room sound treatment

[11miles]

Since my room(studio) is about done, i've already moved the comp inside.

It's beatiful and i really feel comfortable inside.

The sound treatment is now ready to begin.:-)

I was just wondering, i know that covering the wall with the acoustic foam is not the same as putting up the bass traps an mid-high absorbers..., but it will help reducing the echoes and reverb of the room.

Are the traps good oor that too?

[knightfly]

Yeah, the traps will accomplish that better - thing is with absorption, is you need to absorb EVENLY; or, more correctly, you need to END UP with a reverb time in the room that is pretty constant at different frequencies; so if the room is very rigid (concrete walls for example) you'll need more bass trapping, since concrete doesn't let as much bass out of the room - similarly if you use several layers of gypsum, but not quite as much.

So to get the room to sound NEUTRAL, you need to know what the absorption of the total room is at all frequencies, and pick absorption materials to balance that absorption at all frequencies.

When you succeed at this, your reverb time (called RT-60, which stands for the length of time it takes for sound level to decay to 60 dB below the initial level) will be pretty even across the frequency range.

Here is a simple calculator that will help approximate what the RT-60 of your room should be with no treatment -

http://www.saecollege.de/reference_m...r.htm#verbcalc

And a different RT-60 calculator that's online so doesn't require Excel -

http://www.wsdg.com/resources/resour.php?SL=te&BL=4

Once you calculate at each frequency (buttons across the bottom) and chart these, you will know which bands you need to absorb more in order to even out the response; having an uneven reverb time is the main thing that makes a room sound "colored" - so this is a major step in acoustic treatment. You can't fix a problem until you know what the problem is...

The next step is finding materials that will give you the absorption you need at the frequencies you need in order to bring your RT-60 into balance at all frequencies - this takes a fairly complete list of materials and their coefficients of absorption at the same frequency bands you've identified. Here's a couple of these, the second being an Excel sheet from WSDG which is pretty thorough -

http://www.saecollege.de/reference_m...nt%20Chart.htm

http://www.wsdg.com/resources/resour.php?SL=te&BL=6

One of the problems with foam (assuming you stay away from the cheap stuff, which is not only less effective but may be a fire trap) is that foam doesn't absorb to as low a frequency for a given thickness as materials like rigid fiberglass or rockwool; so you're left with a lot more low mid and mid frequency ringing than would happen if using the "good stuff" - this makes your room sound "boxy", and at the same time (since foam is VERY good at absorbing highs) it will also sound DEAD.

Here is a basic idea of some DIY units that can be kept portable and will let you solve most of the problems in a small room -

http://www.johnlsayers.com/HR/index1.htm

And more -

http://www.saecollege.de/reference_m...Acoustics2.htm

As you can see, this isn't a "5-minute solution" - but if you manage to get a good sounding room without considering all this (and more) you'll be doing it by luck. Remember, if the room you record in is "colored", and you lay down multiple tracks in that environment, each track you add to your mix will make the overall mix sound even MORE colored - eventually, the whole thing will just sound like crap and you won't know why.

Add to that the possibility that you'll ALSO be MIXING in that same, colored environment, and it becomes even MORE important to "get it right"... Steve

[JohnnyMan]

Great post!! Thanks for the tips Steve (Knightfly) - and this isn't even my thread!

[11miles]

Although my name is not frank i will be.

I was expecting a response from you steve

But not as thorough as it is!
thanks a lot.

I am at work right now, but i will get into that.

Oh and something else, is there any difference about sound treament when using only nearfield monitors instead of bigger sistem?

I mean there must be some difference, right?

[knightfly]

This is a subject for an entire book (which has been done, BTW - it's called Studio Monitoring Design, by Philip Newell -

http://www.amazon.com/exec/obidos/se...452893-0892119

I don't have the book yet, still chewing my way through Recording Studio Design, which has chapters on ALL aspects of studio design and is an excellent book IMO...

For a couple of generally good answers to your question, I'd check these -

http://www.customaudio.freeserve.co....es/frstand.htm

http://www.genelec.com/support/frstand.php

And for advantages/differences of soffit, or flush-mounting -

http://www.genelec.com/support/soffit.php

Gotta go for now, this should get you started... Steve

[vestast]

Here is a basic idea of some DIY units that can be kept portable and will let you solve most of the problems in a small room -

http://www.johnlsayers.com/HR/index1.htm

Hey Steve - When you say a small room, how small do you mean ? I'm planning a 10'x 20' room right now and have been using that DIY page as a reference for planning.I've been studying that DIY page for a few days now and I'm getting ready to post over at John's.


Thanks
Dave

[geet73]

According to this RT-60 calculator..
4000Hz - .38
2000Hz - .42
1000Hz - .48
500Hz - .53
250Hz - .7
125Hz - .39

What does that mean?
Would getting broadband absorbers between 250Hz and 2000Hz help? I'm not sure how easily one like that can be made.. but yea.