Paramount using JJ 2a3_40

[Paul Joppa]

Seems possible - I'll talk to Doc after the Christmas rush and headquarters flood is resolved. The idea is quite attractive. This would basically be a stock Stereomour, with flexibility for a variety of Magnequest products as upgrades or modifications. There's no way for us to make a full set of manuals of course, and the customer (you!) would have to acquire the iron from Mike. But I could see it being attractive to a few experimenters - and we LIKE experimenters, it's what we do ourselves after all.

I'll want to think about a few other possibilities as well, I'd rather do it right that do it over!

[Fullrange]

Looking forward to your answer in the new year, I will be the first in line for the larger chassis Stereomour to build in stock form and possible option you come up with, will be fine to start.
Thanks for your answer.

[Paul Joppa]

Reminder - this thread has drifted off topic and is now about using high-power 2A3s or 2.5v 300Bs in the Stereomour.

I talked a little to Dan, and to Mike at Magnequest. It looks like the only suitable and currently available output transformer is the TFA-2004. It can be used with the stock plate choke or the Magnequest BCP-15/50mA or the BH-5, without changing the circuit or tube. It should give a bit more power, 1 or 2dB, depending on the linearity of the tube used. At a guess, no more than 5 watts. Distortion will likely go up at full power, from 3% to 5% if the tube is highly linear (most 2A3s and 300Bs are).

Alternatively, you can use the TFA-2004 with the EXO-003 plate choke running 60mA by using a high power 2A3 or a 2.5v 300B - dissipating 18 watts per tube. This will not increase the power any further, but it will bring the distortion back down to the 3% range.

In small quantities it does not make economic sense to use our regular laser-cut plates. I can have Front Panel Express make you a larger (12" square) plate, drilled for the TFA-2004/EXO-003 combination as well as the stock combination - the cost would probably be $100-$150. Bottlehead could probably sell a larger base kit as a separate item. I don't know the cost, but let's say $50-$100 for a total around $200.

This is not now a standard product, and probably won't ever be. Magnequest may at some point offer specific upgrade iron for the Stereomour, and we may come up with circuit upgrades (I am always working on them!) or new versions, and they may or may not be compatible with this chassis idea. Just wanted to be clear about that!

[Doc B.]

My take on this is that if you want an amp that performs like a Paramount, buy a Paramount. I'm going to respectfully remove myself from involvement in this custom one off Stereomour based project beyond offering to put together a kit that is without the chassis plate. We could also supply it with four 12" wood base pieces rather than two 10s and two 12s.