WHAT IS THE SECONDARY VOLTAGE OF FOREPLAY 2 TRANSFORMER

[coca]

I hve missplaced my copy of the manual for my Foreplay line stage amp, Can anyone  tell me the secondary voltage of the transformer for the Foreplay 2? I know all of the other specs. I need to purchase another trans with heavier filaments, but having the same secondary high voltage.
Thanks in avance.

Bernie.

[Grainger49]

It is 125V AC (not center tapped) at 15mA for the B+ and 6.3V AC at 600mA for the heaters.

[Paul Birkeland]

http://www.alliedelec.com/search/productdetail.aspx?SKU=2270001

That is a reasonable substitute for the stock power transformer.  You will need to change the high voltage power supply to a full wave rectifier to use it.  (Ground the red/yellow lead, then run one UF4007 diode from each of the red wires to the B+ feed with the silver band of the diode on the end that connects to the first power supply cap)  A good example can be seen in the Seduction power supply.

[coca]

Thanks gentlemen. I have a couple of PT1 transformers I purchased from Doc. I may have to forego the Bridge rectifer, and try these. I will certainly work something out.

[Paul Birkeland]

The PT-1 is a great choice! 

[Paul Joppa]

Here's an interesting historical note. The PT-1 was originally designed to go into the Foreplay (version I or II),  with enough extra filament current available to run a Seduction as well. I still have that unshielded prototype around the lab somewhere. Over the next several months we gradually determined that the Seduction was too sensitive to the power transformer's magnetic and electrostatic fields, and the PT-1 was modified with the addition of copper and molyperm tapes to reduce the external fields. At the same time we were becoming aware of how much shunt regulation improved the sound of the cathode follower used in Foreplay. Ultimately we used the SEX amp power transformer for Foreplay III as well, which gave it tons of extra power for shunt regulation and experimenting with different tubes. That left the PT-1 used in Seduction only. But as I said, the winding voltages and currents were originally developed for a Foreplay I or II circuit. There's enough heater current to run DC heaters in an old Foreplay, without resorting to a wall-wart power supply.

[coca]

I must get this bug out of my beign. My plan is to use the two PT1 transformers, one per side,  and use 6SN7 tubes having the same operating points as the Foreplay III, but using the same power supply topology as the Foreplay 2, except with chokes instead of resistors. In other words true dual mono supplys. I am concerned with the filament as they will draw 1.2 amps when converting to DC, which is my plan. That puts it right at the spec. of the PT1's filament winding. I also purchased a ccs kit from Doc. quite a while ago, and have not used it. I will have to deal with that later as I am sure there will have to be some resistor changes because the kit was calculated for the foreplay 2, which has different operating points  for the tubes then the Foreplay III.
Thanks again Gents.

Bernie.

[Paul Joppa]

The PT-1 powers two 6DJ8s if it needs to; that is 0.73 amps of DC current. You can easily power a 6SN7 which takes 0.6 amps. Two transformers, one filament each - no problem. :^)

[coca]

Thanks Paul. It's a go.

Bernie.