Sorting out room acoustics

[IanHarvey]

This seems to me an incredibly important subject, but there seems to be little or no traffic on DiyAudio about it:

How does one go about sorting out room acoustics (and/or the speaker-to-room interface) in a methodical way, given a moderate amount of test kit (a decent microphone, soundcard + computer + audio analysis software) ?

Given the number of variables involved (position of speakers, furniture, curtains, treatments such as acoustic tiles), trial and error seems a bit time-consuming. I assume recording studio acoustics people have some tips and tricks.

Any ideas?

Cheers
IH

[Timn8ter]

Here's what I did.

Panels

BFD



Good info here too.

[Nielsio]

My method:

Let everything where it is and use a digital equalizer to flatten + add target curve.

[Nielsio]

I like your panel-idea, Tim.

I think I'll implement mine like this:

#Ceiling
#1st layer damping material
#2nd layer cover layer 1 with thin cloth

I won't use wood like you but only fabrics.

[Da5id4Vz]

If you are not going to use a wood frame you should consider using fiberglass resin compound to harden the edges. This will help prevent the material from sagging.

You should also try to avoid using fiberglass materials not designed as duct liner. The duct liner material has blunt edges to the fibers that are likely much less distressing to your respiratory system.

Ive been very curious about this software:

http://www.rpginc.com/products/roomoptimizer/index.htm

Ive used a number of other RPG products and have been very pleased. The company’s focus is to work with AIA architects and high-end acousticians. They will of course still talk to us mere acoustical mortals, but I think that they sometimes don’t understand what we don’t understand.

This stuff looks real good also:

http://www.siasoft.com/products/

I have mutual friends with and have had the chance to talk to both authors. Sooner or later Ill have to get around to actually trying this stuff. It just doesn’t fit in with my home life and I haven’t had the cahoonas to get paid to do this stuff for a number of years now.

From my own experience, Ive liked the sound best when I can take the EQ out or the signal chain and adjust the room treatments (carpets absorption and diffusion) until I like the room sound and response.

[SimontY]

Always been fascinated by this subject, as it always seems to be the no. 1 barrier to good music reproduction... Most rooms sound crap in some way or another, and my current one is dreadful!

Can anyone offer advise for fixing an overly dead room?? The system sounds dull at low volumes, and wrong at high volumes!

I plan to try and remove some crap from the room, but its just finding space elsewhere!

Oh, one more thing... anyone in the UK know where to find a CHEAP (ie. <£40) SPL meter? Preferably just a cheap analogue one..?

-Simon

[HeatMiser]

IMHO equalization is not the best route to fixing room problems, although it is sometimes the only practical route since we have to live in these rooms as well as listen to music in them.

If what comes out of the speaker is is essentially correct and the only problem is that your room bounces things around in an uneven and unpleasant way, why on earth would you want to equalize the source and purposely force incorrect sound from your speakers in order to fix it? The problem is not the system, it's the room; it seems to me that trying to fix room problems at the source is kind of like trying to "correct" a room with walls painted red by putting green-tinted light bulbs in all your lamps and thereby "equalizing" the light frequencies.

A good start is to try and kill first-order reflections from the speakers to the listening area with panels as previously suggested, or furniture if panels are unrealistic. Put them wherever, if a mirror was placed there, you could see the speakers in the mirror. So on the ceiling at the half-way point like Timn8ter has done is the first order of business, since that spot forms a very short and direct reflection path from the speakers to you. In a perfect world you might want to treat the same spot on the floor, but large panels lying about on the floor are oddly inconvenient for most of us. So settle for a rug.

That leaves a spot on each side wall that might benefit from treatment, or at least being something other than a blank wall. (Owners of open-baffle speakers can skip this part ) It's more of an issue in smaller rooms, but if you can manage clever placement of a bookcase or comfy chair or something there might be a benefit. Or place more panels if that works for your spouse.

Bass management is tougher, since there is a lot more variability in rooms and many speakers are designed in anticipation of "room gain" at certain frequencies.

There are several plans for very inexpensive bass traps around the web, you might see if you can make a couple and try them out in your room, moving them around to see what happens.

[GM]

Can anyone offer advise for fixing an overly dead room??

Use speakers with high directivity, i.e. horns, or at least larger fullrange drivers, which beam somewhat due to design limitations.

GM

[Bill Fitzpatrick]

Originally posted by HeatMiser
IMHO equalization is not the best route to fixing room problems, although it is sometimes the only practical route since we have to live in these rooms as well as listen to music in them.

If what comes out of the speaker is is essentially correct and the only problem is that your room bounces things around in an uneven and unpleasant way, why on earth would you want to equalize the source and purposely force incorrect sound from your speakers in order to fix it? The problem is not the system, it's the room; it seems to me that trying to fix room problems at the source is kind of like trying to "correct" a room with walls painted red by putting green-tinted light bulbs in all your lamps and thereby "equalizing" the light frequencies.

Kudos!

[SimontY]

Use speakers with high directivity, i.e. horns, or at least larger fullrange drivers, which beam somewhat due to design limitations.

lol - ask a silly question, get a silly answer, fair enuf!

More seriously though, taking some of the white polyester damping crap out of my speakers and using several progressively shorter layers of rubbery carpet underlay - tried just yesterday - has made them lighter and brighter, this partly helps make up for the dead room effect.

-Simon