anyone got a set of anode voltage/current curves for this little beastie? Yes, I have checked what Frank has available.... Yves, I recall you have worked with this one?
Hi !
I've used that.
said to be equivalent.
Yves.
I've used that.
An externally hosted image should be here but it was not working when we last tested it.
said to be equivalent.
Yves.
exactly!
And so I figured you would have some idea of a useful operating point... or even may have developed some anode V/I curves!
And so I figured you would have some idea of a useful operating point... or even may have developed some anode V/I curves!
ok Yves, just one more
It looks to be more linear CCS loaded at 10ma and gives plenty of swing too. What was the reason you chose the 14ma point on your RIAA pre?
It looks to be more linear CCS loaded at 10ma and gives plenty of swing too. What was the reason you chose the 14ma point on your RIAA pre?
Hey Down under !
Good question . . . I dunno !
Perhaps to extract the last half dB gain
Anyway, looking at the voltage level delivered by the cartridge, linearity is not the essential issue . . . I think 😎
If you plan to build this preamp, keep in mind it must dissipate a lot of calories.
Make it larger than mine
Yves.
Good question . . . I dunno !
Perhaps to extract the last half dB gain
Anyway, looking at the voltage level delivered by the cartridge, linearity is not the essential issue . . . I think 😎
If you plan to build this preamp, keep in mind it must dissipate a lot of calories.
Make it larger than mine
Yves.
Is it not a 'Variable-Mu' tube...?
Looking at the datasheet it quotes a Mu of 78 at -1V g1 but much lower at higher G1 volts....
It was intended as an RF Amp for UHF Tuners, a successor of the EC97, which had similar charateristics....
RF Amp in tuners were very often Vari Mu tubes to have good AGC functions with fluctuating signals...
Looking at the datasheet it quotes a Mu of 78 at -1V g1 but much lower at higher G1 volts....
It was intended as an RF Amp for UHF Tuners, a successor of the EC97, which had similar charateristics....
RF Amp in tuners were very often Vari Mu tubes to have good AGC functions with fluctuating signals...
Yes, it is !
Anyway, this is not a problem for the CCS loaded first stage at such low level.
It's a bit more objectionable for the second stage indeed . . . but not so much . . . just lightly colored 🙄
PC 900 Noise Issue
From the GRAAF WFB ONE preamp I don't get schematic diagrams. The phono input stage produces very loud pink noise and shoot noise sometimes, independend of the fact, what load is on the input. Even while shorted input the unwanted noise is still present in such kind, if there would be an additional serial resistor between input and grid in use. The tube is a PC900 in a SRPP configuraion (in front of the actually RIAA stages).
Circuit describtion is here:
http://www.whatsbestforum.com/showthread.php?7932-Pre-Amp-with-Phono-needs-new-tubes
Here is the diyaudio thread to the Graafiti WFB ONE:
http://www.diyaudio.com/forums/tube...iti-wfb-one-schematic-needed.html#post3496713
This unwanted noise is to obeserve by all brands of this tube. A second device from a Graaf WBE provides also this unwanted noise - thus the reason isn't a faulty part - rather a faulty design of the input stage. Sound is sweet and lovely but the noise too hard.
Who can give me some advices to reduce the noise, particularly while shorted input ??
From the GRAAF WFB ONE preamp I don't get schematic diagrams. The phono input stage produces very loud pink noise and shoot noise sometimes, independend of the fact, what load is on the input. Even while shorted input the unwanted noise is still present in such kind, if there would be an additional serial resistor between input and grid in use. The tube is a PC900 in a SRPP configuraion (in front of the actually RIAA stages).
Circuit describtion is here:
http://www.whatsbestforum.com/showthread.php?7932-Pre-Amp-with-Phono-needs-new-tubes
Here is the diyaudio thread to the Graafiti WFB ONE:
http://www.diyaudio.com/forums/tube...iti-wfb-one-schematic-needed.html#post3496713
This unwanted noise is to obeserve by all brands of this tube. A second device from a Graaf WBE provides also this unwanted noise - thus the reason isn't a faulty part - rather a faulty design of the input stage. Sound is sweet and lovely but the noise too hard.
Who can give me some advices to reduce the noise, particularly while shorted input ??
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maybe this could be the reason. I will check this in the next time. by post #4 about the URL
http://www.diyaudio.com/forums/tube...iti-wfb-one-schematic-needed.html#post3497900
you will find the schematic of the noised RIAA amplifier.
a grid stopper resistor of 1K at the input haven't any effect concerning
the noise behaviour; both at open and shorted MC input there is identical noise level to observe. But there is no oscillation present - thus the reason for this very special noise behaviour must be an other than unwanted oscillation.
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