BOZ Bias Guidance

[SRMcGee]

Folks:

I hope this request isn't seen as being inappropriate, but I could use some guidance as to how to set the bias on a Bride of Zen preamplifier pcb that I bought on ebay. For the record, I would note that it has been more than 20 years since Nelson Pass released the BOZ design, so it cannot be covered by patent. Still, I appreciate that I may be walking a fine line on this forum and apologize if anyone takes offense.

Nelson's BOZ article is based on his original design, which included a MOSFET on each channel and a 60 VDC rail. The board I've got uses jfets instead and the rail on this build is 24 VDC. Where should I be measuring and what is the ideal reading?

The photos were lifted from ebay; sorry about the resolution.

Regards,
Scott

 

[Dennis Hui]

Hi Scott,

There's an old thread on the jfet boz:

Jfet BOZ

Hope you can find the info you're looking for there.

Dennis

 

[SRMcGee]

Dennis:

Thanks for the link; I had reviewed that thread and confess there's a lot I didn't understand. In any event, I didn't find a clear answer to my question there. Still hunting...

Regards,
Scott

 

[mjf]

.......have you built it?

imho the voltage between drain and ground should be around half of the psu volts.......12V or so.