What type of OC 703, unfaced, or foil ???

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GlowPlug

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I wanna make a few DIY broadband panels, and I found a real good price on a 12 pak of 2" 703, (or atleast I think its a good price :confused: ) But, do I want to get the UNFACED 703, or the FOILED 703?

I found a place selling a 12 pak of 2'x4' UNFACED 2" 703 for like 80 clams, and a 6 pak of 2'x4' FOILED 2" 703 for 57 bucks.
 
Plugz,

> do I want to get the UNFACED 703, or the FOILED 703? <

You want both, so get some of each. For bass traps straddling corners the panels should be four inches thick with foil. So make a sandwich from one of each type, and mount them in corners with the foil facing toward the room. For first reflections and general ambience control, two inches thick without foil is preferred.

--Ethan
 
Ethan Winer said:
You want both, so get some of each. For bass traps straddling corners the panels should be four inches thick with foil. So make a sandwich from one of each type, and mount them in corners with the foil facing toward the room. For first reflections and general ambience control, two inches thick without foil is preferred.
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ahhhhhhh, very interesting. Thanks for the tip Ethan!
So, the foiled face 703 Fiberboard, serves as a kinda 'poor man's dampening membrane!

Would a 6" of 703 give me better results than the 4" panels, and would I still only use one 2" FRK 703 in front (facing the room) with the additional 4" panels of unfaced 703?
 
i'm asking the same question. im making bass traps. I'm not sure why you want foil facing the room? wouldn't that create a reflection of the sound?
 
Kasey said:
i'm asking the same question. im making bass traps. I'm not sure why you want foil facing the room? wouldn't that create a reflection of the sound?
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of high-mid and high frequencies yes. This means that bass traps are for bass n low-mid only.
 
but if you wanted to absorb low, mid and high all at once wouldnt you just want unfoiled? wouldn't anyone want that? would that make it not work as well for the bass frequencies?
 
It think it just works the same at bass frequencies. The reason for wanting to absorb lo->mid and reflect mid->high is because low/bass frequencies are what cause most of the problems acoustically in a control room. The mid->high frequencies may be be level, and adding absorbtion would screw that up. Also many people don't like a dead sounding room, but want to tame the bass, so install bass traps to only trap bass, leaving the mid->high frequencies to reflect around the room.
 
mine are unfaced, but this is my first studio, eventually when I am older and wiser I will have a more "balanced" room. Recently I had to move int oa 9'x11' room, so I had to intall a lot of absorbtion. i have 2 2'x7' bass traps and 2'' - 3'' foam. The room sounds a little dead, so judging by that, I'd say foil on the front is the best way to go for bass traps.

ps...is you have a 14'x35' room, never give it up!!!
 
Kasey said:
but if you wanted to absorb low, mid and high all at once wouldnt you just want unfoiled? wouldn't anyone want that? would that make it not work as well for the bass frequencies?
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Kasey,

First of all - if you look at the charts on this material (unfaced) - in general they work better for high frequencies than for low frequencies - so if you use all unfaced you can suck the highs out of the room before you ever have a chance to finish dealing with the lows........

Also - it isn't that they don't absorb high frequencies with the facing - just not as much - so it gives you a chance to create a balanced room environment if you do it right.

Compare (for example) 4" 703 plain and 4" 703 unfaced:

Product...density...125hz.....250hz.....500hz...1000hz... 2000hz..4000hz
703, plain..3.0 pcf..0.84......1.24.......1.24......1.08........1.00......0.97
703, FRK...3.0 pcf..0.88......0.9......... 0.84......0.71........0.49.....0.23

Note the increase at 125 (I wold assume the trend continues below 125 but cannot swear to that as it has not been tested by the manufacturer) - and it still absorbs at the higher frequencies - just not as much as the unfaced.

I hope this clears up your questions.

Rod
 
Technically a 'bass trap' captures low frequency and reflects higher ones.

While bass is the bigget problem in most home studios they in fact need absorbtion at all frequencies.

So the fact that your 'bass trap' is also trappng mids and highs is for the typical home recorder a good, not bad, thing.

Then there is the fact that the smallest unit of 703 that you usually can buy is a bale... a two foot high stack of two by four foot panels. It is a rare room that needs more than one bale or 703, efficiently placed, to treat. So buying two one bale each of FRK and unfaced is going to likely have a bunch of leftovers. And how soon are you going to need more? If you are a provessional trap manufacturer that is one story, but a home studio owner?

Sy my usual suggetion is to buy one bale of unfaced, experiment with different locations and thicknesses, and then make your traps.
 
Kasey,

If you are planning a control room, just be aware of early reflections bouncing of walls within 15 ms… (travel less than 15 feet before getting to the mixing spot). They are causing phase problems and comb filtering (degradation of frequency response) At those spots, you really want to absorb almost everything, mostly in mid and hi s. To find out what are those spots where the reflections are bad, just use a measuring tape. Also, have someone hold a mirror against the walls while you are sited at the mix position. At some places, when you see the speakers in the mirror, this is the spot you want to kill.

I hope you understand what I am trying to explain (I am a French speaking Canadian.. but I am learning fast!! :-) )
Mike
 
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