Russian 6922 works well with low voltage, 9v works ok with some gain.
42v to 140v show no detecable ( sound Quality) difference or percieved gain
42v to 140v show no detecable ( sound Quality) difference or percieved gain
It can "gracefully" limit peaks making distortions less harsh than without it, if there is not enough SPL from the amp/speaker combination to reproduce them.
6N23P is the Russian version of the 6922/6DJ8.
6N6P is more like a stronger version of 6CG7.
6n23p / 6n2p / 6n1p and analogs of these are dual triodes...
I use these for preamps of SRPP schematics... And i supply it by low woltage. I built using there tube di-box (with output transformer to get balanced line out)
If you are interested - i could start another thread.
I use these for preamps of SRPP schematics... And i supply it by low woltage. I built using there tube di-box (with output transformer to get balanced line out)
If you are interested - i could start another thread.
I got to build this one.
Been looking for a simple, dirt cheap and easy to build "tube effects" amplifier and this one seems to fit perfectly. 😉
I'm curious about the biasing though, is there actually any? The cathode is tied to ground and the gate is just -via the volume pot- connected to ground and the input.
Been looking for a simple, dirt cheap and easy to build "tube effects" amplifier and this one seems to fit perfectly. 😉
I'm curious about the biasing though, is there actually any? The cathode is tied to ground and the gate is just -via the volume pot- connected to ground and the input.
bias is an interesting subject indeed. Is it biased because of the differences in potential resistively?
....I'll let you think about it for now...
....I'll let you think about it for now...
Bias is zero volt. You can see plate curves on such love anode voltage and see the current and distortions on zero volt bias.
Zero bias valves tend to suck grid current which will slowly destroy any pot which is sitting on that grid. Zero bias should only really be used when the proceeding stage is able to supply ample current to drive the grid current. Otherwise a DC blocking cap is in order and the question is do you want a cap on the input of an amp ?
Running any of the ECC88 variants down at these low voltages will also produce similar results even if its negatively biased. A sub 50V ECC88 design is possible but will have its limitations, and this is where the ECC86 takes over duty. I say even if a valve can be run well below its stated anode voltage - you should question if the compromises are worth it. Its now simple to develop a nice flat high voltage preamp power supply using switchers for peanuts so why not give the valves the voltage they want rather than introducing compromises.
Shoog
Running any of the ECC88 variants down at these low voltages will also produce similar results even if its negatively biased. A sub 50V ECC88 design is possible but will have its limitations, and this is where the ECC86 takes over duty. I say even if a valve can be run well below its stated anode voltage - you should question if the compromises are worth it. Its now simple to develop a nice flat high voltage preamp power supply using switchers for peanuts so why not give the valves the voltage they want rather than introducing compromises.
Shoog
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Guys, than you for your interest for this schematics.
Especially for Shoog.
About zero bias on the grid.
1) Certainly, zero bias is not a good in usual tube schematics. But there - because anode voltage is very low - grid current will be VERY low and will not damage the pot.
And - as right said Shoog - it makes possible not to use split capacitor.
2) Cathode was "grounded" without resistor to get a higher gain of circuit.
tenta, you were some late... I just sold on Ebay last ready PCB for this schematics.
Especially for Shoog.
About zero bias on the grid.
1) Certainly, zero bias is not a good in usual tube schematics. But there - because anode voltage is very low - grid current will be VERY low and will not damage the pot.
And - as right said Shoog - it makes possible not to use split capacitor.
2) Cathode was "grounded" without resistor to get a higher gain of circuit.
tenta, you were some late... I just sold on Ebay last ready PCB for this schematics.
No problem, my plan is to breadboard it first, and if I like it I will hardwire it.
The schematic in the ebay listing shows an alternative LED bias, did you find that it sounded better without it or?
The schematic in the ebay listing shows an alternative LED bias, did you find that it sounded better without it or?
LED gave nothing in sound.... But it indicates current flow whet filament heated and flashes on peak 🙂
if it's needless, you can shunt it.
if it's needless, you can shunt it.
This is an interesting project if we want to try low voltage preamplifers with TUBES. I wonder how the 6GM8 does it? And has anyone built with 6GM8 or ECC86?
I was recently dealing with this low voltage circuit. With some modifications to the power supply, i made it to work without hum.
6J1 preamp
6J1 preamp