[Joachim]

Shure you can modify a Transformer, but you shouldn't do it

 

[rico]

I just mean, if i build an exact copy, what power transformer (hammond) should i use? Just to match the one on the schematic...

[Joachim]

Hi rico,

it's a general problem with the "exact" amp clones. Normally you have no chance to get the original transformers from the manufacturer. And most replacements like the transformers from Hammond, aren't fit the specifications excatly. This is especially critical with the output transformer which is an important part of the sound-shaping.

The power transformer is not that sound-critical. Important for the original sound is the HT voltage which is 350V-0-350V in the Recto. Also you need a filament supply 6x300mA (for 6 12AX7) 4x900mA (for 4 6L6) what sums up to 6,7A. I'm sure this is the reason why killigrew uses the 372JX which has only 300-0-300V but an 8A filament winding. Unfortunately no other Hammond transformer meets the filament specs for the Recto. I think the the 5V winding is needed for supplying the switching matrix.

As I'm not the recto expert I can't decide if the 1650T is a close replacement but if killigrew used it in his amp I'm sure it will also sound great in it.

However, if you need an 100% replacement for the Recto magnetics you will need to order custom made tranformers. Or you look for a supplier who sells Recto-like replacement transformers but I havn't seen one yet.

Regards,
Joachim

[rico]

That is a good answer, thank you very much Joachim. I think i go with hammonds, if it's okay - then it's okay, if not - i will try something else.
Thanks!

[TubeLeo]

There is nothing more to say. Joachim you are so right.

Bye the way. I also use the same parts from hammond and they work quite well so far.  

If you want to build an exact copy of the rectifier you can use the 5V winding for the rectifier tube. Thats what i want do to.