Transformer Windfall. Now what?

[Sodacose]

I came home this afternoon, expecting to find my 18V 10VA toroidal in the mailbox. And I did, or so I thought. I was a bit surprised by the weight of the box, but went inside to open it without thinking twice. Upon opening the shipment, I found a 20V 25VA toroid AND a 50VA toroid with 120V (100V tap) secondary and dual 6.3V secondaries.

Woot!

The 20V transformer will work just fine for my 18V regulated PSU project and now I've got the beginnings of a new...uh...something!

Anyone have any designs that can make use of this extra transformer? The heater secondaries are both rated at 2A and the 120V secondary (w 100V tap) is rated for 250mA. 150V B+ or 250V B+ with a voltage doubler?

I could use a tube buffer for my Tubelab SSE maybe. Tube phono-pre? Headphone amp? Who's got a good low-ish voltage tube design?




PS I did contact the manufacturer to let them know of the mix-up and expressed my satisfaction with the shipment even though it obviously wasn't my order. We'll see if they want me to send anything back.

 

[lexx21]

The #26 tube preamp uses pretty low voltage.

 

[Sodacose]

Thanks, Lex. I'll check that out.

Currently also looking through 6Y6 schematics. I've got the beginnings of an audio boner...

 

[Sodacose]

Erm, that #26 tube preamp thread is a hot mess. Anyone happen to know where I can find a proven schematic?

 

[lexx21]

LOL.... yes it is my friend... yes it is.....LOL.

That is one huge thread, but the benefit is that you see what people have tried, operating points, what worked, what didn't.... etc.

There is also some stuff on the Bartola Valves site where he uses a 26. He has several modifications that he has done to it.

 

[Sodacose]

Ah, the Bartola Valves site is a little easier to digest. I've never played with DHT's, so this is interesting. Thanks!

In case anyone else is reading:

http://www.bartola.co.uk/valves/dht-pre-amplifier/26-dht-pre-amplifier-gen2/
http://www.bartola.co.uk/valves/dht-pre-amplifier/26-dht-pre-amplifier-gen3/

 

[lhgin]

I would check out VT52.com. Pretty interesting stuff there, and proven to work. I've tried a few of his design.

 

[hidnplayr]

Something with EL86 (OR PL84) output tubes might work.

 

[Sodacose]

Spending a lot of time reading on the forum and elsewhere, I think I've found somewhere to take this 'freebie'.

I think I'll use the 120V and one of the 6.3V secondaries to power an Aikido cathode follower (perhaps 6DJ8's @75-80V each or another valve with a voltage doubler).

If this works out, I may use the other 6.3V heater tap for a 12-24V supply to power a T-Amp, DAC, phono-pre or something.

 

[Ketje]

A small stereo amp is a possebility.If you put in the voltagedoubler to replace the bridge rec. with an extra RC supplyfilter,less hum,somewhat lower voltage,than this one can be used.
Mona

 

[Sodacose]

Been doing lots of reading on designs and I think I've narrowed it down to a SE 12B4 or a RH84. The 12B4 design would draw something like 60mA, while the RH84 would draw more on the order of 100mA (I'd bias it somewhat lower than the recommended 48mA per pentode). Each would require a voltage doubler (200V needed on the output for 12B4, 300V for the EL84).

I've got a pair of 6BQ5's in my collection so I'm leaning towards the RH84 (or a SET EL84 design if needed).

With the 250mA transformer voltage doubled, am I going to be running this thing too close to its limits? Should I trust in Antek's claim that their toroids can put out 20% more than rated?