No need to apologize, the simulations you did were fine, since you showed the relative performance with and without the feedback. I was also wrong in saying changing the OPT model would not impact the THD results, of course it will, since UL tap's position changes the amount of LFB for the output tube.
Sorry I have been away, yes I only using 1/2 of each 12ax7 of course you can just use 1@12ax7 but had 2 50 year old 12ax7 sitting in the draw so that is why I used 2 tubes instead of 1
Thanks changed all you suggest in your schematic and seems to be good altho I have lost a little bit of gain and the punch has taken a little bit of a dive but may try lowing the 2.2meg to see. I have ordered 2 matching pairs of JJ EL34L to see if that sounds better then the EL34B?
just ordered 2 matching pairs of JJ E34L so I will drop them in to see what a better sound I get.
Even better would be/try to find some old/NOS 6550s man if lucky could score some old Tung-sol 6550s for pretty good deal....they sound fing amazing in anything imo....The TS to me have/almost like they have that EL34 character but bigger smoother into KT66/KT88 like etc...I don't think they sound as much like a Beam type imo, the GE/Sylvania 6550s sound more/closer to that beam type/bigger 6l6 etc.
Either way the JJ E34Ls will be a good improvement over those EL34Bs no doubt about that....but if dead set on EL34s actual NOS Tesla's/RFT's/Winged Cs etc again noticeable improvement, or if you can afford XF2s rofl, XF3s/4s not too bad but definitely not XF2s, Winged Cs were always iffy to me though they can almost get a bit too "Sharp/Edgy", Some may like that though. I don't know I like the the Mid emphasis with EL34s a lot/that harmonic swirl that pours out etc....but they do/can get real compressed real quick....vs like TS 6550s more open/wide/liquid like Extension/more "vowel" like etc.
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Thanks to LAZAROIU for this better drawing I did of my schematic I have changed a few resistors by adding and removing Cap this is the final changes as the amp has great low end as well as high end I'm very pleased with the end result. thanks to all who input into getting this right for me. I know it is a little different too the original that Lazaroiu posted but for me it didn't quite sound as good as I have it now.
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Glad I could help, it seems that the changes were not major but rather to adapt to your source signal.
Congratulations and anytime we can improve any project!
I re-did this amp with most of what was discussed with rubber grommets and I say if others build this let me know as I have found it to be the best so far I have built the low end is excellent without having a tone control added. cheers
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