Compression?

[Structo]

I was playing my D'Lite 44 ( 6L6's) the other day and I noticed something I hadn't before.
I had it on clean and had the volume and master cranked.
When I dug into a string, the attack was almost muted and the note swelled dramatically..
Sounded like crap basically.
I have 110K/ 120K plate resistors on the PI.
I am running it into a 2x12 with Tonkerlites.

Is this normal or is something going on.

I have 220K/150K Rp on both V1 and V2.
Rk on both is 3K3 and 2K2
With 4.7 uf, 10 uf, 4.7 uf, 4.7 uf on V1 and V2 respectively.

Could this be simply speaker compression or the amp?
I don't notice the compression so much when in OD.


Would changing the plate resistors on the PI to 100K/ 100K have any effect on this?
Or could it be the filter caps simply being overwhelmed?

Thanks for any thoughts or comments on this.
Of course I don't operate this amp at those setting normally.
Kind of like driving a car, I wanted to see what it would do wide open.

Oh and the bias is set at about 32ma.

[Wayne]

Blocking Distortion?

[ic-racer]

Blocking Distortion?

Thats what I was thinking also. I remember a web site (but can't remember where) that showed an oscilloscope waveform almost cutting off to zero and coming back.

[Wayne]

http://www.duncanamps.com/technical/overload.html

[Structo]

Hmmm, so it sounds like I need to measure the plate voltage again of V1 and V2?
I can't remember where they're at.
I did change one of the dropping resistors but can't remember what the voltage is.
Probably change the FET resistor?

[Fischerman]

Structo,
If it doesn't happen when the Master Volume is low and does when it is cranked then it sounds like it could be the power tubes. I have a power scaled amp and if I turn the power scale control down but leave the MV up then I can get my amp to do that (i.e. notes/transients pull so much grid current that the voltage drop across the 220k bias splitters biases the tubes into cutoff). But if so then I'm not sure why your amp would do it. Maybe something in the bias circuit is bad/wrong?

Try to isolate exactly what stage is doing it then go from there.