B1 with Korg Triode

I think it could do without either buffer, but in that case it means that one will have to know exactly where it can work, (if you have a previous stage with low output impedance and the following stage-amp with the high input impedance). But, if you produce it as a standalone unit, you don't always know where or how the user will put it, so..
What I like to see is some sort of Pass hybrid, where this tube will provide voltage gain. The rest is a common FW stuff :). Jfets at the input, mosfets at the output. Let's call it "the J-tube" :D
 
The one and only
Joined 2001
Paid Member
Depends on what you mean by "too high".

For those that didn't read the pdf, here's the curve.
 

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Some people made plexiglass boxes (laser cut or 3D printing ?)
but frankly, who knock the glass or shake his preamp in everyday listening.

Just touching the volume control on mine (not a stepped control) gets me the fairy dust sound that ChuckT mentioned. That would create a reasonable possibility that typing on the keyboard a foot away is introducing noise into the audio too.
 
The one and only
Joined 2001
Paid Member
Two replies,

If touching the volume control gets a reaction you want to check to see
that the case of the volume control, and maybe the faceplate is grounded.
This is a common problem.

And no, there is nothing sacred about feedback / no feedback, as 2 pico
well knows.....
 
Health warning: this circuit may be unsuitable for people suffering from cap-neurosis :cool:

A cap here, a cap there, caps everywhere :buehehe: Such is life, one has to choose. Active components or passive, no way around. Well, then, let's build an expensive preamp, with silver wiring, Jupiter capacitors, golden or wooden case with anti-resonance-ultra performing shock absorbers. Battery supply. That, driving a thousand J-fets amp, connected to a SAL fullrange driver in a J-lo horn. Heck, why not? :D
 
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If touching the volume control gets a reaction you want to check to see
that the case of the volume control, and maybe the faceplate is grounded.
This is a common problem.

I have a plastic knob on the volume control. I'll have to see if I have any way to shoot a video of it in action with good audio but I can pretty much play a song with different ringing sounds by tapping or brushing anywhere on the plastic case, pcb, components or cords plugged into it. If I really upset it the ringing takes about 1-2 seconds to fully fade from my ability to hear it.
Maybe I have an odd one that likes to sing. I need to experiment with my buffer one and see if it does the same. Although I keep thinking I may disassemble it and my recently completed B1 to make the B1 with Korg :D
 

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Are there any JFETS that handle high voltage and could be used with more conventional tubes in the same circuit?

Easy to obtain current production, UJN1208K, sort of burly for a preamp. As for other options that may be nearing unobtanium, I won't be of much help there, my knowledge is stunted :p. I know it's no longer exactly the same design, but it's for a follower, plenty of MOSFET options.