Well, it was just a question of time to make an update to the VT-25 DHT preamp. I wanted to try the BSH111BK as lower FET as shown below:
The result is visible on the frequency response. It does have an improved FR and the bandwidth gets up to 800kHz on same testing conditions. If you increase the HT to 280-300V you can increase the anode current to 30mA which should be good as well.
The bass on my system is fantastic now. Stronger than with previous setup. That is what you get when you marry low ra (4P1L pair) with a high-quality OPT.
I have a pair of pre-soldered BSH111BK boards (which are painful to solder) so I will give them away on a first come first serve basis
Weather is really nice today in London, so I’m going out right now…