Total Domination VFET (TDV) Amp (using 2SK2087C)

[swak]

To have a sit amp that is h2 dominant on the entire power bandwidth you need to increase vds and bias proportionally else it will become h3 dominant from a certain point if you increase only vds. If you increase only the vds without the bias you will get better performance(lower thd) but the amp won’t be h2 dominant on the entire power bandwidth.

This was my impression looking at measurements posted here, thank you for confirming that.

This makes me think I will keep the voltage at or even a bit below 37V.

 

[von Ah]

I’ve been cycling through a handful of my power amps in the recent weeks. My TDV stepped up to the plate today. I heard something new in a familiar song this evening. THAT is the sign of a good amp.

 

[toto34]

Hello, can we use a 36 volt voltage instead of 37.5 volts for your circuit?
Should the intensity be reduced or increased?
Thank you in advance.

 

[ra7]

Yes, 36V is fine. Anywhere up from 20V should be fine. Playing around with the operating point will result in different sound because the VFET device curves are not flat with respect to the drain voltage. This triode behavior is similar to a 300B for example. This is the fun part where you can get different sound by changing either the drain voltage or the drain current. It is a fun experiment. Just be sure to not exceed the dissipation limit of the device.

 

[toto34]

Hello ra7 thank you for your reply.