BOSOZ rail voltage

[pro]

Some one knows what is, at the listening, the differences by running Bosoz at +-30V and at +-60V?
Ciao.

[eLarson]

I run mine at +/-30... and the -30 is rather wasteful on my part since I use constant current sinks to hold the current as steady as possible. I love the sound of it.

[Alain Dupont]

pro,

Look at the balzenpre.pdf file, Nelson explains distorsion for different rail voltages...

Figure 11 shows the THD & noise, again for four different rail voltages.
The output is at 2 volts and is plotted versus frequency. The figure is the
same from 20 Hz to 20 KHz.

Regards.

Alain.

[pro]

Thanks Alain, I already knew the difference in TDH, but my question is another one: in a listening test, how is it effected from this difference in tdh+noise?
Thanks
Ciao.

[Alain Dupont]

Pro,

>> in a listening test, how is it effected from this difference in tdh+noise?

Well, good measures do not define good sound.
If you use lower rails, but with higher bias, it somehow compensates.

I have built a CCS-X-BOSOZ, and in my listening tests higher voltage & higher bias gave better definition, for 60 volts on the upper part of the 2 * IRF610 and 40 to as much as 60 mA bias for each MosFet.

The results:
Better micro dynamics, wider soundstage, and greater depth.

PS:
I plan to make tests with 70 volts rails ; my only problem is to dissipate
a lot of heat on the 2 * 750 Ohms {3 watts} drain resistors...

At this time I have built and stuffed all Pcb's for the ccs-x-bosoz, the Apox circuits are completed ; it remains the enclosures to built or buy...

Regards.

Alain.

[pro]

Thank you Alain.
I'll plan a 60V reil.
Why don't you try to use those Vishay resistor. They ar rated 50W on hetsink, but can also dissipate 5.5W without, so that you can just attach them to the bottom of the case. Ther is the 1K2 value that is good for 58 ma at 70V (4.2W).
I am planning to use a case of a Rotel pre that I have already modified meny times. For now, i am using his power supply, very well made, but for the bosoz I mast change avery thing because the PS is only 27V unregulated. I just want to use the input
selectors unbalanced and the motorized volume control, a very good Alps 50K blue series to use on the output of the bosoz, so I can use it
that is a double pot and not quadruple. Also veri good is the mute section that puts output to ground when I switch it on and off, and when I push the dedicated button (also from remote control).
For balanced input I'll see. Not balanced output at moment, because my Zen V4 is steel unbalanced.
Let me know wath do you think abaut.
Ciao.

[Alain Dupont]

Pro,

Good idea about the Wishay resistors, the only thing
is that they are big... I would like to minimise parasitic capacitance in particular.

I have placed holes underneath to have better ventilation...

Will try Wishay 10 watts in a future version...