Seeking a compact mono power amp for making a speaker active

mihalis

Hi all,
I have a speaker that I built in high school for a speaker building class (yes, a speaker building class). I had wanted to make a stage monitor, but ended up with essentially a single home stereo speaker that is pretty good quality, but has been utterly useless since then. (It could be a center channel, but I don't have a setup that advanced with my TV.)

I'd like to buy or make an amplifier that could either be fastened to the top of the speaker or embedded in it to make it an active speaker, which I could then use as a keyboard or laptop amp, probably just for rehearsal as the speaker is not very rugged.

So it needs to be 10" x 8" or smaller, I'm guessing about 50W would be sufficient power, and I'd like to spend $200 or less if possible. I'm not that picky about the sound quality, so something based on an IC is fine.

Such things must exist since there are plenty of active speakers, But I'm not having much luck finding any for sale on their own. If I go the DIY route I'd prefer something relatively ready-to-go like a kit, as my skills are limited. But I'll try anything--this has been bugging me for years. Thanks for any advice you can offer!

The Scum

There are definitely some power amp kits around. I can't recommend anything specific, but I can give you a few terms to search for:

Old Colony sound labs offers hifi kits, and ave had a few power amps through the years.

A Nelson Pass Zen amp might fit the bill...low parts count, and low power, but great sounding.

You might look DIY webpages concerning class D, and class T amps, and what people are calling "chip amps."

Keep in mind that with nearly any power amp design, the power supply and heatsinking are rather critical.

substitute · pushin' record Joined: 10 Mar 2004 Posts: 213

I remember seeing a power amp kit on the JLM audio site, it was pretty cheap, I think 60w. I can't seem to find it now, but their site is sort of hard to navigate so I might not be looking right. I think PAIA has something as well. I've always wanted to get around to attempting to try to make one of those, so please post your results.

substitute · pushin' record Joined: 10 Mar 2004 Posts: 213

ok found it...

http://www.jlmaudio.com/JLM%20AMP.htm

mihalis

Thanks for the ideas! The JLM kit looks quite suitable. I also found this 200W Velleman kit from Old Colony, and a kit sold at chipamp.com, which seems to be based on a 68W IC.

In all cases I'm a bit intimidated by having to deal with the enclosure, the heatsink, and the power transformer on my own, but it doesn't look like there's much choice in the matter. Considering the large heatsinks I see on people's projects, I'm even more curious about how they handle it in powered speakers like the ones I have, which are quite solid and compact with no ventilation other than the bass port. If anyone has suggestions for enclosures of the size I mentioned, I'd welcome them. I'll definitely post my results, though it will probably be a while before I have any.