Bottlehead Forum

Conversion of Paramour to 45, non-shunt regulated

24.18.240.124

In Reply to: RE: shunt regulation for upgraded paramour I ??? posted by praff on June 04, 2007 at 11:49:27

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...

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RE: Conversion of Paramour to 45, non-shunt regulated - praff 05:02:17 06/05/07 (0)

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