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Post by highanddry on Feb 28, 2019 22:22:42 GMT
I am about to build some 4' x 8' gobos. I have seen some beautiful builds that used 4 inch OC 703 per side. Would 2" per side be adequate for most applications? I don't expect these to be bass traps. Nor do I expect them to achieve total isolation. I plan on putting a 3/4 piece of mdf in the middle.
any feedback would be greatly appreciated
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Post by Hexspa on Mar 1, 2019 3:59:59 GMT
The thicker the panel, the better the absorption. I would only use a 2" panel if I was trying to improve speech ambience. When I doubled my RFZ panels from 2" to 4", I noticed a tremendous improvement in stereo clarity down around 200-400Hz. Remember that sonic issues in most small rooms are especially troublesome in the 250Hz and lower region.
In short, try to use as thick a panel as you can manage - you'll be happier in the long run.
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Post by highanddry on Mar 1, 2019 4:51:40 GMT
I am thinking 2' per side. the gobo will have a middle section of mdf or sheetrock. and 2 inches on each side. I have a lot of bass traps and they are almost all 4 inches. So I know the value of that. these are gobos and I don't expect them to be bass traps per se
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Post by Deleted on Mar 1, 2019 9:54:26 GMT
What size is your room? and for what use you are building these?
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Post by highanddry on Mar 1, 2019 10:15:59 GMT
to cut down on mic bleed from different instruments, for a vocal booth. etc I won't be using them in one room. I have super chunks in my corner and over a dozen bass traps in my home already. a couple clouds too. What I want to build are gobos. They can be seen in many recording studios. they have been used for years. I have seen them in all sizes.
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Post by rock on Mar 1, 2019 14:35:14 GMT
My comment is regarding the MDF sandwiched in the middle. I'm not sure if you're better off leaving it out. If you do, you can get twice the absorption from both sides since each side will "see" a 4" thick panel instead of only a 2" panel against a reflective surface. Low freqs will easily flank around the gobo so adding mass in the middle seems mostly futile. But I don't have any data so unless someone can share their experience, you'll either have to test or just go with your gut. BTW, I have 4" gobos without MDF and they seem to work well but I never tested them against "sandwiched" gobos.
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Post by highanddry on Mar 1, 2019 18:25:16 GMT
My comment is regarding the MDF sandwiched in the middle. I'm not sure if you're better off leaving it out. If you do, you can get twice the absorption from both sides since each side will "see" a 4" thick panel instead of only a 2" panel against a reflective surface. Low freqs will easily flank around the gobo so adding mass in the middle seems mostly futile. But I don't have any data so unless someone can share their experience, you'll either have to test or just go with your gut. BTW, I have 4" gobos without MDF and they seem to work well but I never tested them against "sandwiched" gobos. Very good point. Thanks for the input and the real life experience sharing with your 4" gobos. I get a lot of conflicting info and opinions on another forum. But I always defer to Ethan's. I notice his mini gobos have a barrier in the middle. But also have an option for no barrier. realtraps.com/p_minigobo.htm I am also looking at these. www.primacoustic.com/gotrap/specifications/I am using 3/4 mdf to construct these. In terms of cost and straightness I determined that was my best option. 10" wide. As of now I want to make them just under 8 feet high by 4 feet wide. (I wanted them to be 8' but after measuring from my carpeted floor to ceiling I realized that would be an inch or so too high. I guess the carpet and pad rendered my ceiling height just under 8'. What did you use for your absorbent material?
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Post by rock on Mar 1, 2019 21:02:00 GMT
I use mineral wool because around my area, it's available in local stores at a pretty reasonable price.
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Post by highanddry on Mar 2, 2019 6:06:54 GMT
Same Here. I have used it for many panels. 3" batts.
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Post by Hexspa on Mar 3, 2019 0:30:34 GMT
I misunderstood. When I went to Sonic Ranch, they had gobos around the drums. They were pretty thick - maybe a foot or so. While I don't recall what they used for an absorbent, I doubt they had a reflective center mass.
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Post by highanddry on Mar 4, 2019 4:35:17 GMT
I misunderstood. When I went to Sonic Ranch, they had gobos around the drums. They were pretty thick - maybe a foot or so. While I don't recall what they used for an absorbent, I doubt they had a reflective center mass. I don't believe the center mass is intended for reflection. I believe it is for blocking. At least that is what I understood
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Post by Hexspa on Mar 4, 2019 4:47:45 GMT
I misunderstood. When I went to Sonic Ranch, they had gobos around the drums. They were pretty thick - maybe a foot or so. While I don't recall what they used for an absorbent, I doubt they had a reflective center mass. I don't believe the center mass is intended for reflection. I believe it is for blocking. At least that is what I understood What happens after it gets blocked? Assuming you use 2" rigid absorbers, bass frequencies are like wide receivers* and will just go around - like rock said - and the midrange frequencies will bounce. Acoustic energy don't quit!
*I know f-all about football but a little about acoustics.
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Post by highanddry on Mar 5, 2019 1:02:29 GMT
I wonder why real traps offers the mini gobos with 2" per side and an option of center or no center
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Post by Hexspa on Mar 5, 2019 12:21:28 GMT
I wonder why real traps offers the mini gobos with 2" per side and an option of center or no center I'm not sure exactly how they're made but, from the site:
The optional isolating barrier is available for 3- and 4-inch thick panels only.
The explanation I can come up with is that this serves as a reflecting device. I don't know everything about sound but what else can sound do? It can transduced into heat, transfer energy into sympathetic vibration, move around and through things, or bounce.
The bottom line is that, if you put a reflector in the middle of your panel, you end up with two thinner panels above a certain cutoff frequency. If you put a reflector on one side then you have one thicker panel. Should you not use a reflector then the some sound will be absorbed and the rest will pass through.
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Post by highanddry on Mar 9, 2019 1:03:58 GMT
My comment is regarding the MDF sandwiched in the middle. I'm not sure if you're better off leaving it out. If you do, you can get twice the absorption from both sides since each side will "see" a 4" thick panel instead of only a 2" panel against a reflective surface. Low freqs will easily flank around the gobo so adding mass in the middle seems mostly futile. But I don't have any data so unless someone can share their experience, you'll either have to test or just go with your gut. BTW, I have 4" gobos without MDF and they seem to work well but I never tested them against "sandwiched" gobos. Well... I have my sides and ends cut. I am proceeding slowly but surely. I just went and got the middle barrier cut .. It is 94 x 46. And it is freaking heavy. mdf is heavy stuff. According to some quick googling, a 4 x 8 piece of 3/4 mdf is 96 Pounds !! So I am rethinking this big time. these almost 4 x 8 gobos are going to weigh well over 100 pounds.. with the sides and ends mdf as well probably 125 !! pretty unwieldy for a home studio? I may be better off building them half size and stacking. Or going without the middle barrier. I am using a 2 3" batts of rockwool. So I have 6" per panel. maybe no barrier at all
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