Any opinions on unity gain power amp?

wdyn1 · 02:09 AM

Anybody have any input on opamps similar to LM3886 (ie. power handling, PSRR, THD+n, cost) that are unity gain stable? I was almost liking the OPA549 until I saw that they were US$18 each. And then the OPA541 at US$122!!!

danielwritesbac · 14th December 2008, 07:24 AM

I think this is a nearly "flat amp" with LM3886: http://www.diyaudio.com/forums/showt...86#post1670086

When I made the request on that post, I was thinking that LM3886 could be good if something else were used for the majority of the gain.

Other options include power amp transistors, which is simplified by using an op amp as a substitute for most of the predrive, and there's also the more complex option is using an approach similar to Class G, if one needs quite a bit more power output or slightly less energy consumption.

wdyn1 · 14th December 2008, 03:43 PM

Yeah, I saw that post earlier. Thanks, but not exactly what I had in mind.

The general idea that I had was absolute simplicity. It just seems like everytime I read about a gainclone, the talk is low parts count and short feedback. What lower parts count and shorter feedback than non-inverting unity gain can there be? Let the preamp handle the voltage gain and volume control at the same time. Of course it'll take building a slightly specialized preamp, but that's no problem. Anyway just a thought. I think I found what I'm looking for: OPA548. It'll take a little more care with the power supply, but I'll give it a shot (eventually

).

I built a few opamp controlled, tranistor power stage amps in college and they were ok. I even made a floating supply +/-100 volt which was cool, but wasn't worth listening to. I'm just really thinking simplicity now.

Thanks,
Nathan

13th December 2008, 04:42 PM	#1
wdyn1 diyAudio Member Join Date: Nov 2005	Any opinions on unity gain power amp? Anybody have any input on opamps similar to LM3886 (ie. power handling, PSRR, THD+n, cost) that are unity gain stable? I was almost liking the OPA549 until I saw that they were US$18 each. And then the OPA541 at US$122!!! Last edited by wdyn1; 25th June 2012 at 02:09 AM.

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14th December 2008, 07:24 AM	#2
danielwritesbac diyAudio Member Join Date: Nov 2007	I think this is a nearly "flat amp" with LM3886: http://www.diyaudio.com/forums/showt...86#post1670086 When I made the request on that post, I was thinking that LM3886 could be good if something else were used for the majority of the gain. Other options include power amp transistors, which is simplified by using an op amp as a substitute for most of the predrive, and there's also the more complex option is using an approach similar to Class G, if one needs quite a bit more power output or slightly less energy consumption.

14th December 2008, 03:43 PM	#3
wdyn1 diyAudio Member Join Date: Nov 2005	Yeah, I saw that post earlier. Thanks, but not exactly what I had in mind. The general idea that I had was absolute simplicity. It just seems like everytime I read about a gainclone, the talk is low parts count and short feedback. What lower parts count and shorter feedback than non-inverting unity gain can there be? Let the preamp handle the voltage gain and volume control at the same time. Of course it'll take building a slightly specialized preamp, but that's no problem. Anyway just a thought. I think I found what I'm looking for: OPA548. It'll take a little more care with the power supply, but I'll give it a shot (eventually ). I built a few opamp controlled, tranistor power stage amps in college and they were ok. I even made a floating supply +/-100 volt which was cool, but wasn't worth listening to. I'm just really thinking simplicity now. Thanks, Nathan