SF 1979 deluxe reverb push pull circuit

[LoveChet]

See wiring diagram. Can anyone explain in general how the push pull volume is designed to work. If I have drawn the circuit correctly when you pull the volume knob out it shorts the 23 meg resistor and in doing so allows more signal to go the grid pin 7 of the V5 vibrato tube. It seems odd that V5 is involved

[Helmholtz]

Schematic not showing.

[LoveChet]

[Helmholtz]

That wiring can't work without a DC blocking coupling cap.
Don't you have a full schematic?

[LoveChet]

This amp has been modified and one of the mods changed the tremolo to be tube bias controlled rather than the stock circuit so possibly the V5 became available for the type of push pull mod. The mod also added a master volume knob and I havnt looked into the wiring for that

[Tom Phillips]

In addition to Helmholtz' comment, it doesn't make any sense that the circuit you show would feed the "Vibrato tube" as you describe it. At least not in the stock circuit. Has V5 been repurposed in your modified amp?

[Helmholtz]

Sorry, can't help without knowing how exactly V5 is wired to the amp.

[Helmholtz]

Nevertheless the original schematic might give some clue.

[LoveChet]

It has a dc blocking cap. I forgot it when drawing schematic. But in general I was looking for your general experiences on how fender deluxe designed their push pull. I will continue and make a schematic for entire amp showing the V5 tremolo as its used plus the master volume mod

[LoveChet]

My questions revolve around determining if it's a stock fender design or a much different approach by someone else. More confusing is that the amp sounded awesone and I NEVER pulled out the push push so I dont know what it did !

[Helmholtz]

Did you search for the schematic?

[LoveChet]

The schematic I am using as a base to work off of is the silver facev Fender Deluxe Reverb. The amp as it stands is 95 % the same. Its was mfg in 1979. Then I am tracing the tubes, wires, and components to locate modifications and drawing a complete schematic for next owner and for me to get it working. I am not sure if the volume push pull is stock or a mod. It's probably a mod. I do know that is has mods to add a preamp fat switch, grid bias tremolo control instead if standard tremolo, a master volume, plus an fx loop via an added tube.

[Helmholtz]

Please post the schematic here.
My time is just as valuable as yours.

[g1]

I'm attaching schematic for SF Deluxe with push-pull boost circuit. Perhaps that is what you have, perhaps the boost circuit is modified. In any case it may help you.
I'm wondering if the 23Meg is not 3Meg3, I don't know if I've ever seen a 23Meg.

[glebert]

The schematic I am using as a base to work off of is the silver facev Fender Deluxe Reverb. The amp as it stands is 95 % the same. Its was mfg in 1979. Then I am tracing the tubes, wires, and components to locate modifications and drawing a complete schematic for next owner and for me to get it working. I am not sure if the volume push pull is stock or a mod. It's probably a mod. I do know that is has mods to add a preamp fat switch, grid bias tremolo control instead if standard tremolo, a master volume, plus an fx loop via an added tube.

That does not sound like 95% the same as the stock schematic.

I have a SF Bandmaster Reverb from same era, with stock MV and boost. It uses the same mechanism for boost as the Deluxe Schematic g1 gave above, but the MV pot on mine is a very weird double wiper thing (they used the same thing on Twins etc). If it has one of those you can look at the schematic for those to see if yours was modded to something similar.

The boost effect on my amp is barely noticeable, if anything adds harsh treble. I've never heard anyone that liked the stock boost on this era amp.

Also, the same amp you were trying to figure out six years ago? https://www.thegearpage.net/board/in...-pull.2033370/

Since the tremolo was modified to be bias wiggle, perhaps Rivera used the V5b triode as a gain stage since it didn't have to drive the trem roach?

More context on apparently the same amp: https://music-electronics-forum.com/...couple-of-mods