Hi all,
i'd like to build a simple buffer around 6N6P, but the 'task' is to employ gas tubes. years ago i acquired nice NOS Siemens 0A2 and 0B2, four of each and so far i'm in the process of learning, how to incorporate them correctly. i know they don't like a capacitor next to them, and the current they ideally prefer (15-20mA) is exactly what i want to put through each side of 6N6P.
please look at the attached schematic from the web.
questions are -
a) would it be more beneficial to use pair of them in PSU (300v) - if yes, how exactly ?
b) or at the cathode, one per each, to regulate 150V - and how ?
Thank you for any suggestions, respecting the idea of using gas tubes.
all the best,
misok
i'd like to build a simple buffer around 6N6P, but the 'task' is to employ gas tubes. years ago i acquired nice NOS Siemens 0A2 and 0B2, four of each and so far i'm in the process of learning, how to incorporate them correctly. i know they don't like a capacitor next to them, and the current they ideally prefer (15-20mA) is exactly what i want to put through each side of 6N6P.
please look at the attached schematic from the web.
questions are -
a) would it be more beneficial to use pair of them in PSU (300v) - if yes, how exactly ?
b) or at the cathode, one per each, to regulate 150V - and how ?
Thank you for any suggestions, respecting the idea of using gas tubes.
all the best,
misok
I can see no purpose for voltage regulating tubes in that cathode follower circuit. Some people might use a CCS in the cathode circuit, but a CCS (current regulator) is the inverse of a VR tube (voltage regulator).
If you want to throw your money away, treat them as 90volt zener diodes and build your regulator around that.
thanks for tips. well, i know few brands/individuals use them is audio, i probably have to study more about their applications. at the same time, i don't need it to be an engineering delight, i just want to use them and not bother trying to sell them for a few bucks.
The produce a pleasing glow as they are effectively a neon.
I know that oscillators and early computers used them for stabilisation but no need for audio applications as there is no scientific or practical need for them.
I know that oscillators and early computers used them for stabilisation but no need for audio applications as there is no scientific or practical need for them.
i've seen them both in PSUs (as one of the filtering stages, removing ripple i guess) and signal tube biasing. and yes, they are beautiful and i just want to try their influence on the sound, so i picked one of the simplest circuits. (6n6p is my favourite, i've built two preamps around them.)
Find a circuit which needs a regulated voltage. Most audio circuits do not need this. Used correctly, VR tubes should have no influence on the sound. Used badly, they could inject noise. However, if a regulated voltage is required and you do not regulate then this could have an influence on the sound.
For a circuit that would work well for the 6N6P. look at Sy's Heretical Preamp-
The Heretical Preamp | SYclotron Audio
Adjust the CCS to feed the 6N6P correctly and you would have a fantastic buffer, and it can easily be built as the output capacitor version, rather than the DC servo version for reduced complexity. A 150v supply would be fine for this build.
They make a nice big fat zener diode, and can be used as a quiet substitute for one if implemented correctly, they aren't practical, but neither are vacuum tubes in general, so an odd comment all things considered. Sure, there are "better" solutions, but when used correctly they work fantastically well. I have used them as references for mosfet followers to make regulators before, and they can be very quiet, especially when fed with a CCS. Double as a fancy indicator lamp too.
The Heretical Preamp | SYclotron Audio
Adjust the CCS to feed the 6N6P correctly and you would have a fantastic buffer, and it can easily be built as the output capacitor version, rather than the DC servo version for reduced complexity. A 150v supply would be fine for this build.
They make a nice big fat zener diode, and can be used as a quiet substitute for one if implemented correctly, they aren't practical, but neither are vacuum tubes in general, so an odd comment all things considered. Sure, there are "better" solutions, but when used correctly they work fantastically well. I have used them as references for mosfet followers to make regulators before, and they can be very quiet, especially when fed with a CCS. Double as a fancy indicator lamp too.
A (IMO) reasonable place to use stacked gas discharge regulator tubes is in the screen grid supply of full pentode mode "finals". A stack of 2X 0A2s and a 0B2 will be close to 400 V. and that number is good for several different O/P tube types. An interesting "trick" is feeding the V/R stack with a CCS, which allows stack current and g2 current to "always" be appropriate.
^ I've done exactly that (with two 0D3 for 300v) on PP 6V6GT finals, and it works very well. Cascoded DN2540 for the CCS, and it was a very trouble free way to go.
FWIW, I'm thinking a 0A2/0A2/0B2 V/R stack in each channel could support the screen grids of PP 6L6GCs or even PP KT88s.
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