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Author Topic: some help with mixing room acoustics  (Read 1697 times)

julian

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some help with mixing room acoustics
« on: June 24, 2007, 03:22:19 am »

ok, this is my first post, and i don't speak English really well, so forgive my spanglish ...

im from Argentina, i work for a professional sound services "corporation"   (me, my boss, and a new guy in "sales department"    Wink     ) , we have a recording studio, and some times i bring work to my home, editing, pre mixing etc, so , i have a pair of studio monitors and a daw in my room.

the thing is, my two monitors are really close to me right now, to avoid the bad acoustics and because i put them just over my old table, i have done a few measurements of my monitor and i realize that i have a really, really, bad problem around 130hz. but if i bring the monitor to the edge of the table, the measure improves a lot

right now im applying some equalization to deal with this, but i would like to deal with the acoustics indeed

i have some hypothesis

-the table is 1.3mt x 0.9mt  , is the table making some mirror effect ? (i don't know the english terms for this acoustics things)     345/(1.3*2) = 132hz      is this right or im just talking nonsense ?

-can the table and the parallel roof create a resonance mode?

-the things get worse if i turn on both speakers, i think this is because they combine but starting in the same freq that i already have troubles.

-or im just hallucinating all this confused by a lot of room modes  ?             (yes my room is quite square ...)      



so

can i try breaking the parallel with something in the roof ?

i think im going to put the monitors over stands, it is better if i put the monitors a bit higher and inclined forward ? im not sure of that because i also have a lot of comb filtering with the table ...

do i burn the table and buy something smaller  ?  


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Ethan Winer

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Re: some help with mixing room acoustics
« Reply #1 on: June 25, 2007, 01:45:11 pm »

Julian,

Your English is fine.

Quote:

is the table making some mirror effect?


Probably, but that's the least of your worries, and not difficult to deal with. All rooms need:

* Broadband (not tuned) bass traps straddling as many corners as you can manage, including the wall-ceiling corners. More bass traps on the rear wall behind helps even further.

* Mid/high frequency absorption at the first reflection points on the side walls and ceiling.

* Some additional amount of mid/high absorption and/or diffusion on any large areas of bare parallel surfaces, such as opposing walls or the ceiling if the floor is reflective.

Once these are done, then you can worry about desk reflections.

--Ethan

julian

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Re: some help with mixing room acoustics
« Reply #2 on: June 26, 2007, 12:02:35 am »

thanks for the answer Ethan.

yes i'm aware of that

i have some absorption/diffusion, planning some more, and also thinking the nice way to put some traps in my bedroom ... not an easy thing.


but what really amazed me, was that if i move the speaker just from the edge of my table to the center (half meter) then i have a boost of almost 6dB of difference at 130hz , and not with a small Q,     110hz to 260hz

not moving the microphone, measuring with a transfer function

i think it is too much difference to not to worry about it, more than half of the equalization i'm doing it because of that half meter that i need to get the monitor in position.







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franman

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Re: some help with mixing room acoustics
« Reply #3 on: June 29, 2007, 03:49:51 pm »

Julian,

Reflections off consoles (or tables) can be very pronounced and can cause deep dips or peaks in your response. Ethan is correct when he states that you need to implement some (a lot) or broadband trapping first. The reflection issue is most likely best addressed by moving the speakers onto some stands and off the table so that the reflection misses your ears. Also, if you want to understand how this affects your work, more the microphone around and make a series of tests. You will see that the freq of the dip/peak moves as you move the mic around.. It's not like you're 'missing' that one frequency because your head moves around all the time. It's a deep notch but it's a 'moving target' if you follow me... Very Happy
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