5e3 Power Transformer Question

[AppleScrappler]

The PT in my 5e3 is a Heyboer and offers two center taps for the high voltage. Just wondering what the difference is. the specs are as follows:

370red - 0red/yellow - 50red/blue - 370red

am I correct in assuming that using the red/blue tap to ground would reduce the voltage from 370v to around 320v - 330v? whereas using the regular red/yellow to ground would leave it at about 370v? I just want to be clear on how all of that works before I change anything. it's surprisingly hard to find the info on this! maybe I'm not using the right search words...

[txstrat]

Red/yellow is the center tap. Red is HV. Red/blue is the bias supply tap (50vac).

[AppleScrappler]

Great! thanks! i knew i had some suspect information there from an old forum... just glad I didn't kill myself experimenting :P

soooo to utilize that bias supply tap I'd just wire it to a diode (what type?) in series with a resistor (what value/wattage?) and the to a pot an then.... i don't know where... and I'd have a pot to adjust the bias on the power tubes? a quick instructional on how that works would be great from anyone willing to take their time on an amateur like me with silly questions. I searched the forums and only came up a little more confused. thanks!

[txstrat]

You can use almost every other schematic from Schematic Heaven. Where All Good Amp & Effect Designs Await Resurrection... to copy the bias part of the circuit.
I like sort of this (look on page 2): http://www.webphix.com/schematic%20h...d_50w_100w.pdf
The bias pot is set up as a variable resistor to keep the bias voltage up in case the pot fails. With a 50v winding I usually use a 470 ohms 1w resistor in series with a 1N4007 diode.
BTW for a 5E3 you wouldn't need a bias supply cause it's cathode biased.

[AppleScrappler]

Thanks Strat! yeah I realize the 5E3 is cathode biased but was just curious because I've never built an amp using a bias supply tap before and am always curios to learn as much as possible about EVERYTHING so I might better understand amps and design one someday that's tailored to my whims.

again, many thanks!