I'm experimenting with something new, affordable, and best of all--sounds good.
I purchased a pair of 8" diameter x 48" long cardboard tubes from Home Depot (they're used for forming up concrete piers) and stuffed them with twelve 3" M&K drivers. I ported the array (by standing the tube on some quart sized paint cans
) to increase bass extension and basically wired it up to run as a 4 ohm load.
I'm very impressed! The cardboard is only 1/8" so I expected the possibility of vibration and resonance, but guess what? Due the the fact that the tube is round, there's strength and very little reflection to cause standing waves. The sound is pure--almost uncanny.
I spent $3.75 apiece on the M&K drivers and the tubes cost $7.00 each. There's no crossover, so the overall expense for this project is basically peanuts. There's no way I expected this thing to sound so good.
Of course, my little class A amp has something to do with the sound, but an amp can't do much without decent speakers.
Just had to share...
I purchased a pair of 8" diameter x 48" long cardboard tubes from Home Depot (they're used for forming up concrete piers) and stuffed them with twelve 3" M&K drivers. I ported the array (by standing the tube on some quart sized paint cans
) to increase bass extension and basically wired it up to run as a 4 ohm load.I'm very impressed! The cardboard is only 1/8" so I expected the possibility of vibration and resonance, but guess what? Due the the fact that the tube is round, there's strength and very little reflection to cause standing waves. The sound is pure--almost uncanny.
I spent $3.75 apiece on the M&K drivers and the tubes cost $7.00 each. There's no crossover, so the overall expense for this project is basically peanuts. There's no way I expected this thing to sound so good.
Of course, my little class A amp has something to do with the sound, but an amp can't do much without decent speakers.
Just had to share...
Attachments
Hi Carpenter . It just acts as a series crossover . The speakers placed at ear height will reproduce full band ,the lower ones only bass . Depends how you did the serial parallel connection between them .For example you've got 3 stacks of paralleled drivers ,the 2 lower ones will have 1 cap each (for example :100 uF ;50 uF ).
See also Parts Express: Project Showcase
(just to see the EQ needed )
See also Parts Express: Project Showcase
(just to see the EQ needed )
I have thought of stuffing, but the sound is resonate free, so I can't see any reason for the additional dampening.
I'm guessing the little M&K drivers (which are really tiny and have small motors) have a fairly high Qts. They feel/sound right at home with the volume I gave them, and also may account for the extended bass response in the relatively large tube. These most likely are not bass drivers, so it's pretty cool to be getting full spectrum.
The most important thing to me is keeping the delicate nature of sound that emanates from the cone of a small speaker. Large cones sound just a tad clunky in comparison. I'm getting plenty of texture, nuance, etc that a large driver masks.
There's a line array drawing on my web site if anyone is interested--just click on my name above the avatar.
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Gotcha. I was over analyzing your original remark--now I understand completely. Thanks for the advice.
That's a terrific idea, jrenkin!
I decided to allow the enclosure to do whatever it wanted as an experiment in minimal design. I've read of speaker enclosure that are designed to resonate in order to enhance the speaker. Seems, in this case, it hasn't done any harm.
I'll have to give your idea a whirl.
Ummm, no...
No matter how you wire it the "open" drivers will still see the caps that are in parallel with the driver (more or less a resistor) as a shunting capacitance to ground.
I'd opt for an inductor in series with the drivers you wish to roll off... IF that is something you want to do...
_-_-bear
Very nice. You may want "wood wedges" in the back too. It would help keep things aligned and give you something to mount binding posts through if you didn't want the wires entering top or bottom. I don't like loose wires, so posts at the back seems more elegant to me.
How are you managing the top and bottom? Is one or the other sealed? Seems like there are a million options in this design.
I have also been trying to think of ways to divide the tube inside to make it into a TL or folded horn. Hard to do well without being able to cut some pretty difficult parabolas...
I hope you play with this concept a lot. Very impressive, may be versatile, fun and cheap. I don't have time myself, a busy physician with a 5 month old kid and three projects on the table (big BIB 2 way, PP EL34 and SE 300B) sigh...nothing happening fast around here...
So I plan to live vicariously through you
@ Bear
Maybe you're right .Consider me a complete newbie who just collects some information from the "net". I've read that this so called "gradual release" is applicable to series connected drivers ,this to avoid combing and too much HF lobing . So this can be done by reducing the number of cones emitting HF by simply shunting with a cap the lower ones which would reproduce bass only , ideally only one driver would play HF ,the ones below gradually would play the lower frequencies.
I would be grateful to Carpenter if he can do such test.
Maybe you're right .Consider me a complete newbie who just collects some information from the "net". I've read that this so called "gradual release" is applicable to series connected drivers ,this to avoid combing and too much HF lobing . So this can be done by reducing the number of cones emitting HF by simply shunting with a cap the lower ones which would reproduce bass only , ideally only one driver would play HF ,the ones below gradually would play the lower frequencies.
I would be grateful to Carpenter if he can do such test.
I know nothing about line arrays, but with something like this, could you simply divide the line into top and bottom sets and use and inductor (1st order) to roll off the highs in the,say, bottom three drivers and a capacitor to roll off the lows in the top ones? Essentially a simple two way with multiple drivers and first order xover? Or even do it 3 way?
Or would this just trash carpenter's purity....
Lovely comments, and certainly interesting information from everyone. Thanks for sharing. Ever since I built a pair of T/Ls for my friend using Audio Nirvana Cast 10 full range drivers, I've been smitten with the purity of sound of a crossoverless speaker system. With today's receivers, one can easily employ the subwoofer output port to pick up the first octave, but that's as far as I would go. Everything in audio is a compromise of one sort or another, and losing the crossover and dealing with the subsequent frequency response problems is one compromise I can not only tolerate, but enjoy.
I've built some very large home audio systems, ridiculously large in fact. Discovering simplicity is the other extreme, and a very good way to go.
I've built some very large home audio systems, ridiculously large in fact. Discovering simplicity is the other extreme, and a very good way to go.
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