sound Quality of OPA549 when compared with LM3886

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#4
searched and found few but there is pretty less information. I see more people using LM3886 instead of OPA549. So just thought to start a thread on OPA549.

I found even peter daniel says about it as initially it was not good but after burning for a day it sounded more resolution and good vocals.

Anyway I have the OPA549 ill try myself using that but if i could get any design ideas that makes it better would be a better... like using washers improved some part etc..
 
#5
the OPA549 datasheet has no useful audio distortion curves

the related OPA541 does - and shows the worst possible distortion profile for audio - the distortion rises at low levels indicating output crossover distortion


most specialized audio chip amps show low distortion at various power levels with much better profile than OPA541

LM3886, other audio chip amps have more loop gain due to decompensation for Av_min >10x compared to these internal unity gain compensated industrial power op amps

likely also have output protection circuitry better tuned to audio demands


there really is no reason to believe that either of the OPA541, 549 have anything special to offer in audio
except that they are different, more expensive - both of which attract some novelty interest

Ray Samuels Aduio gets away with selling a US$3k headphone amp with bridged OPA541
 
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#6
I used OPA549 as an audio amp too, in Nelson's Super Symmetry topology. That's the only AB class amp that I kept and still listen to occasionally - it regularly surpasses the expectations.

Here is the sch. (small error - 220p caps should be 5-10 times smaller)
An externally hosted image should be here but it was not working when we last tested it.
 
#14
rhythmsandy said:
...but its still unbelievable that OPA549 sounds like Audionote....
Click to expand...

No, it sounds better (not a big fan of Audionote). Not much of a believer too. I build and test.
Anyway, the SuSy circuit shown in post #6 is the best amp that can be built with OPA549. If you want to go with a single chip per channel, the best sounding solution is the amp based on Walt Jung's paper on composite amplifiers (see sch.) where the sound character of an amp is predominantly determined by input OpAmp.
OPA549 used alone in standard GC configuration sounds inferior to LM3886.
 

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#15
I liked the OPA541 because of the jfet inputs. I did not like the crossover distortion, which is especially visible during square wave testing. I had a brief flirtation with chip amps, but get more pleasing audible results with tube amps and solid state Class A.
 
#16
hi andrew please read this link.. http://www.diyaudio.com/forums/chip-amps/11755-opa541-opa549.html
http://www.diyaudio.com/forums/chip-amps/45655-lm3875-vs-lm3886-vs-lm4780.html

Hi Juma thanks alot Iam using OPA1612 as pre for the opa549. Soon or later I will be using OPA627 for the amps.

I do accept that audio note is a pure classic way of building amps but I generally dont believe 100% on figures since I believe that clarity and musicality are two different worlds...

In my experience i found many amps which are very very clear but fail to drag into musicality..

so I personally judge the amps based on listening but generally take opinions of people since if some experienced audiophile says this is good and this is way too good and beyond expectations then I try that instead of wasting money on every single schematic..
 
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#20
finally the amp is working and im in love with the mids of this chip still its in basic opamp schematic..

I am thinking of using nelson supersymmetry on this... but im pretty ok but if the amp is biased in Class A then i think its worth trying supersymmetry.
 
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