BOSOZ Volume Control

[rothko]

--- I have a plan to build SOZ and BOSOZ. For BOSOZ, I prefer to use relay volume control similar to Aleph Pre. But output resistance value of relay volume control of Aleph goes under 300[Ohm] in middle position. In BOSOZ, 5[kOhm] volume is recommended. Is there any problem to use low resistance volume in output of BOSOZ?

--- I think that SOZ can be driven by BOSOZ or Aleph Pre. Which combination will be better between (SOZ+BOSOZ) and (SOZ+ALEPH-PRE)?

--- PassDiy announce that there will be new power amplifier design soon. Do I need to wait new design, or build SOZ at this time? Does anyone have information of new power amp which will appear on PassDiy site?

Thank you!!!

 

[Nelson Pass]

No problem with low resistance loading the BOZ or
BSOZ, but of course you get lower output.

 

[rothko]

Thank you, and one more question.

Thank you, Mr. Pass!

I have one more question.

I have two transformer. One has 45V secondary, and another has 60V secondary. I hope to use these transformers for BOSOZ.
If I use these transformers, there will be voltage unbalance between positive rail and negative rail. Is it possible to drive BOSOZ with unbalanced power supply? (+60V, -45V)
Or, is there any way to solve this problem?

 

[GRollins]

The immediate solution that comes to mind is to use the 45 volt rail on the bottom and replace the resistors under the gain devices with current sources.

Grey

 

[Nelson Pass]

I'm struck by the notion that the secondary voltages
of the transformer will result in more like +80 volts
and - 60 volts, but that is not a problem if you are
willing to adjust the resistor values a bit, or, as Grey
suggests, substitute constant current sources for
the resistors to the negative rail.

 

[rothko]

Thank you! Mr. Pass and Mr. Grey.