Versatone (modified) Git Amp

[CJ]

finally got something i like after trying the AC 15, Elpico, Watkins Dominator and Divided by 13 guitar amp circuits,

this is a single channel version of the Versatone Pan-O-Flex amp, (Carol Kaye, Jack Cassidy)

original version here with 7591 fixed bias,
signal is split into two power amps, one for bass, one for treble, two different sized OPT's and a 8 inch and 12 inch speaker

 

[CJ]

they split up the treble and bass tone networks so a splice job was perfomed to get them back together,

6V6GT tubes were used with cathode bias.

there is only one lytic in the signal chain, the cathode bypass cap on the power tubes. so lots of feedback used, 1,2 and 3 cathodes, plus OPT f/b on 3rd cathode,

note voltage divider on phase splitter instead of cathode bias resistor,

Dang! Please insert 12AY7 for V1.

never mind, fixed it,

 

[CJ]

wave forms look very nice throughout, due to all the f/b.

it does clean good and it crunches like grandma's dentures,

tone knobs much nicer than Fender tone stack but that ain't sayin much,

preamp waves top, OPT sec outputs bottom,

that is all i have to offer at this particular juncture in time.

 

[Gus]

The first schematic is Interesting. I think it is something that might be fun to experiment with
a link
https://en.wikipedia.org/wiki/Versatone
FWIW A friend that was studying jazz guitar and had 7 string custom made archtop guitars asked me about making a cross over network to drive a bass amp and an open back guitar combo. It turned out that a cross over to drive the amps did not sound good an overlap circuit with different slopes turned out to sound much better. We did not get to the next stage of building a combo of a solid state bass amp for the bass speaker and a tube amp for the open back guitar speaker, getting the tone controls correct etc.

 

[musipol]

Hi CJ, Are all the scope traces the result of sine wave sig gen inputs?

 

[CJ]

those last 3 waveforms are taken off the output transformer speaker wind, sine, sawtooth and sq wave input to the amp,

 

[Flatpicker]

Not the Pan-O-Flex, but here is a good demonstration of a Versatone amp. Wish I knew what model this one was. He doesn't say and I didn't see it on any of the closeups of the panel, but it sounds great. I don't think I've ever heard a spring reverb sound so good as this one when he kicks it in on channel 1 at the 1:47 time mark.

 

[capacitor]

The Pan-o-Flex is the big build I'm planning out. Tube vibrato/reverb added, twin 7591 power amps via a couple of Hammond chassis, the works. Huge fan of Carol Kaye's work (and she really seems like an amazing person) It will sit on top of an open back 10"/closed back 12" Mesa cabinet if all goes as planned.

 

[CJ]

Here is a thread which has some tidbits of info

https://www.talkbass.com/threads/versatone-pan-o-flex-copies-are-they-there.926609/