LM4702 reference design note 1490 - ideal 1st amplifier?

Spasticteapot · 23rd October 2007, 01:09 AM

I'm looking to build my first proper solid-state (non-chipamp) amplifier, and the LM4702 looks like a good starting point.

http://www.national.com/an/AN/AN-1490.pdf

I'm thinking of building an exact copy, but with four channels, and using a 30-0-30 transformer for lower voltage rails and power output.

Any thoughts/advice?

Thanks!

kesee · 23rd October 2007, 04:57 AM

Quote:

Originally posted by Spasticteapot
I'm looking to build my first proper solid-state (non-chipamp) amplifier, and the LM4702 looks like a good starting point.

http://www.national.com/an/AN/AN-1490.pdf

I'm thinking of building an exact copy, but with four channels, and using a 30-0-30 transformer for lower voltage rails and power output.

Any thoughts/advice?

Thanks!

Hi,
Goto Chip Amps >LME49810 - a new cousin for LM4702 thread and you will get lot of information

Regards KC

myhrrhleine · 23rd October 2007, 06:40 PM

Looks like a fun project!
Go for it

Leolabs · 24th October 2007, 02:39 AM

What kind of power transistors are u interested in??

Spasticteapot · 24th October 2007, 03:01 AM

Quote:

Originally posted by Leolabs
What kind of power transistors are u interested in??

MN2488/MP1620s. They're about $2.50 each, but I'm not quite sure how I'm going to match them.

Leolabs · 24th October 2007, 03:05 AM

Why not try something like the SAP15??

SpittinLLama · 24th October 2007, 10:57 PM

Might want to try the LME49810, mono so easier to layout a board. Seems to be easier to get fully stable too. The mono version of the LM4702 is not far away from release. Also might be easier to work with. Laying out a stereo board can be a little bit of a pain. IF you use Darlington devices, don't try to use more than one device per side in the output stage or you may never get it stable.

-SL

Spasticteapot · 24th October 2007, 11:01 PM

Quote:

Originally posted by SpittinLLama
Might want to try the LME49810, mono so easier to layout a board. Seems to be easier to get fully stable too. The mono version of the LM4702 is not far away from release. Also might be easier to work with. Laying out a stereo board can be a little bit of a pain. IF you use Darlington devices, don't try to use more than one device per side in the output stage or you may never get it stable.

-SL

I won't. I'm following the reference design to the letter, aside from decreasing the voltage rails (which I have been told won't cause any problems aside from a lower power output.)

23rd October 2007, 01:09 AM	#1
Spasticteapot diyAudio Member Join Date: Jan 2006 Location: Wisconsin....what did you expect?	LM4702 reference design note 1490 - ideal 1st amplifier? I'm looking to build my first proper solid-state (non-chipamp) amplifier, and the LM4702 looks like a good starting point. http://www.national.com/an/AN/AN-1490.pdf I'm thinking of building an exact copy, but with four channels, and using a 30-0-30 transformer for lower voltage rails and power output. Any thoughts/advice? Thanks!

23rd October 2007, 06:40 PM	#3
myhrrhleine diyAudio Member Join Date: Jan 2006 Location: Avalon Island	Looks like a fun project! Go for it __________________ Just because you can't hear it doesn't mean no one can.

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24th October 2007, 02:39 AM	#4
Leolabs diyAudio Member Join Date: Dec 2004 Location: Bukit Mertajam	What kind of power transistors are u interested in??

24th October 2007, 03:05 AM	#6
Leolabs diyAudio Member Join Date: Dec 2004 Location: Bukit Mertajam	Why not try something like the SAP15??

24th October 2007, 10:57 PM	#7
SpittinLLama diyAudio Member Join Date: Apr 2005 Location: In the Wild, Wild West	Might want to try the LME49810, mono so easier to layout a board. Seems to be easier to get fully stable too. The mono version of the LM4702 is not far away from release. Also might be easier to work with. Laying out a stereo board can be a little bit of a pain. IF you use Darlington devices, don't try to use more than one device per side in the output stage or you may never get it stable. -SL

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