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Another Composite cab build - inspired by Zac

Petebass

Petebass

Dec 22, 2002
8,802
212
53
QLD Australia
www.talkbass.com
#1
You've probably all seen the threads by zac2944, who's speaker cabs made from composites have been nothing short of sensational. I decided to have a go at building a composite 1x12 myself. I used an Eminence Deltalite11 2512, a textile dome tweeter by Vifa, and a 4th order crossover at 3.5K.

Here's a quick sequence of pics of how it came together:-

Front baffle cut out of foam, and edges reinforced with strips of fibreglass tape.
05Bafflecutoutedgereinforcement02.jpg




Fibreglass the front and back panel on both sides of the foam, but only glass one side of the other 4 panels initially.
11Backpanel02peelply.jpg




A quick strength test on what will become the back panel. It can support my entire 180 pounds of weight without bending, not even a little bit.... and that's with exposed edges. It'll be even stronger again once it's glued into place and the edges have support. Not bad for what is essentially just a piece of foam.
13strengthtest01.jpg




Assemble the cab with the glassed side on the inside, leaving exposed foam on the outside for now.
20Assembley05.jpg





Glass the remaining 4 walls with one continuous piece to form a "Monocoque". Joint-less and super strong!
23Glassingtheoutsidemonocoque01.jpg



From here the rest of the build is essentially the same as for a wooden cab so I'll just skip ahead to the finished product.....
Here it is, a 1x12" Fibreglass speaker cabinet for bass guitar! Signed, sealed, delivered, ready for it gigs, and only 21.5 pounds of weight!
35FinishedCompositeCab.jpg



Just for kicks I also built a plywood version of this cab that is identical except in every other way except for the material used for the panels i.e same speaker, same tweeter, same crossover, same internal volume and porting, same EVERYTHING except one is wood and one is fibreglass. Tests show they both produce identical frequency response in the lower frequencies. The fibreglass cab at this stage has a mild 3dB more than the wooden cab at 500Hz and 2k, but considering the materials used on each cab couldn't possibly be more different, this sort of deviation is more than acceptable.

I wonder if adding a little bit more internal lining to the fibreglass cab will fix that slight difference in the mids?
 
#2
Petebass said:
Just for kicks I also built a plywood version of this cab that is identical except in every other way except for the material used for the panels i.e same speaker, same tweeter, same crossover, same internal volume and porting, same EVERYTHING except one is wood and one is fibreglass. Tests show they both produce identical frequency response in the lower frequencies. The fibreglass cab at this stage has a mild 3dB more than the wooden cab at 500Hz and 2k, but considering the materials used on each cab couldn't possibly be more different, this sort of deviation is more than acceptable.
Click to expand...

This is fantastic, Petebass--Not just for the end result, but particularly because you built the B model for comparison. Innovation is one thing, but if the concluding line is, "It sounded great" well, of course it did, because the maker spent time and money doing it and we're not likely to expect anything different. You, however, must have had great science fair projects in middle school, because you got a handle on the scientific method, control groups, and the whole prototyping mentality.

My congratulations, and thank you for sharing the thinking, the testing and the final product but mostly for the compliment to your readers here who, I hope, will appreciate the very high bar you set for shade tree innovating.
 
#3
Petebass said:
From here the rest of the build is essentially the same as for a wooden cab so I'll just skip ahead to the finished product.....
Here it is, a 1x12" Fibreglass speaker cabinet for bass guitar! Signed, sealed, delivered, ready for it gigs, and only 21.5 pounds of weight!
35FinishedCompositeCab.jpg
Click to expand...

I want one...when's it for sale?...:smug: I love my Bag End cabs, but do not want to lug them out of the house. This could be a nice portable gigging cab. And I want one with a cool builder's logo...;) Composite Ultra Lightweight 1x12 Bass Cabs by PeteBass...!
 
#9
lomo said:
Cool. How much does the wooden one weigh and what thickness plywwod was used?
Click to expand...
Over the years I've devised a system of making my plywood cabs pretty light. Most commercially made cabs use 15mm (0.6 inch) ply but no bracing. I use 1/2 inch ply (12mm) to save weight but brace it for extra stiffness.

The wooden cab weighs 12.45kg (27.45 pounds). It is slightly bigger physically than an Epifani UL112 (IMO one of the better lightweight commercial 1x12 cabs available), but feels noticeably lighter. I wasn't able to put the UL 112 on the scales to verify it's weight, but the website says 31.9 pounds, making my wooden one 4.45 pounds lighter and the composite cab 10.4 pounds lighter than one of the lighter 1x12 cabs on the market.

Oh and for the record, the composite cab is not braced. I fully intended to brace it when I started the project, but that pic of me standing on the rear panel convinced me t at least try to eliminate the bracing and see what happens. I can always add bracing later but at this stage, there's no plans to do so.

Here's a pic of the wooden one. They look pretty similar except for the thicker panel edges and a different handle on the composite cab.

22FinishedCab-Wood.jpg
 
#10
zhaddock said:
What type of foam did you use and what type of adhesive did you use to glue the panels together?

Looks awesome! Now I'm inspired to build one!

Z
Click to expand...

I used the same foam as Zac, Extruded Polystyrene (XPS). Please not this is not the stuff they use for broccoli boxes and beanbag filler. That's Expanded Polystyrene and they're very different foams.

The adhesive was the same Epoxy resin & hardener used on the fibreglass, but with the addition a powder which contains thousands of tiny micro balloon spheres.

Have a look at the thread for Zac's original composite build. He went into great detail of his build process. I did vary it to suit my own personal talents, to not stray too far outside my comfort zone, and via some input from friends who are versed in composites, but the original thread contains everything you need to piece together your own composite cab:-

http://www.talkbass.com/forum/showthread.php?t=432560
 
#11
Lee Barker said:
This is fantastic, Petebass--Not just for the end result, but particularly because you built the B model for comparison. Innovation is one thing, but if the concluding line is, "It sounded great" well, of course it did, because the maker spent time and money doing it and we're not likely to expect anything different. You, however, must have had great science fair projects in middle school, because you got a handle on the scientific method, control groups, and the whole prototyping mentality.

My congratulations, and thank you for sharing the thinking, the testing and the final product but mostly for the compliment to your readers here who, I hope, will appreciate the very high bar you set for shade tree innovating.
Click to expand...
Wow such wonderful comments from such a legend in the bass community. I'm blushing. Thanks so much for the kind words Lee :)
 
#14
the_hook said:
I'll take one of those too...:p I like the handle on this one more. What's the wattage capacity, ohms, and does it have speakon(s)?
Click to expand...
Where shall I send the invoice :)

It uses an Eminence Deltalite11 2512 speaker which is rated for 250W RMS. Yes both cabs have 2 x speakon connectors (Neutrik of course), but the wooden one also has two jack connectors. Each cab is 8 ohms. I have a 2 ohm capable amp so I could potentially run 4 of these babies... oohh yeah!!!
 
#15
mikell128 said:
It looks great, how does it sound in comparison to say an Epi ul112??
Click to expand...
Recently I went to Bass People here in Sydney to drop off a bass that needs some repair work. At the time I had completed the wooden cab but not the composite cab. The guys asked me to being in the wooden cab so they could have a listen. Well it turned into a mini 1x12 shootout and I was pleasantly surprised by how well my little cab did.

My wooden cab was the lightest of the lot. That was pleasing. The next lightest was the Epifani UL112. My cab was noticeably lighter than the UL 1x12 despite being slightly larger, so I'm clearly doing something right in the weight minimisation department even on the wooden cabs.

It's amazing how different my cab sounded in their showroom compared to at home. My cab didn't sound like any of those there, and nor should it, but it was closest to the Epifani UL12 in terms of SPL and bottoms, and being one of my personal favourite 1x12 cabs I wasn't upset by that at all!! As far I'm aware, the Epi 12's are modified OEM versions of Eminence Deltalite11's. So the existence of any similarities was going to depend on exactly how modified theirs is. But there are also a hundred other little design differences at play as well. I don't mean to give the impression they sound the same, it's merely a family resemblance of the Deltalite 12" speaker.

How did it compare to some of the other cabs in the store? Well the Markbass 121h had a different vibe all together and was less loud than mine. It also had more going on in that sub 60Hz range than mine, but it lacked any punch in the low mids. The Aguilar DB112 not only weighed a hell of a lot more, it also had a far more "cut through" type tone than mine. The Schroeder Mini was not my cup of tea at all. Unfortunately an Aguilar GS112 wasn't available because I really like that cab. It would also have been nice to have an Accugroove Tri 112 to try it against but when you're as great a shop as Bass People, good cabs sell and sometimes you run out of stock. Good to see they're moving lots of great cabs :)

All of these cabs have metal based tweeters and it showed. Mine had IMO a "smoother" response in the highs. Again, that was pleasing, though at the one gig where I was able to use my new 2 x 112 rig, I had to boost highs to get the snap that I like for slapping. Mind you the dB meter was reading 118dB on stage on average with the louder passages going up to the low 120 dB region. That's was much louder than we usually play. Most of the time we're averaging 110dB on stage with 116dB peaks, so I should probably use these cabs at a "normal" volume gig before deciding on any tweaks. And the reviews from the band and the sound guy (who's opinion I respect) were very favourable, so I'm not too far away from where I want to be.

All up it was a very informative day and a big thank you goes out to the guys at Bass People for putting up with me for a little while...... and for doing such a brilliant job on the bass that needed repairing. Pardon the shameless plug but these guys deserve it!
 
#16
Petebass said:
Where shall I send the invoice :)

It uses an Eminence Deltalite11 2512 speaker which is rated for 250W RMS. Yes both cabs have 2 x speakon connectors (Neutrik of course), but the wooden one also has two jack connectors. Each cab is 8 ohms. I have a 2 ohm capable amp so I could potentially run 4 of these babies... oohh yeah!!!
Click to expand...

You're in Australia....I'm in Canada...shipping will probably cost more than the cab!...:rolleyes:
 
#20
Petebass said:
I used the same foam as Zac, Extruded Polystyrene (XPS). Please not this is not the stuff they use for broccoli boxes and beanbag filler. That's Expanded Polystyrene and they're very different foams.

I looked up XPS and one of the listings by one of the companies here in the States is Styrofoam. Is that what your panels were, Styrofoam covered in Fiberglass? Thanks
Click to expand...
 

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