John Curl's Blowtorch preamplifier part II

[john curl]

Not really. The BLOWTORCH was special in that the case was thick enough that we did not really need shielded cable in the interior, so long as we kept our leads separated in the air from each other. Most here will not go so far as to make a case this thick, for this purpose, use cable so expensive, break in the cable on the spool itself for 30 days or more, before cutting and wiring it in, and finally, this special silver cable is not available, anymore.

[kannan_s]

Thanks John
I do not intend to bring any controversy in to this thread but was curious about it, that is all
kannan

[john curl]

What I just told you is actually enough to understand why we wired the BLOWTORCH that way.

[syn08]

Originally Posted by Bas Horneman

Oooohhhhhhh boy....here we go again

No problem, as a moderator you will move the discussion to the cables thread.

[Bas Horneman]

No problem, as a moderator you will move the discussion to the cables thread.

Sorry I am retired.

[john curl]

It is not that important to talk about cables in this case. It is really what we did with hookup wire, rather than interconnect cables.
Given the tone of this website, it is better to avoid talking much more about this particular subject.

[kannan_s]

Can we talk about output impedance?
- as we see more Hi end preamps today can drive less than 100 Ohm load. Is it advantageous to have lower impedances ?
Kannan

[john curl]

The output impedance of the BLOWTORCH is 1K ohm It is too high for some, low enough for others. Tubes usually have this sort of output impedance. Feedback preamps have a lower drive impedance.

[1audio]

Actually there are legitimate issues about internal wiring that have nothing to do with magical properties of unobtainable conductors. There is a lot to be considered around input/output isolation, chassis-signal grounding, influence of the shield enclosure on the signal performance, etc. Anyone who has calibrated a long scale AC voltmeter or wide band scope has seen the effects of removing the shield cover from the AC circuitry. Also issues around vibration affecting the conductors (especially biased conductors) and the associated shields/grounds can be very significant. In the Blowtorch with relatively low gain and a heavy enclosure these issues will be reduced a lot but not eliminated.

[mos57]

Originally Posted by 1audio

Actually there are legitimate issues about internal wiring that have nothing to do with magical properties of unobtainable conductors. There is a lot to be considered around input/output isolation, chassis-signal grounding, influence of the shield enclosure on the signal performance, etc. Anyone who has calibrated a long scale AC voltmeter or wide band scope has seen the effects of removing the shield cover from the AC circuitry. Also issues around vibration affecting the conductors (especially biased conductors) and the associated shields/grounds can be very significant.

I think these above are very important issues, never enaugh understdood.
Can anyone suggest/explore his experiences in these questions here or these are OT?

Francesco.