Room Treatment

[punching_sandwiches]

Hi guys,

so I tested my room using the old 'Alvin Lucier - I'm sitting in a room' trick

(http://www.youtube.com/watch?v=sCgicEWD ... re=related) -//If you don't know about it

and it appears that I have huge problems with around 133hz.

To fix this do I need Bass traps? Or regular acoustic foam?

Also where are hot spots to prevent this sort of thing? - Corners behind speakers?


My room is a fairly standard cube (though with one curved wall), my desk is up against one of the walls like it should be.
I only have one room so all my instruments/skip raided percussion/soldering workshop fill up most of the space.

[ffrgtm]

edit: wtf... post went to a completely different thread...

[ze2be]

I dindnt get the "trick" from the video. What trick?

[punching_sandwiches]

The trick is to first record something (in the video it is a paragraph of text spoken) then to play that back into the same room it was recorded in and record that.
Do this a hand full of times (maybe even more) and what happens is that each recording amplifies the resonances in the room.
It's a great art piece but also fantastic for finding what frequencies your room resonates at.

In an ideal environment the sound should be pretty much dead.

In my case I get a HUGE peak at 133Hz after only a few rounds. This is telling me that that is a problematic frequency in my room.

I was wondering if this frequency constitutes bass traps or another type of room treatment.

[Winterpark]

...My room is a fairly standard cube (though with one curved wall)....

you're going to get strong room nodes if you have even wall dimensions.... including Width, Length and Height... so this sort of cube-type room should really be avoided.

a way to lessen this is with bass traps in corners.... you could move the monitors out from the walls a little, and putting acoustic treatment on the sides and above 'prime' listening position will also help.

If you have a "huge" peak at 133Hz... then you've probably got another peak at 66.5, and 266 etc...

[UnCL0NED]

Uhhh... I'm no expert, but this sounds like a very dodgy way to find resonating peaks in your room.
If your serious about room correction, I would recommend to get specific equipment for a more accurate readout.

Anyway if you do this, I think you have to make sure you know the frequency graph of your microphone you re-record with and that this is correct. Otherwise it will be only the mics frequency peaks you will be correcting and not your room.
Also make sure you put the mic exactly in the place where you would normally sit when you mix. You obviously will find inconsistencies anyway! But this way you at least make corrections for your sweetspot.
And also: why don't you just use some white noise instead of music?... If the music you use, misses a few frequencies (or are only very quiet in the mix) that are a problem in your room, you will never find them this way.

[Winterpark]

yeah... just looked at that youtube link... that's not an accurate way of testing.

you're pretty much just accentuating the original source material, (which may have had a peak at 133Hz) with both the EQ curve of the microphone and speakers that are playing it back.

[Der_Makrophag]

A good way to get an idea about resonating frequencies is listening to a sine sweeping slowly up or down the spectrum. This makes it also possible to pin down the frequency very exatactly. However, it depends on you rears and speakers and so on, but you coul'd anyway record the signal with your microfone and see what the sepectrum looks like. And if you really find it a good idea, do the trick in the video. But use maybe white noise as a source or the sweeping sine. This will be better than "any signal".

But in the end, what you hear does matter or? If you have high resonance at 130Hz it should sound really muddy on the bass and droning sound.
I also have problems right now, but at lower freq. (you better also check them) and I am not even able to listen to musik without cutting the bass, so producing is impossible.
So I also need to improve my room. Maybe I will return here, after I got smarter.

[Forge.]

that track was performance art - or musique concrete, or similar - it is not a recording for audio engineers to test room acoustics

[tech44]

http://www.gearslutz.com/board/studio-b ... acoustics/

More info than you'll ever need to know about room treatment in that forum. From what I've read bass traps are probably the answer since most acoustic foam doesn't fix low end issues.

[ze2be]

White noise seems like a good idea. Prob best to have a look first with an analyzer to make shure its flat.
I got a Rode NT3 and it looks like it has a nice flat frequency response from the company measurement:


..is that 0, 10, 20 decibel vertically?

edit:picture size

[Der_Makrophag]

I am not sure what the unit "dB re 1 V/Pa" means.
Why dont you use Spectrum inside Live?

White noise will be suitable, when you want to record the signal with your microfone. If you want to do it by hearing, I suggest the sine sweep, as the problematic frequencies will be (partially) masked with white noise (inside your hearing system, not by the room!).

[ze2be]

I am not sure what the unit "dB re 1 V/Pa" means.
Why dont you use Spectrum inside Live?

Yes, but that picture was the graph of my microphone. And to be able to read the spectrum in Live more clearly, it helps to know the graph of the mic. Was just wondering if 10 means 10 db. Probably. In that case, its just 2 decibels out of range at the top and in the bottom. If so, I can adjust the recorded audio with an eq, before I check it on the spectrum-analyser. Ill have a go at it.

[ze2be]

OK, I tried the noise trick. In the picture here the dark line is the white noise before the room recording. The bright line is when the same audio is recorded with the NT3 microphone. The grid is in steps of 6db. Appears that from 100 Hz and down, I loose about 12db. There is also a dip around 10kHz. Is this OKish, or is it bad?



I wonder why 0db on Lives faders equal to -36db on the spectrum..

[Forge.]

I wonder why 0db on Lives faders equal to -36db on the spectrum..

because -36 dB is only the level of certain frequencies. It all adds up together.

it is a SPECTRUM of many frequencies. "spectrum" is telling you what is going on for each frequency band.