1100a2 bias question

[Perry Babin]

Did you check those resistors?

 

[mnhiphop101]

Back at this amp. Those resistors are fine. The amp seems to be responding to both bias pots now but one of the channels distorts around 1.5vac and the other distorts around 15vac.

 

[Perry Babin]

Post photos of the distorted waveforms.

Are the signals clean at the output of the last op-amp before the differential amplifier at the front end of the power amplifier section?

 

[mnhiphop101]

Any higher and It goes from that to an unrecognizable signal

 

[Perry Babin]

Are the signals clean at the output of the last op-amp before the differential amplifier at the front end of the power amplifier section?

Have you tried disabling the over-current protection to see if the signal was clean?

Does the amp do this with and without a load?

 

[mnhiphop101]

Which op amp?

How do I disable the over current protection?

I just noticed the rail voltage on one side is 56v/ -56v and 109v/-109v on the other side. What would cause that?

 

[Perry Babin]

The regulation doesn't deem to be working on the higher voltage supply.

To disable the over-current protection, lift Dx05 and Dx07 for each channel.

Check the signal marked L_core and R_core.

Does the distortion remain in all crossover modes?

 

[mnhiphop101]

Ok did all that.

The signal is distorted at L_core and R_core

 

[Perry Babin]

Is it distorted at LP., HP and full range?

 

[mnhiphop101]

Yes. While I was testing it I tried turning the bias pot and it started drawing 4.5a and now even with the bias turned all the way down its still drawing 4.5a

 

[Perry Babin]

Which group of FETs are heating up?