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-   -   OPA541 and OPA549 (http://www.diyaudio.com/forums/chip-amps/11755-opa541-opa549.html)

Mad_K 27th February 2003 10:18 PM

OPA541 and OPA549
 
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I have just done a comparison test of these chips for my own girly-man amp, and I thought I'd share.

I used P.Daniels minimized circuit. 600VA 18-0-18 trafo = +/-26VDC rails. Standard components.

Remember these are only first impressions.
I hadn't really expected much difference between the chips, and I certainly didn't expect the audio quality they produced!

OPA549 (max +/- 30V, 8A/10A continous/peak)= BIG sounding chip! Heavy bottom, a little laid back. Reminded me of the Audio Note Kit Two I used to have. Very nice.
http://focus.ti.com/docs/prod/produc...tNumber=OPA549

OPA541 (max +/-40V, 5A/10A cont./peak, FET input)= More neutral. More open and detailed, but not fatigueing. My preference so far. Sounds more like my Aleph 30.
http://focus.ti.com/docs/prod/produc...tNumber=OPA541

Asen 27th February 2003 11:24 PM

Have you made a comparison with LM3875?

Thanks

Mad_K 27th February 2003 11:41 PM

No, because I can't get it. They only have the LM3886 where I buy my parts, and National wouldn't sample me any. Haven't tried the 3886 either. I have tried the TDA2050 though. I found it to be much more colored, and a lot less stable.

I have to moderate the differences mentioned above, after switching back and forth a couple of times (and a few hours of burn-in). They seem a lot more alike now. The 549 clearly has more power, and less percieved distortion. I also added a 0,1uF between the rails and between testing them, and it seems this made up most of the sonic difference mentioned above. (First 549 without, then 541 with and now 549 with the 0,1uF). I think they would be more alike with 35V rails on the 541.

For my first clone, I'm going with the 549...

argo 28th February 2003 05:22 AM

Mad_K

Did you bought the opa chips in Norway or you got samples from Ti?

argo

Mad_K 28th February 2003 10:56 AM

They where samples;)

I also tried to disconnect the 0,1uF now = did not sound much different, a little darker perhaps..

lawbadman 10th March 2003 06:15 PM

Hey Mad_k,
Did you use a regulated power suppy for your OPA549 and OPA541 amplifier?
If you do use a reg PSU, do you have a circiut diagram so thas I can build one?

Thanks

Mad_K 11th March 2003 08:33 AM

No reg. supply, sorry...:(

pundip 11th March 2003 02:41 PM

Mad_K,
I am thinking about building an amp based on the opa541. What current limiting resistors did you use? Also does anyone know if the opa541's have thermal protection?

Mad_K 11th March 2003 03:05 PM

Quote:

Originally posted by pundip
Mad_K,
I am thinking about building an amp based on the opa541. What current limiting resistors did you use? Also does anyone know if the opa541's have thermal protection?

Didn't use any:cool: Since this was only a test-setup...


Read the datasheet, it's all there;)

pundip 11th March 2003 08:08 PM

Hi,
Are you going to be using current limit with your gc? I am not sure I should just short the limit pin to output out limit resitor


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