I thought I would include a signal flow diagram for the DJ mixer as I didn’t get too far into that in my last post. It roughly looks like this: (I apologise about it being cut off at the end, I was using A3 paper and my scanner only has an A4 bed)
So overall there are two channels, each with selectable Line or Phono inputs. The phono input obviously runs into the phono preamplifier. After the EQ sections there are the VCAs, appropriate summing then output section. Note, the two boxes that have been cutoff on the right read Output Board and Headphone Amp.
And how is it being powered? I’m using a Power One supply, a HBB15-1.5-A which spits out a very ample 1.5A per rail. I had to modify it for the +/-18V rails I’m using in this application, which required changing 2 resistors. Old Crow has a good guide on how to do for his CrOwBX on this page:
For the HBB15-1.5-A the part references don’t line up and with my particular model (which dates from 1994) the two resistors are R27 and R19. I changed these to 2K2. I believe there were quite a few revisions of these PCBs so I wouldn’t blindly copy these changes unless you have the exact same revision.
For audio work, I usually build external power supplies so I’m keeping my eyes open for an enclosure that will fit this. I had some heavy duty 21mm Hirose HS21 connectors lying around and decided to use those for the industrial surplus 2.5m Power cable.