That's awesome! Yep I'm sure I put a 1M stopper at the concertina, I remember tying different values at some point, and there was no high end loss even at 1M.
Thanks for confirming the dc coupled PI. Yea the amp works so well with single coils because of the unbypassed, perhaps dark flavored, cathodes. Makes a tele really thick . I have a 3 way bright switch across the V pot that really lets you dial in the clarity, especially when the amp is half cranked. Now rob that extra triode and put it in front
After lots of fiddling, I am running V1 in parallel, output through 22nF to one Volume knob (wired Plexi style, not 5E3 style), and both V1 and V2 cathodes fully bypassed. The loss in volume/gain with the unbypassed caps wasn't cutting it for me. I ended up with a Tweed tone control (again) with 500pF and 10nF. Still getting by with 22k on the cathodyne grid. 12AY7 in V1 for the win. Great amp!
Qustion here, is the 18K plate stage considered a Cathode Follower(looking at original schematic)? Is that why it can be DC coupled, in the original schematic?
However there is signal coming off the plate too, no? through the small 820pf coupling cap? or is that a function of the varistors?
So based on that, I would think this schematic would work, but I don't think it will, certainly with no grid resistor before the 18K stage...
Magnatone213_zps770a9d3 edited.jpg
You do not have the required permissions to view the files attached to this post.
Your modified schematic (without varistors) may well work ok, but you would need to confirm the stages are being adequately biased, and the frequency response is acceptable.
The 18k allows the 820pF cap to pass inverse phase signal to that being passed through the varistor network in the cathode leg - which is the basis for the phase shift configuration originally attributed to Moses, and used by Magnetone to achieve its vibrato effect.
