Does anyone have any experience with the Sovtek 6C45pi-E tube.
I'm intending to use them in my transformer coupled preamp instead of the Raytheon 5842A and was wondering if anyone had a good advice about the bias operating point.
They wil be used with the existing power supply wich means that, depending on the current drawn, there wil be something btween 160 and 170V on the anode of the tube. The interstage transformer is a 4200/300 Ohm type rated at 30mA DC current.
I'm intending to use them in my transformer coupled preamp instead of the Raytheon 5842A and was wondering if anyone had a good advice about the bias operating point.
They wil be used with the existing power supply wich means that, depending on the current drawn, there wil be something btween 160 and 170V on the anode of the tube. The interstage transformer is a 4200/300 Ohm type rated at 30mA DC current.
All I know (if I remember right) is that their data looks like either both halves of a 6080 in parallel (less dissipation), or a 6336's triode.
If you don't mind even more tubes than a 6AS7-based OTL, it's a good candidate.
Hmm, 4200 ohms sounds a bit high for it, and 300 ohms sounds a bit low.. I guess you're going for distortion or voltage, not power output, eh?
(Unless that's the existing tranny and you just wanna reuse it, in which case the low Rp should swamp resonances and such very well. )
Tim
If you don't mind even more tubes than a 6AS7-based OTL, it's a good candidate.
Hmm, 4200 ohms sounds a bit high for it, and 300 ohms sounds a bit low.. I guess you're going for distortion or voltage, not power output, eh?
(Unless that's the existing tranny and you just wanna reuse it, in which case the low Rp should swamp resonances and such very well. )Tim
yeah, youre thinking of 6S41S tim
6S45P-E (some people like to muck up the translation from cyr. to latin, and use latin mixed with made up stuff like "pi" damn that irks me.)
its a little 9pin triode, Pa = ~8w IIRC.
its supposed to be pretty close to one of the old WE tubes.. (437A i think? memory is dead here, and im too lazy to look at data of the WE ones..)
http://www.mif.pg.gda.pl/homepages/frank/sheets/112/6/6S45PE.pdf
6S45P-E (some people like to muck up the translation from cyr. to latin, and use latin mixed with made up stuff like "pi" damn that irks me.)
its a little 9pin triode, Pa = ~8w IIRC.
its supposed to be pretty close to one of the old WE tubes.. (437A i think? memory is dead here, and im too lazy to look at data of the WE ones..)
http://www.mif.pg.gda.pl/homepages/frank/sheets/112/6/6S45PE.pdf
6C45P is a stunningly linear valve. It wants >10mA of anode current before it wakes up properly, but can operate with quite low anode voltages (100V). There does tend to be a bit of grid current, so you have to be careful if you take liberties with the (150k max.) grid leak resistor. Because Cag is so high, you can't really use it as a gain stage unless you drive it with a cathode follower (or a moving coil cartridge) unless you don't care/can't measure the HF response. It makes a superb cathode follower, but you need a >100MHz oscilloscope handy to find and tame the oscillation.
why is the input resistance so low for this tube?
3,5 kohm@60MHz
And I see a slight problem with the anodevoltages you espect to have in your circuit, max anodevoltage for the 6C45 is 150V.
I have to admit that I'm planning to use them in one of my amplifiers, and I have bought a couple of them, but I havn't tried them out yet.
But what's it like to use 6C45 as the front end in an amplifier?
somebody said something about the need for a cathode follower to drive this tube because of the high input capacitance.
3,5 kohm@60MHz
And I see a slight problem with the anodevoltages you espect to have in your circuit, max anodevoltage for the 6C45 is 150V.
I have to admit that I'm planning to use them in one of my amplifiers, and I have bought a couple of them, but I havn't tried them out yet.
But what's it like to use 6C45 as the front end in an amplifier?
somebody said something about the need for a cathode follower to drive this tube because of the high input capacitance.
Various comments
The 6C45 should be low noise because if its high gm (it only just meets the lower limit of its specification, though). I haven't used it in a low-noise amplifier. It should be ideal for medium output (0.5mV) moving coil cartridges.
All valves have low input resistance at HF because of frequency dependent losses in the micas, the glass, and various inductances and capacitances. We are not operating at 60MHz, so we can ignore this problem.
Cag is claimed to be 5pF, and mu actually is 52. A typical gain stage would be likely to have a gain of 45, so we could expect 240pF input capacitance. Most transformers or gain stages don't like that sort of load, hence my comments about usage.
The 6C45 should be low noise because if its high gm (it only just meets the lower limit of its specification, though). I haven't used it in a low-noise amplifier. It should be ideal for medium output (0.5mV) moving coil cartridges.
All valves have low input resistance at HF because of frequency dependent losses in the micas, the glass, and various inductances and capacitances. We are not operating at 60MHz, so we can ignore this problem.
Cag is claimed to be 5pF, and mu actually is 52. A typical gain stage would be likely to have a gain of 45, so we could expect 240pF input capacitance. Most transformers or gain stages don't like that sort of load, hence my comments about usage.
Well, I'm just going to ask some rather odd questions.
But I Became a bit worried about the input capacitance when fdegrove said that this tube need a buffer-stage.
Actuall my plans was to use 6C45 as the first tube in an amplifier, the signal comes from a source through a pot and is den fed to the grid. But is this "impossible" because of the input capacitance?
I have attached a schematic of a circuit with a bufferstage, but the pot is placed between the buffer and the 6C45, but will this circuit still be an good alternative if the resistance of the pot is kept low?
In my circuit om going to use current feedback, and the gain will only be about 15-25. Will the current feedback provide some kind of compensation for the high input capacitance?
But I Became a bit worried about the input capacitance when fdegrove said that this tube need a buffer-stage.
Actuall my plans was to use 6C45 as the first tube in an amplifier, the signal comes from a source through a pot and is den fed to the grid. But is this "impossible" because of the input capacitance?
I have attached a schematic of a circuit with a bufferstage, but the pot is placed between the buffer and the 6C45, but will this circuit still be an good alternative if the resistance of the pot is kept low?
In my circuit om going to use current feedback, and the gain will only be about 15-25. Will the current feedback provide some kind of compensation for the high input capacitance?
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