Op-amps in LXH2

[Rafa]

The thing Im having trouble with are:
-intolerable intermodulation distortion in the LXH2(marshall sim)
- I can't get the opamps properly biased it seems, distortion dissapears when the signal is week, I have already cheked everything.
Cheers
Rafa

PD:Im sorry Im posting this again but Lounge was not the right place, so the other post could be deleted.

[AJS]

Hello,

Did you solve this already?

I might have a similar problem, especially at high precense settings.

I did a listen with my probe and found that op amp 6 might have a problem. I'm not sure if the PCB design is wrong, or if I made a mistake somewhere, anyway the circuit gates weak signal and a localized it to OP nr 6.

Will investigate more soon...

[Rafa]

No I havent yet, Ill try soon.
The "presence" is not actually presence its another gain control , In mine its seems a bit harsher
Cherrs
Rafa

[km-r]

ive noticed the "gain" in the presence knob too...

i used DUAL OP AMPS! TL072

i dont have the cab sim.
i cant get a clean signal though...

i will dig my lxh2 tonight...

[AJS]

Yes, presence is probably not exacly th right name... But km-r: Do you experience gating effects?
I also only built the ampsim based on the pcb from prophecysound i think it was called. I believe you used the same Rafa? Does your gating get worse at high (max) "presence"? Does you gain pot work perfectly or does it induce gating at some setting as well?

[km-r]

AJS,

my current ampsim doesnt gate in any gain setting... i remembered having gating when i paralleled a 100n cap on the 1k resistor before the diode clippers
IIRC that mod is stated in krister's website...

i dont have the cap now, and i used 1n4001 as clippers.