Focusrite ISA 110 HPF / LPF Distortion

[outoftune]

hi, a client has brought me a Focusrite ISA 110 rackmount ( http://www.soundonsound.com/sos/jun00/articles/focusrite.htm )

The preamp functions properly, but as soon as I engage the HPF or LPF I'm getting a drop in level and a lot of distortion.

I have the schematics and I'm guessing it's one of the 5534 opamps, just wondering if anyone else has experienced this issue before?

 

[gyraf]

My first guess would be a dried out electrolytic - or a 5534 like you mention.

Make sure to put in a IC socket when replacing opamp - the pcb doesn't like multiple soldering cycles.

Jakob E.

 

[outoftune]

yes a dried out electrolytic was one of my other suspicions. thank you for the suggestion jakob, much appreciated!!

 

[outoftune]

hi, jakob was right, it turned out to be a cap if anyone else is experiencing this issue!

 

[synthiaks]

Wow..when caps from what you consider being yesterday dry out (2000), you know you are getting old. Or focusrite put some low quality caps in that 3000£ strip.

 

[gyraf]

I don't think it's about low quality parts, but about the rather high temperature inside those units.

You can easily run audio much cooler, but it won't sound as good...

Jakob E.

 

[synthiaks]

Oh... If i understand you correctly:

Running Transistors/ICs responsible for the amplification at the maximum to get maximal headroom will run the circuit hotter, This will heat the CAPs and dry them faster?

I have a couple of active faders from East Germany that have caps with burn marks from the transistors they decouple. I guess you can't put the caps to far away because that would introduce noise, and they need to be big enough to let the low end through. I might have it all wrong though?

Sebastian