Jfet BOZ

[Zen Mod]

Originally posted by Blues



Ok. On 2nd thought, if we can tune it to the load line without a cascode and we have enough voltage swing with a single jfet...let's keep it simple! ..........

exactly............
me (humble,as always) thinks that Papa's intention was exactly that- answering on original question..........

there are more than few non-minimalistic preamps around .......
taking it in more complicated way- it will look as chopped xcccscdwhatever BOSOZ or The Pumpkin..........
and that's entire another story...... where to stop in adding parts and what is improvement,but real one.......

Battery PS would make it a killer...we won't worry on rectified PS noise.

next step is little preamp ditto in giant horn ..........hehe

[steenoe]

Originally posted by Babowana




Yea . . . thanks for reminding me of it ^^

Oh, I forgot that Blues also got a special F4 front end from Papa ^^

Babowana, where was that F4-frontend posted?

BTW, thats a nice and simple J-fet BoZ. Just read through the whole thread backwards, that was a bad idea Better start from page 1.

Steen

[Zen Mod]

Originally posted by steenoe


Babowana, where was that F4-frontend posted?

BTW, thats a nice and simple J-fet BoZ. Just read through the whole thread backwards, that was a bad idea Better start from page 1.

Steen

from my rusty memory

http://www.passlabs.com/np/FORBLUES.pdf
that was for some F , not 4

[steenoe]

Originally posted by Zen Mod



from my rusty memory

http://www.passlabs.com/np/FORBLUES.pdf
that was for some F , not 4

Oh, the J-fet frontend for Zen V4, for a moment I thought......

Steen

[mpmarino]

On this pre - Do you guys think the attenuator (volume control) should go on the input or the output? I'm talking about a 'twisted' constant impedance relay setup - or similar.

Steen,
where ya been? I'm waiting for someone to comment on how this thing sounds. I'll give you an hour or two to get one together

[Zen Mod]

Originally posted by mpmarino
On this pre - Do you guys think the attenuator (volume control) should go on the input or the output? I'm talking about a 'twisted' constant impedance relay setup - or similar.

.............

when you use that sort of three legged fuses,you always must use pot on input,just because any not-attenuated signal will drive little bstrd in saturation and output sig will be more than clipped.
just look at bias voltage present between g-s and compare it with blabla 2V from CD out..........

[Zen Mod]

Originally posted by steenoe


Oh, the J-fet frontend for Zen V4, for a moment I thought......

Steen

as subject sez..........greedy boy

[mpmarino]

What would I do without you? Thanks

3 legged fuse

[G33/33]

Originally posted by Nelson Pass
Yes, the minute you are willing to bias the input at other than
ground you can make for great improvement.

As to the question about cascoding, yes you can, but you no
longer have the load-line cancellation discussed earlier, and
you will have to alter other parts of the circuit.

Thank you Mr. Pass,

Actually I've been playing with this jfet for few weeks when I got time before this thread started.
Still scratching my head how to improve it's sound. Cascoding with 2SK246 make the high freq. a little bit harsh and I have to bypass the drain resistor with 100pF.

The circuit was taken from www.tubecad.com, a variation of Aikido circuit. I have built the tube version and i'm very very pleased with it's sound.

The jfet version sounds better than few preamp already made but the tube version still better. I wonder if this circuit still have room for improvement.

This is the actual circuit.


rgds,
G33/33

[Blues]

Originally posted by steenoe


Oh, the J-fet frontend for Zen V4, for a moment I thought......

Steen

The sound is . I love its sound more than the A3.

Now this Jfet pre-amp looks delicious...I'm thinking of using an sj74 instead to match my Zv4jC.