Bottlehead Forum

General Category => Technical topics => Topic started by: Jim R. on June 14, 2014, 06:50:32 AM

Title: considerations and calculations for plate load resistors/chokes.
Post by: Jim R. on June 14, 2014, 06:50:32 AM

Subject line says it all -- I probably know this but a little confirmation and filling in the missing holes would be good.

Circuit would be paramour II 45 driven by 6j5, no chunt reg, and maybe not even a ccs.

Thanks,

Jim

Title: Re: considerations and calculations for plate load resistors/chokes.
Post by: Paul Joppa on June 15, 2014, 03:06:39 PM

No time to write a book  :^)  but here's some simple considerations:

The 45 is much more linear than a 6J5, so even if the 6J5 is run at half its available peak output voltage (6dB eadroom) the distortion will be comparable with a resistor load. You may get lucky and see cancellation of even harmonics  but then the odd ones will be doubled.

With a high impedance load the driver distortion will be much less than the output tube.

If you do not want any solid state, then a choke load on the driver allows greater headroom and high load impedance at the same time. More inductance sounds better, but I have never heard a choke that sounds quite as good as a C4S. YMMV!

Title: Re: considerations and calculations for plate load resistors/chokes.
Post by: Jim R. on June 16, 2014, 05:35:36 AM

Paul,

Thanks. I did say, "maybe" no c4s. I'm not necessarily looking for best objective performance, but best subjective performance in my particular setup. Make sense?

-- Jim