Let's discuss room correction

[DonH56]

I think Andy is a member here. I have used the program and it is a very good tool even though I cannot take full advantage without a miniDSP or other compatible DSP board.

 

[ex audiophile]

I bought the AVM60 because of the generally xlnt reviews of ARC (as well as the processor). My experience level is well below novice. Borrowed my kid's laptop and actually got the program going and had good fun; I believe ARC now goes up to 2000 but the consensus from what I've read is that sub 200 is where the process is most useful. After fitting some earplugs (the sweeps are loud!) and warning the wife I ran a bunch of sweeps and the corrections were impressive, at least visually. I transferred the modified settings to the AVM and generally really liked the change. My only problem was that the subs (2 GE XXL) were set low for my taste in movies (I can watch the Stone Giants chapter of the hobbit over and over) but it was good in that i discovered the Anthem remote has a "levels" button so i can boost or cut channels as I wish and not have to go into setup. I'd like to explore REW now that I have a mic but not sure how to get the modified info into the AVM, and I'd have to borrow my kid's laptop again and listen to rap music. Hopefully our leader will publish more info on REW (much appreciated btw) and I can move forward with room eq. I think the bottom line is that it is fun to do (more so than reading Dr. Toole's book, sorry) and can help us with the low end.
tip of the day for bassoholics: if you haven't heard smoking joe kubek (RIP) and his buddy bnois do outta mind outta body give it a listen. Involuntary hip swinging rating is off the scale, be sure to turn it up. Almost caused me to order two of SVS' new 16s.

 

[oivavoi]

I find it interesting, btw, that people in this thread in general seem to like the effect of room correction in their system. While several audio experts and gurus have been skeptical of room correction, in principle and on theoretical grounds:
- Floyd Toole: http://www.aes.org/tmpFiles/elib/20170321/17839.pdf (see section 2.4)
- Siegfrid Linkwitz: http://www.linkwitzlab.com/frontiers.htm#K
- Earl Geddes: http://gedlee.azurewebsites.net/Papers/directivity.pdf

But still, many people seem to like what room correction does. I find this puzzling and interesting.

 

[edd9000]

I think you need to consider it as two separate issues. Where the room is modal below 300hz or so and above. I'd agree there is no real correction of room reflections etc, however some tailoring/eq I don't think does any harm.

Below 300hz or so I wouldn't use a system without it. But I'm in both camps, having built my speakers around Geddes CD horn ideas.

 

[oivavoi]

I think you need to consider it as two separate issues. Where the room is modal below 300hz or so and above. I'd agree there is no real correction of room reflections etc, however some tailoring/eq I don't think does any harm.

Below 300hz or so I wouldn't use a system without it. But I'm in both camps, having built my speakers around Geddes CD horn ideas.

Agreed. That is also in line with my experience - below the Schroeder frequency it is indispensable, above it may create something artificial. But my point is that many people also like what room correction does above the Schroeder frequency. This is something which they "shouldn't" do according to some theories.

 

[DonH56]

RC cannot completely correct reflections though some active schemes make a valiant attempt. My room is so dead that it works just fine full-range. I suspect most people have rooms that are "small" relative to bass frequencies and thus benefit from LF correction. Above that is much more a factor of the room and their taste IMO, i.e. how the room is treated and what the listener likes to hear. Some people like a really live room, some dead, most probably in between, and add on top of that whether the target curve matches what the listener likes to hear. I could probably boost the highs to unbearable levels for my sons but it would sound great to me. Someone who really does not like highs, maybe thinking them too "hissy" or obnoxious, may turn them down more than someone who likes the sizzle of a high hat more.

Or something like that. - Don

 

[edd9000]

Agreed. That is also in line with my experience - below the Schroeder frequency it is indispensable, above it may create something artificial. But my point is that many people also like what room correction does above the Schroeder frequency. This is something which they "shouldn't" do according to some theories.

I suppose what I mean is, I don't consider it "correction" as such above 300hz, and more just eq. Now if this is eq assisted with measurement to provide a better perceived balance in sound, I'm all for it. Modern DSP based eq should be entirely transparent with regards to signal quality.

 

[DonH56]

EQ is not correction?

The dynamic range of the DSP is usually not the issue, assuming the filter structure was properly designed and gain leveled, but rather what the algorithm does with the information. That varies wildly among different schemes... Some implement just a basic EQ (typically PEQ) whilst at the other end they work in time and frequency domain to adjust EQ and phasing/delays to optimize the impulse response to meet the target curve. Or so I have experienced/observed/read.

For example, if the DSP works to remove reflections, that can remove some of the sense of "space" in the sound. It would be more accurate but less desired by many listeners.

With a live room, SBIR and comb filter effects can make it very hard to get even frequency response. The old "move your head an inch and the sound changes by a mile" problem. RC can attempt to compensate with multiple mic placements and such but the end result will be compromised. I know folk who have saved two (or more) setups, one for a solo listener, and one for when the whole family is spread across the seats.

And so forth. Only so much RC can do within the room and speakers it has. Some have made an argument for adding many more speakers around the room to provide a way to recreate whatever sound space is desired. Others, e.g. the big Beolab, build many drivers into a single cabinet and use them with DSP to direct the sound field appropriately. The next few years are likely to be exciting...

 

[edd9000]

I suppose its just semantics.

I have not seen a system that can remove reflections without passive treatment , or the use of constant directivity. I use DRC which indeed does attempt to correct for phase/delays but it doesn't stop the reflections or their effects. But I haven't tried any others. As a solo listener I do only correct for where I listen and I'm happy with the end result.

At the end of the day it is still personal taste. The CD horns in my speakers, or some dead rooms I have listened in do sort of give a headphone sound with no space. This isn't an issue to me, If the recording has "space" and ambiance it still will. I have never liked speakers that create a sort of false sound stage, Shahinians and the like.

I have had many audiophiles listen to my corrected system, even demoed correction in their systems, I don't think I have converted a single one, because at the end of the day, it no longer sounds like a normal hifi.

 

[oivavoi]

I have listened to several corrected systems, and also tried it out myself. What RC can do, in my experience, is to give a better view into the recording venue or the virtual stage that the mastering engineer created. But I lose the feeling that there are musicians playing in MY room. Which one is the most accurate out of this two psychoacoustic illusions? It's debatable. But then again, I've always liked omnis...

 

[Fitzcaraldo215]

I have listened to several corrected systems, and also tried it out myself. What RC can do, in my experience, is to give a better view into the recording venue or the virtual stage that the mastering engineer created. But I lose the feeling that there are musicians playing in MY room. Which one is the most accurate out of this two psychoacoustic illusions? It's debatable. But then again, I've always liked omnis...

Yes, it is debatable, and also perhaps genre dependent. As a classical music lover with a lot of live concert experience, "they are here" makes zero sense to me. I do not think it is achievable or even worth achieving. Even a string quartet is quite implausible in my room, which would also sound terrible if they tried. As would even a solo violinist, lutenist or whatever.

I discovered that "you are there" is a much better paradigm, especially given my perspective in the audience at live concerts, and I find three factors support that exceedingly well in reproduced music when combined, in no particular order, as follows: DSP Room EQ, Multichannel, and hi rez. I can relate this paradigm to my actual concert attendance and listening to pure acoustic music in real space. In many decades of prior fruitless audiophile searching, his has been my greatest discovery, and it has been very satisfying over the last 9 years.

Good luck to those with other genre preferences. I wish you as much listening enjoyment as possible, and I am not putting down the music in any way. Sincerely. However, I still strive without success to understand the sonic reference for comparison in your head and what it is based on. No offense intended, I just do not get it.

 

[Nightlord]

'My' loudspeaker designer operates from a loge paradigm instead.. As if the room you are sitting in is a loge box that opens up to the event location at the loudspeakers. I'm happy with the results, so that seems like a good paradigm.

 

[oivavoi]

Good comment Firzacaraldo. My listening is fairly evenly divided between classical, jazz and pop/rock/electronica. Fully agree: a full orchestra can't fit in my room. And btw, I'm fully convinced that multichannel is the way to go for classical. In the future I'll probably have a multichannel setup, but my current living room doesn't allow for that.

Concerning omnis and the feeling of having actual musicians in my room: for me, I think the reference is mostly based on my experience as being an amateur musician and singer myself. So far, almost all speakers I've heard sound artificial. They sound like speakers. They don't sound like real music to me. I've never heard a musical instrument or a singer emanate sound like a speaker does. It is much more multidirectional. When I play a grand piano for example, the sound comes from everywhere, and goes in all directions. A boxish speaker, by comparison, doesn't sound like that at all. Now of course, one can argue that the goal of high-fidelity is to reproduce what the mastering engineer intended, that what counts is what is recreated as a total sound field, and yadi yada yada. (edit: or to sit in the loge box, yes). But still, for me... it nevertheless sounds fake. It sounds like music coming out of boxes. The only two setups I've heard which sounded "real" to me, in spite of some shortcomings, was a dipole setup (Piega Master One) and an omni (MBL 101). Both very expensive, unfortunately. The best conventional setups I've heard - Beolab 90 and Grimm LS1 - weren't even close when it came to convincing me that I was listening to real music and real instruments, and not just hifi.

I find that good omni setups - and with omnis a "good setup" includes having a fairly large room - recreate acoustic music like jazz and classical in a much more lifelike manner than conventional speakers. At least comparing to two channel, that is. But on electronic music it may sound somewhat strange, given that this is music where my main reference is directional PA. You win some you lose some.

EDIT/Clarification: but to answer your question, I guess the thing is that I'm not satisfied with "being there" in the audience. I want to mingle with the musicians while they are playing on stage. So that is the difference in subjective reference, I guess. So far, I've only had that experience with omnis and dipoles.

 

[Fitzcaraldo215]

The sad truth is one cannot recover what was not obtained in the original recording in the first place. By that, I mean if you expect that by some magic of finding the right speakers - omni, dipolar, bipolar monopolar or whatever - that are going to provide some spatial sense you seek, I am afraid that is always going to be limited by the recordings themselves.

It is possible to achieve what you want with certain very specific recordings miked and engineered for such. So, I think you you are misfocused. You should be searching for recordings, less so for speakers.

 

[Blumlein 88]

For me the higher frequency correction has been alot about an elaborate tone control. With the Tact gear you can hold 9 different target curves in memory and switch instantly with a remote. I would have one curve for my best most finely balanced reference recordings. One which toned down bright recordings. One that helped dull recordings. One for midrange forward recordings. And one for recessed midrange. These alternate curves weren't too radical just a step in the right direction. So bright recordings might not be completely fixed, but nudged a better direction for my tastes.

 

[Blumlein 88]

You are there, they are here, or I have an open window to the venue. All can be nice, and enjoyable. Peter Walker liked the idea his Quads could be like having your room attached to a recording space and his speakers were open windows into that space.

I have done recordings of 5 friends with one mic for each person. It wasn't in a very large space, and they were arranged somewhat in a circle around the edge of that space. I can play that back over my 5 speaker surround video system by putting one mic in each channel. For realism that is excellent. My room is not dramatically different in size. The speakers are close to where the musicians really were in the other space. And while the radiation pattern of the speaker is not the one of the person/instrument combo it is far closer than you usually get. The sound image is a real image in my room and not a phantom image for each musician. So it sounds right over nearly the entire room and is like recreating at least a plausible and correct soundfield you can move around within. The playback of that recording is among the best I have ever heard at being both they are here and I am there realism. It also sounds extraordinarily real from outside the door of that room or down the hall or from on the front porch.

Of course this would not work for so many recordings. This is a special situation all the way around. I also don't think I have a single speaker that could recreate the sound pattern and live acoustic size of something like a grand piano. For most other instruments however a good speaker being a real source is close enough it gets along ways across the gap between real and fake.

 

[amirm]

I find it interesting, btw, that people in this thread in general seem to like the effect of room correction in their system. While several audio experts and gurus have been skeptical of room correction, in principle and on theoretical grounds:
- Floyd Toole: http://www.aes.org/tmpFiles/elib/20170321/17839.pdf (see section 2.4)

While that section is completely correct and worth a read, the ending is what I recommended:

"In the low-bass frequency range equalization can be very useful as a means of attenuating prominent room resonances at a single listening location."

If you hear Dr. Toole speak in person you will see him make EQ mandatory in bass regions seeing how passive treatment (acoustic products) have so little effectiveness.

Above transition frequencies measurements are misleading and need some psychoacoustic processing to matter. Even then care must be taken to not chase a pretty graph at the expense of good sound.

 

[amirm]

- Earl Geddes: http://gedlee.azurewebsites.net/Papers/directivity.pdf

Earl used to fight DSP/EQ tooth and nail years ago but eventually had to concede its usefulness. Here is an example post from back in 2010:

 

[oivavoi]

The sad truth is one cannot recover what was not obtained in the original recording in the first place. By that, I mean if you expect that by some magic of finding the right speakers - omni, dipolar, bipolar monopolar or whatever - that are going to provide some spatial sense you seek, I am afraid that is always going to be limited by the recordings themselves.

It is possible to achieve what you want with certain very specific recordings miked and engineered for such. So, I think you you are misfocused. You should be searching for recordings, less so for speakers.

Partly agree. Busy day at work today, will post more later....

 

[Burning Sounds]

Thanks guys, excellent input.

Btw, has anybody here tried the freeware "multi-sub optimizer"? I'm thinking of trying that out and see if can do as good a job as dirac in the bass region. Right now I have a small "how cheap can you go" project, to try and see if I can get better sound than most audiophiles while paying less than they do for their power conditioners. Therefore interested in freeware.

I went to a demo put on by Linn over the weekend. They showed a browser based version of their Exakt system which they said they intend to make freely available (no date given, unfortunately). The "before and after" demo sounded very similar to what I hear when I switch in Acourate's filters in JRiver on my system - subjectively the sound was smoother, female vocals sounded very nice. I have a bit of a love/hate relationship with my room correction - jazz vocals can sound very good, but rock often seems to lose some of its raw power - everything sounds too smoothed over - maybe not PA system enough to sound real..