[sdiy] Amp-in-a-chip

[jpdesroc at oricom.ca]

Hi,
I had to solve the same problem to get
a reasonable amp for my bench.
I had 2 choices:
-Buy an used hi-fi amp and set it up
under my bench.
-Build from nothing a standard power amp
using a power opamp + supply.

I chose solution #2 so I had to pickup
a good & reliable power amp chip.
I stopped my choice on the LM12.
http://eshop.engineering.uiowa.edu/NI/pdfs/00/87/DS008704.pdf

Check those links on it:
http://www.tech-diy.com/earlychipampdesign.htm

http://www.diyaudio.com/forums/showthread.php?s=&threadid=13811&highli
ght=

It is an early chip but still available at Digikey.
Just adjust the opamp's gain with the feedback resistor
to your wish, put 47k input resistors on both input pins
and that's it. Make sure you have a descent power supply
since this amp is capable of power around 40-50w easily
into 4 ohms. I mounted my LM12 circuitry under my bench
with its supply then I ran a shielded cable from its input
to a 1/4" plug input with volume control on my bench top.
I then wired a speaker to it in a small enclosure
on my bench. You can also wire a Ceiling type speaker.

Hope this helps.
JP



---- Message original ----
De: lightburnx at yahoo.com
A: synth-diy at dropmix.xs4all.nl
Objet: [sdiy] Amp-in-a-chip
Date: Sun, 3 Feb 2008 20:11:16 -0800 (PST)

>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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