Bottlehead Forum

Bottlehead Kits => Legacy Kit Products => Paramount => Topic started by: ducati guy on December 30, 2009, 03:30:43 AM

Title: DHT driver for paramount
Post by: ducati guy on December 30, 2009, 03:30:43 AM

I was wondering if anyone has tried a DHT as the driver, using separate tubes for the shunt regulator and driver. Not sure how complicated it might be, but it piqued my interest. Would a 26 be an appropriate driver?

Title: Re: DHT driver for paramount
Post by: Len on December 30, 2009, 04:53:35 AM

I'm in the middle of wiring in a 3a5 for the driver in my Excite. Running at 4ma, 100V just like the 5965, so the C4S remains the same. 4 D cells for filaments to start, series/parallel for 2.8V about 100ma IIRC.

I'll post results when it's done.

Title: Re: DHT driver for paramount
Post by: Paul Joppa on December 30, 2009, 06:41:16 AM

Here are three problems you must work around to do this:

1) two independent filament supplies, since the shunt regulator is cathode-driven

2) Low gain - 12AT7 has a mu of 60, most candidate DHT drivers will be around 10.

3) Relatively few DHT drivers are rated for high plate voltage - the regulator must sustain 350v (300v when the new board is ready)

There are solutions to all these of course. Good luck!