Question: Hoffman 1 & 2 Channel AB763 bus voltage design

[RoadShow]

Hi,

So, while digging in researching a design question I have, I came up with a different question regarding the Hoffman 1 & 2 Channel AB763 bus voltage design. 

I've included 3 screen shots below:

One is a screen shot where the bus system on the 2 channel design has the trans followed by the B+ voltage followed by 2 10k power resistors to develop the C and D bus voltages.  The agrees with the layout for the other Fender AB763 designs by Fender, Sluckey's Deluxe Reverb and Mojotone's Deluxe Reverb.

One is a screen shot where the bus system on the 1 channel design has the trans followed by the B+ voltage followed by a 1k power resistors to develop the C bus voltage and a 4.7k power resistor that develops the D bus voltage.

I also have a table that shows voltages in the system from the relative schematics (??? where there was no documented voltage), and while there is variance, they are in the same ballpark/general range except the Hoffman 1 channel is much higher on the C and D bus voltages.

So, my question is, why the lower resistor values on the 1 channel design with higher voltages on the C & D buses?

I built the Hoffman 1 channel a year ago and have been using it trouble free so far, but now I'm curious.

Thanks.

[Willabe]

Doug might have wrote why in the amps write.

Read them.

[EL34]

Probably because Fender did that from whatever schematic I used at the time.
There are many AB763 amps and not all are the same
Look at these schematics , these are all AB763 amps
Deluxe reverb, Vibrolux reverb, Bandmaster reverb, Pro reverb, Super reverb, Twin reverb and Dual Showman Reverb

[RoadShow]

Doug might have wrote why in the amps write.

Read them.

I did, nothing there.

[RoadShow]

Probably because Fender did that from whatever schematic I used at the time.
There are many AB763 amps and not all are the same
Look at these schematics , these are all AB763 amps
Deluxe reverb, Vibrolux reverb, Bandmaster reverb, Pro reverb, Super reverb, Twin reverb and Dual Showman Reverb

Gotcha, that explains it then.  Just thought that both of those would be the same.

Fender even flipped the 1k & 4.7k on some...

Thanks

[stratomaster]

The hot swapped rectifier/standby could be improved. 

[pdf64]

I can't think of any AB763 models that hot switch their valve rectifier.

[EL34]

Gotcha, that explains it then.  Just thought that both of those would be the same.

It all depends on which AB763 you are building
Go to the library here and look at some of the models I mentioned above and see what each one uses in those positions.
A deluxe Reverb is different than a Twin Reverb and so on
A Deluxe Reverb has two 10k's
A Super Reverb has a 1k and a 4.7k


Here's our Schematics library for Fender amps
https://el34world.com/charts/Schematics/files/Fender/Fender_Schematics.htm