Paramount v1.1s with 45s

[Quiet_Storm]

I'm in the process of modifying the crossovers in my loudspeakers, and while I'm paying for the shipping (perfectly rationale of course!), I'm considering buying some of the parts for an upcoming conversion to 45s. From what I understand, switching from 2A3s entails increasing the cathode resistance to 6 kohms. What power rating should I be looking for? Would two 3 kohm 12 watt Mills resistors work?

Also, it sounds like switching the BCP-15 would be a good idea. Would there be much difference between changing the parafeed capacitor to 9 or 10 uF?

Thanks as always for the input!

[Paul Joppa]

Since the question came up on the Stereomour board, I should probably be clear here:

Paramount was designed so it coule be built as a cap-coupled 300B amp, or a direct coupled 2A3 amp. It can be made to work with the 45, but it was not designed for that originally and we do not have a specific recommended design for that application.

A number of Bottleheads have made the conversion anyhow, and seem to be happy with the results. They will likely post with comments - I just wanted to be clear that the 45 conversion was not part of the original design intent.

[Quiet_Storm]

Thanks and understood. I know this is off the officially sanctioned path, but I'm eager to try some new things and learn in the process 

I'd be particularly interested in anyone's experience with the stock plate choke vs. various Magnequest options and how they sized the parafeed capacitors. I'm a lowly mechanical engineer that understands voltages and resistances fairly well, I haven't had much exposure to chokes and capacitance.

[Grainger49]

IIRC, the Paramount OPT is not optimal for the 45 tube.  The impedance needs to be higher, say 5000 Ohms.  But it will work and will sound good.  Just not as good as it can.

You will need to adjust the cathode resistors to the 2A3 configuration.  You might need to adjust the B+ some so you don't put too much voltage on the tube.

[Doc B.]

Changing to MagneQuest Paramount iron that is also optimized for use with 300Bs and 2A3s will not necessarily improve anything with respect to the use of 45s vs. using the stock iron with them.