Tranny Blues

[bubba2]

I have a transformer with strange secondary outs.
( No! it's not the cross dressing type)
They read as follows:
RED wire = 350V/ 0.18A
Brown wire = 50V/ 0.5A
Orange wire = center tap( I presume)
Brown wire = 50V/ 0.5A
RED wire = 350V/ 0.18A

Blue wire = 5V/ 3A
Blue wire = 5V/ 3A

Yellow wire = 3.15V/ 2A*
Green wire = center tap ( I presume)
Yellow wire = 3.15V/ 2A

White wire = 3.15V/ 2A
Black wire = center tap ( I presume)
White wire = 3.15V/ 2A*

I'm thinking that if I take the outer white and yellow wires* I would have 6.3V.
But would I still have just 2A for heaters?

Does this tranny have enough amps to drive a couple of el34s/6L6s and 3 x 12ax7s
for say a 50watt marshall type amp? I don't think there's enough current for the heaters.
Maybe alright for a power amp?
Please let me know your thoughts and opinions.
Thanks for any help.

[Ballz]

Well, it looks like you have 2 x 6,3V windings, which is a big bonus.

Now, heater current for 2 x 6L6 is about 1,8A, so there´s one of the windings gone/used up already. EL34:s and 6V6 draw less current.

The other winding could be used for the preamp - 2 A is a lot for a preamp, at 0,3A per tube, you are home.

If I were you, I´d stay away from parallelling the windings to get more current capacity - but others may say otherwise . I would use them separately, with separate fuses.

BUT: look at the B+ winding. 180mA isn´t all that much if you start using 6L6:s or EL34:s.

Check the tube sheets, and calc from there.
I would happily use this tranny in a 18W or similar p/p amp, but nothing bigger. But then, that´s me, and I´m not the borderline guy.


Cheers /Richard

[bubba2]

Thanks Ballz, I checked out allen amps http://www.allenamps.com/transformers.html
and noticed he sold one similar with 180ma on the b+ windings which he
says is enough for el34s but I think it could be borderline.
Perhaps I'll save it for another 18watt down the line.

[zaphod_phil]

Now, heater current for 2 x 6L6 is about 1,8A, so there´s one of the windings gone/used up already. EL34:s and 6V6 draw less current.

6V6s draw less current than 6L6s, but EL34s draw more. Or did you really mean to say EL84s?

[bubba2]

After doing some footwork on the net I came up with this,
(please don't flame me if it's wrong, I'm not an EE).
heater current:
12ax7=0.3A
5881=0.3A (seems a bit light for a power tube)
6V6 =0.45A
6L6 =0.9A
EL84= 0.76A
EL34= 1.5A
6550= 1.6A

This tranny may be o.k with 5881, 6V6, EL84s and perhaps 6L6s but not
EL34s, oh well, still very useable.