I'm also interested in this op-amp. I'm thinking to use it for a subwoofer amplifier. According to the specification, this guy can draw whole lotta current, much more than LM3875 which is the famous op-amp for gainclone, can. It seems to be an interesting experiment to play with this little guy. Anybody tried this op-amp?
Hmmm... I haven't had any problem with sample program with National. Though I prefer TI simply because I'm in Austin, TX. The samples from TI are delivered usually in 1-2 days after the request which is COOOOL. :)
BTW, how does your OPA549 based amp sound compared with other audio gears you have? I'm much interested in building a subwoofer amp using this guy.


diyAudio Moderator Emeritus
2002-04-03 7:15 pm
Rotherham, England

I am currently playing with a couple of OPA549 in inverted mode, and I have to say, despite constructional difficulties caused by me buying surface mount rather than staggered pin versions, they sound pretty sweet.

They are not quite as open and extended on the very top as the LM3875 chips, but that could be just due to components or layout, more experimentation is needed.

I am also running into problems with thermal shutdown, but I think this is because I am running them on a 30-0-30 dc supply which is right on the limit for these chips.:devilr:
yeah, and whats very cool is, for germany they need only one or two days also!

Go with it for the subwoofer, will be ok.
I will try out OPA544 next. I don´t really need the power. Very cool are those high voltage high current OP amps in TO3 with 8 pins - only i don´t know how to mount them on a heatsink - if i drill than many holes there is not much heatsink left for thermal contact.

till said:

BB has the advantage they sent me samples. National seems not to like me. I ordered LM3875 etc. 3 month ago, national website says order in process since then - nothing arrived.

National seems to have cut sending samples outside of the USA. I don't get them in Brazil anymore and a friend told me in Argentina neither. Apparently Europe is too.

BB and ADI keep delivering.

Pity BB does not include their OPA512 in their sample program, which is TO3 and goes up to +/-50v, probably delivering close to 100W. Looks like an LM12 version.


Thanks for the replies. ;) I'll go with OPA549, which I already have, for the subwoofer project.
BTW, is there any pcb for 2-way active crossover available online? I posted a question about pcb, but I couldn't get any answer. I hope I can this time. ;) I know it's not very complicated, and point-to-point wiring is okay with it. But, I might need to build couple of it.

I checked linkwitzlab.com, and indeed, the documents are very helpful to understanding the theory of active crossovers. However, I couldn't find any PCB image for download. I can etch copper clad boards to make PCBs, but cannot design the PCBs. A link to a free download would be greatly appreciated. Thanks.


On Hiatus
2002-11-05 6:14 pm

ANTHONY2181 said:
Hi has any one experimented with the opa549 power op amp from Burr Brown? Anthony
An interesting IC - powerful! 10A peak. 8A continuosly.
Max Voltage = plus/minus 30Vdc

opa549.pdf (315 KB,Rev.C) (Updated: 08/08/2002)
OPA549 Spice Macromodel .zip

OPA549 can drive motors and also be used
as a powerful Ajustable PowerSupply. And power amp.

The picture below shows an appl. from datasheet:
Adjust. 1-25 Volt Output
Adjust. 0-10 Ampere CurrLimit
with 2 potentiometers.
Probably you can use another OPA549 as a Negative PSU
to get a dual supply. plus minus 8 Ampere!



  • opa549 psu.gif
    opa549 psu.gif
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On Hiatus
2002-11-05 6:14 pm
oh what a lot of difficult questions

till said:
does national send out samples to best part of sweden? and btw, were is best part of sweden? if its best part of sweden mus be better than here. How far away from the coast and temperature at the moment?
I live in the far north of Sweden, like 65degrees north.
I live some 120km from the Coast of Bothnic Sea.
Right now is -1.5 centigrade below water frezingpoint.

Sun is shining! Very rare this time of winter.
It is all white with snow,
and it is very bright,
when sun shines upon all this whiteness.

National doesn't send anything to me.
I have to order from www.elfa.se

/halo - will watch TV this Friday Night
till said:
If using speakers with high enough impedace, why OPA549, wouldn´t be 548 better?

If you're saying that OPA548 would be better than OPA549, is it because of THD? Would the defference btwn 0.01 and 0.0015% be audible? Just curious. :confused: And I see that those THD values were specified at different output powers (70 and 35 Watts).
Well... at the same PS voltage, OPA549 can give more current than OPA548 can. So, "power-wise" I would go with OPA549 especially for the subwoofer project that I'm planning. ;)