n00b: How cheap can a subwoofer amp be made?

[Sillyboy]

So, I can get this plate amp for $50. http://www.mcminone.com/product.asp?...Fid=50%2D6266A

Seems like a good deal, but I am curious if something similiar could be made (sans variable xover is fine) DIY style...even cheaper?

[lndm]

Maybe you could look at a gainclone. I don't know how cheap they will be in your part of the world. They are basically available as DIY kits. IMO they would make a fairly good basic sub amp.

[jaudio]

I don’t think you can build a cheap (cost) subwoofer amp. About time you order all the parts, you would have spent over $50 not to mention the building time. I would buy the sub amp and build a gain clone for the highs and midrange.

[lndm]

That sounds good. But what if you already had a power xfmr and some bits laying around, maybe an old broken amp? Plus, there is always the possibility of a goodwill find that will do the job on its own.

[jaudio]

Originally posted by lndm
That sounds good. But what if you already had a power xfmr and some bits laying around, maybe an old broken amp? Plus, there is always the possibility of a goodwill find that will do the job on its own.

Youre right. If you have most of the parts,go for it. I go to goodwill too,the thing with goodwill and other second hand place is,they more than llikely will not have what you need when you need it. Goodwill is very good,if you are buying for future project. Go to Goodwill and the Salvation Army, you might get lucky the first visit.

[Sillyboy]

Thanks for the input everyone.

I am just now starting to read about amps (and I guess for this question, power supplies), but how about older computer power supplies. If i tear into one, will I find a useful power transformer?

(I seemed to have collected computer parts over the years, the way most you collect amp parts -- I have a 350w ps right next to me...)

[lndm]

Computer supplies are typically switch mode. That means no big power xfmr. Switch mode power supplies can be used for audio but most choose to use conventional supplies instead. If you do not know what you are doing, the switch mode supply can give you problems and in my opinion they are a little too complex for a first power supply.

edit: the single most useful thing to me that I find in old computer supplies are the high voltage electrolytic capacitors.

[ifrythings]

150W RMS into 4ohms???? well.... the datasheet for the transistors says 100W???.

Heatsink looks a bit small for that power rating to, but I maybe wrong?

[jleaman]

YOU might be better off with that plate amp and some mod's. The reason for that is because you can spend 50$ on a gain clone but then you still have to build a cross over. Buy a plate amp then modify it Change cap's resistors etc etc.. Another idea change that small heat sink like *ifrythings* suggest's.

[davidlzimmer]

I was going to do like you untill I stumbled across that deal. At the price, I wish I could by more.

I and several others in the subwoofer thread bought that very amp and all were happy with it. It works fine with my LM3875 Gain Clone and I use less than half volume on a 4ohm speakers. I've run it for hours and the heatsinks never get hot. The only cheesey thing about it is the wimpy power cord. Meant to replace it but never got around to it.