Not enough voltage ?

Hi Forum. Can anyone help where to solve this problem. Searching through forum the did'nt help.

I have built a modified version of ESP project 3a, with a simple diff input amp ( to transistors, 2 resistors) single transistor VAS and a FET output stage. It works well, but.. it have a +/- 28v rail but start clipping at 20v - is that what to expect, or can it be better, and if, where should i look for errors ? Thanks for comments.
 
Stormo,

If you use Mos at the output, you have to use one power supply for driver stage, and another one for the output Mos, because Mos needs several volts to be turned on (4 or 5 v) .

I suggest you use 36 v for driver, and 28 v for output. Psu for drivers can be small, 50 mA is adequate, preferabily well regulated.

Regards, Pierre Lacombe.
 
More information

Thanks for the ansvers. I forgot to mention that the 20v vas 20vpeak=14v-rms. It must be able to sving more. In my simulation (attached) it will sving rail to rail. Why dosnt it in real ?
Why the big DC-offset ?

Regards, Stormo
 

Attachments

  • diff.jpg
    diff.jpg
    61.7 KB · Views: 140