This Bass Trap Picture...(Update)

[camistan]

The picture below of the rear wall in this studio is pretty similar to the design I plan to have in mine.

The question I have is this...

The bass trap looks to possibly have a cloth front, but it looks as if there are 5 boxes with thin slats running through each box. If I made a rear bass trap with hangers in accordance with diagrams posted on this site, still used a plain cloth front, except I made 5 boxes with thin slats to go in FRONT of the cloth (as depicted in the picture), would the boxes with thin slats effect the performance of the bass trap?

(FYI...my bass trap- Opening (cloth area) of trap= 6 ft 6in height x 7 ft 5 in width x 24 in deep/corner traps will be made according to corner trap design on this site/Ceiling will be approx. 8 ft with clouds extending from the front of the control room to the rear. See this post if necessary:

http://www.johnlsayers.com/phpBB2/viewtopic.php?t=4827

Thanx & GOD Bless
Stan

[kendale]

Aloha Stan,

Forgive me if I'm wrong, but I think the rear wall treatment you are refering to in the picture is a diffusor rather than a bass trap. (It looks like a cloth covered RPG QRD 734 (see attached.)

One of the reasons I think this is:

Low frequencies are big waves, consider that a 50Hz wave is 6.6m (21' 8'') and a 30Hz wave is 11m (36ft) long! That's 11m peak to peak -There's a lot of guys around here who would love to surf a wave like that! So to stop it requires special techniques.

The diffusor pictured does not have the depth needed to absorb such a long wave.

In any case, here's a link to the SAE website which has some great info on bass traps. http://www.saecollege.de/reference_material/index.html
Click on absorbers in left hand column and then click on the low frequencies tab at top of page.

Hope this helps.

Aloha

[bpape]

Actually, I think the're Abfusors - Normal QRD diffusors but with absorbitve material on the face to provide some absorbtion in the highs. Even if it's not, they'll provide little to no effect in the bass.

The bass 'traps' in that pic are the wood slatted corners beside the diffusors and are slotted Helmholz types.

[kendale]

Aloha,

Ah yes, Abfusors. Thank you Bryan!

Aloha

[camistan]

bpage & Kendale,

Thanx a LOT for the response and info. I've done a lot of searching on here, but I gotta admit... I missed this part of the SAE site. (I scanned the SAE site only for what I "needed" at a given time, but not in depth)

I just printed that whole section on acoustics and absorbers along with putting it in a "favorites" folder.

Got some readin' to do...

Thanx again

[camistan]

Ok, let me try this again...

Please correct me on my assumptions below if they are incorrect. Also any advice/critiquing will be appreciated...

Based on the design I have for my control room,

http://johnlsayers.com/phpBB2/viewtopic.php?t=4827

1.) I would build a Helmholtz Resonator that would extend along the left wall from the control room front to the corner traps in the rear. (This wall is opposite of the sliding door wall). This (left) wall would give me absortion of the low-mid frequency range.

2.) The right wall (wall side that has the sliding glass doors) will be reflective as far as the glass door is concerned. What is reflected from the glass door that is in the low-mid frequency range should either be caught by the Helmholtz Resonator on the LEFT wall, or be reflected to the Corner traps or Bass trap in the rear. (I haven't done any Ray-tracing of the reflected areas in my control room, but once I do, I can have a more "precise" idea about the location of sound reflected areas in my control room). Even after the Helmholtz Resonator, Corner traps and Bass trap, I know there may be more fine tuning needed, but for now, all I'm saying is based on the BASIC reflective angles I've seen, if the Helmholtz Resonator extends the length of the left wall to the corner traps, it should catch or reflect the mid-low frequencies. The same should occur in the reflected frequencies on the right wall.

3.) The higher frequencies will most likely be reflected by the glass door and Helmholtz Resonators. These reflected frquencies should be absorbed by the Corner traps or Bass trap.

4.) The center trap on the rear wall will be a Bass trap. This trap will have insulated hangers for LOW frequency absorption. This Bass trap would be 24" deep, 6ft 6in in height, and 7ft 5in in width. This trap will be made like the following link (3 posts from bottom of page):

http://www.johnlsayers.com/phpBB2/viewt ... =bass+trap

5.) In the control room layout I had on my studio page, you'll notice I had another set of larger speakers a little more than half way from the front wall (in front of the mixer) to the rear wall. These speakers (JBL LSR 6332 speakers-15" woofers) will be soffit mounted. Because of the acoustic treatments mentioned above (Helmholtz Resonator-Corner traps-Bass trap) I would assume these would be sufficient to reflect & absorb sound from the larger speakers. According to JBL, the listener should be 6-10ft from the speakers. My plan is for the listening position to be 8ft from the speakers. The distance from the speakers to the bass trap wall would be approximately 10ft. Also, in looking at my control room design, I may have to put some type of absorber on the back wall of the larger soffit mounted speakers for wave reflection from the near field monitors at the mixer position. (For larger speakers, see #7 below)

6.) What from what I have read, a diffusor spreads reverberent sound evenly through the room. Even though this is helpful for standing waves, shouldn't the splay walls correct the standing waves problem? By having a diffusor, wouldn't it possibly be necessary to have to re-adjust for reflecting waves spread out by the diffusor? It seems that a diffusor would be good in the "fine tuning" stages of room treatment. What are your thoughts on this?

7.) From a post I submitted a while back it's evidentally possible to build a soffit box for the speakers. I just want to be sure through construction that ALL of the sound will travel forward and the baffle area will not be too small/narrow for speakers the size that I want to install. This is critical due to the size that the baffle may need to be. To get the best overall sound from my JBL's, it may require baffle space that I can not accomodate.

8.) In the design I have seen for most bass traps, there is a cloth front that covers the hangers, rockwool etc. Even though I may have been looking at an "abfusor" in the picture above, it still seems building a Bass trap is in order. I'd still like to know if I built 5 boxes with narrow-thin slats inside them to be placed in front of the cloth (or 1 continous box for that matter) would it affect the performance of the Bass trap?

Well, I think that's about it. Right now I just want to get my info straight so I'll know how to frame up the inner frame of the Control room. I already pretty much have how I want to do it, EXCEPT for the rear wall. Once I get answers to this post, it will make things a lot clearer on how I should proceed.