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 ????
Now I am planning to give more power and change the transformer from 25Volts (34Dc) to 35Ac (49 DC) did any one try this ????
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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!
At upgrade version with the IGBT Voltage is +42 -0-42 I think this is the limit but doses it worth the change ??
I built a car amp some years ago using IRF530 and IRF9530 worked great.
I tried the new and improved IRF530N and bang oscillation killed the fets.
The IRFP240 9240 pair work well but are in the bigger TO247 package.
I tried the new and improved IRF530N and bang oscillation killed the fets.
The IRFP240 9240 pair work well but are in the bigger TO247 package.
What about the 20 K resistors from the collectors of T8 and T9 to ground? I don't see that in your schematic with the modifications?