BillFitzmaurice.info

Yes, I ask a lot of hypothetical questions. It's a part of how I learn. Probably annoys some of you, so just tell me when I'm asking too many.

I've done a fair amount of fiberglassing in the past... Everything from boat hulls to auto-sub enclosures to household furniture. It's just always been a cool hobby to me. I keep looking through the builds for the DR-series boxes, and I keep thinking that I could build some of those parts from fiberglass about as easily as I could wood. Would probably use the mold method for these parts to maintain consistent shape. My only concern would be that with it being a horn, that it could somehow affect the sound differently. Most of the plans call for 1/2" BB ply as I've read... Getting 1/2" of fiberglass would be overkill in terms of side-by-side comparisons between it and plywood... And in the end, that many layers would probably negate any weight savings a person could achieve. However, the thought still remains in my head: What's stopping me from making some of the internal parts from fiberglass? I don't have my plan CD yet, so forgive me if I'm misusing any of the part names, but in the DR-series, items like the first section of the horn where there are multiple angles going on. Or the butt cheecks.

Please keep in mind that I'm not serious about doing any of this (yet), but I'm curious what the reasons would be that I shouldn't do this.

There are a few on here (search "Marco Ursin") that have built out of composite materials with great results. I think fiberglass alone as the construction material would be too heavy.

DJPhatman wrote:There are a few on here (search "Marco Ursin") that have built out of composite materials with great results. I think fiberglass alone as the construction material would be too heavy.

^This is true.

My thoughts are (and only because you can get it cheaper than we can here):
Baltic Birch is the arguably the best ply for speaker cabs because birch naturally has a better midrange response. I note in the new DR plans that the horn sheaths are specified to be baltic birch or italian poplar and this may well be the reason.
Yes you can tweak it in with EQ, but if mid range response is naturally there, it is so much easier to not have to worry about it.
I know that fibreglass shell drums kits are quite/very loud. This is because they project better.
I'm not sure how that equates to speaker cabs though.

Fibreglass cabs would be very good for weather though...

Grant Bunter wrote:Fibreglass cabs would be very good for weather though...

It'd make for an interesting twist to the "sound for my boat" questions.

bitSmasher wrote:

Grant Bunter wrote:Fibreglass cabs would be very good for weather though...

It'd make for an interesting twist to the "sound for my boat" questions.

Uh huh lol, why did you think I posted that?

Grant Bunter wrote:

bitSmasher wrote:

Grant Bunter wrote:Fibreglass cabs would be very good for weather though...

It'd make for an interesting twist to the "sound for my boat" questions.

Uh huh lol, why did you think I posted that?

I'm already toying with the idea of gelcoating whatever cabinets I make. Which also means I will probably FG a layer on the outside to ensure a hard backing...

Just kinda posting this up as a source for all my findings on the topic...

http://www.youtube.com/watch?v=ZyVfepNV ... re=related


Can't help but let the brain go wild with this one... Either 1/4" foam walls wrapped with 2 layers of 10oz mat on either side, or 1/4 balsa wood would be close to 1/2"... A bit less actually. That portion would have to be tested for what materials would make the proper thickness... Either a thicker Balsa or an extra layer of FG.

If you go to talkbass.com and do a search on composite cabinets, you'll find a boatload of information. What seems to work really well is using EPS foam panels laminated on both sides. It makes for very stiff and potentially very light components.

thekl0wn wrote: Can't help but let the brain go wild with this one... Either 1/4" foam walls wrapped with 2 layers of 10oz mat on either side, or 1/4 balsa wood would be close to 1/2"... A bit less actually. That portion would have to be tested for what materials would make the proper thickness... Either a thicker Balsa or an extra layer of FG.

Dead reckoning is used on most builds, but your chamber areas will change with thinner material.

You can't use matting with foam, as polyester resin will eat the foam. Epoxy or vinylester are your best bets, both a far more expensive: and few thin enough to properly saturate matting.

It's not as easy as it sounds, trust me. If you're really wanting to: go for it, but it won't be nearly as cheap as you think: esp with all the learnin' you'll be getting on the first cab.

Monomer wrote:

thekl0wn wrote: Can't help but let the brain go wild with this one... Either 1/4" foam walls wrapped with 2 layers of 10oz mat on either side, or 1/4 balsa wood would be close to 1/2"... A bit less actually. That portion would have to be tested for what materials would make the proper thickness... Either a thicker Balsa or an extra layer of FG.

Dead reckoning is used on most builds, but your chamber areas will change with thinner material.

You can't use matting with foam, as polyester resin will eat the foam. Epoxy or vinylester are your best bets, both a far more expensive: and few thin enough to properly saturate matting.

It's not as easy as it sounds, trust me. If you're really wanting to: go for it, but it won't be nearly as cheap as you think: esp with all the learnin' you'll be getting on the first cab.

Vinyl foam is actually what I was referencing to gain my material thickness without adding layer after layer of FG. Though most of the designs wouldn't require it, it works well even with rudimentary thermoforming. Only downfall being that it seems like it was fairly heavy, especially once saturated/bonded. I don't recall ever making any parts in any of the boats using this foam, but was used quite a bit in the mold-making process on the last hull. And I have used it manufacturing a few trim pieces for normal ski boats. Might have to grab some scraps and do some weight testing.

I should probably note that I do have a fair amount of experience with fiberglass... There's at least three unlimited hydroplanes within eyesight of my house. (well, at least the shop they're in is in eyesight) Granted, I'm usually the mix-bitch or the cut-bitch when the resin and Kevlar meet.

And I never said it would be cheap... My projects/hobbies never turn out to be cheap... No matter how hard I try to be a normal human, the urge is too great.

I do believe it'll cost far more then an epoxy/cloth layup.

By a fair bit.

It won't be as easy to make as ply, and more expensive. You do get lighter weight and a weather proof build (sans drivers) Damn near indestructible also.

Good luck with it!

Grant Bunter wrote:Baltic Birch is the arguably the best ply for speaker cabs because birch naturally has a better midrange response. I note in the new DR plans that the horn sheaths are specified to be baltic birch or italian poplar and this may well be the reason.

Probably because BB and Italian poplar ply are the most likely to be void free.

I suspect the whole sound quality vs. materials debate is nonsense cooked up by oddiophiles.

It would seem to me that FG would be most advantageous where curved surfaces are involved, either for aesthetics, or where a snug fit is involved.

A few years ago, I built a subwoofer for underneath the back seat of my Nissan Titan King Cab, forming the bottom of the sub right in the cab, for a perfect fit.

YMMV