What Material Transfers Sound The Least?

[iskim86]

I'm looking for materials to build an amplifier isolation cabinet...

I was thinking plywood, but then I thought there's gotta be a better material to use. the goal here is to isolate amp sound from outer noise.

what materials transfer sound the most ineffectively?

[tim_ado]

you could make it out of ply or anything then line it with that foam stuff or any sound proofing material

[iskim86]

you could make it out of ply or anything then line it with that foam stuff or any sound proofing material

yeah i'm gonna pad the inside with mass-loaded vinyl, but i want extra isolation

i think i'll go with MDF

[tim_ado]

yeah i'd say MDF would be better than ply

you could always do a layer of balsa, would be easy since it comes in sheets then the vinyl

i hear egg cartons do alot of noise reduction but i cant see the practicaliy of lining an amp with them

[GregP]

The egg carton thing is a bit of a myth. They have a similar look to soundproofing baffles, so people just concluded that the uneven surface could diffuse soundwaves. The problem is that almost all audible frequencies just pass through them without taking a hit whatsoever. So, it's not really doing anything except acting as a placebo.

What apparently DOES work is rock wool-- but if packed in very densely. A simple thin layer won't do the trick.

The other thing to do is make a box within a box. In-between the 2 boxes should be some sort of material that is soft enough to absorb vibration. This will decouple the inner box from the outer, which will go a LONG way toward isolating the sound. Indeed, this is the main thing that separates built-to-order soundproof chambers from DIY "soundproofed" rooms. If built to order, you can float the floors and walls... essentially a huge "box within a box". With the relatively small project of an amp isolation box, you can literally build a box within a box. The aforementioned rock wool would be a good in-between material.

Make sure you're aware of heat concerns, particularly if you're planning on recording tube amps. Find out what the tolerances for the circuitry and tubes are, find out how much heat is generated inside the isolation box, and always be aware of these factors while recording. Better to pause a session for a while to let things cool down than to ruin your equipment.

Greg

[orgmorg]

What apparently DOES work is rock wool

Ya, but shearing those boulders is a real pain.

[thegarehanman]

Why not make a chamber with dual plastic or metal shells that have a vacuum in between them and as little material as possible connecting the two shells together? Sound can't travel through a vacuum, after all. Or maybe that's a bit unrealistic...

[tim_ado]

or make an air tight platic layer inbetween and fill it with water???

too extreme??

[prs man]

birch core plywood works vary well but a little expensive [ you get what you pay for]

if the cab is a closed back be sure to port it so your speaker have room to breath.

[black_labb]

im pretty sure that the egg containers are infact great for the job. they are the right type of material, and the shape reflects any sounds back into itself to be absorbed if the first hit doesnt fo it.

[tim_ado]

i know that they use things that look like egg cartons (eg same shape) in things like echo chambers

but unless someones tried it i couldnt say for sure

[Setch]

See gregs post about egg boxes - he's bang on the money.

[marksound]

Dave Weiner (Steve Vai's band) has a pictorial on his forum on building a custom iso box. Unfortunately, the forum is down.

Here's the link for when it comes back up. Use the search function.

http://daveweiner.com/phpBB2/index.php

[aidlook]

or make an air tight platic layer inbetween and fill it with water???

too extreme??

Sound travels even faster through water than air...

And if it's air-tight, the best thing to do would be to suck out all the air inside, leaving a vacuum

[tim_ado]

really i figured you know like underwater no alot of noise............no??

but the vaccums a better idea ................no one can hear you scream in space;)

[GregP]

Nope, aidlook has it right... underwater, sounds are amplified and carry a great distance! Wonder how feasible a DIY vacuum 'barrier' would be. I have no frame of reference... might be butt-simple, but I suspect not. Takes an awfully rigid sealed structure to support a near-vacuum state without air pressure crushing it.

[thegarehanman]

If you're creative about the shape, it wouldn't be so hard. A 4" diameter schedule 40 pvc pipe(about $5 for 5 feet at lowe's) can hold a 25"Hg vacuum with ease. Obviously you'd need two pipes, and larger ones that 4" at that, but I think the finished product would be akin to one of those bazooka tube speakers in a air tight jacket. Anyhow, I think that that's a really impractical idea, a padded box would be much more economical and probably plenty sufficient for the job.

[GregP]

Still, it's fun to dream. ;-) The problem I see with the 'tube' idea (even with larger tubes) is that there would still be non-vacuum area, where the pipe walls touch each other. The "stitches" in the quilted jacket, as it were.

[tim_ado]

make it out of a tin can then the vaccum make a parabola then you have half amp half death ray..............myth busters.......anyone anyone

[probus]

I'm looking for materials to build an amplifier isolation cabinet...

I was thinking plywood, but then I thought there's gotta be a better material to use. the goal here is to isolate amp sound from outer noise.

what materials transfer sound the most ineffectively?

You need to separate two things when talking about sound isolation. One thing is to isolate sound vibrations through air, second thing is to prevent mechanical vibrations from transferring through material.

The denser (heavier) the material you use to build the cabinet, the better it will function in isolating the sound traveling through air. So, about the best material here would be concrete. You'd probably want to use mdf for practical reasons. Egg carton won't help you at all. Isolation is always a lot more effective than sound absorption, so concrete is better here than the rock wool.

Other thing is to isolate vibrations traveling through material, so if you would put your amplifier right into that concrete (or mdf etc.) it will probably resonate and transmit the sound that way outside the box. Unless you go into that box in a box thinking or use some sort of soft foam feet to isolate the amplifier as much as you can from the box mechanically.

I don't know exactly what you are trying to do here, but if you’re hoping to record the speakers inside this isolation box I'd also put some sort of absorbers inside to reduce echo to make the recording clearer. Rock wool would be perfect for this, but as has been said, it must be thick enough to absorb low frequencies. If it will only damp the highs, the recoding might come out sounding weird. Yet if your box isn't massive enough it will leak the lows anyways and help the balance. I would start with a layer of one or two inches of dense wool inside the box. That would give you a pretty good isolation against vibrations mechanically as well.

[tim_ado]

mmm u seem to know what your talking about

not sure about the concrete though

like recording studios dont sound proof with meer concrete

i could be(and most probaly are) wrong

[probus]

mmm u seem to know what your talking about

not sure about the concrete though

like recording studios dont sound proof with meer concrete

i could be(and most probaly are) wrong

Well, it depends. Usually studios aren't located in buildings specially designed for that, and usually you don't need that much of attenuation anyways. For example here is a concrete proofed room in my school, used for measurements where you don't want any outside noise:

http://www.acoustics.hut.fi/introduction/tour/k15.html

Room acoustics is a different subject altogether.

[tim_ado]

yeah u gotta raise the floor so i guess making a seperate elovated box inside would be good

here is a concrete proofed room in my school, used for measurements where you don't want any outside noise:

yeah we have a drum room at my school that has no echo...like none

you can feel its different as soon as u step inside

[dh7892]

underwater, sounds are amplified and carry a great distance!

Just for the record, sounds are most definately NOT amplfied underwater. Where would the extra energy come from? The speed of sound in water IS higher than in air and sound waves in water DO travel long distances very well. The problem comes when trying to transmit sound waves from air into water. The two materials have very different densities and so there is an impedance mis-match. Because water is denser, a lot of the sound wave energy gets reflected back into the air rather than transmitted. The amount of energy transmitted is related to the frequency of the sound and the relative densities of the two materials. Lower frequency sound waves transmit better than higher frequency ones. Try listening to music in the bath and then put your head underwater (don't actually have the stereo in the bath!!!). You'll notice that the higher frequency sounds get attenuated much more but you'll still hear the bass. The same effect happens between other interfaces (air -> brick for example). That's why you can hear bass through walls even though lower frequencies are less energetic than higher ones.

Anyway, Probus is right with all the stuff he's been saying. Just to add and idea into the mix; what about trying to use Zorbathane and the material to isolate the box within the box. I don't know how easy it is to get hold of but I think people use it to isolate vibrations in sensitive measurements for scientific experiments.

[ToneMonkey]

I'm with GregP on the rockwool. A while back I was specifying a generator and went to have a play with it (this thing was an absolute monster - I seem to remember that it was a V24 diesel - it was bloody load, I know that). As the enclosure that it sits in has to let air in and out, but also had to keep the massive amount of noice low, they used acoustic enclosures at either end of the generator enclosure. All this consisted of was rockwall sandwiched between perforated steel sheets (holes about 2mm wide and close to each other). The whole sandwich was about 50mm thick and sandwiches were equally spaced with an air gap between them (again about 50mm spacing between sheets). The whole enclosure was about a 3m cube. You could stand at one end of it and shout your head off, the person standing on the other side couldn't hear a single word. Being the sad git that I am, I found it absolutely amazing (pity that the rest of the gen set was a steaming pile).