Spare Parts Subwoofer

I have an AB International Pecedent 400 amp:


  • 145w per channel @ 8 Ω
  • 270w per channel @ 4 Ω
  • 400w at bridged mono @ 8 Ω
  • 2 x 1/4" phone jacks (unbalanced)
  • Dual 5-way binding post outputs
  • Passive Cooling combined with high efficiency output stage for reduced operating temperature
http://www.abamps.com/pdfs/400a-man.pdf




I also have a 15 Johnson 15" 2-way active speaker, less the amp.
Similar to this Harbinger piece:


9k=


APS Series Powered Loudspeakers




I would like to explore the folly of combining these two items to make a powered subwoofer for a live band application. The gigs will be modest (-100 people) with an occasional outdoor venue. The program will be classic rock with a live drummer (mic'd kick & snare) sometimes electronic drums. The goal isn't volume so much as hearing some kick in some of annoyingly live venues we find ourselves.



Are these components worth the lives of the trees that might be sacrificed for an enclosure?


Should I just Sawzall the horn and duct tape the amp in the hole and spray paint the mess in camo?


Should I sell my blood and whatnot to use the proceeds for a real subwoofer?


Any and all thoughtful responses and smarmy wisecracks will be greatly appreciated.


Thanks,


Norm
 

Xoc1

Member
2008-11-08 8:25 pm
Devon UK
The 15" driver might just survive being used in a reflex cabinet.
Maybe make one with port tubes and you can retune, reuse the cabinet if the driver dies
www.fane-acoustics.com/downloads/Cabinets15inch125Lres.pdf
The amplifier is pasively cooled and won't like being shoehorned into a speaker cabinet.
You will need some filters for the sub amp - both high and low pass.
Some info on what PA equipment you would be uing this with would help!
 
The 15" driver might just survive being used in a reflex cabinet.

Sound like it's hardly worth the effort.

Some info on what PA equipment you would be uing this with would help!

It's a cheap Behringer powered mixer with a blown amp running a pair of new Alto Powered 12" Truesonics for mains and a pair of the same 15" Harbingers/ Johnsons, (in rough shape) for monitors, a third Johnson with a blown amp would be the hypothetical sub-donor.

We'll have some acoustic kick drum and/or a full electronic set going through the system. Maybe I'll mix a litrtle kick into the 15" monitors for a little extra bottom, if it's not too distracting.

We're playing two nights in a room that's about 25'x 40' with a 15' tin ceiling for up to 75 people. Very live space. The first night we'll be hosting an open mic which will enable us to hopefully dial in the sound (at others' expense) for our Friday show.

Thanks all for the help, if we really need a sub, we'll just go the slacker (non DIY) route and buy one.
 
Make the subwoofer.

You have a 15" driver sat there doing nothing - so long as it fits in the van, there's no harm in using it.

Also means you can distribute bass sources a little better, which will give a more even response.
Bass reflex cabinets are easily survivable - its in one now!
Horns, however, put weird stresses on the driver cone, which is why some cones end up "tenderised".

I'd stand by my suggestion of ~70L (maybe a little bigger), tuned circa 60Hz. Don't ask any really deep bass out of it, and you'll be fine.
It'll provide some kick, but won't flap your t-shirt (that's what multiple 18"ers are for).

Chris
 
Make the subwoofer.

You have a 15" driver sat there doing nothing - so long as it fits in the van, there's no harm in using it.

Also means you can distribute bass sources a little better, which will give a more even response.
Bass reflex cabinets are easily survivable - its in one now!
Horns, however, put weird stresses on the driver cone, which is why some cones end up "tenderised".

I'd stand by my suggestion of ~70L (maybe a little bigger), tuned circa 60Hz. Don't ask any really deep bass out of it, and you'll be fine.
It'll provide some kick, but won't flap your t-shirt (that's what multiple 18"ers are for).

Chris

Here's what I'm going to try:

I have a 7-band guitar stompbox eq that I'll put on the input side of the amp. I'll keep the speaker in the plastic cabinet, disconnect the tweeter and see what happens.

Thanks