Need help with Giesberts HEXFET AMP

[mits1978]

Thank you all I read all articles and the help I got was valuable. I did all corrections and modifications. I put I bias 30mA and dc offset around 0 with the trimers because I don't like to hear noise from loudspeaker

Now I am planning to give more power and change the transformer from 25Volts (34Dc) to 35Ac (49 DC) did any one try this ????

 

[mterbekke]

Thank you all I read all articles and the help I got was valuable. I did all corrections and modifications. I put I bias 30mA and dc offset around 0 with the trimers because I don't like to hear noise from loudspeaker

Now I am planning to give more power and change the transformer from 25Volts (34Dc) to 35Ac (49 DC) did any one try this ????

I never did, didn't dare to.
The fets are specd at 100 V max, so you're definitely pushing it.
The amp sounds best with 2 fet's in parallel. Bass articulation all the way through to the upper regions get a lot more clear as well. Imho of course, and if you can get it stable.
The fet's need decent thermal cooling and a tight coupling to the idle current transistor as well as driver stage. I found no problems when those things were done well. Parallelling the irf's also made it easier to get the heat on the heatsink.

Goodluck, it's a great amp!

 

[mits1978]

At upgrade version with the IGBT Voltage is +42 -0-42 I think this is the limit but doses it worth the change ??