An early LM12 chipamp design

jackinnj · 19th July 2005, 10:11 PM

i came across this looking for an article in Radio Electronics (no longer published) --

http://www.tech-diy.com/earlychipampdesign.htm

scooby300 · 19th July 2005, 11:07 PM

I think i`ve got some of these old chips around somewhere ? (just got to find them).

It would be nice to power then back up just to see if they work!.
Plus see if they sound any better or worse than the new lm chips (lm3875 , lm4780) .

scooby300 · 19th July 2005, 11:32 PM

I think i`ve got some of these old chips around somewhere ? (just got to find them).

It would be nice to power then back up just to see if they work!.
Plus see if they sound any better or worse than the new lm chips (lm3875 , lm4780) .

cm961 · 20th July 2005, 12:42 AM

I built a four channel LM12 amp. It sounded great. The transformer was undersized though, you could hear a compression type sound. Then the crossovers stopped working.

Pete

carlosfm · 20th July 2005, 12:43 AM

A portuguese diyer friend has made one, some time ago.

Is this a gainclone?

Tekko · 20th July 2005, 09:08 AM

I´d like to get two of these, 300 watts into 2 ohm if i paralell two.

Anyone got two to sell ?

DC Dave · 20th July 2005, 05:13 PM

Quote:

Originally posted by Tekko
I´d like to get two of these, 300 watts into 2 ohm if i paralell two.

Anyone got two to sell ?

Digikey still sells them. Not exactly cheap though, $20 per ic
http://www.digikey.com/scripts/DkSea...338604&Site=US

Here's the datasheet from National.
http://cache.national.com/ds/LM/LM12CL.pdf

Could be a fun project for people looking to try a different chip.

Tekko · 20th July 2005, 05:23 PM

Nevermind. I found a better suited ic.

XELB · 21st July 2005, 02:17 AM

How does it sounds ?

If it sound great, I think this could be a nice OpAmp for a active subwoofer

( I guess...

)

jackinnj · 21st July 2005, 11:25 AM

I am surprised that no-one has (apparently) seen that the article contains a schematic and PCB layout for a 12V switching power supply for the LM12.

19th July 2005, 10:11 PM	#1
jackinnj diyAudio Member Join Date: Apr 2002 Location: Llanddewi Brefi, NJ	An early LM12 chipamp design i came across this looking for an article in Radio Electronics (no longer published) -- http://www.tech-diy.com/earlychipampdesign.htm

19th July 2005, 11:07 PM	#2
scooby300 diyAudio Member Join Date: Mar 2005 Location: England Cheshire	I think i`ve got some of these old chips around somewhere ? (just got to find them). It would be nice to power then back up just to see if they work!. Plus see if they sound any better or worse than the new lm chips (lm3875 , lm4780) . __________________ You won’t know until you listen

19th July 2005, 11:32 PM	#3
scooby300 diyAudio Member Join Date: Mar 2005 Location: England Cheshire	I think i`ve got some of these old chips around somewhere ? (just got to find them). It would be nice to power then back up just to see if they work!. Plus see if they sound any better or worse than the new lm chips (lm3875 , lm4780) . __________________ You won’t know until you listen

21st July 2005, 02:17 AM	#9
XELB diyAudio Member Join Date: Dec 2004 Location: Lisboa	How does it sounds ? If it sound great, I think this could be a nice OpAmp for a active subwoofer ( I guess... ) __________________ If you want power you must add control

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20th July 2005, 12:42 AM	#4
cm961 diyAudio Member Join Date: Jun 2001 Location: Peterborough, Ontario	I built a four channel LM12 amp. It sounded great. The transformer was undersized though, you could hear a compression type sound. Then the crossovers stopped working. Pete

20th July 2005, 12:43 AM	#5
carlosfm Banned Join Date: Mar 2003 Location: Lisbon, Portugal	A portuguese diyer friend has made one, some time ago. Is this a gainclone?

20th July 2005, 09:08 AM	#6
Tekko diyAudio Member Join Date: Jan 2005	I´d like to get two of these, 300 watts into 2 ohm if i paralell two. Anyone got two to sell ?

20th July 2005, 05:23 PM	#8
Tekko diyAudio Member Join Date: Jan 2005	Nevermind. I found a better suited ic.

21st July 2005, 11:25 AM	#10
jackinnj diyAudio Member Join Date: Apr 2002 Location: Llanddewi Brefi, NJ	I am surprised that no-one has (apparently) seen that the article contains a schematic and PCB layout for a 12V switching power supply for the LM12.

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