ZVex SHO "Crackle OK" - getting rid of the crackle

[O]

I got my hands on an SHO and I love it... except for the crackle when I turn the knob. Is there a way to fix that? It makes my amp sound horrible if I adjust the volume.

Is it even fixable? Or is the crackle part of the design?

Thanks!

[dosmun]

That is just the way it is.

[casey]

if you mean that it crackles when you turn the knob, that probably means you need to replace the pot.  make sure you match it up with the right
type and value, and that'll be it.

[bwanasonic]

if you mean that it crackles when you turn the knob, that probably means you need to replace the pot.

Normally that would be the case, but as one might guess from a knob labeled "crackle OK", the crackle is intrinsic to the SHO. Just don't adjust the volume knob and you should be OK! :wink:  :lol: (just kidding). I'd have Z. vex do any modifications if it were my pedal, strictly from a resale point of view, but I'm not sure this is offered as a *mod*.

Kerry M

[Jaicen_solo]

the crackle is intrinsic to the design, as it is varying the DC bias to ground. If you look at this schematic from AMZ, you can see a DC blocking cap in series with the gain control, which eliminates crackle. This mod should be fairly simple to achieve on the SHO.

http://www.muzique.com/schem/mosfet.htm

[puretube]

me thinx Z wudda had decrackled it himself, if possible...

[O]

Hmm... well, thanks for the responses y'all. I guess I'll just learn to not adjust the level while playing... (can't sell it since it was a b'day present)

[Alpha579]

other than that how are you liking it? i'd love to get my hands on one of these  

[stm]

I don't know the exact electronics of the preamp, but it is clear the Crackle OK pot sets some bias and has DC across it which cannot be removed easily without affecting the gain/frequency response of the thing.

I think I DO have a solution, however, just send me USD 250 and I'll disclose it...

No, just kidding  :lol:

I imagine that you could add to your box a momentary pushbutton that places a capacitor across the crackling pot, so you just press the pushbutton and at the same time adjust the knob. This will affect the frequency response while it is being pressed, but at least you shouldn't hear the crackling, which can be annoying and disturbing, especially when playing in a band situation.

Following image illustrates the general idea:


http://tinypic.com/view.html?pic=21pt9f

Hope I get a complimentary Seek-wah from Mr. Z...  :lol:

[Sam]

The Crackle is OK.    It's supposed to crackle.

[jrc4558]

Isn't it cool when it crackles?

[Alex C]

How can I add crackle to an existing pedal?  

[Paul Marossy]

I'm sure that Mr. Vex has it that way for a reason...

[puretube]

How can I add crackle to an existing pedal?  

throw out a blocking cap... :lol:

[Peter Snowberg]

One way to reduce crackle is to replace the pot with a conductive plastic unit.

If you want to add crackle..... :lol: find an emitter (or collector) resistor somewhere which is touching the audio path.... replace it with one of maybe 50 to 75% of the stock value and put a pot in series with it so you can adjust from 50% to maybe 200% of stock value. The lower quality the pot, the more crackle you'll get.

[swt]

Please leave it as it is. It's a hell of a booster...the best i've ever tried. i could finally get one...the design is so clever. The pot has some dc bias in it, and there is no way to add a cap or anything to solve it. There's no way for me to tell you more because i respect Zachary, and i would be telling you the tricky part of the circuit. Just go to zvex page, and read what it says about this...and a 60s console preamp...check some schems for that...and you'll get what i mean.

[Sam]

Please leave it as it is. It's a hell of a booster...the best i've ever tried...

I couldn't agree more. I love my SHO.

Mod your Boss pedals, leave the Zvex ones alone.  :wink:

[Paul Perry (Frostwave)]

Even when there is DC running thru the contact, some pots are much quieter than others.
Maybe (I havn't tried this) one of the conductive plastic style pots would be quieter? Hell, for all I know, maybe lubricating the pot would help???

[Torchy]

crp

[zachary vex]

clev·er     P   Pronunciation Key  (klvr)
adj. clev·er·er, clev·er·est
1] Mentally quick and original; bright

hey, i didn't write it... i just looked it up.  8^P