DRC, Digital Room Correction- is it the poor relation to Room treatments?

[Fitzcaraldo215]

Hi Fitzcaraldo215,

 

You can look at the graphs and believe they tell you all you need to know.

Or you can decide a representation should not be confused with an experience.

That is certainly a personal decision.

 

Have you ever been in a room that has been fully and properly treated with something like ASC's wonderful Tube Traps?

I would highly recommend trying it some time.

 

Just my opinion of course but I believe looking at graphs and believing one can derive an understand of experiencing something is like looking at photos of a beautiful woman and believing you've made love. ;-}

 

Best regards,

Barry

www.soundkeeperrecorings.com

www.soundkeeperrecordings.wordpress.com

Barry Diament Audio

 

Barry - I have indeed heard rooms treated with ASC devices. But, with no prior listening experience with those rooms before and also listening to them with unfamiliar equipment, I am left with a big question mark about what I heard.

A local dealer sells ASC and has several rooms treated with them, and I thought their setups sounded"good" with some caveats, but I never heard anything I would go gaga over or convince me to undertake the considerable investment to follow that path, at least not with this dealer. When I asked about before/after measurements, they did not seem to be able to come up with any. I got the distinct impression that their view was they were selling "audio accessories", not comprehensive room treatments to minimize room effects. I am quite sure that those ASC treatments did change the sound in those rooms, but how effective they actually were was left to powers of suggestion and belief.

Some people have a sense of perfect pitch. Others claim to know sound when sound is "right" when they hear it, even if they lack a sonic reference they can switch to for comparison. If you and your clients believe you can optimize a room's acoustics by ear alone, then more power to you.

I think it is true that every tool has its limits and its effects. Tube traps are no magic bullet. They come in myriad shapes and sizes and choosing the right ones is both an art and a science, I believe. Same goes for other treatments. Room EQ is no magic bullet, either. It also requires great care in selection, calibration and fine tuning based on listening.

There is no substitute for listening, because that experience is ultimately what we want to try to optimize. But, I firmly believe that measurements are absolutely necessary, otherwise we are operating totally in the dark in configuring and evaluating the infinite number of possibilities that can be potentially deployed in a given room.

To deny the art of room acoustics is wrong. But, just as wrong is denying the science of it, including measurements. There is a happy medium between the two somewhere. As for my own fantasy room, I would under no circumstances allow it to be treated without comprehensive measurements done by someone who understands and respects acoustic measurement, its value and its limitations, as well as the tools in the toolbox to minimize the effects of the room.

[bdiament]

Hi Fitzcaraldo215,

 

I believe you misinterpret what I've said regarding measurements and seem to have missed the part where I said I use them. (I've even mentioned my favorite of the several tools in the "toolbox" here.) The most important thing to measure, in my experience, is decay time in the room at various frequencies, particularly from ~300 Hz downward. This tells us where and to what degree the room is "ringing".

 

Measuring frequency response is, in my experience, looking at symptoms and not at the problem (which is time-based and not amplitude-based). It might be a useful as a check but is not what I would recommend for diagnosis. Higher up in the frequency range, reflections are a matter of geometry so here again, a frequency response is the wrong measurement as it will not tell you where the reflection points are.

 

As far as using devices like Tube Traps, I think a lot of folks place a few pairs in a room and consider that "treated". It takes a lot of these to fully and properly treat a listening space. In terms of where to locate them and what size to use, as I said in an earlier post, one needs to find fractional positions along room boundaries -- specifically 1/2 points and 1/4 points. A $10,000 frequency response measurement isn't of any use here but a $2 tape measure can provide precision.

 

I agree that denying the art of room acoustics is wrong if one seeks to get the best performance of which a space is capable. Measuring is a good thing but only if one makes the correct measurements and understands what they are telling us, as well as what they are not telling us.

 

Best regards,

Barry

Soundkeeper Recordings

http://www.soundkeeperrecoridngs.wordpress.com

Barry Diament Audio

[dallasjustice]

I agree that time domain is important below the transition frequency. I think both step response and spectrogram can be very helpful.

 

However, one shouldn't wholesale disregard the SPL. For example, SPL in combination with an ETC or phase plot is very useful in identifying SBIRs. All rooms have them and they are worth treating, if possible.

 

 

Hi Fitzcaraldo215,

 

I believe you misinterpret what I've said regarding measurements and seem to have missed the part where I said I use them. (I've even mentioned my favorite of the several tools in the "toolbox" here.) The most important thing to measure, in my experience, is decay time in the room at various frequencies, particularly from ~300 Hz downward. This tells us where and to what degree the room is "ringing".

 

Measuring frequency response is, in my experience, looking at symptoms and not at the problem (which is time-based and not amplitude-based). It might be a useful as a check but is not what I would recommend for diagnosis. Higher up in the frequency range, reflections are a matter of geometry so here again, a frequency response is the wrong measurement as it will not tell you where the reflection points are.

 

As far as using devices like Tube Traps, I think a lot of folks place a few pairs in a room and consider that "treated". It takes a lot of these to fully and properly treat a listening space. In terms of where to locate them and what size to use, as I said in an earlier post, one needs to find fractional positions along room boundaries -- specifically 1/2 points and 1/4 points. A $10,000 frequency response measurement isn't of any use here but a $2 tape measure can provide precision.

 

I agree that denying the art of room acoustics is wrong if one seeks to get the best performance of which a space is capable. Measuring is a good thing but only if one makes the correct measurements and understands what they are telling us, as well as what they are not telling us.

 

Best regards,

Barry

Soundkeeper Recordings

http://www.soundkeeperrecoridngs.wordpress.com

Barry Diament Audio

[dallasjustice]

I have used tube traps in my room. They aren't useful unless there's a lot of them in the room. Also, just putting velocity traps in the corners and spaced out into the room doesn't directly deal with the root cause for axial mode ringing. The problem is the parallel walls. IME, the best solution is to use pressure based absorbers on the surface of the parallel walls. Tube traps primarily work off velocity. Of course, one could cover the entire surface of the wall with tube traps, but that could get really costly in terms of real estate.

[bdiament]

I have used tube traps in my room. They aren't useful unless there's a lot of them in the room. Also, just putting velocity traps in the corners and spaced out into the room doesn't directly deal with the root cause for axial mode ringing. The problem is the parallel walls. IME, the best solution is to use pressure based absorbers on the surface of the parallel walls. Tube traps primarily work off velocity. Of course, one could cover the entire surface of the wall with tube traps, but that could get really costly in terms of real estate.

 

Hi dallasjustice,

 

As I've said on a number of occasions, such as in my post, "As far as using devices like Tube Traps, I think a lot of folks place a few pairs in a room and consider that "treated". It takes a lot of these to fully and properly treat a listening space."

 

Having heard and worked in a number of rooms that were fully and properly treated, I can say that covering the entire surface of a wall with Tube Traps is not recommended and is far from necessary.

 

As to needing a lot of them in a room, so? Room modes must be treated wherever they occur and they're not going to occur in just a couple of corners behind the speakers. When an inadequate amount of these are used, due to economics or any other reason, it is not in the least surprising that the results will not be optimal. It would be like wanting to use DRC but limiting the application to just two or four frequencies.

 

Best regards,

Barry

Soundkeeper Recordings

http://www.soundkeeperrecordings.wordpress.com

Barry Diament Audio

[Hipper]

GIK make Soffit Bass Traps which go down to 50Hz and a bit below. I use them:

 

GIK Acoustics Soffit Bass Trap - GIK Acoustics Europe

 

They also make tuned traps down to 40Hz which I haven't used:

 

Tuned Membrane Bass Traps Archives - GIK Acoustics Europe

 

I have nine Soffit traps in my 420cm x 386cm room plus other panels but I also use EQ. Indeed I found I had boomy bass on a very few tracks (six) and using the Real Traps free test tone download I was able to find that it was at a frequency of 42/43Hz. I suppose I could have tried a tuned trap but instead used EQ as near as I could get it (44.5Hz) and this did the trick.

 

From what I know now (and of course I'm always learning) I suggest:

 

1. Treat room.

2. Position speakers and ears (chair), concentrating particularly up to 300Hz or so.

3. EQ - based on a microphone initially, and then test tones and your ears to finish off. Your ears are different from a microphone, and different from mine.

4. Vibration control.

 

Vibration control is what I'm up to at the moment, in part employing Barry Diament's suggestion of a ball bearing system via Symposium Acoustic products. What I've found so far is that these type of products give improvements of a type that nothing else does - at least, items 1 to 3 above cannot do this. I can only refer you to Symposium's site for what to expect and why. What he describes is exactly what I hear:

 

Symposium Acoustics: FAQ