#1
hey............just picked up this 4x12 cab made by this cabinet maker guy for $25....empty. No worries, I got speakers.....but, it has like this 1" polyfoam stuff lining the inside top, bottom, left, right and back of the cab......does this stuff help the sound be more...........focused? The wood is plywood, no idea how many layers, and I'm not about to try and count them, but I think it's like 5/8" thick? Pretty solid cab......I mean for $25 it's not shabby looking, you know.

So about the foam......good, bad, indifferent? Also, I have some 4x12 cabs from Shred Muzic that I bought a while ago, they have chipboard for the construction.......I've loaded one of the "Shred" cabs with Celestion G12mg30's..............but.......it just doesn't sound right.........I'm using a.........(oh gads here it comes........) Marshall VS100.

should I transfer the Celestions over to the "new" cab, and line the "Shreds" with this polyfoam? Or just throw rocks at all of it!

I have heard of people putting foam or some kind of "insolation" inside cabs before.....just cant remember the jists of it..........
#3
Foam can be used to reduce vibrations from inside the cabinet, or to make the cabinet appear 'bigger' to the speakers and improve bass response. I say put the Celestions in it and see if you like it or not, if you don't than you can always swap them back pretty easily.
"Everybody, one day will die and be forgotten. Act and behave in a way that will make life interesting and fun. Find a passion, form relationships, don't be afraid to get out there and fuck what everyone else thinks."
#4
Yeah...the guy I got it from had his bass player make it.......he said it sounded good. He had 65watters in it, and had great bottom end.........

eh.....I'll slap 'em in and see what the cat'll drag in!

Thanks guys!
#5
Speaker building is another one of my hobbies Adding foam or insulation to an enclosure reduces reflected waves, which, funny enough, acoustically increases the internal volume, as the random hero said. Try the cab with your Celestions with all the foam in. Try removing some foam, or just one side. Try it with no foam at all. Your ears are your jury

From http://www.kbapps.com/construction.html

Audio speakers that don't have enough damping material sound "loud", even at low volume. Damping material is necessary to absorb sound from the rear of the cone, sound that would otherwise be bounced around the box and reflected out through the cone. Damping material suppresses mid-range peaks, making the response curve smoother. If you are building a port, keep the port free of damping material. Put damping material on the interior of the back panel, one side, and either the top or bottom. The idea is one layer of material in each dimension will absorb reflections. Some builders will put damping material on all the interior walls. Make sure the walls near the woofer are heavily covered. In addition to absorbing reflections, damping material can be used to increase the effective cubic volume of the speaker enclosure. A 20% effective volume increase can be achieved by stuffing the enclosure will material. Don't compress the material. For adjustment of how much to material to use, judge by your ear. Add more material to the enclosure that sounds "loud" at modest volume levels. Fiber glass is the most widely used material. Acoustical grade fiber glass can be bought for this purpose. You can also substitute other materials such as polyester batting, rug underlayment, even old rags. Don’t use dense materials that would significantly change the enclosure volume.
#6
i heard before that u dont want foam in a guitar cabinet, read that somewhere a while ago, and i think it had something to do with the wood of the cabinet helps shape the tone, and the foam messes with it...cant remember was a while ago, and as far the foam helping make a box seem bigger, that doesnt apply to guitar cabinets, the box volume for guitar speakers is of no consequence, they dont rely on box volume to help "cushion" the speaker, car audio speakers need that because of hard hits and lots of cone excursion inward, the air volume in the box gets compressed and cushions the speaker so it doesnt bottom out and destruct....so dont worry bout the foam for box volume. I guess try it with foam in, and if its easy to take out try with it out. i know there is a good article on that somewhere, might be able to find it. The foam might have been BECAUSE it was for a bass, maybe help clean up some of those LOW frequencies, which can sometimes get a lil muddy. For a guitar tho i dont think u need it, and may not want it.
#7
Quote by shinedown98
i heard before that u dont want foam in a guitar cabinet, read that somewhere a while ago, and i think it had something to do with the wood of the cabinet helps shape the tone, and the foam messes with it...cant remember was a while ago, and as far the foam helping make a box seem bigger, that doesnt apply to guitar cabinets, the box volume for guitar speakers is of no consequence, they dont rely on box volume to help "cushion" the speaker, car audio speakers need that because of hard hits and lots of cone excursion inward, the air volume in the box gets compressed and cushions the speaker so it doesnt bottom out and destruct....so dont worry bout the foam for box volume. I guess try it with foam in, and if its easy to take out try with it out. i know there is a good article on that somewhere, might be able to find it. The foam might have been BECAUSE it was for a bass, maybe help clean up some of those LOW frequencies, which can sometimes get a lil muddy. For a guitar tho i dont think u need it, and may not want it.


I agree, and should have probably added that. You really want guitar cabs to resonate. They are part of the instrument and overall sound. That's probably the main reason his MDF cab sounds like crap... it doesn't resonate well. Plywood will do a whole lot better, and will resonate better without damping material. I was just suggesting to experiment because he might like the sound of one layer of foam on the bottom... never know.

And I think the damping material doesn't affect the excursion of a speaker, it helps keep it from being boomy, meaning the cabinet reproduces certain frequencies more efficiently than others. It seems to me you are thinking of ported vs. sealed. In a sub or full range set-up, that is desirable. In a guitar cab, you want the cabinet to compliment the speaker.
#8
yea i guess it wouldnt effectively make the volume larger, didnt go to bed, lol...lil out of it and all over the place with that.....basically what it boiled down to is box volume for guitar cabs doesnt matter.
#9
Oh, no, the volume matters. If it's too big, the resonant frequency will be too low. If it's too small, it'll be too high. Think about it. You don't want to put a 10" speaker in a 4x12 cab, nor do you want to place a 15" speaker in a cab designed for an 8" speaker (if you could fit it.)
#10
Thanks guys! Yeah...I tried it and is sounded like CRAP! So........I guess the next step is to pull the foam out and try it.......can't be any worse than it was....... that's for sure.

One thing I did do......I measured the inside of the "New" cab, and found it to be 10" deep from the back of the cab to the inside front panel.....The "Shred" cab is 13" front to back.......again, the construction of the "New" cab is plywood, and the "Shreds" are chipboard.....I know that something like 13 ply Baltic Birch high tech, low drag....wood is the best, but, this is what I have, and now I'm doing the backpedal shuffle to salvage either the "New" cab or the "Shreds".

So. lets keep this going....the more info I can gleen from you guys the better decisions I can make.....and live with! Hahahah!!!
#11
Ok....well the trip to the studio might have been a bit bumpy.......I got to thinking, and pulled the jackplate off.....yup. there's the answer. Wire came off......put it back on, and it sounded ok......I won't know for sure until I get it to the studio again on Friday.......then I'll give it a good testing.

Let's hope, yeah?
#13
Well, the finger crossing musta done it! It sounded really good! Loud as hell and that was with my Marshall VS100 on about 4 and my pedals about halfway! I emailed the guy I got the cab from asked if his bassplayer buddy would mind building me another one, just like this one......he said the guy got back together with his ex, and he hasn't spoken to him in a couple of years.........Crap!

So now, do I attempt to build a second cab, (mind you my carpenter skills are NOT the greatest.......just look at the coffin style guitar case I made for my Paul Stanley Apocalypse! Oh! You can't......I still haven't finished it!) , or buy like a Marshall cab and call it good.......they are not as cheap as what I could get the materials for tho.....I don't care about my time.......it's just shelling out the big money for an already made cab.........

Thoughts? Ideas? Unknown Uncle with money to blow?
#14
haha, yea building a cabinet is not all that hard if u got the right tools, typically guitar cabinets where the corners meet, u should use some type of joint, rather then just butting the cut end of one piece to the other piece, this allows more surface area for glue because u arent supposed to use screws either. Ive heard this cuts down on tone if u dont use a joint and if u screw it together. Plus the inside of a guitar cabinet isnt subject to a lot of internal pressure like a car audio box, so screws probably arent really neccesary anyhow if u use a quality glue, i recommend gorilla glue (make sure u dampen each surface where the glue will touch, and apply a THIN layer, it expands when it dries and could push the joint open if u over apply...if ur not sure how much to use, use some scraps and test amounts to see what worked best. Good ole wood glue would prolly suffice. Far as the joint, this could be difficult without a descent amount of skill and/or the right tools http://www.about-building-in-canada.com/wood-joints.html on this page go down to rabbet joint and the lil pic on the left see how they notched it, this works pretty good for speaker boxes. You could probably get away without a joint, but itd help..and if u really cant make a joint id put some kinda thin square stock (wood) glued to the inside corner to both panels for structural strength. If u really wanna build it, and dont know how, pm me and i can try to help ya a lil more, Or, just buy one and save ur self some work, but lose some fun!