Fast GB: LM4702 high power amp test board ;) - Page 3

veteran · 2nd June 2006, 10:58 AM

AmpsLab are using TDA7250 in there amplifier. Maximum output current is quite similar to LM4702... 5mA

So we have good base to build powerful amplifier. They are using Sziklai style output section:
http://www.ampslab.com/tda7250cfp.htm

dfdye · 2nd June 2006, 11:14 AM

I agree that an emitter follower is indeed an appropriate solution, but I was hoping for something a little more elegant. I was leaning toward a complimentary feedback pair, but I was a little hesitant since I would like to add a few more pairs of transistors to the output stage to make it capable of driving harder loads, and I haven't quite gotten the "triple" CFP to take multiple output transistors. I know that this is not a new problem, nor have I really tried hard to get it to work, so I guess I just haven't gotten it to work YET!

Edit: Woopsie! Looks like I didn't take a close look at the schematic.

At first glance I thought it was a simple emitter follower.

dshortt9 · 2nd June 2006, 03:46 PM

This output has intrigued me - I may try it. The negative thermal coefficient of the lateral mosfets helps keep them thermally stable.

http://www.ne.jp/asahi/evo/amp/J49K134/report2.htm

dshortt9 · 2nd June 2006, 03:51 PM

OR perhaps the 2sk215/j78 driving transistors?

veteran · 2nd June 2006, 08:05 PM

Quote:

Originally posted by dshortt9
OR perhaps the 2sk215/j78 driving transistors?

Why not a single pair of MOSFETs for a good start?

veteran · 13th June 2006, 07:12 PM

My LM4702 PCB

steven344 · 14th June 2006, 11:52 AM

We ordered some from you,Do you have a board layout for the dracula amp?

steven344 · 14th June 2006, 11:58 AM

What do you think of using this type of output

veteran · 14th June 2006, 03:44 PM

Quote:

Originally posted by steven344
We ordered some from you,Do you have a board layout for the dracula amp?

I putted one Dracula amplifier board into your package

It's double sided and hard to manufacture home way.

Quote:

Originally posted by steven344
What do you think of using this type of output

Few posts forward:
Fast GB: LM4702 high power amp test board ;)

I think that Sziklai style output section can be a good choice - but first I wont to try MOSFETs here... They can be placed into my board without any modifications.

veteran · 16th June 2006, 09:17 PM

2nd June 2006, 10:58 AM	#21
veteran diyAudio Member Join Date: Feb 2004 Location: Poland	AmpsLab are using TDA7250 in there amplifier. Maximum output current is quite similar to LM4702... 5mA So we have good base to build powerful amplifier. They are using Sziklai style output section: http://www.ampslab.com/tda7250cfp.htm __________________ Simple audio solutions blog.unisonus.com

2nd June 2006, 03:46 PM	#23
dshortt9 diyAudio Member Join Date: Apr 2001 Location: Milwaukee, Wisconsin	Inverted "Daulington" This output has intrigued me - I may try it. The negative thermal coefficient of the lateral mosfets helps keep them thermally stable. http://www.ne.jp/asahi/evo/amp/J49K134/report2.htm

13th June 2006, 07:12 PM	#26
veteran diyAudio Member Join Date: Feb 2004 Location: Poland	My LM4702 PCB __________________ Simple audio solutions blog.unisonus.com

14th June 2006, 11:52 AM	#27
steven344 diyAudio Member Join Date: Jun 2005 Location: ohio	nice board We ordered some from you,Do you have a board layout for the dracula amp?

16th June 2006, 09:17 PM	#30
veteran diyAudio Member Join Date: Feb 2004 Location: Poland	__________________ Simple audio solutions blog.unisonus.com


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2nd June 2006, 11:14 AM	#22
dfdye diyAudio Member Join Date: Dec 2005 Location: USA	I agree that an emitter follower is indeed an appropriate solution, but I was hoping for something a little more elegant. I was leaning toward a complimentary feedback pair, but I was a little hesitant since I would like to add a few more pairs of transistors to the output stage to make it capable of driving harder loads, and I haven't quite gotten the "triple" CFP to take multiple output transistors. I know that this is not a new problem, nor have I really tried hard to get it to work, so I guess I just haven't gotten it to work YET! Edit: Woopsie! Looks like I didn't take a close look at the schematic. At first glance I thought it was a simple emitter follower.

2nd June 2006, 03:51 PM	#24
dshortt9 diyAudio Member Join Date: Apr 2001 Location: Milwaukee, Wisconsin	OR perhaps the 2sk215/j78 driving transistors?

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