Thor Bias

[MadMac]

Hi.  I don't think I've quite got my Thor build right yet.

I can dial in all of the bias voltages as per schematic i.e. Q1=6.5 and Q2=4.5 and all of my other voltages seem to be very similar to those found in other threads.

It sounds good when playing chords but when playing individual notes it sounds as though the fets are not biased correctly and seems to have an odd sound mixed with the distortion that sounds almost like a tremolo set to a fast speed.

Is this noticeable on other builds when playing lead or does it usually sound smoother?

It seems to sound correct at the gate of Q4 with the audio probe but then on the drain I get the odd tremolo sound either that or the problem is just amplified at this point in the circuit.