What is this chip?

[trodas]

This is a chip on my X-Fi that is probably a input opamp, because it definitively pass the audio signal from the mic... but searching for M33078 returned only results like:
http://www.alldatasheet.com/datashee.../ADM3307E.html
ADM3307E - 15 kV ESD Protected, 2.7 V to 3.6 V Serial Port Transceivers with Green Idle

...witch is certainly not the chip we see above. Any help/ideas what it is and mainly a Hi-Fi replacement suggestion?

[lineup]

It is probably
MC33078 = LOW NOISE DUAL OPERATIONAL AMPLIFIERS

See for example Douglas Self test:
http://www.dself.dsl.pipex.com/ampins/webbop/33078.htm

It is made by several companies:
http://www.onsemi.com/PowerSolutions....do?id=MC33078
http://focus.ti.com/docs/prod/folder...t/mc33078.html
http://www.st.com/stonline/products/...77/mc33078.htm

[trodas]

Looks like you are right and it is just a normal double opamp...

This should be it:
http://focus.ti.com/docs/prod/folder...t/mc33078.html

...so a great audio replacement would be a AD8599:
http://www.analog.com/en/amplifiers-...s/product.html

Right?

[lineup]

Yes.
AD8599: Dual, Ultralow Distortion, Ultralow Noise Op Amp
Comes in 8-pin SO package.
And there are several other good dual opamps that could replace.
But that one looks good as far as I can see.

[trodas]

Yep, but I want the absolutely best possible opamp there, so, AD8599 is the name of the game.

The opamp is used in the RMAA tests, so, it is sort of nonsense to have anything worser that the best you can get, so you by loopback then can measure the impact of even slight changes, like heatsinks on the opamps/DAC...

You cannot measure the output changes properly, unless you got same quality (preferably much higher quality, but what is better in SOIC NARROW that AD8599?) opamp in the input stage.

[trodas]

Damn!
The suggested replacement for the MC33078 opamp, the AD8599 one seems to be good choice, but...!

This time the opamp is powered from +5V only (the leg 8), leg 4 is NOT connected to the -5V as all other opamps there on the X-Fi Fatal1ty - but to ground. Hence this one is getting only 5V. AD8599 require by specs at least 9V. I'm affraid that it will not work good there... time to find another opamp, +5V capable one

[lineup]

Originally posted by trodas

AD8599 require by specs at least 9V.
I'm affraid that it will not work good there...
time to find another opamp, +5V capable one

you will find one. for <= 5 Volt
no problem.
When you go to www.analog.com or any other manufacturer
you should click Selection Guide ... or something like this
This way you can select low voltage op-amps.

Texas even has Selection guides. As other manufacturers have, too.
Which will guide you through your requirements.
Start for example here:
http://focus.ti.com/analog/docs/arti...selectionguide


From www.analog.com
I may suggest something like this one: AD823
I do not know if it comes in same package, same pin layout, as your original dual op-amp
But you may have a look yourself to see if it fits:
AD823 - Dual precision Op-Amp

[trodas]

Thanks for the suggestion! I think I go with the AD823 ... LM4562 can also work on the just +5V, but... I did not think it is as quality, as the AD823 one - but - I better ask - do I'm right about the choice?