Is there a cheap way to reproduce 400 W @ 8-ohms?

[IDSKoT]

Hey, guys. I was just wondering if there was a cheap way to create an amp that is capable of 400w @ 8-ohms of clear power? The power can go down to ~250-300.
Right now I have my eyes set on the Bash 500w Plate amp with 500w @ 4-ohms, so I assume 250W @ 8-ohms at .5%THD ($185) or a Pyle Pro amp that claims to produce 300 @ 8 ohms <1% THD ($157.)


So, I'm wondering if something can be built for cheaper, or if not cheaper, a bit more expensive with much better reliability / sound quality. Currently, I'm unemployed. But I'm willing to save up quite a bit once I return from my trip. I don't really want to go over $250. If that's at all possible.
Thanks for your responses.

[wg_ski]

Cheaper? If you have to buy all new components, no. If you have a huge stash to work from, can get an 70-0-70 600VA or higher trafo (or two 35-0-35's), 10 pounds of heatsink, and a pair of 20kuF/150V caps for next to nothing - and have done this before, yes.

[Bigun]

Don't know if it helps, but for my subwoofer I went with a commercial BASH 500W. There's a lot in one of these, no way I could make it for the price US$228.

http://www.creativesound.ca/details.php?model=BASH500

At this power level, the BASH Class-D amplifier saves a lot of wasted heat. Class-D is not something I would tackle as a DIY, although some do.

[IDSKoT]

Originally posted by wg_ski
Cheaper? If you have to buy all new components, no. If you have a huge stash to work from, can get an 70-0-70 600VA or higher trafo (or two 35-0-35's), 10 pounds of heatsink, and a pair of 20kuF/150V caps for next to nothing - and have done this before, yes.

Hah. Heatsink shouldn't be a problem. I have a lot of spare metal laying around, as well as lots of fans. However, the rest may be a problem.

Originally posted by Bigun
Don't know if it helps, but for my subwoofer I went with a commercial BASH 500W. There's a lot in one of these, no way I could make it for the price US$228.

http://www.creativesound.ca/details.php?model=BASH500

At this power level, the BASH Class-D amplifier saves a lot of wasted heat. Class-D is not something I would tackle as a DIY, although some do.

Yeah. I know in car audio applications, there are a lot of multi-channel A/B amps that can get pretty high WRMS @ higher ohms.

[Wavebourn]

http://cgi.ebay.com/GEMSOUND-XP-550-...arms=72%3A1234|66%3A2|65%3A12|39%3A1|240%3A1318|301%3A0|293%3A1| 294%3A50

[IDSKoT]

Originally posted by Wavebourn
http://cgi.ebay.com/GEMSOUND-XP-550-...arms=72%3A1234|66%3A2|65%3A12|39%3A1|240%3A1318|301%3A0|293%3A1| 294%3A50

Good find! Thanks. However, there's a small problem. I'm going on a trip soon, so I want to make sure I have enough money. So I wouldn't be buying anything until after wards. But, I completely forgot to check eBay. I'll save up onc eI get back and check again. Thanks.

[Wavebourn]

Welcome!
It was just an example. I once needed an amp, cheap. I bought broken Gemsound for $30, found a banana tip inside that shorted one rail to ground (it rolled under the PCB), replaced a fuse, checked... It worked, but after trying it I desired to replace the power tranny: I installed one with lower voltages so got less sag, but less of "max power" that was specified. I did not need that "max power" for a fraction of a second. I keep it ready for occasions when I have no amp to go with: it is well known fact that a shoemaker has no shoes... Tomorrow Russian community will celebrate an anniversary of WW-II victory, so the amp will drive my speakers in Civic Park of Walnut Creek.

[dangus]

With some luck you can find used semi-pro power amps at good prices. I got a Behringer EP-2500 for around $250, which is an insane amount of watts per dollar. I suspect the onslaught of 2U Chinese amps has reduced the value of big old workhorses like the Peavey CS800, so you might get one of those cheap too. Try pawnshops, music stores, sound rental outfits. eBay could be good if the seller is close enough that you can pick it up and avoid shipping.

Otherwise... consider using a parallel-bridged arrangement of chip amps. The amp portion will be cheap enough, but coming up with a power supply will be harder. (Rental outfits might have dead amps that would be valuable sources of parts: case, power supply, heat sinks...)

And, keep your eyes open. I noticed a big black thing on the floor behind the counter of a music store/pawn shop. It turned out to be a broken NAD 2200, which they generously sold me for $75. About $20 worth of transistors got it working.

[IDSKoT]

Originally posted by dangus
With some luck you can find used semi-pro power amps at good prices. I got a Behringer EP-2500 for around $250, which is an insane amount of watts per dollar. I suspect the onslaught of 2U Chinese amps has reduced the value of big old workhorses like the Peavey CS800, so you might get one of those cheap too. Try pawnshops, music stores, sound rental outfits. eBay could be good if the seller is close enough that you can pick it up and avoid shipping.

Otherwise... consider using a parallel-bridged arrangement of chip amps. The amp portion will be cheap enough, but coming up with a power supply will be harder. (Rental outfits might have dead amps that would be valuable sources of parts: case, power supply, heat sinks...)

And, keep your eyes open. I noticed a big black thing on the floor behind the counter of a music store/pawn shop. It turned out to be a broken NAD 2200, which they generously sold me for $75. About $20 worth of transistors got it working.

Thanks for the ideas. I'll definitely check out those places.

I need to research more, however. So I can figure out how to fix broken amps and the like. The most knowledge I know of "look for the burnt marks and replace everything around it."

[mosfets]

Apex JR may be of interest.