JFET Vulcan Build Probs

[diskoduck]

Hi everybody,
I tried to build the JFET Vulcan. Everything fine with the exception that I got no sound out of it:-)
After checking my whole build up and down three times I explored that I have to bypass the 100pf cap from stage one to stage two to get a full bodied sound.
What leads me to my first question: 100pf over a 2.2M resistor work as hi-pass right?
So why is it placed in series in the signal chain?
If I then additionally pull the JFET out of the second stage I got more volume ( first time I got workable volume at all).
I don't use metall film caps.
So maybe anyone any idea on this?
Any tip would be appreciated.

diskoduck

[WGTP]

If I understand your discription, it sounds like the 2.2M/100pF is not connected.  It should work without the 100pF cap.  The cap in PARALLEL (is that possibly the problem) with the 2.2M resistor passes more highs, so it "brightens" the tone.  Also, from what your saying, the second stage must have some problems.   

[diskoduck]

Thanx for your reply,

thats what strange: the parallel 2,2M and  100pf seem to be a bottle neck. As I pass them I got signal at the end of the circuit.
I suspected the jfet in the second stage blown up but if I swap the fets in the different stages it remains always the second stage that is malfunctioning.
Another thing I found is that I don't get enough drain voltage (2,5v). Doesn't that point to the 2,2M or 10 M resistor at the source?
I wish I had breadboarded the thing before....:-(

[diskoduck]

I forgott:
if I bias the drain voltage so that it is near to 4V, it doesn't has any influence to the overall output.
As I pull the second fet out the Vulcan gets 10 times harder.......:-(

[diskoduck]

I meassured:
Fet 1:
D: 4.08
S: 1.64
D: 0.5

Fet2:
D: 2.27 !!!
S: 2.22
D: 0.85

So could maybe variance of the drain and emitter resistors of fet2 cause all the trouble??

[WGTP]

It looks like the seconde stage isn't wired correctly, but the first stage looks good.  If you by-pass the entire second stage and just use 1 and 3, does it work, but with less gain?   

[diskoduck]

I can't verify that, because I can`t hear how the Vulcan would sound with all three instances.
If the 2nd stage is inserted, signal drops to inaudible.
Do you think it would be a good idea to unsolder the above mentioned resistors?

[WGTP]

By-passing the second stage and just using the 1 & 3 should get you a nice distortion, but not a lot.