1700 ct OT and 6l6

[Merlinb]

but now it works a lot better , the vibrating is gone and amp responds faster and smoother, still when the amp is dimed the sinus wave get fully squared, not just on the wave tops but it really turns into a square box LOL

If you input a clean sine wave into a PP amp (i.e., no preamp/PI distortion) then it will always clip on both sides, symmetrically, assuming the power valves and PI are fairly well balanced.

[Chiamp]

Thanks for the replys !

I am curious if I changing the cathode (bias test resistors) to say 10R

would this bump the Class a bit closer to ideal to be a better match for this set up 1700 and 6l6 ??

to get more even harmonics going
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for fun I have now also altered the PI values to 110k on both sides
and 820r cath to 27K tail 5k NFB and 400R to ground to see what it did
sounds much better but still some harshness when played really loud would , specially when hitting the strings hard there is a little harshness on the top,
bumped the v1 a plate voltage to 210v by raising the first cathode a bit sounded much sweeter and raised the headroom,

[MWJB]

A Twin Reverb is usually around 1900ohms per side, so 1700 isn't that far off, there are plenty of 4x6L6 amps that sound fine with 1700ohm OT primaries. The 10R cathode resistors will mostly just give you a different method for masuring plate current (dc/10, rather than just reading current for what it is). Rebiasing would push you nearer to a different class of operation, but I wouldn't really go above 17.5W (38mA per tube @460v) unless you know that you have very robust 6L6s...so your amp is really AB and that is pretty much that.

BF/SF Fenders typically used a NFB ratio of 9:1 for 2 & 4 ohm speaker loads & 18:1 for 8 ohm loads, you currently have 13.5:1. It's the ratio that's important, more than the specific resistor values.