Experienced only: What have you done with room correction?

You cant correct a room with DSP. I have tried and I can confirm it does not work. It comes back to the time domain response. You can correct tone using EQ but you cant fix ringing which is the real issue. So throw your mini DSP away as it wont work. 

Some of us want perfect sound by cutting corners and using room correction. You cant have it both ways. Perfect sound comes at a cost there is no free lunch you have been warned

Erik,

  My experience with room correction via Velodyne SMS1 can be mostly a good thing if your subs and sats have a chance of being married. If there is no match with those to begin with, then it is same as being shot in the eye with a toothpick by some who say they are sorry but can hardly keep from laughing.

 OTOH, if I leave this task to myself, and a sub full of knobs, I will surely leave out something and not know the difference. 'Oh, there's deeper, fined tuned bass in this recording? I must have tweaked something to the left.'  

I’ve heard TacT (now Lyngdorf) completely transform a couple big $$$ systems to the point where you wouldn’t wanna listen to the system without their RC.  Avoid it at your own risk.  The ONLY reason I didn’t incorporate it into my system until now is because I was writing equipment reviews and couldn’t use it because it wasn’t appropriate for reviewing purposes.  Now that I’m free I’ll be all in for adding some kinda RC. 

I've been using a Velodyne SMS-1 with a pair of HGS-15s to augment KEF Reference 1s with excellent result.  I'm going to try a second SMS-1 in a stereo configuration in which L & R from the Ayre preamp will pass to separate SMS-1s.  RS-232 will connect the SMS-1s so only one needs to be addressed for settings to be applied to both.

I've been using Anthems ARC for several years (as a dealer and consumer) and as long as you have the expectation that its not a cure all to the system it is a great tool to use. Getting into the advanced adjustments allows for fine tuning to my ear on my system. I also use REW to measure the before to see what the in room response is. 

I've used 3 different REQ solutions in my A/V systems:  Dirac Live, Audyssey MultEQ XT32, and ARC Genesis. I consider them all effective, to varying degrees, with respect to reducing room colorations and providing a more convincing audio experience, at least to my ear.

However, REQ is intended to remediate only room anomalies. It is not a panacea for speaker or source aberrations. And I've always found further improvements to the sound are possible via manual adjustment downstream. YMMV

I had a dedicated music room built. 

For somebody who does without even tone control, obviously automatic room correction is out of my league. Went with building a dedicated listening house instead.

I’ve heard TacT (now Lyngdorf) completely transform a couple big $$$ systems to the point where you wouldn’t wanna listen to the system without their RC.  Avoid it at your own risk.  The ONLY reason I didn’t incorporate it into my system until now is because I was writing equipment reviews and couldn’t use it because it wasn’t appropriate for reviewing purposes.  Now that I’m free I’ll be all in for adding some kinda RC.

@soix like a TDAI amp, or what?

people in apartments, or homes that are not easy to change things in, may only have limited passive options… and RC becomes the only viable option.

I avoid tone or EQ for my mains.   I use a Velodyne SMS  1 x over / EQ , that is the extent of my electronic room correction.    I barely use the sub but using the SMS -1 makes the low end just right 

 like a TDAI amp, or what?

@holmz Correct.  Back when I heard the TacT correction I was reviewing equipment so really couldn’t use it in my system, but now I’ll absolutely be looking to add some form of RC without a doubt because the benefits are amazing unless maybe you have the flexibility to turn your listening room into an adult romper room.   I now have a tube pre and a completely upgraded McCormack amp so not sure Lyngdorf has something for me (although if they did I’d buy it in a heartbeat if in budget) and I’ll definitely add some GIK room treatments, but I’m also fully intent on incorporating some form of RC in the near future.  Might be as simple as something like a DSpeaker Anti-Mode 2.0 or something, but it’s gonna happen because IME the results are more than worth it.  FWIW. 

I started with quitting trying to make a mid sized strange configured room work and moved the 2 channel system to a different larger room. Used calculators to determine how much acoustic treatment where to position, and where to best position speakers and sitting position. The treatement was for the time domain and positioning was for room nodes. I over compensated on room treatement and then removed treatment until it was just right. I used Room EQ Wizard for dialing in my active crossovers and use DSP for minor frequency correction.  

Best thing I ever did for room response was move my sub about 4’ BEHIND my listening position.  Suggested by Paul McGowan of PS Audio.

It really works!

I have used Audessey XT32, YPAO, MCACC, and Dirac. IME, Dirac is probably the best of the bunch.

There are two room correction programs, Audiolense and Acourate, that I have used for 2 channel music and they are next level. Mitch Barnett has written several articles on both of these programs on Audiophilestyle.com. Mitch is the proprietor of Accurate Sound and offers DSP room correction service for those that don’t want to spend the time learning the programs. He is extremely knowledgeable and patient. These programs reside on your laptop. One measures their listening room with a calibrated mic and develops convolution filters that are loaded into ROON or JRiver. The improvement is not subtle. Highly recommended.

I gave up and built a dedicated room to the specs of the U of Salford's School of Acoustics. I put record shelves and book shelves behind the speakers on the long wall and added 2 woofers. Magic!

I started updating my system 3 years ago.  After, i got all the components, one of the first things I bought was room panels.  I have two bass traps sitting behind the system, 6 first reflection panels, and 3 diffusers .  Room is 12 x 17x 8. Very good decision; I feel you can be changing out components trying to improve your sound when the next big bang for your buck is the room treatments.  My panels lowered listening fatigue, took to a much better place and improved sound stage.  I currently walk around the room and feel the sound doesn't change.  Many times you will have node cancellations whiere there is hardly any response at a given frequency range.  I do have one small bass peak in the left rear corner.  Bass is flat to 30Hz and good response in mid 20's.  There are several other things I have done to further refine the sound, but if I had done all that without treatment, I would be wondering why it doesn't sound right. 

PS  Eric has always been a proponent of room treatment and his posts/advise helped me make the decision to put up panels.  Thank you.

 Lyngdorf room correction transformed the sound of my Dali Epicon 6 speakers and Harbeth 40.1s in my systems.  Much improved bass, midrange clarity and overall musicality. 
 

The Lyngdorf room correction also improved the sound of my friends AudioVector R3s nicely in his room.  Tighter and more articulate bass as well as improved midrange clarity and refinement. 

I'm about to find out. I just took delivery of Legacy Aeris with Wavelet processor. I have high hopes.

I've used bass correction in situations where it's just a joke without it. Sometimes we don't get to move the speakers where we want. In at least some of those cases judicious use of room correction can make the listening experience dramatically more enjoyable. In the lower bass time domain issues aren't as big a deal to human hearing. My experience lines up with research I've seen on the subject. If the severe peaks and dips can be reduced with dsp it sounds better than not doing it even if it doesn't address some of the time domain issues. Above 100 Hz things change and time domain becomes very important. Thankfully, absorption becomes increasingly efficient and less costly as frequency goes up.

I’ve used TacT, Dirac, and Anthem. A few things:

• DRC can be fantastic, especially when using digital xovers for subs. It can smooth bass response, and the good products can also remove excess brightness if you tell them to.
• The better the digital processing in the convolver, the better it will sound. The best of the ones I’ve tried is the Anthem STR, which works at 192 kHz and 32 (I think) bits.
• Different products don't all work to the same level. YPAO in particular seems to have a bad reputation. ARC and Dirac have good ones. Even ARC is better or worse (from what I read and discuss), depending on whether it comes with a subwoofer or a full processor.
• With previous products, I’ve heard minor side-effects when I engaged the DSP. With the Anthem STR, I do not.
• It’s important to have a well-calibrated mic. The cheap items in a manufacturer’s lineup often will have worse mics.
• No automatic system will always arrive at sound the way you want it. Every automatic solution should be tuned by ear (assuming the devices allow that) to dial it in. IME, it can take several iterations to get there.

I am using 3 different DSP technologies and they all improved the sound in the rooms in which they are used. I use: whatever Emotiva offers in the MC 700, whatever Integra offers in its receivers, and whatever DSpeaker (model 2 or some such) uses. I don't care what they call these methods, I only care that they work - and they do. I notice someone suggested that you throw your equipment away because they don't work. This is certainly unhelpful, not to mention arrogant and disrespectful. Disregard such nonsense, please, and continue your quest for good sound in your home. It does make a great deal of difference where the microphone is placed during the testing phase of the procedure. I always place it on a pillow (because my clothing absorbs sound - we are trying to simulate a listener's head) and prop it up on cardboard boxes so that is "head high."  If you placed the microphone on an 18 inch squarr marble slab on the seat you usually occupy, the results would be very different. Emotiva's fanciest system, which I help a friend to install, has a very detailed (and lengthy) setup involving multiple mike placements which produced a really remarkable (if I were a less reserved person, I would say "spectacular!") improvement in a loft usig Magnepan 1.7i speakers and a single subwoofer. Happy listening.

So-called room EQ is fascinating I think. First it helps to understand the behaviour of sound in your your room in terms of the broad division of frequency bands into specular, transitional and modal. Room EQ certainly helps with tonality across the frequency spectrum. You also want to know the reverberation behaviour of your room EQ can’t help much with that.

My room is quite dry in acoustic terms due to its construction (a Japanese style timber house) so I’m good to go with room EQ. My RT60 (an approximation, because small room behaviour doesn’t give us a diffuse field) is around 200 ms until the bottom octave where it increases to 300 ms. If you live in a concrete apartment block, those figures will be significantly higher and you’ll have to add absorption first.

I model my room in REW and Amcoustics room simulators to get a handle on Schroeder frequency (which divides specular and modal) room modes and influence of loudspeaker position. When I bought new speakers a year or so back I positioned them, measured FR at listening position, moved the speakers in 200 mm steps laterally then longitudinally, measuring at each step until the most problematic nulls were minimised. You can’t fix severe nulls with EQ so this comes first.

I use a Mac as source running Apple Music (now with hi-res and spatial audio aka Atmos) and Sonarworks software to EQ, then USB over Thunderbolt to the DAC. I like Sonarworks because it measures ~37 locations spread around the listening position to get a better model of room behaviour before running EQ. I used their mic in a Røde shock mount pistol grip handle and their sonar location method is completely fun.

My previous speakers (Audio Physic Tempo 25) were a bit warm in the mid-bass but otherwise pretty good FR-wise. Running Sonarworks EQ full-range along with the B&K 1974 curve improved mid-bass FR smoothness (expected) and resulted in even better delineation of the stereo image (which I didn’t expect) so I was very happy. AP speakers have great timbre and EQ didn’t harm that at all.

My new speakers (Audio Physic Codex) are close enough to full range so bass issues that didn’t arise before presented themselves (reinforcement at 25 Hz being the rooms lowest lontitudinal mode was beneficial but a 15 dB bump at 50 Hz from the room’s second longitudinal mode was deleterious). EQ fixes errant peaks unproblematically. Those speakers were also a bit shy in the mid bass (opposite to their smaller brethren) as room modes in the transitional zone (250-700 Hz in my case) had a negative influence and EQ coped quite ok with that, balancing mid-bass with midrange nicely. EQ also provides a bit more lower bass extension (but don’t go overboard as high levels can damage speakers).

In my experience, even with excellent speakers, careful positioning followed by judicious application of DSP has no real downside. With the smaller speakers, bass distortion (I use Fuzzmeasure for analysis) rises but doesn’t sound too bad, but headroom is an issue then. With the larger speakers, bass distortion is insignificant and higher levels are comfortable.

Btw I’m aware Acourate and Audiolense are very cool but I haven’t gone there as running things in a Windows VM doesn’t seem with the effort. If you use a Windows PC source, by all means try them.

Very nice detailed explanation of frequency-dependent sound behaviour at SynAudCon here.

I use the "artificial Ficus Tree" room correction technology.  Depending on your room size, but 1 to 2 dozen 6' Artificial Ficus trees and scatter them around the room behind and besides the speakers, behind the speakers, behind the listening position and in the corners.  It's a time proven technique to take care of room anomalies.  And much cheaper and better sounding than active solutions.

@bpoletti I’ve heard live ficus trees produce a more natural sound.  Heh heh. 

I am deeply impressed by the technology. 🙂

Interesting discussion and the tech is tempting to try out. One question; doesn’t the DSP do it’s own A/D and D/A conversion? After spending a relatively large sum on a DAC, it seems counterproductive to have the signal reconverted twice more downstream by a much lower cost device… am I off-base here?

@burtlake 

Depends really on where you do the DSP.  If you use Roon for instance, you do it all before the streamer gets the data. If you use a DSP capable streamer/DAC then no difference.  If you use it only for the subwoofer (like I often do) then it's out of the way of the main DAC/Amp chain.

@burtlake

Interesting discussion and the tech is tempting to try out. One question; doesn’t the DSP do it’s own A/D and D/A conversion? After spending a relatively large sum on a DAC, it seems counterproductive to have the signal reconverted twice more downstream by a much lower cost device… am I off-base here?

@erik_squires

Depends really on where you do the DSP. If you use Roon for instance, you do it all before the streamer gets the data. If you use a DSP capable streamer/DAC then no difference. If you use it only for the subwoofer (like I often do) then it’s out of the way of the main DAC/Amp chain

Running DSP software on a Mac/PC source is similar to using a streamer (which is just a dedicated computer) as a source, everything is done in the digital domain upstream of your DAC.

The current line of miniDSP boxes running Dirac (like minDSP Flex and SHD) take digital in (USB/Toslink/SPDIF coax on Flex, plus Ethernet and AES-EBU on SHD) and do the DAC job themselves. Because you send them a digital signal, there’s no redundant ADC/DAC conversion stages. There’s also a studio model of their SHD which sends digital to a downstream DAC. The SHD models use a 96 kHz internal sample rate, so a Mac/PC can theoretically do better (Dirac and Sonarworks say 192 kHz there). The Flex uses 96 kHz also but says 48 kHz with Dirac licence, that may be across the board for their stuff?

I was using Tidal and thought about MQA but that makes DSP hard, fortunately Apple decided to do hi-res (and multichannel Atmos) on Mac around that time which made for a very simple setup (and I was happy to entirely avoid the AVP/AVR world). But consequently I can’t say anything useful about sonics via the miniDSP devices.

Thanks for the clear explanations! Didn’t realize all the possible executions. 

burtle,

Please tell me which advice/direction/system from the above

you plan to employ???

Also, will room correction removed unwanted distorted viewpoints?

Erik,

Full disclosure: We design and manufacture speaker systems (in the USA) that use full DSP, specifically digital crossovers and room correction.

First, DSP (Digital Signal Processing) is a broad term. Basically, anywhere there is digital signal there is DSP. Digital crossovers and room correction are a subset of DSP.

DSP/room correction (DSP/RC) can be much more than amplitude correction, often refereed to EQ. DSP/RC users only applying EQ are using only part of the technology's capabilities. There are simple units that are basically digital equalizers.

Comprehensive DSP/RC systems compensate for amplitude domain and time domain anomalies. Don't underestimate the importance of time domain corrections.

During the development of our Apollo series speaker systems we studied analog passive crossovers, analog active crossovers and digital crossovers for them. We developed the Apollos using all three technologies. Exploring digital crossovers allowed us to experiment with DSP/RC. We found that there are two basic categories: Manual, that requires much experience to sort out and semi-automatic, which are more user friendly. Our supplied DSP unit is user friendly.

We found that applying DSP/RC to a poorly designed speaker doesn’t automatically turn it into a gem. What we did prove to ourselves is that applying DSP/RC to a good speaker allows that speaker to get much closer to its full potential and do so in a much greater variety of listening rooms. And in many cases, improve the measured performance. Time domain issues inherent in the design are corrected.

IMHO, I have found that properly applied high quality DSP/RC makes the system sound more balanced from top to bottom, improves resolution, improves dynamic contrast, eliminates stress and just sounds more complete.

BTW, ASP (Analog Signal Processing) is a term not often used by audiophiles. Basically, anywhere there is an analog signal there is ASP. Technically, ASP/RC can be developed and applied to a system.

I've used a couple of versions of Anthem's ARC over a decade or so, with many loudspeakers. On general principles, I turn it on only if the positive effect on smoothing in-room frequency response seems "worth it" and the better the resolution of your system is, the easier it is to hear the software doing its thing.

Three observations:

1. After the measurements are made, I inspect the in-room response curves and apply RC only up to the lowest frequency at which it seems to be making a meaningful difference. Ideally, no higher than 500Hz, never more than 2000Hz.

2. Attempting to correct a dip in FR is much less likely to help the cause than a judicious trim to a peak.

3. The benefits for a multichannel system are especially evident.

4. Having capable DSP room correction won't eliminate the need for room treatment with physical measures in certain situations.

@jeffseight 

i was pondering a low cost experiment with the DSpeaker system for about $300, but when I noticed the analog in/out I started thinking about the extra D/A conversion and decided for now to focus on room treatments, which is also what the above responses suggest anyway.  Will be giving GIK a call next week…

My experience with room correction involves two different correction systems.  The first DSP/RC was part of Sanders 10 speaker system.  Roger Sanders programmed and included a dbx VENU360 DSP/digital crossover with the system purchase of his 10 series electrostatic speakers.  I bought a dbx from Sanders to use with Innersound EROS speakers.  The EROS speakers are the predecessors to his Sanders 10 speakers.  The crossover portion of the dbx is necessary for use with Sanders or Innersound speakers.  The DSP/RC RTA (real time analyzer) in the dbx is set up using a microphone.  Full set up process is easy to do and gives the music the right weight and resolves room and bass resonances.  In other words, the music sounds really good!  Check the Sanders web site for more information.

My current RC system is a Lyngdorf TDAI 2170.  While this unit is an 80 watt integrated amp with Room Perfect room correction, I don't use the amp portion of the 2170.  The 2170 is very flexible and I can use it as just a preamp with Room Correction, which I do. Room Perfect allows me to set the crossover point for the high pass and low pass filters so I send the high pass to a Sanders Magtech amp which drives Magnepan 3.7i speakers.  The low pass is sent to a Dayton Audio sub amp driving four AudioKinesis subs.  Room Perfect room corrects by analyzing, via a microphone, various test tones and sweeps taken from random microphone placements (usually seven or eight locations) in the room.  The correction produces a sound without the negative influences of the room.  The bass is clean and articulate (though I believe the four sub system from AudioKinesis has a lot to do with that).  Soundstage, depth and detail are outstanding.  The sound I hear makes my toes tap and when my toes are tapping I know the sound is good.  Hit the Lyngdorf website for more information.

Passive room treatment (if it's allowed) is always the best first choice.

I'm currently using one of MiniDSP's Dirac Live boxes, which corrects both frequency and time domains.

My system is pretty basic - homemade speakers using Alpair 10.2 full-range drivers, FLAC rips on a PC played through Foobar2000, and a tpa3620-based chip amp.

The Dirac Live correction makes a profound difference. This is in a rented pre-war NYC apartment, which isn't optimal acoustically. I can't play loudly, so also dialed in some "smiley face" EQ. 

It's night and day better with room correction.

Before that, I used MathRoomEQ, a plugin for Foobar2000. That made things better, but Dirac Live puts more there, there.

I built my system around the principles of Edward Choueiri and his BACCH system. It’s the last piece I have to add. As of now I try to find room spaces when I move that are not square which help with avoiding standing waves (Modes /Nodes) and keep the speakers off the walls as much as I can. There is lots of great information here and ways to do this. I have large full range 20.1 Maggie’s which are as close to line source as I could get, four large subwoofers (also asymmetrically placed in the room) and measured the room (speakers and listening position) with Room EQ Wizard and then input that data into Multi Sub Optimizer via an Earthworks M30 microphone to generate filters everything running out of my Mini DSP with balanced connections which is processing all filters at 56bit/ 96kHz. There are no A/D conversions, it’s digital from start to finish. I’ve ripped out the analog crossovers and use the Mini DSP to input directly into the amps which power the speakers actively. As others have alluded it is almost impossible to correct a bad room with room correction alone. You can very effectively do it by adding more subwoofers. . . Most of the shorter wavelengths die fairly quickly on reflections and room treatments work great for those, the worst offenders are the lower order notes that cause all the issues. It’s crazy to listen to the system before the filters are built (scared the daylights out of me) and to also see the filters that are created after all the processing is complete. The results are stunning.

Thanks,

Steve

I have a dual system. I use a Sonora streamer with PSAudio 2 channel  with bypass for an anthem home theater. I looked long and hard to see how to do room correction for both. First I ended up with a JL CR-1 so sub could be used for both. But first I did speaker placement and room acoustic treatments. That is a must. 
 

Arc was pretty straight forward. It does all the work but I did not like it for 2 channel.   I went with roon and used a convolution filter from 1khz and down. Makes a huge improvement in SQ. Well worth the effort. 

At one point used DRC Designer - a room correction software working in both the amplitude and time domain - over my previous, passively configured all-horn speakers. At the same time at had those speakers high-passed, digitally, just below 80Hz in conjunction with a pair of tapped horn subs (that I still use with my current speakers), so: 3 filtering processes overlaid, incl. the passive XO.

Anyway, DRC Designer was a sonic double-edged sword; on the one hand it made for a flatter and more decent/"correct" presentation with more extended HF and a resonance suppression at ~125Hz in particular. On the other hand it took a "shine" off the sound with a mildly bleached/stale and even sterile imprinting. I finally realized that I wanted my main speakers and overall configuration to be something else, finding it better to just leave those main speakers play full-range as they were (preferably with an SET), flaws and all and great qualities as well, without subs augmentation. That, however, wasn’t where I was heading.

What I have now is fully active with only a single element of filtration, namely a Xilica digital XO/DSP. No room correction or passive XO parts of any kind. We’ve measured the HF/MF horn in each channel, near field, to address slight frequency response irregularities with a few mild notches and a single (also mild) peak suppression. Everything wrt. to the chosen values of gain and Q here, as well as the remaining filter settings, has been done by ear in the listening position over a period of time. Delay adjustments was the last, major area in the tweaking process, that are sometimes revisited (in conjunction with speaker positioning) for minute adjustments in the wake of changes elsewhere in the chain, should they occur.

I use ARC. It does what it's supposed to, with no bad side effects. 

Room treatment,  except my Monitor Audio PL300ii's still sounds like Monitor Audio, but not bouncing all over the place now. I have acoustic panels on every void space on the walls,  and of course the room does not look like a dart board.