[sdiy] Amp-in-a-chip

[anthony]

I've made a habit of keeping all of the amp IC's that I scrounge. Some are 
wimpy, but offer soft-clipping, some are borinh like LM836. I think the 
LM380 is very underrated - I love these little guys! They work great as a 
virtual ground too if you have an offset adjust control.

I made a really cool bass amp for my daughter using a TDA2003 that I 
srounged from an old CB and the subwoofer from a PC audio system (the IC 
that was powering it was only a 3 watt amp, but the 4" driver was rated at 
15 watts!).

I've made other amps from individual speakers: I just cut a hatch in the 
back, toss in the circuit and then bolt over the control panel.

One of my favorite amp IC's is the TDA1013A(B). My old Commodore 1942 
monitor had two of these in them. What you have is a voltage controlled 
preamp and a 1 or 2 watt amp that can be used as independantly as you like. 
The big appeal is the preamp being voltage controlled. I've tossed about the 
idea of using two of them in a stereo guitar amp with tremolo: the LFO would 
be quadrature and you could select how wide & wild you want the tremolo to 
be. I thought this might be a good way to get rid of those 6"x9" speakers 
that came out of my old Plymouth Gran Fury (Slant 6 woohoo!).

I have several LA4140's that I didn't know what to do with until I noticed 
that the Roland TB303 used one for the headphone amp. Now I've used two for 
a stereo headphone amp (which was what the portable cassette player I took 
them out of was using them for...).

Sanyo seems to be the king of small ic power amps: the LA4500 is a classic 
and the LA4445 is pretty cool too. Philips has some great ones too though, 
like the aforementioned TDA1013 and the TDA7052 (which is BTL but mono 
only).

National's LM4880 "Boomer" is great for a super-small headphone amp, needing 
minimal parts to operate. Although I have to say "Boomer" is sort of a 
misnomer - putting out 325 mW into 8 Ohm, unless of course you are using it 
for headphones.

So I'm just listing chips I've scrounged from things. If you're going to buy 
something, the LM380 is a nice cheap part, but you'd need 2 for stereo. I 
think it sounds great when used as a small practice amp for guitar, but I 
dunno how it would fare in hi-fi duty. The LM1578 or LM3578 is a GREAT amp 
IC, but again, you'll need two for stereo. And I think the latter might be 
pretty pricey.

cheers,
Anthony

> Hello...
>
> I cannibalized some nice speakers out of a broken hifi
> set a while ago, with the intent to make a simple but
> quality workbench amp out of them. They are 4, 4 Watt
> 4 Ohm speakers, and I may get another bigger one to
> act as a subwoofer. So call it 20-25 total Watts tops.
>
> I've flipped through electronics catalogs and Googled
> around, and found a few single chip audio amplifiers,
> though I'm curious if anyone's done something like
> this before and if they had any advice. I'm fixing to
> scratchbuild a cabinet for the speakers and all.
>
> Thanks...!
>
>
> 
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