Carbon graphite speaker cabs

[Grassie]

Hi everyone,

We all know about the fantastic gear that Rob Green builds at Status-Graphite, and the very clear and resonant properties of woven carbon graphite when used in bass guitar manufacture. But has anyone tried making bass cab enclosures with this stuff? Light weight and resonant? Perfect for cabs, no? What do you all think...?

Cheers

Grant

[Bill Fitzmaurice]

[quote name='Grant' post='939607' date='Aug 29 2010, 04:16 PM']But has anyone tried making bass cab enclosures with this stuff?[/quote]It's been done with PA, the cost verges on astronomical. Bass players being the cheapskates...excuse me, 'thrifty blokes' that they are, I doubt you'll see carbon fiber bass cabs successfully marketed.

[Grassie]

[quote name='Bill Fitzmaurice' post='939609' date='Aug 29 2010, 09:19 PM']It's been done with PA, the cost verges on astronomical. Bass players being the cheapskates...excuse me, 'thrifty blokes' that they are, I doubt you'll see carbon fiber bass cabs successfully marketed.[/quote]
The reason I ask is that I work for a composites company, and was contemplating building my own 2 x 10 cab out of the stuff. Just wondered if it would sound any good. Might have to pick some engineering brains at work...

[lee650]

I believe accugroove brought out limited editions of some of their cabs with the 6" driver being made of carbon fibre, the other speakers were just the same though, not sure how they would sound compared to the normal ones, just something i stumbled across whilst gear surfing, it is a very interesting idea.

[Grassie]

[quote name='lee650' post='939625' date='Aug 29 2010, 09:44 PM']I believe accugroove brought out limited editions of some of their cabs with the 6" driver being made of carbon fibre, the other speakers were just the same though, not sure how they would sound compared to the normal ones, just something i stumbled across whilst gear surfing, it is a very interesting idea.[/quote]
I'm only interested in making the enclosures, not the actual speakers. Been looking at Eminence Neodymium drivers for around £80 each, so will buy everything else I need elsewhere. Can you imagine how light the cab will be if I pull it off...?

[velvetkevorkian]

There's a couple of people on TalkBass who DIY'ed composite cabs- not carbon fibre but some kind of fibreglass IIRC. By all accounts it worked very well, but as BFM says the time and effort compared to a traditional wooden build is much greater.

[Grassie]

[quote name='velvetkevorkian' post='939636' date='Aug 29 2010, 10:09 PM']There's a couple of people on TalkBass who DIY'ed composite cabs- not carbon fibre but some kind of fibreglass IIRC. By all accounts it worked very well, but as BFM says the time and effort compared to a traditional wooden build is much greater.[/quote]
I'm in no rush! It's only something I thought about for the first time yesterday. I'm definitely going to look into it further though. If it's going to be too much hassle, then I'll go the wooden route anyway. Carbon graphite is sexy stuff though...

[Mr. Foxen]

In cabs resonant = bad, non-resonant = good.

[velvetkevorkian]

[url="http://www.talkbass.com/forum/showthread.php?t=432560&highlight=composite"]Here[/url] is a long read about it, [url="http://www.talkbass.com/forum/showthread.php?t=549976&highlight=composite"]here[/url] is a slightly shorter thread by the same guy and [url="http://www.talkbass.com/forum/showthread.php?t=663169&highlight=composite"]here[/url] is a somewhat shorter one. You probably want to get a cuppa before trawling through the first two

Keep us posted with how you get on; seems like a win/win if you discount cost...

[Dood]

I've no idea if using such materials will make a great cabinet or not - but I'd defintely subscribe to the build diary! Sounds like an interesting project!

[Waldo]

[quote name='Grant' post='939629' date='Aug 29 2010, 09:52 PM']I'm only interested in making the enclosures, not the actual speakers. Been looking at Eminence Neodymium drivers for around £80 each, so will buy everything else I need elsewhere. [b]Can you imagine how light the cab will be if I pull it off...?[/b] [/quote]

I may be wrong but based on the graphite necked basses that I've owned, I wouldn't describe them as being light.

[velvetkevorkian]

[quote name='Waldo' post='939693' date='Aug 29 2010, 11:39 PM']I may be wrong but based on the graphite necked basses that I've owned, I wouldn't describe them as being light.[/quote]
Speculating somewhat, but maybe this is down to mass; i.e. to make a recognisable neck shape requires quite a large mass of solid material, whereas on a cab you could use much thinner sheets (rather than 3/4" plywood or whatever) because graphite/composites are much stiffer per unit of mass.

I'm prepared to be shot down in flames though.

[MoonBassAlpha]

Think about why noone makes wooden tennis racquets anymore - stiffness and light weight.
You design the resonances out.
There would be a lot more material in a cab though, so that would be the killer, unless you can "acquire" it for less than you'd normally pay for it....

[Bill Fitzmaurice]

[quote name='velvetkevorkian' post='939699' date='Aug 29 2010, 06:55 PM']Speculating somewhat, but maybe this is down to mass; i.e. to make a recognisable neck shape requires quite a large mass of solid material, whereas on a cab you could use much thinner sheets (rather than 3/4" plywood or whatever) because graphite/composites are much stiffer per unit of mass.

I'm prepared to be shot down in flames though. [/quote]
You're on the right track. If a carbon fiber neck is solid it's flawed, as that doesn't take advantage of the stiffness of the material. It should be semi-hollow, consisting of multiple small chambers. But that entails a very high initial tooling cost. That's not as much concern with tennis rackets, which probably outsell electric basses by about a 10,000:1 ratio.
Probably the best material for a bass cab would be carbon fiber honeycomb matrix. It works well enough in F-117s. But it ain't cheap, especially since most of it is gobbled up by the aerospace industry.

Edited August 30, 2010 by Bill Fitzmaurice

[Toddy54]

[quote name='dood' post='939685' date='Aug 29 2010, 11:24 PM']I've no idea if using such materials will make a great cabinet or not - but I'd defintely subscribe to the build diary! Sounds like an interesting project![/quote]

+1 I would be very interested to see how it turns out, and some idea of the cost involved.

[Kiwi]

[quote name='Bill Fitzmaurice' post='939745' date='Aug 30 2010, 02:22 AM']You're on the right track. If a carbon fiber neck is solid it's flawed, as that doesn't take advantage of the stiffness of the material.[/quote]
Steinberger necks are solid and are some of the best sounding and responsive graphite necks ever produced (IMO). However they are a completely different manufacturing process to monocoque "semi hollow" equivalents. While structurally rigid, monocoque construction doesn't always make for a pleasant sounding neck. However the most advanced monocoque designs (such as Status necks) incorporate fill material that selectively dampens some unpleasant frequencies.

Technically superior doesn't always mean better sounding.


I believe honeycomb construction for speaker cabs was discussed on the Talkbass thread but gluing the material became quite critical to its success. Thing is when you push the boundaries of any construction process, the costs go up as the manufacturing process becomes more sophisticated.

[ShergoldSnickers]

[quote name='Crazykiwi' post='939837' date='Aug 30 2010, 10:50 AM']Steinberger necks are solid and are some of the best sounding and responsive graphite necks ever produced (IMO). However they are a completely different manufacturing process to monocoque "semi hollow" equivalents. While structurally rigid, monocoque construction doesn't always make for a pleasant sounding neck. However the most advanced monocoque designs (such as Status necks) incorporate fill material that selectively dampens some unpleasant frequencies.

Technically superior doesn't always mean better sounding.


I believe honeycomb construction for speaker cabs was discussed on the Talkbass thread but gluing the material became quite critical to its success. Thing is when you push the boundaries of any construction process, the costs go up as the manufacturing process becomes more sophisticated.[/quote]
I think Celestion developed some Aerolam based hi-fi speaker cabinets in the 80s. Aerolam is essentially two sheets of aluminium separated by a honeycomb layer of aluminium with the honeycomb tubes at right angles to the sheets. They were also very very expensive. Wharfdale made some melamine sandwich speakers, also in the 80s - two sheets of melamine with a foam core, but for bass cabs I can't see any commercial cost effective advantage over conventional techniques incorporating lightweight ply and well planned and engineered internal bracing.

Having said that, if I had the opportunity to build some carbon fibre cabs for minimal cost I'd be sorely tempted.

[rmshaw37]

to the op - do you with with pre preg or dib dob?

dib dob is essentially firbeglassing with carbon fibre - cheaper but messier and takes longer! not as good a part either, but the moulds would be significantly cheaper

i thought about this myself, but the set up costs would be huge and not necessarily any better - the old addage of if it aint broke don't fix it. saying that, i would be very interested to see if it works!

and yes it would be MASSIVELY lighter than a wooden cab as we work with full floors for f1 cars and they are an easy 1 man lift! shouldn't exceed more than a few kilos!

currently trying to drum up funds for carbon acoustic guitars - i've seen how others make theirs, and we would get the sack if we produced something so wishy washy! lol

[Lfalex v1.1]

[quote name='Bill Fitzmaurice' post='939745' date='Aug 30 2010, 02:22 AM']Probably the best material for a bass cab would be carbon fiber honeycomb matrix. It works well enough in F-117s. But it ain't cheap, especially since most of it is gobbled up by the aerospace industry.[/quote]
Celestion made a compact (stereo, 2-way) loudspeaker system in the 80's called the SL600(/i) made from a material called Aerolam.
Similar principle. Oh, an they weren't cheap!
With reference to the resonant quality of cabinets (mentioned earlier by another poster), all cabinets will have various resonant modes, caused by various factors. There are a number of means of reducing this, a good one being to try to move the resonant frequency of the enclosure that corresponds to its mass either outside the audio band entirely or to a point where it won't be too obtrusive.
I'd assume the primary objective in a low-cabinet-mass hifi loudspeaker system would be to minimise colouration by reducing the enclosure's ability to store energy.
In a bass cab, whilst a laudible objective, I'd consider it secondary to the ability to carry it easily!
Worth a go [i]if[/i] you've got access to the means and materials, as the OP plainly has.
Some areas I can see being worthy of attention;

The front baffle needs to be rigid enough to support the drivers properly

Cabinet bracing might be good idea!

Carbon Fibre is [u]very[/u] stiff, but it is also brittle. Look at the way in which F1 cars and composite cycle frames splinter and de-laminate when crashed hard. Bass cabs take more than a few knocks during their lives! Flight-casing the cabinet would solve this, but negates the weight advantage you worked so hard to secure. Perhaps rounding-off all the external edges and vertices would help (and look nice!), plus some sort of rubber "bumpers" around the areas most likely to sustain big impacts...

Edit for dodgy quoting of BFM and an apology to ShergoldSnickers for not reading his post from 2 hrs previous. Great minds think alike, though!

Edited August 30, 2010 by Lfalex v1.1

[RhysP]

[quote name='rmshaw37' post='939920' date='Aug 30 2010, 12:49 PM']to the op - do you with with pre preg or dib dob?[/quote]
Wow! A post from one of the Flowerpot Men.

[Grassie]

[quote name='RhysP' post='939945' date='Aug 30 2010, 01:15 PM']Wow! A post from one of the Flowerpot Men.
[/quote]
It's pre-preg material. Many thanks to all who have posted advice on this thread, I wanted as many opinions as possible and looks like I got them! Back to work tomorrow, so I shall start asking around to see if anyone has any, ahem, "offcuts" they would like me to take off their hands! Of course, if I can get everything together material -wise, and sort myself out with some practical tips on avoiding the aforementioned unwanted resonance problems, then you'll certainly get to read a build diary. I'm actually quite excited by this. I've managed to bugger up my back over the years lugging around cabs and combos which should've come with health warnings. So the main objective [i]is[/i] weight saving, but certainly not at the expense of sound quality. Like i mentioned before, if it goes breasts skyward then I'll do a wooden cab anyway. Stay tuned...

[lee650]

i cant wait to see the results, could be like garlic bread "the future" very interesting idea, good luck with it - lee