*umbleator step up transformer?

[nickm57]

I guess as the post says....
Is it possible to use the "step up" transformer method to power a *umbleator. 240-9 then 9-240 or what is required to get the correct voltages.

I've never tried this method on any valve gear. What are the draw backs, risks?
As other have found finding reasonably priced unit in Australia is difficult.
Nick

[markusw]

So far I built two tube preamps using this approach, one clean Fender channel and a Non-HRM preamp
See: https://tubeamparchive.com/viewtopic.ph ... t=stompbox

Works fine.

For the Fender channel I didn't use toroids but standard PCB mount flat pack xfmr's, btw.

Depending on the voltage you need, a 240/12 1A wall wart plus a 240/9 for steeping up might be OK.

Regards,

Markus

[nickm57]

cool.
Did you use one of taps off the primary transformer for the heaters?

[markusw]

Actually, the I used a bridge rectifier to get "+/- DC". "+DC" is then downregulated via two separate LM317's to 12.6V for the heaters and 12V for the relais. "+/-DC" is also downregulated via a separate LM317/LM337 combo to give +/- 18VDC for the bipolar supply (for the loop).
Severe overkill, I know

If I did it again I would probably go for a 1-2A 12V-15VAC wall wart and a half-wave rectifier to get the heater and relay voltages.