speaker mounting question?

[nathanvacha]

I Think geekslutz is the right forum, so here goes:

So the word on the street is that you don't soffit mount speakers unless they have a built in compensation circuit... so my situay-shee-on is this: I am short on space. (and by short i mean there is no space) so, out of curiosity, is that any better than a crossover, eq, or low-pass filter? If you can electronically change your bass response, why does everyone say don't eq your monitors?

And the real reason for my post is this... say i have a large-ish moveable bass trap, like made out of a bookcase and fiberglass, can i "soffit-mount", so to speak, my monitors in something like this? Just completely packed around by a foot or so of fiberglass? No, it won't give me top-level-pro-million dollar results, i'm just asking for opinions in context of my small/project studio situation...

Any thoughts would be appreciated

[tINY]

There are two things you need to worry about (and they are related). The first is acoustic loading then, there is diffraction. Sometimes you just look at acoustic loading as "diffractive losses".

The main thing you are changing when you soffit mount a speaker is the front baffle. On typical nearfield or midfield monitors, the front of the loudspeaker is about 8"x20" (give or take 50%). When the baffle is 1/2 wavelength or more, the speaker is puting sound into half-space (or 2-pi space) so it is louder than lower frequencies that radiate into full (4 pi) space.

When you soffit mout a speaker, you change the frequency where this half to full space crossover happens. To complicate things, the baffle "uncouples" near the cross-over frequency of a lot of two-way speakers. Since the woofer is a lot bigger, it uncoulples differently than the smaller tweeter.

If you put 4" of ridgid fiberglass insulation for a foot or more around the speakers, you might be alright. It's worth trying. I'm not sure how this will effect the baffle coupling.

Ethan - any insight here as to how OC705 compaires to air form an impedance standpoint (other than loss)?





-tINY

[Cojo]

Originally Posted by nathanvacha

I ThinkIf you can electronically change your bass response, why does everyone say don't eq your monitors?

Hi!

The EQ switches on the back of the speaker is to compensate for speaker placement in first hand, NOT for room acoustics.

/Cojo

[nathanvacha]

Originally Posted by Cojo

Hi!

The EQ switches on the back of the speaker is to compensate for speaker placement in first hand, NOT for room acoustics.

/Cojo

Okay, so the same could be achieved with a low shelf down? I was reading on this a little bit on the John Sayers forum (where everybody seems to have soffit mounts in their builds) and that was kind of the impression i got.

[nathanvacha]

Originally Posted by Cojo

Hi!

The EQ switches on the back of the speaker is to compensate for speaker placement in first hand, NOT for room acoustics.

/Cojo

Okay, so the same could be achieved with a low shelf down? I was reading on this a little bit on the John Sayers forum (where everybody seems to have soffit mounts in their builds) and that was kind of the impression i got.

[Cojo]

Originally Posted by nathanvacha

Okay, so the same could be achieved with a low shelf down? I was reading on this a little bit on the John Sayers forum (where everybody seems to have soffit mounts in their builds) and that was kind of the impression i got.

Yes, you can adjust for speaker placement with a separate EQ. If a speaker is design to have a flat response in free space then as you move it towards a wall you will have an increase in volume, starting with the lowest frequences, until it's totally flush mounted. Then (in theory) all frequences are 6dB louder but probably only the lower frequences. Then you'll have to messure and EQ to a flat response. The advantage of flush mount speakers is that all sounds are in phase and you don't get the cancellations and peaks you normally would have get if the speaker was placed in a distance from the wall.

/Cojo

[Ethan Winer]

tINY,

> Ethan - any insight here as to how OC705 compaires to air form an impedance standpoint (other than loss)? <

Sorry, no, but this would be pretty easy to measure with ETF or an equivalent analysis program.

--Ethan