Extreme plate load

[Wavebourn]

I'd look at the IXYS IXGH6N170 which has 6pF capacitive load (Crss) when used as a gyrator. 1700 volt capability.

Thank you Michael, it sounds interesting. I never thought of using IGBTs in audio before.

 

[Poindexter]

I don't understand the problem here. Either a Supertex DN2540 or an IXYS IXCP10M45 will give a dynamic (at audio frequencies) load to the device in the high megohms or low tens of megohms for a couple dollars.

/thread.

Poinz

 

[Michael Koster]

Thank you Michael, it sounds interesting. I never thought of using IGBTs in audio before.

I've had great results in a SE amp with local feedback to the driver.

http://www.diyaudio.com/forums/tube...r-triode-strapped-pentode-12.html#post2207735

I think it sounded better than the 5881...

Cheers,

Michael

 

[Michael Koster]

I don't understand the problem here. Either a Supertex DN2540 or an IXYS IXCP10M45 will give a dynamic (at audio frequencies) load to the device in the high megohms or low tens of megohms for a couple dollars.

/thread.

Poinz

It's for an active load for an 808 with 700 volts on the plate. B+ was suggested at 1000V but I would allow a little headroom.

At 20 KHz these devices are all in the megohm range. 1pF is 8M ohms at 20 KHz

Fortunately I doubt an active load above a megohm is needed for a power output stage.

Cheers,

Michael

 

[Bandersnatch]

hey-Hey!!!,
A battery biased pentode with a large cathode resistor will do nicely. I am not certain it will make your impedance, but you can also stack up a pentode on top of a triode( which would also be battery biased to deliver a large cathode'r_set resistance ). There are other ways to bias, but your voltage requirement might tax the simpler ones. It can also deliver mu-follower output Z; so to say much lower than the anode you're seeking to load.

I've done this at about half your voltage and current scale for a linestage and was quite pleased with the results.
cheers,
Douglas