Acoustic Panels: DIY OC 703 or foam wedge panels?

I am finally ready to do some sound treatments to my listening room, and was all prepared to build my own 2'x4'x4"out of the common OC 703 DIY route, but was just given 7 2'x4' Auralex wedge foam acoustic panels. My room is in my basement - approx. 10'x20' with open joist ceilings that are 7' high. I have my room set up lengthwise, using the golden triangle. Front and left wall are drywall, left and back wall are concrete block. I have 2 large, thick rugs down over the majority of the concrete floor.

I'm completely a beginner with these things. Although I've done some research; I can't seem to draw any real conclusions (lots of different products & opinions, I know...).

I'm seeking to add corner bass traps, first reflection points, a "cloud" above my seating area, and something on the back wall. So; my questions are:

1) Can one panel type provide all the treatments I'm looking to for; or both types used, but in different spots?If so, which one's go where?
1) Do these 2 different types of panels do two different things (absorb or reflect, etc.) or the same?
2) Is one clearly better than the other, assuming they do the same thing (the foam wedge panels sure do cost a lot from the looks of it...)?
3) What, if anything is needed to use in conjunction with the foam panels for any kind of backing (mounted to styrofoam, wood, etc. and how thick should it be)?

I don't mind building my own, I was kind of looking forward to it. But, these foam panels were free, and if it would be redundant or inferior; I would be glad to save the $500 or so bucks I was going to spend going the DIY route.

Thanks in advance for any and all advice!!

 

The std thickness for closed cell foam seems to be 2" when ordered from non audiophile cos. I ordered 2 - 12"x25" slabs for c. $40 door to door. I use them under spkrs for isolation. They are for absorption not reflection. For that, you need diffusers.

 

Yes, I forgot to mention that the foam panels I have are also 2" thick.

 

My two cents. You have some very different materials on the two side was it sounds like. That's gonna be challenging.

Foam tends not to be terribly effective below 500 Hz and basically not at all below 250 Hz. I'd skip it for the most part it tends to throw off a room by absorbing only in the highs. Especially given that you have rugs down that are also mostlu HF absorbers.

4" 703 is a much better choice because it'll be effective down to 125 Hz, but it's not a great absorber for the bottom two octaves.

In general I think the best thing to do is bass trapping first. It you're going DIY I'd try maybe floor to ceiling 4" 703 (or better yet, especially behind the speakers, the stuff with the frk on the front, I forget the model number but with that stuff straddling the corners you'll reflect the top 2.5 octaves and possibly absorb even lower frequencies than with the unfaced stuff), straddling the corners with a gap behind and maybe fill the gap with uncompressed pink fluffy insulation.

And maybe I think about trying to build Super Chunk style traps for the wall behind the listening position.

Then you could do 4" 703 at the sidewall and ceiling first reflection points or you might even be able to get away with the acoustic foam for sidewalls once you have the bass controlled, though given the disparity or sidewall materials I'd start by trying as broadband first sidewall reflections as possible.

 

I built all my treatments and got lots of help over at Home Theater Shackhttp://www.hometheatershack.com/#/forums/92?_k=b32w47

I had great results from the 2in 703 product. The 2in 703 panels can be cut with a table saw for custom sizes. I even made 15in at the thickest point corner traps and basically assembled all the pieces to make the traps.

 

"Foam tends not to be terribly effective below 500 Hz and basically not at all below 250 Hz."

My sprks have usable response under 40 Hz. My floor is sprung wood over joists. I use the foam to isolate/decouple the spkrs from transmitting bad vibes to the apt beneath mine. Very effective. Never had a complaint, & I do listen @ hi levels @ times.

 

2 inch acoustic foam panels for absorption -- not for mounting but for airborne absorption, isn't effective at all below 250 hz really and only marginally so below 500 hz. You can look up the absorption coefficients for the materials. The acoustic panels on a wall are a different application and quite possibly a different foam than the stuff used for stands (which also though might not be any more effective at those frequencies as a wall mounted absorber).

 

I agree with the points raised by @chervokas , namely (1) 2" foam is ineffective at low frequencies, (2) foam, if the main acoustic treatment, will throw off the acoustic balance of a room, and (3) a good place to start treating a room is with bass trapping. I would add (4) foam deteriorates over time, while fiberglass panels do not -- after a few years, the foam will crumble and decompose, and (5) treating the first-reflection points on the sidewalls is common advice for a reason -- it makes a difference. I prefer a combination of absorption and diffusion, as is offered by most (not all) fiberglass-based commercial acoustic panels.

Good bass trapping can clarify the sound a lot. The corners are often the place to start. Thicker the better. It is also important IMO to mix some diffusion (of higher frequencies) with the absorption. I have used only commercial products (from ASC, RPG, GIK, and Vicoustic), so I can't give advice on building them that way. But it is important not to deaden the room too much, or the feeling you get in it will be unpleasant.

Some of the acoustics firms (ASC and GIK, for sure) will prepare a treatment plan for you for < $100, which is refundable if you order something. You may want to take these as suggestions, and the firms are in the business of selling acoustic treatments. Yet I have gotten very useful information from ASC and also GIK by doing this. It can give you somewhere to start, whether you follow it strictly or not.

Finally, if you can beg, borrow, or steal some measurement equipment, you might find it informative to see what is happening to the in-room frequency response. Basement rooms can be pretty heavy in the bass, though maybe less so with an open ceiling like yours.

 

Yeah, measuring is the best idea. For $75 you can get an adequate omni with a calibration file and you can use free real time analysis software to run sweeps and look at decay times as well as frequency reaponse curves. Totally worth it both in terms of treatment and in terms of speaker and listening position placement.

 

FWIW, you can find the absorption coefficients for the Auralex line on these pages:

Auralex Acoustics | Performance Data
Auralex Acoustics | Performance Data »

 

Another thing about foam....those cool looking shapes to them catches dust and is very tough to clean. You'll eventually hear about it....

Remember that treating a room, it's a real good idea to have differing materials. You don't really want to heavily treat a room with only one kind of treatment.

Lots of rooms are under or over treated. Don't over do treatments either. Half rounds to break up a longer wall surface are really effectively, but often get avoided due to expense.

CJ

 

My music room is in the basement. I built 8 4'x2'x4" framed 703 panels covered with some kind of "wool" batting (can't recall what it's called) and burlap. Took me about 4 hours, but it would probably take a competent person only around 2.

Placed 4 at the 1st reflection points on each side wall for each speaker, 1 panel straddling each front corner and 1 partially behind each speaker and partially behind a tv. I hung the side wall panels about 4" out from the wall, the rest are on the floor.

While I could use better low bass absorption in the front corners, this setup made an unbelievable improvement in the sound of my system/room. Don't know about foam but I doubt you'll be disappointed if you try some 703. Have confidence in your speaker placement before hanging panels, otherwise if you later move your speakers you'll probably have to rehang the side panels.

The great thing about a basement listening room is that there is very little WAF.

 

Thank you everyone for your insight and wisdom! I decided to ditch the foam and ordered enough 703 to make 15 panels. Frames are made, panels arrived the other day, and I purchased muslin for the back and burlap for the outside wrap.

New questions are: @chervokas - do I need to use the frk-faced panels for all the pieces contained in the traps, or just the outermost/front pieces? And, are you speaking specifically of using this material in the corner bass traps, or on all panels on the front wall behind the speakers? Lastly, is the burlap (or similar) material preferred because it is so light and breathable, or can I use a thicker cloth? The reason I'm asking is I was using some nice, medium weight curtains that I hung behind the speakers to cover the front wall before, and I really like the looks of that material - it was similar in texture to the burlap, but it's more tight and thicker. Is this ok to use that as well, or would it have different/undesirable results?

Thanks again, and I'm very excited to put these all together this weekend

 

Very interesting thread. Can I ask a (maybe) unrelated question ? What are the theoretical benefits of treating a wall behind the speakers ? Never felt the need for it.

 

Yes this is a helpful thread...thanks Jerry James!

I have access to 2" thick mineral wool for a very low cost...a pallet worth for $50. Should this work well in making panels?

As far a a fabric covers, I am interested in using artwork. If I buy the canvas prints from an outfit like art.com, would the print impede the acoustic properties in any way?

 

Recently i was searching for a good acoustic barrier, luckily my search ended up fruitfully with wood acoustic panels. They have an awesome wide affordable range of products. I will recommend you.

 

for abss traps, yes used FRK on the front. this will ensure to make your room not overly damped. bass traps are only for bass traping, without FRK on front, they will absorb secondary reflections which is not desired

for the early reflection panels, do not front with FRK obviously
as for the back wall, id do it last and depending how far your speakers are from the back wall, is not necessarry at all.
start with bass trapping and the earl reflection points on the floor, ceiling, side walls and behind your listening position wall.

 

dont buy mineral wool
get roxul or 703

 

I would be leery of those until they publish broadband frequency coefficients. They mention an NRC up to 0.90 but, unless I missed it, they do not tell you at what frequency. My guess is that they target mid band frequencies to absorb sounds from normal conversation.

When treating an audio room you want to use broadband absorption. If those only absorb from 500hz on up they would not be recommended for an audio room.

 

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When I was remodeling/building the basement music studio, my brother knew a guy with a real estate office that was moving their biz to a new building. They were giving away all of their office furniture. I asked if they had any office cubicle walls they wanted to unload. Turned out they had 30 or more (more than I needed). My brother helped me move them to my house with a pickup truck.

I stripped all the hardware off of them so I ended up with just the panels. Then I went to the lumber company and got wood lathe strips, and stained and finished them. I cut them to length and used Liquid Nails to glue the lathe strips to the edges of the cube wall panels. Found some metal brackets at Lowe's to bolt them to the walls. Acoustic panels on the cheap - super cheap. Another thing that really helps with acoustics in this room is... the walls are two layers of drywall thick. Two sheets of 5/8 drywall Liquid Nailed together for 1.25 inch walls so they don't resonate with sound/bass.

 

You can try acoustic panels for walls. It is usually done on walls or ceilings. Our environmental friendly acoustic panels for walls are widely used in classrooms, recording studios, conference rooms, hotel lobby, auditorium, education facilities, leisure centres, reception areas, studio sound, and so on.

 

I made my own after discussions with a former forum member. I used rigid insulation and built a wood frame and they went from floor to ceiling and spaced a distance away from the corner to absorb reflections.

Not difficult to make if you have some basic equipment.



FRONT







BACK





SIDE

 

A few more shots

 

My suggestion is acoustic panels for walls. Acoustic treatment is usually done on walls or ceilings. Our environmental friendly acoustic panels for walls are widely used in classrooms, recording studios, conference rooms, hotel lobby, auditorium, education facilities, leisure centres, reception areas, studio sound, and so on.