My Stillborn Plan for a DIY Speaker Cab

[Zaphod B]

I really wanted this to work, but I think there is no way. This would have been for a guitar amp cab.

What I wanted to do was build a large array of small-diameter speakers in a tri-angled cabinet. I wanted to use speakers of 4" diameter or less. Hopefully very cheap speakers, as I was thinking that about 30 or 40 of 'em would be necessary to move enough air.

Try as I might, I could not find any speakers that fit all of the following criteria:
-- 4.5" diameter or less
-- High-efficiency (min SPL of 95dB @ 1W, hopefully much better than that)
-- Full-range - full enough to cover the guitar frequency range, anyway
-- Cheap - and I mean dirt cheap

I found some 3" full range drivers (OK, OK, they are computer speakers) that cost like $4.95 each but their efficiency is very low, like around 84dB, so that won't work. And Fostex makes some very small full range speakers in the 5" - 6.5" range but they cost a fortune and require a transmission line enclosure, which would be enormous.

Unless someone can point me to some small, cheap, efficient, full-range drivers that I haven't been able to find, I don't think this is going to work out.

Sure would look cool, though.

[travelin travis]

what would be the point? How in hell are you going to match up the impedance with an amp/amps?

[Zaphod B]

Originally Posted by TravisinFlorida

what would be the point? How in hell are you going to match up the impedance with an amp/amps?

The point would really be just to have a project, and see how it sounds. Plus, like I said, I think it would look major kewl.

Impedance matching - no prob. Do a bunch of series/parallel wiring and with so many speakers you can get pretty much any impedance you want.

[travelin travis]

Man that's alot of speakers!

[Zaphod B]

Originally Posted by TravisinFlorida

Man that's alot of speakers!

No shit - that's why they've got to be cheap!

[travelin travis]

Everything I see is rated at 84db or less too. 95db seems like it would be a rediculously efficient 4" speaker.

[Zaphod B]

Originally Posted by TravisinFlorida

Everything I see is rated at 84db or less too. 95db seems like it would be a rediculously efficient 4" speaker.

You can find dedicated midrange speakers in the 4" range that are more efficient but they don't have the necessary bandwith.

Speaking of efficiency, what strikes me as unusual is that guitar speakers commonly exceed 105dB, but a 12" high-fidelity driver usually won't exceed 89dB. I guess that's the price you pay for having a more controlled response - guitar speakers are anything but linear.

(And I wonder if the "guitar speaker sound" didn't actually arise from repurposed high-SPL speakers back in the dawn of electric guitar amplification, rather than an intentional design for a particular sound. But I'm approaching heresy here, so I'd best be quiet! )

.

[32-20-Blues]

Originally Posted by Zaphod B

I really wanted this to work, but I think there is no way. This would have been for a guitar amp cab.

What I wanted to do was build a large array of small-diameter speakers in a tri-angled cabinet. I wanted to use speakers of 4" diameter or less. Hopefully very cheap speakers, as I was thinking that about 30 or 40 of 'em would be necessary to move enough air.

Try as I might, I could not find any speakers that fit all of the following criteria:
-- 4.5" diameter or less
-- High-efficiency (min SPL of 95dB @ 1W, hopefully much better than that)
-- Full-range - full enough to cover the guitar frequency range, anyway
-- Cheap - and I mean dirt cheap

I found some 3" full range drivers (OK, OK, they are computer speakers) that cost like $4.95 each but their efficiency is very low, like around 84dB, so that won't work. And Fostex makes some very small full range speakers in the 5" - 6.5" range but they cost a fortune and require a transmission line enclosure, which would be enormous.

Unless someone can point me to some small, cheap, efficient, full-range drivers that I haven't been able to find, I don't think this is going to work out.

Sure would look cool, though.

You're a bloody genius. Tom Waits already had a similar idea. Here's an excerpt from an interview between him and Jim Jarmusch, the film director:

TW: Oh, how about this, Jim. You know sound systems in theaters? I hate
'em. Get beat boxes, just start collecting 'em, a wide variety of 'em, and
use their speaker systems, and make a proscenium of beat boxes, you know,
your own sound system, it's all wired into a main box, and you just, you
create this whole world of sound, but it's all found stuff, because people
throw those things out. And it's just dirt plastic, the lowest material,
the cheapest material, cheaper and cheaper to them. They're getting worse
and worse, but they're getting on another level, better and better. But
they vanish after they've been around awhile.

JJ: They're disposable.

TW: People throw 'em away like cigarette lighters.

JJ: But the speakers usually still work.

TW: Yeah. So mount all these speakers in this strange thing and travel
with that. Travel with your own sound system. You don't use any of these
Marshall stacks or any of this bullshit.

JJ: Not only that, but you could build a proscenium of the boxes, like an
arch.

TW: Yeah. And that's what becomes your stage set. And you walk out, and
the curtain comes down off of that. It's just like making the theater go
away. You make everything smaller and go into that world.

[travelin travis]

He must have been stoned.

[Zaphod B]

But, you know, that's a neat idea.

Boombox speakers are small and fullrange. Don't know how efficient they are.

How much cheaper can you get than discarded boomboxes?

I can imagine a kind of post-apocalyptic stage setup, constructed out of broken boomboxes, all of which have my guitar amp running through them!

(OK, that's too wierd for me but I'd sure take all those speakers and wire 'em up and see how they sound! )

[travelin travis]

My first big amp was my sister's old home stereo. I wired up a guitar cable to the wires going to the record player needle. Speakers were two 10 inchers. It kicked the shit out of my buddies crate 212 sound wise (he thought so too). After my sister officially donated it to my cause, I screwed the speaker cabs together, mounted the stereo on top, and hard wired my distortion pedal to the record player. I used it for at least a year before it got dropped on a pumpkin.

[32-20-Blues]

Originally Posted by Zaphod B

But, you know, that's a neat idea.

Boombox speakers are small and fullrange. Don't know how efficient they are.

How much cheaper can you get than discarded boomboxes?

I can imagine a kind of post-apocalyptic stage setup, constructed out of broken boomboxes, all of which have my guitar amp running through them!

(OK, that's too wierd for me but I'd sure take all those speakers and wire 'em up and see how they sound! )

Okay. Here's the deal. I gave you the boombox idea (well, Tom Waits did, but so what?), so when you do it, let me know if it works. I want a wall of Boombox speakers. I mean a goddamn wall of them Oh yes, it will be mine.

[Zaphod B]

I've done similar stuff to various stereos over the years, when I was young, broke, and had no amp. Guitars sound really good full-range!

That reminds me - one of my suitemates in college had a low-wattage tube AM radio. He wired his guitar into the circuitry so as to bypass the AM tuner, and when he cranked that little fucker it had the sweetest sound you can imagine - it sounded just like Clapton's early Cream work.

[Zaphod B]

Originally Posted by 32-20-Blues

Okay. Here's the deal. I gave you the boombox idea (well, Tom Waits did, but so what?), so when you do it, let me know if it works. I want a wall of Boombox speakers. I mean a goddamn wall of them Oh yes, it will be mine.

All right, that's a challenge, and that's a deal.

I'm going to put a "Wanted" advertisement in Craigslist for old, discarded, unwanted and/or broken boomboxes. I won't pay a dime for anything if I don't have to, but I'll offer to pick 'em up.

I'd better clear out some space in the garage!

[travelin travis]

Originally Posted by Zaphod B

I've done similar stuff to various stereos over the years, when I was young, broke, and had no amp. Guitars sound really good full-range!

That reminds me - one of my suitemates in college had a low-wattage tube AM radio. He wired his guitar into the circuitry so as to bypass the AM tuner, and when he cranked that little fucker it had the sweetest sound you can imagine - it sounded just like Clapton's early Cream work.

Mine sounded quite a bit like early guns n roses, a good amount of speaker break up, and high gain but not too high. It wasn't hella loud but it sounded better than most of the amps I couldn't afford.

[travelin travis]

Originally Posted by Zaphod B

All right, that's a challenge, and that's a deal.

I'm going to put a "Wanted" advertisement in Craigslist for old, discarded, unwanted and/or broken boomboxes. I won't pay a dime for anything if I don't have to, but I'll offer to pick 'em up.

I'd better clear out some space in the garage!

This sounds interesting. I want pictures and sound clips when you get the monster together.

If you're serious, I might just send you my old boom box. It's in the attic some where........

[32-20-Blues]

Originally Posted by Zaphod B

All right, that's a challenge, and that's a deal.

I'm going to put a "Wanted" advertisement in Craigslist for old, discarded, unwanted and/or broken boomboxes. I won't pay a dime for anything if I don't have to, but I'll offer to pick 'em up.

I'd better clear out some space in the garage!

Okay, I'm going to get working on it too. If I run into problems, guess who I'll be PMing? I don't yet know how to solder, but I have a pretty reasonable grasp of physics, so I hope it'll work out. I'm planning on using my Epi Valve Junior on this, so I'm going to get out the calculator and mess around with some numbers. Any speakers will do, can't wait to get this started.

[Zaphod B]

Originally Posted by TravisinFlorida

This sounds interesting. I want pictures and sound clips when you get the monster together.

If you're serious, I might just send you my old boom box. It's in the attic some where........

I'm serious. It won't cost me anything but time and gasoline. My wife will think I've gone insane. More insane, that is.

Don't go digging in the attic yet, though, I may abandon the thought after some sober reflection!

[travelin travis]

One thing that springs to mind is variations in volume among all the speakers. I guess that will be dependent on placement.

[Zaphod B]

Yeah, that and efficiency.

What I'll probably try to do is make a wall out of them to see how it sounds as a single array.

It will get hairy, because I'll have to check all those little speakers' DC resistances separately, and the wiring scheme could get ugly.

[Lt. Bob]

I don't think you need to be so worried about efficiency unless you're gonna try pushing them with a Valve Jr or something flea powered like that.
With that many speakers, you're gonna move some air. I don't think you need that many .... one of the best bass cabs I ever heard had only 8-8's in it. Probably you should try 10 or 12 of the little 4's first.

[32-20-Blues]

Originally Posted by Lt. Bob

I don't think you need to be so worried about efficiency unless you're gonna try pushing them with a Valve Jr or something flea powered like that.

See 4 posts up.

[Zaphod B]

Originally Posted by Lt. Bob

I don't think you need to be so worried about efficiency unless you're gonna try pushing them with a Valve Jr or something flea powered like that.
With that many speakers, you're gonna move some air. I don't think you need that many .... one of the best bass cabs I ever heard had only 8-8's in it. Probably you should try 10 or 12 of the little 4's first.

Good point, Lt. Bob.

The reason I was concerned about the efficiency for a working rig was that inefficient speakers, on the order of 83 - 84dB, are enormous power soaks compared to more efficient speakers, and you have to drive much more wattage into them to get equivalent volume levels, then you have to worry about power handling of all those teeny things......

But now I'm thinking more in terms of proof-of-concept.

I hadn't put the calculator to it yet, but here are some rough figures. Let's say that the area of a 12" speaker would be about 128 sq inches, and the area of a 4" speaker is about 13 square inches. You'd need 10 4" speakers to match the cone area of a 12" speaker. To duplicate a 4X12 cab you'd need 40. I guess it depends on how much air you want to move.

[Zaphod B]

Originally Posted by 32-20-Blues

Okay, I'm going to get working on it too. If I run into problems, guess who I'll be PMing? I don't yet know how to solder, but I have a pretty reasonable grasp of physics, so I hope it'll work out. I'm planning on using my Epi Valve Junior on this, so I'm going to get out the calculator and mess around with some numbers. Any speakers will do, can't wait to get this started.

Very cool!

And don't worry about the efficiency part of it. It just means that your 5-watt Valve Jr. isn't going to get you as much volume as it would being played through a regular guitar cab.

[alien]

actually, the idea has been used before

I remember seeing a set of speakers for sale in a used store in Nashville, TN a while back.

It had around 30 4" drivers with four 10" drivers up the middle of the bottom half. There was a horn in the top (probably an old Foster version). Can't remember the make or model, but they lookd alot cooler than they sounded.