Room accoustics

Marquis -- Sun, 12/07/2008 - 08:39

Would like advice as to the most efficient approach to taming room anomalies. For example; what is preferable, passive treatments (base traps, etc.) or active room correction devices such as those offered by Audyssey or Tact for example? I would also greatly appreciate any experienced recommendation as to who makes a superior unit when considering active room correction.

Thanks

Steven Stone -- Sun, 12/07/2008 - 11:34

My system for acoustic treatment is as follows:

Step 1. - use an excel spreadsheet to determine potential problems based on room dimensions.

Step 2 - optimize placement of components based on the spread sheet.

Step 3 - damp first reflection points on side walls.

Step 4 - damp primary floor bounce.

Step 5 - damp ceiling bounce.

Step 6 - damp rear wall and front wall reflections if needed.

Step 7 - use electronic correction for low frequency bulges.

Steven Stone
Contributor to The Absolute Sound, EnjoytheMusic.com, Vintage Guitar Magazine, and other fine publications

Marquis -- Sun, 12/07/2008 - 13:34

Hi Steven,

Thanks a lot for the quick response to my questions regarding room treatment!

Since you recommend getting the ball rolling with spreadsheet analysis it would seem that this would be the time to decide on just how sophisticated I want (or need) to get in terms of purchasing an analyzer or analyzer/processor with a microphone. Specifically, while I understand that good passive treatment is the recommended foundation to this process I may end up needing a bit of electronic wizardry to fill in the gaps when I finish making concessions to the decorator in the house. On that note are there any specific pieces of gear (in the under five thousand range?) that might be on your list of recommendations? Importantly, in the future I may be filling out my current two channel set-up to create a dual purpose hi-fi/home theater situation so multi-channel evaluation and correction might be a desirable trait.

Thanks in advance for any further advice you might have to offer!

Mark

Marquis -- Sun, 12/07/2008 - 16:41

Hi Steven,

I'm not sure that I managed to get a reply to you earlier after your advice on my room accoustic concerns. I really appreciate your advice regarding the use of passive room treatment as the foundation to my attempts. However, I know I'm in for some serious arm wrestling with the resident decorator as I start hanging things all over the room. That being the case, do you have any recommendations for a solid performing multichannel room analysis/correction unit for under $5,000.00?

Marquis -- Mon, 12/08/2008 - 23:25

Hi Steve,

Thank you again for taking some of your time to advise me on accoustic treatment.

At this point I guess I've come to realize the importance of doing what I can with passive techniques but I do have some limits that will require me to try some digital wizardry as well. With that in mind I just have to decide whether to go with an extremely high quality Tact two channel unit or a perhaps a bit lesser quality multichannel room correction separate from Audyssey in order to make my listening room more multi-purpose.

I'll get in touch as things progress and fill you in on my experience.

Mark

skyline1241 -- Fri, 02/25/2011 - 20:30

Thank you so much for your post.

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Tom Martin -- Sun, 12/07/2008 - 11:42

Steven's sequence is good. I am a fan of DSP-based correction, but all the designers of these systems recommend passive treatment first if you can afford it and can live with the aesthetics.

CEO and Editorial Director, Nextscreen LLC

Marquis -- Sun, 12/07/2008 - 16:22

Hi Tom,

Thanks a lot for your input regarding my room treatment questions.

I'm starting to understand the importance of passive devices for accoustic room treatment but I'm sure to be in for some serious arm wrestling with my significant other regarding form vs. function as my listening room is basically what most households would consider the living room. That being the case, I'm looking for some good advice on a multichannel room analysis/correction unit to supplement whatever I can put on the walls, etc. I'd like to live within my means so if you happen to have any recommendations for something under $5,000.00 please let me know.

Thanks,

Mark

Tom Martin -- Sun, 12/07/2008 - 16:52

Well Audyssey, either standalone (The Sound Equalizer) or integrated into an MC controller (Denon, NAD, Marantz and Integra all have such units) is the obvious place to start. Do you already have separate amps? Do you have an MC controller or preamp? A lot of people like TacT, but for MC I think they are well out of your price range.

CEO and Editorial Director, Nextscreen LLC

Marquis -- Sun, 12/07/2008 - 18:03

Thanks for the further response Tom. I have an Anthem AVM30 but recently dug out an old two channel preamp (Hafler 9505) and was disapointed to find that it sounds a bit better than the 30. A close friend that runs Levinson gear had been impressed some years ago when we did a head to head comparison with my all Hafler set-up was not exactly bowled over upon hearing the 30 in combination with the Hafler amps. That's when we pulled out the old two channel piece and realized that perhaps I'd taken one step forward and two steps back in my first foray into using multichannel gear. That being said, I'm still planning on expanding on my number of channels at least for home theater use so multichannel evaluation/correction of the room will be the desired approach.

I did speak with Boz(?) at Tact and found that they are replacing their multichannel room correction unit after the first of the year. I'm told that the new unit will incorporate circuitry of the same quality as their highly regarded 2.2XP two channel unit but will run twelve channels. Alas, the suggested retail was said to be somewhere in the $15,000.00 neighborhood, a bit out of my range.

So, with all of this in consideration is a stand alone Audyssey piece the next best alternative for now?

Tom Martin -- Sun, 12/07/2008 - 18:28

Audyssey is the most proven economical solution. There may be others, like Copland, that are in your price range, but they are 2CH. You can upgrade your AVM 30 to an AVM 50 for $2k, and I believe that will include Anthem's new room correction system. But you don't seem to like your Anthem that much, so maybe that isn't an option.

I think the big question is whether you get an outboard unit or an integrated unit. The former gives you the option to upgrade controllers later. The latter lets you upgrade (maybe!) controllers and will cost about the same (Integra, NAD and Marantz are in the 2-3k range and that if my memory serves me well is the price range of the outboard Audyssey unit).

How do you know you have an acoustics problem (I mean, we all do, but what are symptoms)?

CEO and Editorial Director, Nextscreen LLC

Marquis -- Mon, 12/08/2008 - 03:04

Thanks for all of your interest in offering helpful info Tom. I moved into my current living space about a year and a half ago and have been frustrated with a lack of sonic satisfaction ever since.

I'll spare some of the details of some of the decent gear I have owned previously but after running several fairly notable speakers in and out of here I am currently experimenting either with a pair of Dali MS4s or Revel Salons. The MS4s don't seem quite revealing enough even though they do have some pretty impressive bass. The Salons (which I had owned in my previous home before and enjoyed immensely but eventually sold for financial reasons) were now sounding overly bright and curiously not quite as impressive as the MS4s in the bottom end. I have reverted from my AVM30 back to my old trusted Hafler amps and preamp that I have found satisfying for years so I don't think any of that gear would be the issue. I'm running an Oppo 931H dvd player for the source.

My old (and better sounding) listening space was slightly smaller and fully carpeted while the current listening space has wood flooring. Further, there is a large bay window (2' deep by 11' long) along the 18' length of the room in front of which I have placed the speakers out of furniture layout necessities. The speakers sit only a foot away from the bench seat under the bay window and 4' from the side walls. I now listen, as I did in my past residence from my sofa up against the opposing long wall with a love seat forming an L along the adjacent wall. Further, there is a large rectangular glass coffee table directly in front of my listening sweet spot on the sofa and a large piece of glass artwork hanging on the wall directly behind Specific measurements are as follows: length 18', distance across 14' - adding an extra 2' along the length of the bay window, ceiling height vaults from 8' at one end of the 18' room length to 11' at the other. Seven feet of the 14' depth measurement is wide open to the rest of the house at one end. It would be difficult to rearrange the sofa/love seat layout but I suppose I could lose the coffee table if that seems imperative.

Well, what do you think about my possible need for room treatment at this point?

Again, I'm grateful for any helpful advice you might have to offer.

Mark

Tom Martin -- Mon, 12/08/2008 - 09:55

The answer(s) partly depend on your degrees of freedom: what can you change? Can you change the positioning of the speakers? The listener? Carpet? Draperies? The less of this you can change, the more digital correction is the only choice, if acoustics are the problem. The more you can change, the more it is worth first analyzing what setup alone could do for you.

Second, I'm still not clear on what the sonic problems are. The reason you should think about this is that acoustic correction is likely to make some kinds of issues worse and some better.

CEO and Editorial Director, Nextscreen LLC

Marquis -- Mon, 12/08/2008 - 23:06

Hi Tom,

O.K., at this point I find my thoughts gravitating toward both some passive room treatment along with a digital correction unit from one of the few companies that specialize in this arena. Now, due to my real world budget limitations, all I have to decide is whether to spend my money on a top quality Tact two channel unit with fully balanced ins and outs or a multichannel unit from Audyssey (of seemingly lesser quality) which will allow me to more comfortably expand from my current two channel set-up to a fairly good dual purpose room.

I'll thank you once again for your kind input and get back to you in the near future with a bit of commentary about how things are turning out.

Mark

Norman Varney -- Mon, 04/13/2009 - 09:34

Marquis,
I realize that your post is several months old and that you may be done with the projest, but I thought I would add to what Tom has said:
I too reach for electronics as a last resort. It is always best to address the problem at the source, and with room acoustics, that means passively. I don't know your acoustical issues, so I can't make any suggestions, but I can offer you a few tips:
1. There is a hierarchy regarding performance quality, which is; speaker/listener location, calibration, acoustic treatments, equipment.
2. If you convert your 2 channel into multi-channel, I find it extremely important that the channels timbre-match, especialy the CC with the L&R fronts. If they can't all be the same speaker, it should probably be at least the same brand. Typical systems are not and could benefit from some eq for their CC and sub.
3. Though I am not anti-digital correction by any means, understand that they alter the signal feeding the speaker and cannot alter the signal once it enters the room. There are many things digital correction devices can do, but there seems to be a lot of miss-use and missunderstanding as to what they can do regarding room acoustics.

Norman Varney
A/V RoomService, Ltd.

art noxon -- Fri, 04/22/2011 - 16:38

Hi Norm et al….

Glad to see consensus on this issue of correction vs passive acoustics is in sync with the manufacturer’s experiences with this question.
Hi Norm et al….

Glad to see that the consensus on this issue of room correction vs room acoustics is in sync with the manufacturer’s experiences with this question.

The rule it that it takes a one-two punch and it works every time. First is the setup: Detail the room out as best you can, using traditional room acoustics. Second is much easier: Power up the DSP.

Since the DSP is all about delivering decent bass signals to the listening position, “set the room up with room acoustics first” means to seriously detail the room out with bass traps. This begins with floor to ceiling bass trap in each corner of the room.  It includes bass traps in the plane of the speakers and at the front and back walls. The frequency range of the traps being used varies according to where they are located relative to the speaker, listener and room surfaces. Traps in the plane of the speaker do not need ti go as low as those on the back wall.

Another limitation in DP correction is that assumes reflections bounce off rigid walls. In Europe, where most dwellings are stone or concrete, that is the case. But here in the US we still build with wood studs and sheetrock. And these walls vibrate a lot, when pressurized by audiophile gear.  Vibrating walls modulate reflections. And as well, create their own afterglow tones. WallDamp and other more recent entries into the arena of structural damping act to calm down our domestic twanging walls.

However, what happens in real life is that people tend to want to take the short cut to instant gratification... on the cheap. So, despite the warnings, they just buy the DSP and plug it in. Beaming with satisfaction, they muse at how easy it was to outsmart both the laws of acoustical physics and DSP computational power.

I got to be invited to take part in a TAS interview on this exact topic. The transcript from that TAS ROUNDTABLE discussion on Room Acoustics, Equalization, and DSP-based Room Correction was originally published in The Absolute Sound, October/November, 2004. A copy of the published article can be found, read or downloaded at this location:
http://www.acousticsciences.com/articles/tas-roundtable.htm

It is titled Room Acoustics: Audio’s Final Frontier and the moderator was none other but Robert Harley himself. The discussion participants were TAS Senior Writer Robert I Greene who represented the audiophile perspective, Peter Lyngdorf of TacT Audio who represented the industry of DSP Room Correction and Art Noxon of Acoustic Sciences Corp/TubeTrap who represented the industry of Room Acoustics.

Peter Lyngdorf explained how they always heavily bass trap the room and only then apply DSP.  Having all the memory and speed focused on a few reflection problems gives excellent results. Forcing that same fixed memory and speed to take care of a few dozen reflection problems, all at the same time, just doesn’t work so well.
……………………..Art Noxon