EH Toroidal and Duncan's PSU designer II/Puretube???

[moosapotamus]

WATCHIT!!! : if you want to build the alembic according to the link you posted, be sure to not use the B+ supply as depicted when using the E-H toroid as stepup (that`s a doubler in the schem!)

YES! Absoposolutely, thank you! I picked that up from searching previous threads about the Alembic, but it is certainly worth repeating for the benefit and safety of anyone else who might be considering this. That entire power supply section in the Alembic scheme gets trashed and replaced entirely.

Thanks for the pointer to the 7812 app note, too!  :wink:

~ Charlie

[markusw]

Hi Charlie,

I just built a one channel version of the Alembic. Since there is no B+ specified in the schematics I went with about 370V for B+ which gives you a standard plate voltage of about 250V. I dont´t know if this is the original plate voltage but it sounds great. However, I had to use a 230V/6V trafo wired reversed to get these voltages from 12V AC. Basically, I´ve used the McTube power supply schematics, which runs the heaters at 12.6V DC (pins 4+5) with pin 9 of the tube to GND (should give you an additional hummbucking effect). See also  http://diystompboxes.com/sboxforum/viewtopic.php?t=22867&highlight=

Good luck,

Markus

Added: BTW, on the Alembic hp they say their amp is run at 300V supply. In the original Fender preamp stage there is 250V on the plates (as well as in the Mesa Bass 400).

[PaulC]

One of the reasons for using 12.6VDC heaters is that the tube draws 1/2 the heater current vs the normal 6.3vac set up.  Makes it easier on the wall wart.

There are alot of pwr supply tricks you can do with this tranny/wall wart.  1st is the obvious high voltage step up for the B+.  You would also half wave rect/filter/reg the 12 VAC for your 12.6VDC heater supply.

Then you can also set up two more half wave rects for +- 12 VDC for any opamps you may want in there.

So you'd get around 300vdc/+12vdc heater voltage/+- 12VDC dual rail opamp supply all from a 12 VAC wall wart.  This is what's done in the v-twin pedal.  Very cool!  PaulC

[aron]

Paul,

Can you help me figure out how I could get these voltages from this transformer (if possible).

125VDC to tube.
+8 and -8 for heaters.

How do I get the bipolar voltages?

Thanks,

Aron

[puretube]

answers to be found here:

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