• RE: Research and real life - David Aiken 13:54:43 02/11/08 (0)
  In Reply to: RE: Research and real life posted by jimgrocecfp@hotmail.com on February 11, 2008 at 11:59:49

  Jim,
  
  I'm sorry that things got diverted by what is actually long standing and probably not resolvable disagreement between Klaus and I, and also between Klaus and Ethan, about room treatment and especially treatment of first reflection points. Ethan and I are both pro room treatment and treatment of first reflections, and so is F. Alton Everest if you read his "Master Handbook of Acoustics" which I think should be essential reading for anyone considering room treatment or interested in room acoustics in listening rooms. Klaus on the other hand takes what I consider a fairly narrow view of the research he's read, especially that of Floyd Toole, and simply tends to state that room treatment is unnecessary whenever he enters a thread.
  
  Ethan is extremely pro room treatment as you would expect from someone who makes and sells acoustic treatment products. While I'm more hesitant than he is to recommend treatment of first reflection points to everyone, since I have come across people who don't like the result and have come to accept that there's an element of preference involved, my personal position when it comes to my own room is completely in line with Ethan's and I think using absorption at first reflection points yields quite noticeable benefits in terms of imaging and clarity. I think the reason you only noticed a slight improvement with your experiments using pillows on guitar stands is simply that pillows aren't a particularly broad band absorber and they are also probably a little too small in area for effective treatment of a reflection point. I think you would be much more impressed with the results of panels which work over a much wider range and which are considerably larger, say around the 2' by 4' size as a minimum and preferably closer to 3' by 4' or even 4' by 4' in size.
  
  If you look over posts here over the last few years, I think you'll find that with only a couple of exceptions, Klaus being probably the strongest of those, most people posting here are in favour of room treatment. Given that this board was established for discussing the practical aspects of room treatment that's really not surprising and the distribution of opinions represented here will definitely be strongly skewed in favour of treatment. In my experience the opinions of most people who have listened to music in treated rooms is also in favour of treatment but some people aren't prepared/willing to treat their own rooms because their room is a living room and there are certainly strong visual impacts from room treatment. Most acoustic treatment products are not attractive additions to a living room, and there are also often placement restrictions on where things can go in a living room given the existing furniture and the functions the room is serving apart from housing an audio system.
  
  If I were asked for a priority order for room treatment, what I would say is:
  
  - bass trapping is the highest priority and I think every room benefits from bass trapping
  
  - if you're interested in improving imaging/soundstage and tonal accuracy, I think treatment of first reflection points is the second priority, especially in regard to side walls and the wall behind the speakers. I think ceiling treatment is probably a good idea, especially for lower ceilings but lower ceilings also give you less space in which to do it, but I don't have ceiling treatment in my room because I don't want to have to drill permanent mountings into the ceiling and I've yet to come across a way of sticking any acoustic treatment to a ceiling that will both hold up long term and not mark the ceiling. Every trick I've tried for holding foam tiles to the ceiling without marking or damaging the ceiling has eventually resulted in the tiles falling off, and anything other than foam tiles is even heavier and requires attachment techniques I don't want to use. On the other hand, if you find imaging and a clearly defined soundstage distracting as some people certainly seem to do, then I would expect that you might well prefer the sound of a room in which first reflection points are untreated.
  
  - finally, after bass traps and treating first reflection points, I'd consider adding diffusion to the area behind the listening position if that's possible but diffusion requires space in which to develop and you really need around a minimum of 6' or so behind you if diffusion is going to be really worth while.
  
  Klaus will almost certainly disagree with me on any recommendation for treatment. Ethan on the other hand would probably recommend more bass trapping than I would employ on the basis that bass trapping in corners always smooths the room response and that more trapping smooths things even more. He's right but I think my threshold for accepting the visual impact of a lot of bass traps is lower than his. I'm happy just to treat the 4 room corners though I do agree that treating the wall/ceiling and wall/floor junctions as well would certainly be more beneficial than just treating the wall/wall junctions as I do. That puts me in the middle between Klaus and Ethan: I agree with Ethan about the benefits of treatment and that more is almost always better than less, but I tend to be more concerned about the visual impact than I think he is.
  
  I also think that the only person who has to be satisfied is the person who owns the system because they're the person who spends more time listening to it and the point of this hobby is musical enjoyment. If acoustic treatment doesn't add to your enjoyment, then don't do it and most definitely don't do it if it detracts from your enjoyment. The only other thing that needs to be said is that if you're going to add absorption to a room, ensure that the absorption is broad band and covers as much of the audible frequency spectrum as possible. The worst thing you can do is to use narrow band absorption, especially if it's basically only absorption of the high frequencies with little or no mid-range and bass absorption. The resulting sound will simply be tonally unacceptable with a dull top end and a poorly defined bottom end, possibly with room decay times in the bass frequency that destroy the clarity of legato playing by the musicians. The basic rule, if you're going to do any acoustic treatment at all, is to do a good job on the treatment that you do implement. If you can't do a good job, don't do it at all because the results may well be worse with a bad job than they are with no treatment at all.
  
  So definitely keep reading things here, and reading Everest's book if you can, and keep thinking about the topic. Try what you can when you can, and definitely don't forget that the point of everything is always musical enjoyment. If you're not getting that you're doing something wrong. You can certainly enjoy music in an untreated room but I think you will get more enjoyment in a treated room. Best wishes in your quest for better sound.
  
  
  
  
  David Aiken
  
  

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