Cascode Design Using 2 Different Triodes?

[abbey road d enfer]

I'm no tube/valve expert, but you might be interested in www.valvewizard.co.uk/mufollower.html and John Broskie's Guide to tube circuit analysis and design at www.tubecad.com/2009/10blog0173.htm covering SRPP circuits.

Mu-follower and SRPP are different animals; their advantage is reducing the output impedance and increasing the drive capability.
Cascode's advantage is reduction of Miller capacitance by making the input tube operating as current amplifier with no voltage gain.

 

[Wilhelm]

I'm not worried either by Joule effect.

It would need to be designed in. It's feasible but it's an element of complexity.

Tell me why a constant forcet would provide damping. In a resonant system, damping is provided by a speed-dependant term.

Whatever the rest of the chain, the input stage is crucial in the global noise performance. Low-noise design is governed by adequating the input stage's OSI to the source.

Good luck with it!Either way, the ribbon in such a microphone will have to be supported by some suitable, flexible material - and the amount of displacement, caused by 1-10 milli-amperes of idle-current, can easily be accomodated for simply by choosing the polarity-connection, that makes the ribbon "squeeze onto" the suspension-material.

I'm no tube/valve expert, but you might be interested in www.valvewizard.co.uk/mufollower.html and John Broskie's Guide to tube circuit analysis and design at www.tubecad.com/2009/10blog0173.htm covering SRPP circuits.
Regards,
Ivan

Thanks a lot for all good suggestions and ideas !