made something up but not sure is it at it's best yet?

just made this thing, tested sounds ok , but not sure is it correct or anything can be optimized? suggestions? ;D


Thanks!

68uF in the NFB loop! Is that right?
As a rule of thumb, the LF corner frequency of the NFB loop should be similar to the corner frequency of the output path.
At the moment, the output path corner freq is 14Hz (2.2uF/5k) and the NFB loop is between 0.02-0.1Hz (68uF/20k-120k). I would use a somewhat higher value for the output cap (10uF) and 2.2uF for the NFB loop.
The resonance between xfmr inductance and output cap can create a serrious hump in the low frequencies. The low-ish value makes it close to the audible LF, with the risk of introducing distortion. Increasing the value of the cap puts the resonance away.

Has to be a typo.  Look at the pic, the only cap I see that could be big enough for 68uf is the green axial lytic and that looks like it's in series with one of the transformers.

It's probably 0.68uF, and if this is so, it's in the "safe" area...

Does it give you enough gain? Are the distortion characteristics pleasant throughout the gain range?

Sorry it is a typo fixed the schematic back to 0.68...........
I think it give a little less gain then usual, but is loud enough with a tube condensor mic ,It will hit the input of my console go clip (red) when the gain control is half way up, also the (distortion) tone is pretty warm to my ear  ........ I build this to taste the tone of being parallel.

You could (if you really wanted), split the 12au7, leave the first stage as is, then feed the remaining stage with an attenuator, configured as a cathode-follower. That would give you a nice drive/output control if you wanted.