FatPants crackling noise/ out impedance

[jstbrowsin]

Hi guys I love the sound of this pedal and what it does to my amp. I can get quite convincing tele sounds and all sorts of cool lower gain amp tones running along side my amp OD.
Is it normal to get a crackling noise when adjusting the Fat pot on this pedal? When I had this on my breadboard it did the same thing, so I thought maybe it is similar to the SHO? If so can the crackle not ok mod be applied in this box also?
Also I seem to have lost a fair bit of amp sustain when using this pedal. Is this possibly due to output impedance phase issue previously discussed? I'm using a 2N5458 for the Jfet.

Does anybody have the same issues?

[masterlk]

yeah the crackle is ok! I haven't experienced the loss of sustain so I'm not much help there.

[jstbrowsin]

Are you running a J201? Maybe that is my problem I'm running 2N5458.

[masterlk]

Yeah I am running the J201. Madbean suggests biasing the transistor at 17k and I like that setting but I also liked it around 19.96 I think the reading was. Very squeeky clean sounding. Great on the neck pickup of a strat.

[jstbrowsin]

yeah thanks for that info I tried biasing at 17k but I couldn't get anything out until I changed the source resistor to 1k but maybe my problem could lie there maybe I'm just clutching at straws really. . . maybe I chuck a J201 in there and see if there is more sustain there.
Hopefully  fingers crossed eh

[jstbrowsin]

Just a thought when you biased your fet was the pot fully open or closed?

[masterlk]

I had a buddy over that day and he was running the controls...I'm not sure how he did it. I am a noob to pealbuilding so he was giving me some help.

[jstbrowsin]

ok thanks anyhow dude. . . 

[jstbrowsin]

just a quick note for anybody looking here. I swapped out the 2N5458 JFET and replaced with the J201. I gained back a little more sustain which is nice to have again. I'm still working on the eq side of things as 22nF in C3 is a little to high for my setup, great tele tones from a strat.  But with that config the treble seems to slightly overpower the body of the tone so I'm trying to compromise at the moment. The 10nF is better with a nicer presence to it the body is back, but lacks the "twang" you get from the 22nF 
I'm thinking I might try 15nF and maybe a 4n7 on a switch and report back. Stay tuned . . .

When biasing the fet does one bias with pot fully CW or CCW??? Anyone? 

[madbean]

A J201 generally biases at about 22k. With the FatPants, you have a a 5k1 in series with a 50k trimpot, so with the trimmer set at about 17k you should expect to get the most out of the transistor. Obviously, there will be a little play with that, but about 1/3 up.

[jstbrowsin]

Thanks Madbean, I think I should have explained better my last question. What I meant to say was do I bias with the "fat" pot fully open or closed or half-way??  
As I remember with the pot fully closed I couldn't get it biased to half voltage as the voltage was too high. but when the fat pot was fully open I could get the half V. Am I doing something wrong? Should I change the value of R3 back to 470Ω?

oops sorry I meant bias at at max voltage in my case I think it was about 16 - 17V