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Old 22nd Oct 2019, 9:35 am   #44
Argus25
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Join Date: Oct 2016
Location: Maroochydore, Queensland, Australia.
Posts: 2,679
Default Re: Single-ended Transistor amps.

Quote:
Originally Posted by kalee20 View Post
....though in terms of power gain the input capacitances of the MOSFET have no effect as the resulting input current is 'wattless.' I did consider it before I posted!
I agree and its nice with the EF98 that for practical purposes its input with the 10M resistor behaves as an "R" and not a "Z", so you can drive that from practically any audio source without loading it differently over the frequency spectrum.

It is a lot of fun making these amps. Probably an MPF102 would subs directly in for the EF98 (along with the 23:1 transformer) if one wasn't keen on the vacuum tube. But EF98's are pretty cool, working with the 12V anode voltage and if you throw in another EF98 as a pre-amp, the heaters just go in series.
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