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40.0.40.10
I have been reading the thread about the shunt regulation in the Paramour II and it has really peaked my interest. I have the iron upgraded C4S paramour I and just aquired a set of 45 tubes. I am going to mod for the 45's soon. Anyway...I noticed in the thread below that Doc said his project may work on the Paramour I, but saw no answer. Does anyone know if this mod would fit into the paramour I??????
So I'm sitting here waiting while the chicken in the oven cooks, and reading this thread. I wrote down the various incarnations of Paramour (which was my first full design for Bottlehead - my baby!) and I count 40 different versions, without including experiments like 76 drivers, TFA-2004 output trasnformers, etc. That is 1560 different conversion processes, if you want to convert from any one to any other.
For almost all of them, you are going to be on your own, with such help as you might find here on the forum.
Conversion to 45 operation (no shunt reg) requires a larger cathode resistor and a reduction of the high voltage. The Paramour II manual includes instructions (and the kit includes parts) for a 45 conversion. The PM-II upgrade manual includes instructions as well. For the original Paramours, I think 45 conversion mods have been posted but I don't recall whether anything has been posted about converting an upgraded Paramour to 45 operation. It would vary slightly depending on whether the old upgrade, or the new BH-5/BH-6 upgrade parts were installed.
For the shunt regulated 45, we can cut the list down. First, the PT-2 power transformer is required - the older Hammond simply does not have the ratings. The values might vary slightly between the stock and old upgrade transformers (4K impedance) vs. the newer BH-5 transformer (3K impedance) but I think we'll only work out the numbers for the 3K output - the 4K will still work, with less power but less distortion. The high voltage power supply will be the same as for the 2A3 (the shunt reg will cut the voltage to an appropriate level for 45s). The shunt reg relies on a large plate choke, so unless this amp is for tweeter duty only, some upgraded iron is required.
The shunt reg version uses a much lower gain driver, about 10dB less gain. If you don't have 10dB more gain available, it won't work for you without changing something upstream. I'll look around for a different tube which might restore the gain, but no promises...
PJ...Thanks for the post. Sounds like to simplify things, you guys should stop making so many improvements!!!! Just kidding, that's what I appreciate about the BH effort. Always looking to improve upon the latest incarnation.
Sounds like the shunt regulation is going to require a little more work and money right now than I want to put into the amps. So I will put that on the backburner.
However, I could use just a little more guidance on the conversion to implement the 45. I know I got in on the very last batch of upgrade iron for the paramour 1, so I think I have the latest iron (don't have the amps in front of me right now, so I can't verify). I have searched the archives and can't find anything on converting an iron upgraded paramour 1 to 45 operation. I haven't modded the amps any further than with the C4S and upgraded iron.
Would the 1600 ohm resistor still be appropriate for replacing the cathode resistor in dropping the plate current?
What would be necessary to modify the power supply to supply the correct plate voltage?
Ideally I would like to try this mod...and eventually maybe design the circuit with a switch to go from 45 to 2A3 with a flip of the switch. I'll try just the mods first though. Any help would be appreciated.
if you have the C4s, as you do, then you have a spare triode in the 12at7. You can use that as the basis for a shunt v. regulator.
If you have the current PT-2 power transformer and the iron upgrade, it's possible. I won't be writing a blow by blow manual for this upgrade, so you would have to refer to a schematic and sort out where everything connects. Mostly it's a matter of reconnecting the 12AT7 socket to accommodate the 6CM7 and the shunt regulator connections. But you may also have to redo some of the grounding connections and the wiring of the bottom leg of the output transformer primary. I guess you could say this would be our first "advanced" kit.
Thanks for the info....very much appreciated. I am going to have to study the circuit a little as this is a bit over my head.
I read PJ's posts about converting to the 45, but since I have upgraded the iron and the C4S, I am still not sure what to do. I know that the 270ohm power supply resistor was cut out for the upgrade with the new choke.
Do I just need to replace the the cathode resistor with a 10 watt 1600 ohm resistor to ge the appropriate values for the 45 tube or is there a mod I need to do to get the power supply prepared for the 45's? Or do I need to modify the values of the resistor on the C4S board also?????
How do I get ahold of this schematic? Also, is there enough gain in the seduction with the recomended cartridges to run the 45 paramour 2's to full output(I have 100k pots on them). Right now I am using a modified Precision Fidelity-C7A(no linestage)but I would rather listen to an all out designed 6DJ8 phono pre. Thanks, Paul
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