and you really cant make a mistake this way. With Dirac I had to keep switching between the top/front/oblique view to see where they wanted me to place my mic so it was a bit more tedious.
Its a toss up when actually making corrections though, because dirac offers a fully customisable target curve and the ability to correct the impulse response. Sonarworks on the other hand has some presets you can pick or a basic curve that can be customised by overall tilt and bass boost. It does, however have options to choose how much correction you would like via a dry/wet knob and an advanced menu that lets you choose how far up or down you want to make corrections and by how much (normal, reduced or no boost).

Sound: My first impressions somehow were that Dirac was a LOT better than SW, I'm not sure why. It felt like Dirac opened everything up like lifting a veil, fixed the bass modes/nulls as much as possible while SW was only helping with the bass and not too much else (relatively). I think I was really biased somehow on the first few days I actually compared them, probably just hyped knowing that Dirac corrected the impulse as well and allowed me to tweak the target more.
BUT over the last two days or so, I find them a lot closer in performance. Maybe it was also affected by my tedious first attempt at comparison where I had to change volume (8 steps on the GO2A), then quit one application, start up the other and change the output device in the system preferences, while in my second attempt I just an SW into Dirac and then turned on one of their corrections alternatively so it was a more direct A/B.
Based on this second A/B setup, I think SW does a slightly better job dealing with the bass correction (also is able to make your speakers go lower than Dirac), and Dirac does do a bit better up top, making things a bit cleaner with transients. Small differences, and probably only noticeable when A/B-ing.
They both do a really good job turning my speakers' messed up response in this crappy temporary university room into something far more enjoyable. I know this room was bad, but this kind of gives me a glimpse of how bad. There is actual soundstage now, and bass! With sonarworks on the extended bass correction setting, it shows that it makes my speakers go down to 50-60Hz, something I'm not used to hearing at all and its a bit messy without actual treatment so I stick to the normal setting.

Interface: I prefer SW on this. Its a cleaner more straightforward setup, albeit a bit annoying when I plug/unplug a device and it throws a pop asking if i want to apply correction to the current device (a minor issue though). Dirac has crashed on me randomly a few times too so that factors into my preference a bit.

I wont write too much more here since you probably will get their trials and check them out for yourselves and make a choice based on your subjective preferences. I ended up buying SW because they offered a 50% education discount so that made it much much more worth it (a steal I'd say).

I havent proof read this post, so there might be some minor corrections when I do later today.

 

It's not obvious, but you can manually edit the target text file and change the min and max frequencies that are included in the correction window. To values that are lower and higher than what you can get by dragging the left and right handles in the GUI. In case that's what you were referring to when you say SW can make your speakers go lower than Dirac.

 

Yeah I dragged the handles all the way and tried with Dirac but sonarworks still managed to correct the 60-100hz range better.. You can also see this in the measurements from REW that I posted earlier
Edit: from the graphs, it looks like SW did a better job beyond 100Hz as well. I didnt realise this before but it makes sense now why i prefer SW's bass correction

Oh I also forgot to mention earlier, sonarworks has a phase correction option and that adds to the overall result pretty significantly as well. I use the minimum phase filter since that sounds best to my ears. @Hrodulf had mentioned that the phase correction does clean up the impulse response indirectly so I guess that makes Dirac and SW so close.

 

I sold @philipmorgan my DDRC-24 as I got better results using balanced connections with my Ayre preamp, so I kept my DDRC-22A instead.

I initially was very anti-DSP with the thinking that adding another AD/DA conversion didn't make sense with a turntable, but I found it to be completely transparent. Before I went down to try out Dirac in @shotgunshane's room, I sent him the following:

I resisted room correction for the longest time because I had some sort of notion that I wanted to keep my analog signal "pure" from my turntable or after the output stage of my DAC. I tried so many variations of room treatment, three speaker changes, 5 or 6 amps and 3 different preamps before I finally realized that my room was causing the issues and not my speakers or components. I gave up holding onto my notions of analog purity and tried Dirac and now I'm a believer. I found the actual AD/DA conversion made by the miniDSP module is completely transparent. I've switched preamps and amps since I started using Dirac and found that with room correction active I could clearly hear the differences between components. Even using my turntable, I've never heard better sound. It really is the biggest performance jump out of my 2-channel setup outside of upgrading speakers.

 

Interesting. Do you recall how many bands of EQ the miniDSP units allow?

 

It often baffles me that people argue about the "natural-ness" of DSP, while without it one can get bass peaking in the excess of 10dB in typical small rooms. I know it feels good to preserve the original samples and whatnot, but I wouldn't put it before preserving the original tone of the sound.

5 for non-FIR units, 10 per output for SHARC units.

 

You've got a valid point there. Do you guys over at Sonarworks have a hardware solution in the works? I'd hate to switch back to REW and minidsp after getting your software package!

 

The hardware question pops up every now and then at strategic meetings. From a business perspective starting to produce hardware is scary stuff. I'm sure you've read about Schiit audio and their adventures. For us the first question would be cheap vs. expensive, because the latter can be hand assembled, but former will need serious design-for-manufacturability know-how we currently lack.

Currently the best bet would be measuring your room and sending the file to our support guys, they'll use an experimental version of our software to make a miniDSP compatible file.

 

I've seen untold benefits from Anthem's ARC system in two rooms in our house. Our great room is an open concept with a 7.1 theater integrated into it, featuring a Hsu VTF-15H that sits behind the listeners. ARC puts everything where it's supposed to be up there. The acoustics in that room are shit anyway so I can only expect so much.

But, in my treated audio room downstairs, I run a Statement D2 and ARC pays huge dividends in making this small room believable, deep, and wider than I could ever hope for. Bass is handled by two SVS 12's and I do have bass trapping in here, but before ARC it was hit or miss. Now it's perfectly centered, fast and punchy but not bloated. ARC has done what hours upon hours of repositioning and REW analysis have not. Maybe I just suck at the latter, but ARC makes it easy and doesn't offer any sonic consequences that are offensive to me, at least.

I'd love to try some other options but since I'm 90% analog, it has to be built into a device and I just don't see anything else I can afford that offers the complete package I have in the D2.

 

Any thoughts on Dirac for a simple two channel living room with low end bookshelf speakers (ELAC B6) and no sub?

 

Dirac is pretty nice that it's easy integrate into a MiniDRC box. If you're running a computer setup, then Sonarworks Reference 4 might be a better idea.

 

Should work well. I've been quite impressed by Dirac at home, where I'm currently testing it with an AudioControl processor. Like @Hrodulf says however, if your source is a PC, Sonarworks makes a bit more sense.

 

Thanks. For this room I just use an Apple airport express and an emotiva 100 amp. It sounds good, but better is better. $400 for the minidsp seems like a great way to buy and try this tech, with some easy resale options.

Forgot to say I already have a UMIK-1

 

I'd recommend Dirac, even with a smaller bookshelf speaker setup. It did a lot of good things for the imaging and tonality of my Overnight Sensations.

 

A question for the guys who used DRC (Dirac or Dirac like setups): My room has several siting spots, that are on different distances from the speakers and my only aspiration for the DRC is to minimize the issues of my room nodes but mantain good sound on the 3 different distances... As far as i could research... Dirac can do 3 different settings for calculate the corrections (Chair, Sofa, Auditorium)... I think the latter can work better for my situation.
If not, i will go with the "analog" room treatment... Do someone has experience with Auditorium mode? does it work properly?

 

Interesting nerdy discussion about pitfalls of room correction.