VJr meets Supro styled circuits - Suprolicious, Super-Oh, S16 and Super-V

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rollie
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Joined: 11/05/2011

This was taken from a thread on my old site ... it's about converting the Epiphone Valve Junior ( EVJ or VJr) into an amp circuit based on Supro circuits of the past

Jan 23, 2010
Suprolicious schematic, there was a request on sewatt.com for a schematic so I did one ...
I put this schematic together from the Watts Tube Audio Suprolicious EL84 layout, I've yet to try it, but want to... http://www.rh-tech.org/public/EVJ_Supro_schematic_V1.jpg

Jan 31, 2010
Here is a couple pictures of the Super-Oh VJr circuit I built. It's the Suprolicious circuit with the Supro 6424 tone control. It's the best VJr so far! BTW, the Supro 6424 is the basis for Ken's (Watts Tube Audio) "suprolicious" circuit.
http://www.rh-tech.org/public/Super-OH2_preamp_layout.jpg
http://www.rh-tech.org/public/Super-Oh2_gut_shot_800x444.jpg
http://www.rh-tech.org/public/EVJ_Supro_Tone-Control_Schematic_V1c.jpg

Update: The suprolicious and Super-Oh were nice (in ways I loved them, in-your-face sort of punky tone) but they were really limited (they'd didn't handle humbuckers very well), they were really dark and could get way too ugly, so I took the S6616 Supro schematic and came up with the S16 Vjr.

After building the Watt's Tube Audio designed "Suprolicious" and my slight alteration the "Super-Oh" finally the new wore off and I realized there were issues so next came my VJr version of the S6616 which I call the "S16". (schematic is here: http://www.rh-tech.org/public/EVJ_Supro_S16_Schematic_V1c.png ) The S16 circuit is the front-end from the S6616 grafted onto the VJr. output section, with corrected bias and a smaller second dropping resistor (stock a 4.7k changed to 2.4k, I used two 4.7k resistors in parallel). The tone control used in the S16 is right from the S6616 circuit.

My conclusion on the 6424 tone control ("Page tone control"), I finally decided that the tone control in the Super-Oh has to go, it is way too interactive with the volume control, it's more of a high frequency gain control than a tone control. Which should have been obvious from looking at the circuit, it doesn't have to go away, it just needs to go into a different location. The tone control in the S16 (a guitar-like treble cut control) is so cool because it only affects the amp's treble response, not the gain/volume. Update, talking with someone who built a S6616 he tried the S6616 tone control with the cap on the plate and with the pot on the plate, he said there was more effect with the pot on the plate and cap to ground ???

The way the Super-Oh worked, you can do sort of a mid-volume back and forth thing, turn up the volume and turn down the tone for a darker sound, turn down the volume and turn up the tone for a brighter sound. But to really get the full volume treatment out of this amp both have to be up and then the guitar controls everything. OK, for guitar, but you have to learn how to use it. BTW, a friend has been using a "Super-Oh" styled amp for his (dirty) harp amp and it's the best sounding harp amp he's had to date, but it still needs the tone control moved to the next stage.

May 16, 2011
OK, one small modification and this amp is finished!!! The Suprolicious was a great rock-n-roll amp but ... it could be way too muddy and get into ugly break up ... I changed out the first cathode resistor from the stock 1.5k to a 3.3k and now it's a new amp, named the 'Super-V'. Upon studying the S6424 circuit I finally noticed that the preamp stage with the 1.5k cathode shared that cathode with the tremolo circuit triode ... so in effect the first stage has a 270k plate with a 3k cathode resistor!
Here's the Super-V schematic documenting the amp as it was when sold: http://www.rh-tech.org/public/EVJ_Super-V.png here's another schematic with the power supply rail redrawn: http://www.rh-tech.org/public/EVJ_Super-V_Schem-new-view.png In the Super-V I used the 15watt ClassicTone Champ OT, wow, a perfect match with the SE EL84!!!

My next Supro based project took most of the Supro character away ... dubbed the Science Project, because of the added stuff, a lossy tone control, a MOSFET source follower, a master volume and VVR. It's not an interesting amp anymore, it doesn't have the in-your-face attitude, but it's the nicest cutting Strat tone amp we have at church. Bright but not too bright, easy to dial in to be clean with just a touch of hair, touch sensitive so it just barely breaks up or breaks up pretty easy. A really nice amp in its place, it's not your typical pretty much only overdriven tone VJr, in fact it's an amp that's best running in the clean zone, so I suppose it needs reverb then right. Here's the power supply, PA only VVV: http://www.rh-tech.org/public/Science_Project_Power_Supply.jpg

Suprolicious_V2-pcb_V1 section.jpg
rock_mumbles
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Joined: 11/05/2011
Supro-like Vjr pcb conversions