BOSOZ I/O and Switching Recommendations

[Fox]

Zapped,

If you want both unbalanced and balanced outputs the best way is to follow Nelson's recommendations in the BoSoZ-article. If I remember correctly, Nelson designed the pre-amp to have both balanced (XLR) and unbalanced (RCA) outputs. He used RCAs for each XLR-polarity, resulting in 2 RCAs per channel: XLR pin 1 to RCA-ground of both the RCAs, XLR pin 2 to the positive polarity RCA signal-pin and XLR pin 3 to the negative polarity RCA-signal pin. For single-ended poweramps you would just need to use 1 RCA per channel and because you have both the polarities of the balanced signal available, for each channel you can choose to use the inverting or the non-inverting output.

Hope this makes some sense,

Fox

[Zapped]

Thank you, Fox. Actuallly, I already have a chassis which has space for one set of XLR inputs, and 4 phono jacks on the input. It also has space for one set of XLR outputs and 2 phono jacks on the output. That's it in terms of space.

I realize this eliminates the possibility of picking inverting or noninverting output when using unbalanced output. but am not concerned with that too much. My real dilemma is how I can use this chassis and whether I have to use switches or shorting jumpers to do so. I have the advantage of a (up to) 6 position, 8 deck switch. A real beauty made by Shallcross in the late 1960's that I bought as new old stock surplus from Fair Radio for $6 a few years back. I am switch-rich here, you might say, but space poor on the chassis.

I appreciate your help.

[dqswim]

In my case with an output attenuator (2 pole, one L, one R) between the +, and - outputs when I used the single ended outputs I had to ground the un-used output or I got a nice hum. Took me quite a while and many posts to the forum before I could figure out this problem.

I don't know if this will be the case with your output control but something to keep in mind, or atleast not repeat.

-dave