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home studio acoustics

Discussion in 'Recording' started by radiophonic, Feb 21, 2001.

  1. radiophonic

    radiophonic Guest

    It seems that everyone here has to deal with this eventually -- what are your tricks to tame small rectangular room problems?

    I find smatterings of details for room treatments involving Owens Corning 703, but very few details on actual implementations.

    What are people doing for a low cost solution? Are you hiring consultants to measure your rooms?

    Say for a standard room size of 12x10 w/ 8ft ceilings, and a materials cost of $500-$1000, what can be done to balance the sound for mixing?

    Looking forward to the approaches...

    Graham
     
  2. Tymish

    Tymish Guest

    There are a few books on this subject with plans. One I recommend is "How to Build a Small Budget Recording Studio From Sratch" by F. Alton Everest and Mike Shea from TAB books. I hope it's still in print but there are others. Getting the basic principles of acoustics is most important first. Room modes, reflection, refraction, absorbtion etc. A solution for one room is a disaster in another.
     
  3. John Sayers

    John Sayers Active Member

    graham - we are currently treating a small control room for FUNKY in Macedonia. You can check it out at our
    Studios Under Construction site
    http://www.angelfire.com/al3/studio/index.htm
     
  4. radiophonic

    radiophonic Guest

    I do have one of the recent F.A. Everest books - sound studio construction on a budget. The typical setup for the type of room I'm currently in resorted to a recommendation for an RPG solution - which is not something I'd call 'shoestring budget'. I need to finish the book - but I was rather disappointed that it didn't include more in the way of plans for construction and room treatment.

    I'll do some more reading... anyone else have a good book recommendation (and/or a referral to someone in Dallas?)

    Thanks,

    Graham
     
  5. JCG

    JCG Guest

    Actually, the "slat" type diffusor that RPG makes is not that difficult to build yourself. Everest's "Master Handbook of Acoustics" (at least the 3rd and 4th editions, don't know about earlier ones) has the math you need (and it ain't that much, QRD diffusors are actually pretty simple). It's also in Everest's contributions to the New Audio Cyclopedia (in a bit more detail, including how to calculate theoretical min and max frequencies). Alternately, AcoustiSoft's ETF measurement software includes designer software for QRD diffusers and Helmholz (sp?) resonators.

    Hope this helps,
    John
     
  6. John Sayers

    John Sayers Active Member

    Here's a link to a helmoltz calculator. It's an Excel file so you must have excel on your puter. :)
    http://www.lis.net.au/~johnsay/Acoustics/Images/Helmholtz.xls
     
  7. Ethan Winer

    Ethan Winer Active Member

    Graham,

    > I find smatterings of details for room treatments involving Owens Corning 703, but very few details on actual implementations.<

    I suggest you check out my article "Build a Better Bass Trap" from EM. It's on my web site's Articles page:
    http://www.ethanwiner.com/articles.html

    This article shows how to build real bass traps for not much money. Let me know if you have any questions afterward.

    --Ethan
     
  8. Rick Powell

    Rick Powell Guest

    For Ethan:

    I have read your article and have it archived. What size trap and plywood "resonator board" thickness would you suggest for a resonant frequency of 49 hz? This is the worst of the frequencies in my rectangular room.

    Thanks,

    Rick Powell/Studio71
     
  9. Ethan Winer

    Ethan Winer Active Member

    Rick,

    > What size trap and plywood "resonator board" thickness would you suggest for a resonant frequency of 49 hz?<

    How have you determined this is the worst frequency? From measurements alone? I'm sure if you build the traps as shown in the plans you'll see a big reduction in standing waves at all the low frequencies.

    --Ethan
     
  10. Aaron-Carey

    Aaron-Carey Active Member

    Regarding accoustics, The F. Alton Everest stuff is talked about, and is very good in theory, although many consider Everest to be the "Roger Nichols" of accoustic design. I am notgonna say anything bad, but read into that what you wish.

    I would very very highly reccomend a book called " Handbook for Sound Engineers the New Audio Cyclopedia"
    This book has LOTS of good pages on accoustics, even some by George Augsperger! Not to mention there are pages on everything to do with studios including grounding, op amps, summing, you name it.

    Also do a search on the internet using keywords " Augsperger, Newell, and Hidley "
    Many accoustic areas cannot be " scaled down" but the principles still apply
     
  11. JCG

    JCG Guest

    Aaron,

    I have the current (second) edition of the New Audio Cyclopedia and most of the sections on acoustics were written by... <drum roll please> ... F Alton Everest. I would recommend Philip Newell's books as well (and Jeff Cooper's if you can find it), but no one else (that I've seen) includes the construction detail and background that Everest's books have. As for Everest, I'd recommend The Master Handbook of Acoustics (especially the 4th edition, which came out last Spring) or his stuff in the Cyclopedia over either of the two Everest "Build a Studio..." titles, unless you are (luckily) in a situation very close to the example studios he discusses in those books. I don't think the "Build..." books add much to what you can glean from the Master Handbook or Cyclopedia.

    My $0.02 (Canadian),
    John
     
  12. Rick Powell

    Rick Powell Guest

    Ethan,

    This is a room mode that calculates out to 49 hz (parallel walls at 11'-6"). It is confirmed by a frequency sweep I did in the room, and by the excess energy created in the room by a bass "A" note with a fundamental frequency near 49 hz. But I agree there are many reasons to do a broadband treatment. I recall a note in your article indicating the "low" bass trap was effective around 70 hz; I just want to make sure, if I build it to the specifications in your article, that it is broadband enough to catch the 49 Hz wave. Or if I should use a larger or deeper trap, or go slightly thicker on the resonant plywood.

    Thanks,

    Rick Powell/Studio71
     
  13. Ethan Winer

    Ethan Winer Active Member

    Rick,

    > I agree there are many reasons to do a broadband treatment. I recall a note in your article indicating the "low" bass trap was effective around 70 hz; I just want to make sure, if I build it to the specifications in your article, that it is broadband enough to catch the 49 Hz wave. Or if I should use a larger or deeper trap, or go slightly thicker on the resonant plywood.<

    Good point. I "tested" the traps I built for my studio by playing various sine waves and touching the trap panels. If I felt it vibrating I assumed it was working at those frequencies. I verified the low-bass traps down to 60 Hz. They may work lower than that. But I can't see any reason not to build a few of the low traps five inches deep instead of four if you'd like to ensure they go down a little lower.

    --Ethan
     
  14. Kris

    Kris Guest

    Can't seem to link to your bass trap article, are you sure that the address is correct?
     
  15. Ethan Winer

    Ethan Winer Active Member

    Kris,

    > Can't seem to link to your bass trap article, are you sure that the address is correct? <

    Yep. Here it is again:
    http://www.ethanwiner.com/articles.html

    Then scroll down a bit to that article.

    --Ethan
     
  16. riconga

    riconga Member

    Lacking the physics background to approach the problem scientifically I found (after numerous experiments with bass traps sonex ect.) the biggest improvement in my small rectangle room came after i treated the cieling with regular acoustic cieling tiles (the 12x12 ones you glue on) I cant do the math but it sounds a lot better!
     
  17. genebail

    genebail Guest

    Does anyone know the equations to figure out the effective frequencies for a quadratic diffusor. Everest just makes reference to the depth of the wells relating to the low end and the well width to the high end. Is it just the quarter wavelength rule?
     
  18. JCG

    JCG Guest

    genebail,

    Everest's articles in the latest Audio Cyclopedia include these equations, but I'm at work (tsk, tsk) and don't have the book handy. I do recall that one of the equations (there are two - one for low cutoff and one for high) includes either the number of wells or the prime number used to calculate the quadratic residue (can't recall which), so it's not just 1/4 wavelength. If I remember by Monday (no Internet at home at the moment), I'll bring the equations to work and post them...

    My $0.02 (Canadian),
    John
     

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