Cheap Subwoofer build for less than £150

[llyrroberts]

Hello!

Me and a friend run a mobile disco business, we are only 16 and do disco's for our friends and family. Our sound setup is 2x active carlsbro 300W rms gamma 15" and kam mixer, laptop VDJ.

We want to build a Sub woofer to give the crowd 50-150 a good kick in the belly! We have quite good woodworking skills, I have seen 15" active PA subs for £200 from Thoman and studio spares, and would like to build something similar.

I was thinking maybe a 15" driver but am not sure which kind of box to make.

Our budget is small, less than a 150 hopefully!
Any suggestions? Plans?

Thanks in advance!

Llyr

[NurEinTier]

150 pound...active or passive? Purely for dance dj'ing?

Active I don't see much options, spent a bit more and get the Thomann housebrand.

Passive could be done but again the cheap PA brands will be hard to beat.
Ultra cheap woofers 4x15" or 8x12" (Skytronic?) plus wood may be within budget. Horn type.
In a small room that will be ok but a pure PA sub with a powerful amp will kill it.

[Piek]

Hi,

try www.speakerplans.com .

-Micha

[richie00boy]

I think you are expecting too much from a single 15 inch driver as a sub, remember you are already using a pair of 15 inch drivers for main speakers. With that level of main speaker I would say you need an 18 inch per side to keep up really.

The problem with trying to use 2x or even 4x 15 inch per side would be that the resonance frequency might not be hardly any lower than what you have now, so the amount of sub effect would be minimal, it would be just be louder overall.

Also as your main speakers are active, you would need to build/buy a crossover and amp to power the sub(s) which I think is going to put you well past your budget. You might be lucky with a used amp, but even then I think it's going to be tight.

[simon5]

He could build one tapped horn per side.

He said he was good with woodworking.

That's what I'd do, two tapped horns down to 40 Hz.

But then, you need an amplifier that you can adjust the lowpass and the highpass on it, to avoid sending stuff under 40 Hz to it and avoid sending midrange to it...

[llyrroberts]

Yeah i probably am asking to much out of one 15", passive would be cheaper i think, I'm have been looking at speakerplans.com they look good, can anyone think of any good budget 15" or 18" drivers? In UK!

[richie00boy]

You can't do passive as the amps are inside your main speakers, you need another amp for the sub.

[valleyman]

Are these the speakers you're talking about?
http://www.getinthemix.co.uk/Carlsbr...0-Speakers.htm

The specs say -3dB @ 50Hz, -10dB @ 40Hz.

If that's the case then I'm not sure how much benefit you'd get form a sub especially for £150.

You're going to be looking at something to cover only 40-50Hz. Bear in mind that sub 40Hz is not required for PA use really and many amps will put a steep crossover here so as not to waste excursion. There is little to no content below 40Hz in disco music anyway.

I'm assuming here that improving power handling by taking some low end strain off the main speakers isnt your goal, and if it is, extra active crossover is required which I'm sure will push you way beyond budget

[llyrroberts]

I just feel I push the active carlrbro's to hard I'n terms of bass, even though i haven't ever been able to peek them! I would just like a sub to give a good rumble, so the crowd can feel the bass, more than hear it! A friend of mine told me a disco is not a disco without bass that makes your chest move!

[dangus]

Look at bandpass designs too, with peaks in the 60 to 100 Hz range. There's probably some of those at Speakerplans. Also, the forums there are good; maybe you'll find some leads on good value drivers.

One advantage of separate subs is you can put them on the floor where they'll couple to the room better, or better still, in a corner. Presumably you're putting the main speakers up on stands, so the bass is going to be weak. Once you have a sub (or 2 or 16), you can high-pass the signal to the mains so they'll have more headroom.