No input cap on JFET buffer

[Le québécois]

Last night I played with transistor buffers (the one you put directly in your guitar). The input capacitor in the range 0.022 up to 0.33 uf change the sound of my guitar and I'm looking for transparent buffer so I'm not happy with that.
I also tried Jfet version (shem can be found at beavis audio here: http://www.beavisaudio.com/techpages/Buffers/).... still unhappy.

Then, I have found this link in another thread
http://www.till.com/articles/GuitarPreamp/index.html

I want to try it but there is no input cap so I'm afraid to plug my guitar into that. The absence of input cap will let DC in my guitar pickup right? .... unless JFET gate are totally isolated from the drain and source? On the other hand, the absence of input cap look interesting since it may be more transparent in respect to my guitar tone?

any advise or even other buffer suggestion are welcome. I will also try IC buffers but I'm looking for a warmer tube-like sound and apparently it's JFET or nothing!

thanks

[earthtonesaudio]

That circuit does not require an input cap.  The gate is biased at 0VDC which should be the same as your guitar so no current flows (ideally).  In practice there will be very tiny leakage current (picoamps or less) through the JFET gate but the magnitude is so small that it can be safely ignored.

[merlinb]

I want to try it but there is no input cap so I'm afraid to plug my guitar into that. The absence of input cap will let DC in my guitar pickup right?

The JFET gate is VERY well insulated from the other electrodes, so it definitely won't let DC onto your pickups!

On the other hand, the absence of input cap look interesting since it may be more transparent in respect to my guitar tone?

If you need total bass transparecy then you can always just use a bigger input cap. There's nothing to stop you using a great big 10uF input cap, and get total transparency down to milliHertz! Whatever it is that's causing you trouble, the input cap ain't it...

[Johan]

the link to www.till.com... is not a buffer but an amplifier. big differance
J

[Le québécois]

the link to www.till.com... is not a buffer but an amplifier. big differance
J

Oups ..... My bad! But is'nt It also a buffer? (high input Z low output Z).
I'm actually playing with it on my breadboard and this thing sound great with it 7 parts count! I have change R3 to 4.7K and this way, I have more or less unity gain with my setup.

[merlinb]

Oups ..... My bad! But is'nt It also a buffer? (high input Z low output Z).

It has high input Z, but the output Z is about 6.8k, which is basically the same as a guitar pickup.

[Le québécois]

It has high input Z, but the output Z is about 6.8k, which is basically the same as a guitar pickup.

So I go back to the initial problem. This thing won't drive long cable better than my guitar.

[earthtonesaudio]

It has high input Z, but the output Z is about 6.8k, which is basically the same as a guitar pickup.

So I go back to the initial problem. This thing won't drive long cable better than my guitar.

Not necessarily.  A guitar pickup's impedance is primarily inductive, whereas the Tillman preamp's output Z is primarily resistive, so the treble cut will be less and start higher.

[Gurner]

As an aside, 4.5V DC or even 9V DC won't kill your pickups..... we're talking less than 2mA through the pickup ....the average pickup wire can handle tat fine.