Opamp Burr brown not working, where Tl072 and RC4558 are working

[nonoxxx]

Hello,
I am actually prototyping a pedal for a friend, it's basically a RAT whith a second gain stage on a proto board, the goal is to reproduce the sound of the death metal band Obituary, the goal is reached and it sound extremely massive, but there is something weird :

The circuit works really well with a TL072 and a RC4558 but if I swap to a burr brown 2134PA there is near no sound (extremely low in level and gain) ,i have tested two 2134 and I am sure that one is working, it was on a modified tube screamer tha i am using often )

the circtuit is quite simple it consist of a first stage RAT like  with clipping diodes, a low pass to remove some highs , a voltage divider to level attenuation and the second stage equivalent to the first but with no diodes, + a voltage divider to limit the volume.

All Input are biased with a 10k resitor to 4.5 , there is 9 v on pin 8,the ground is OK  ... all is fine and working fine except when I put the Burr brown's.

Does anyone have any thought ? (I can live  without the Burr brown lol but for what I know these kind of opamps are a direct swap to rc4558)

Thanks

[bluebunny]

Sorry, can't give any insight into your technical problem, but when I see the words "RAT", "second gain stage", "death metal" and "Obituary", then it makes me think that a 2134 might be wasted on this pedal!   

[nonoxxx]

lol I had notice that the burr brown is a cool opamp for high gain things due to the low noise, and the bass are really tight 

[bluebunny]

Actually, I think I may have spotted a small difference in the respective datasheets.  It looks like the 4558 inputs can swing to within a volt of the supply rails, but the 2134 can only manage to within 2.5V.  So if your signal is hot enough going into either of the opamp halves, then this might upset the 2134.  I guess you could take some measurements to check this out.  TL072 can take inputs up to the V+ rail (although not all the way south).

(Apologies if my datasheet-fu is out of whack...)

Edit: to clarify this applies to inputs.

[nonoxxx]

Thanks for your reply , English is not my native language and for this kind of technicals explanation it's hard for me to understand.

So if I understand correctly,  it is the biasing of the inputs that can be to hot for the Burr Brown?

[bluebunny]

I don't think biasing is relevant, but simply that the signal voltage may be too high.  Measure the voltages at the input pins with a working (4558) chip to see what they are.

[nonoxxx]

VOltage at pin 3 and 5 ? I will check that

[nonoxxx]

I just checked

there is 3.30 V at pin 3
and for a reason that I don't know there is 0.8 V at pin 5, I will try  to figure why