Doers and Pretenders - Electronic Room Correction

[Boomzilla]

There are an increasing number of "Electronic Room Correction" systems being marketed, but they seem to vary in intention, capability, and implementation. The consumer, however, is usually given either insufficient or misleading information when trying to evaluate the technologies and capabilities.

From my reading, it seems that such systems break down into two broad categories:

1. Glorified equalizers - These systems normally use a (sometimes calibrated, sometimes proprietary) microphone to be placed at the listening position. The mic listens to a noise-burst or tone-series from the source, intended to evaluate the frequency response at the listening position. Then the source box typically applies cut to "level out the peaks." Normally, the dips can't be equalized because they're the effects of room cancellation. The more sophisticated of these systems also engages each speaker in the system individually to assess phase. So far as I can tell, the majority of AVR equalizers are in this category.

2. Time-based room compensators - These systems use a similar microphone and test tone sequence, but (unlike the equalizers) listen to the acoustic signature over a time window. This is normally accomplished using some variant of Fast Fourier Transform equations. The source box then creates an "inverse echo" of the actual room, and then applies that to all program signal. Additional equalization to flatten the frequency response may (or may not) be applied, but the prime intent of these compensators is NOT to flatten frequency response, but rather to remove the "sonic signature" of the listening room itself.

Some systems offer mixtures of Nos. 1 & 2 above in varying proportions. Other systems take measurements from multiple room positions to assess acoustic signatures. But which are which? Normally the vendors who supply such systems are vague in the extreme about their technology and intended uses. The consumer is further confused by the wide variety of proprietary system names that are not helpful in determining the functions of the correction systems - "Room-Perfect, YPAO, DIRAC, etc." are typical.

So which of the systems on the market do what? And, more subjectively, how efficient are they at achieving their intended purposes?

Thanks - Boomzilla

[klinemj]

As you said - most AVR's have type 1. And, that includes the Emotiva options that have EmoQ and if folks apply REW filters (at least that is my understanding).

On the type 2...I know Dirac does, and as I recall - at least the more recent versions of Audyssey correct in the time domain. When DIRAC was at Emofest demonstrating DIRAC prior to the XMC-1 launch, a statement was made that DIRAC was the only option that adjusted in the time domain. Many here came back and said "oh no....Audyssey does..." Clarification came back from Michael at DIRAC that basically said, "well, technically, they do...but ours is so superior to theirs" There was a technical rationale...can't recall what it was, but it had to do with the math behind DIRAC's filters vs. those in Audyssey. I will see if I can find that....but, with the forum revision, it may be tough to find or no longer exist. Other than those 2, I've not really looked into which ones are the type 2.

Mark

[klinemj]

That was easy...click on the following: OLD EMOFEST NOTES

Check the part that says "UPDATE: The DIRAC that was run..." for the statement on time domain. Dirac corrects impulse response and ansat tested it vs. Audyessy and did indeed find DIRAC did better on taming impulse responses.

Mark

[Boomzilla]

Thanks kindly, Mark - My understanding, though, is that DIRAC also requires the input from a second program (REW or "Room Equalization Wizard)? Also, from reading the XMC-1 comments over time, it seems that the DIRAC/REW/Mic-Calibration/Measurement processes are independent, manual, and overall, rather complicated. Is this so?

I also got the distinct impression (although I might be wrong again) that the XMC-1/DIRAC systems were primarily intended, designed, and implemented for multi-channel home theater use rather than 2-channel. This isn't to say that they can't or won't work with 2-channel, just that their primary design (and voicing) was for HT use.

Audissey is also, if I understand it correctly, primarily a HT design that was intended primarily for multi-channel movie sound?

So my current understanding is that DIRAC / Audissey can be kludged to work for stereo-only, but that stereo was never their primary design intention.

[Perpendicular]

Great Thread! I've always wondered about the different room correction technologies. It can be so confusing on which one is best to use and the good ones claim they are the best. Back in 2008, I purchased a Denon AVR, had it for a couple of weeks and returned it because I didn't like what I heard when I played music. With movies, I loved it. I swapped the Denon for a more expensive Pioneer SC-07 which I still have and use now in one of my two systems. Overall, I seem to like what MCACC does to correct and help make my system sound better in that room. Now I'm in the market for a new subwoofer and replacing that Pioneer AVR. I think I find the right brand/model only to discover that it doesn't have all the features I'm looking for. So, I've been seriously thinking about replacing the subwoofer first and just getting a cheaper AVR to get by for the next year.

[Perpendicular]

^ Oops! I left out the part that the Denon had audyssey room correction.

[geebo]

Apr 13, 2017 10:56:12 GMT -5 Boomzilla said:

Thanks kindly, Mark - My understanding, though, is that DIRAC also requires the input from a second program (REW or "Room Equalization Wizard)? Also, from reading the XMC-1 comments over time, it seems that the DIRAC/REW/Mic-Calibration/Measurement processes are independent, manual, and overall, rather complicated. Is this so?

I also got the distinct impression (although I might be wrong again) that the XMC-1/DIRAC systems were primarily intended, designed, and implemented for multi-channel home theater use rather than 2-channel. This isn't to say that they can't or won't work with 2-channel, just that their primary design (and voicing) was for HT use.

Audissey is also, if I understand it correctly, primarily a HT design that was intended primarily for multi-channel movie sound?

So my current understanding is that DIRAC / Audissey can be kludged to work for stereo-only, but that stereo was never their primary design intention.

Dirac can be used for 2, 3 , 4, 5 etc channels. It's not channel dependent. They even sell a two channel version that is a little cheaper than the multi channel version but is otherwise the same. Dirac adjusts each channel independently of the others so the number of speakers you have won't affect the adjustment of any individual channel.
Dirac does not require input from REW. Dirac is very simple to use and I can do a complete run in about 20 minutes or so.

[Boomzilla]

Thanks, geebo - Lots of misunderstandings alleviated in one swell foop! I appreciate it.

Boomzilla

[klinemj]

Apr 13, 2017 11:23:58 GMT -5 Boomzilla said:

Thanks, geebo - Lots of misunderstandings alleviated in one swell foop! I appreciate it.

Boomzilla

Building on Geebo's comments, if you were to buy Dirac for a PC, independent of it coming with an XMC-1, it is available in 2-channel and multichannel versions. From what I understand, they are basically the same except the multichannel version includes ability to do "chair, sofa, and auditorium" measures vs. the stereo only does "chair/sofa" and the 2 channel only shows average measures while the other shows "all" measurements (channel by channel details). And, the stereo version is cheaper. I actually debating buying the PC version but decided to just use it with the XMC as the PC version (for me) would not help for movies since I don't have my BluRays on a NAS playing through my PC. So, I just use the XMC-1 version, but the "full" version.

In any case, as Geebo notes, it's not a "kludge" to apply the multichannel version at all. It's adjusting speaker by speaker and affects playback as such.

Mark

[Boomzilla]

I have a Lyngdorf on order. If I'm not pleased, I'll return it & try the DIRAC. Thanks for all the helpful info!

[Boomzilla]

After a quick set-up of the Lyngdorf Tdai-2170, I threw on some music to assess the room-correction functions of the amp. And...?

It works. It works WELL. With the speakers hard against the wall behind them AND the listening couch in close proximity to the wall behind it, one would expect boomy, thundering bass without any pitch definition at all. With the RoomPerfect correction on, the bass and imaging are equivalent to what I previously had with the speakers 3' out from the wall behind them and the listening couch at least two feet from the wall behind it. That's GOOD performance. Now I still have my room treatments on the walls, and see no reason to remove them, but the fact that I'm getting this good an imaging and bass is encouraging.

I do note that the Lyngdorf doesn't flatten the response of your speakers. It only removes room echo. If you want frequency equalization, you can either engage some of the "built in curves" that the Lyngdorf offers and/or use some external equalization to flatten the speakers' response.

But with just the room correction engaged, I'm hearing a LOT more detail, a lot less congestion when the soundstage gets busy, and it feels like I'm "hearing deeper into the recording" instead of having the room sound predominate.

The fact that these are not night and day differences in my room tells me that:

1. The room (as I've always suspected) has fewer bass problems than most rooms

2. The amount of room treatment on the walls is very close to the right amount

3. The electronics I've been using are very high performers.

So in short, the Lyngdorf gives me as good an image-focus as my best setups (to date) have provided and with more clarity of detail. More listening (and a bit of tweaking with the jRiver parametric equalizers) will be needed before I decide if this thing is a keeper or not, but for now - it sounds sweet!

Boom

[USNRet]

I will not be sending my McIntosh MEN220 (pretty much same as Lyngdorf I am told) back.

[simpleman68]

Interesting thread as I've been looking at this unit that is also made by the manufacturer of my speakers. It affects frequency AND time domain with plenty of easy to adjust tweaking options.

They offer a substantial trade-in credit on the existing Xilica DSP.
Scott

"The Wavelet’s speaker time-alignment and room correction system is licensed from Bohmer Audio and all internal processing is said to be done at a 96kHz sampling rate"

legacyaudio.com/products/view/wavelet-dac-preamp-crossover/

[Boomzilla]

Any further comments I make on this thread topic will start on page 131 (ish) of the "Boomzilla's Journey" thread. Thanks.