HELP ME ON NEVE BA283

[thomasdf]

I don't ! But I didn't think there was that much load on the output Xfrmr's secondary. I'll try that now !

Tried connecting A & J and R7 went up in smoke haha.

My gain resistor (trimpot) is set to 109 ohms.

 

[ruffrecords]

I don't ! But I didn't think there was that much load on the output Xfrmr's secondary. I'll try that now !

Tried connecting A & J and R7 went up in smoke haha.

My gain resistor (trimpot) is set to 109 ohms.

This is because you need to follow the correct procedure for setting up the bias of the output 2N3055 stage. R7 is meant to be in circuit. Without it, the current in the output stage is very small and you have no headroom. You need to turn the preset pot to maximum resistance Usually fully clockwise), connect A to J and then power up. Load the output with 600 ohms and connect your scope across it. Feed the stage with a signal large enough to read 43V peak to peak on your scope. Then adjust the preset pot for symmetrical clipping.

Cheers

Ian

 

[thomasdf]

Interesting ! Will do that tomorrow. Thanks a ton Ian !
Does R7 need to be high wattage?

Also curious as to what’s the best impedance signal for the input. I still need to try a 200:45K transformer instead of the 600:600 I’m using.

 

[ruffrecords]

Yes, it normally dissipates more than a quarter of a watt so a 1W or 2W type should do.

Cheers

Ian