Reduce the crackle on Tonebender MKI?

[carboncomp]

My MKI sounds really nice but starts to crackle to0 much as it decays 

any suggestions?

Q1 = 70hfe ~250ua
Q2 = 120hfe ~250ua
Q3 = 90hfe ~200ua

[carboncomp]

Bump 

[nocentelli]

My MKI sounds really nice but starts to crackle to0 much as it decays

Crackling sound? Do you mean the sustain is not a smooth decay, but instead is gated and cuts out abruptly? This tends to indicate you need to adjust the bias, usually done by altering the collector resistors. Having said that, I am by no means a mk1 expert so i'm sure others with more experience with this circuit will soon contribute.

[carboncomp]

It got typical wavy gate action rather then a smooth decay akin to a MKII,

But there is also is a nasty little fizzy artifact that its quite pronounced during the decay that I didn't get on my last MKI build.   

[nocentelli]

But there is also is a nasty little fizzy artifact that its quite pronounced during the decay that I didn't get on my last MKI build.   

Well, since you've built at least one more mkI than me, I'm afraid I'll have to leave it to those with more experience.

[Arcane Analog]

Crackling, fizzles and artifacting on the note decay is common on MKIs. They are noisy, nasty beasts and dialing them in perfectly is no easy feat. It is all about transistor selection. Keep swapping them out until you have a trio you dig with minimal artifacting.

Here are three originals with lots of lovely artifacting.

[Derringer]

is it typical for an MKII to have some of that fizzy decay?

I'm hoping you say yes, because mine's (si design) always done it (probably only noticeable to me and other builders) and others I've breadboarded did

[Arcane Analog]

Silicon MKII Benders shoulnd not have the gate/artifacting unless you have an external bias control that allows that type of sound on extreme bias settings.  The MKII circuit needs to be tweaked to accomodate silicon transistors.

[Derringer]

thanks for the input
what i Have is basically a Hot Silicon with a J201 in the first stage
I BB'd a stock hot silicon and still had the same thing going on
Q3 was always biased between 4 and 5 volts (9V pwr supply)

[Electric Warrior]

It got typical wavy gate action rather then a smooth decay akin to a MKII,

But there is also is a nasty little fizzy artifact that its quite pronounced during the decay that I didn't get on my last MKI build.  

Just swap around transistors until you find a set that behaves nicely.
You may need to tweak the resistor between Q2's base and 9V a little to make things easier. Vintage units have anything between 180k and 470k there.