VO1263 output tolerance seems to make it unusable for grid biasing unassisted. One might consider using the difference voltage between two Zener diodes, but I worry about noise and insufficient bias current in those Zeners.
why not run the LED at higher current?
few mA wouldn't give too much ageing, higher output current gives less noise, less effect from leakages in C, board
and using the PV diode output current to bias a LED as shunt ref will give some regulation
few mA wouldn't give too much ageing, higher output current gives less noise, less effect from leakages in C, board
and using the PV diode output current to bias a LED as shunt ref will give some regulation
With a maximum of maybe 30uA guaranteed output current, I dunno about stabilizing bias with LEDs. The good ol' LM385-ADJ voltage reference works down to 10uA and could be noise-filtered easily, so maybe that's a good option.
What are you trying to build, a matched gain 2 channel preamp?
What signal source will you use, phono cartridge, CD player, etc.?
(How much input signal voltage do you have?)
How much output voltage do you need?
The above schematic is a mystery to me.
Also, a reference to Scott's G=1000 amplifier does not include a link to it.
What signal source will you use, phono cartridge, CD player, etc.?
(How much input signal voltage do you have?)
How much output voltage do you need?
The above schematic is a mystery to me.
Also, a reference to Scott's G=1000 amplifier does not include a link to it.
http://www.diyaudio.com/forums/grou...1000-low-noise-measurement-amp-ikoflexer.html
The control loop idea is brilliant but won't work without major redesign, for triode.
The control loop idea is brilliant but won't work without major redesign, for triode.
why not?
at least for this tube it looks like O 100 nA grid leakage at typical ~-1 Vbias given the graphs with 10 Meg grid leak bias
so the "opto diff amp" servo Scott shows would have enough "authority" if you wanted ~ 1 mA in the tube, would then have ~ 1 uA in the opto PV
at least for this tube it looks like O 100 nA grid leakage at typical ~-1 Vbias given the graphs with 10 Meg grid leak bias
so the "opto diff amp" servo Scott shows would have enough "authority" if you wanted ~ 1 mA in the tube, would then have ~ 1 uA in the opto PV
Jcx , you cannot get the sound of tubes without tubes, I am a SS guy first and foremost.
I designed a 3 transistor 3 tube amplifier that can't be beat by Silicon alone.
I gave up and and now have 6922 tubes in my equipment. I won't be going back to SS alone.
The band sounds like it's in the room. By the way a 6922 tube can be had for less then $10
I designed a 3 transistor 3 tube amplifier that can't be beat by Silicon alone.
I gave up and and now have 6922 tubes in my equipment. I won't be going back to SS alone.
The band sounds like it's in the room. By the way a 6922 tube can be had for less then $10
Last edited:
- Status
- Not open for further replies.