Zvex Super Hard On

[frequencycentral]

I just built a SHO for a friend, using my super compact layout below. Nice boost, but it does indeed crackle like grandpa's 78's. Might seem like a daft question, but why not just ground the source, remove to resistor to ground at the output, and use a pot configured as a voltage divider at the output for a volume control? Or am I missing something?

[Paul Marossy]

Wow, that is really compact. It could even easily go into a guitar control cavity. Not bad for a "Cyborg Perf Boy from Outerspace". 

[BoxOfSnoo]

I've only read that it might affect the tone, though I haven't tried it myself.  I made mine with a master volume and SWTC hanging off the end and I know I like it enough that I'm leaving it well enough alone!

Here's some history... http://www.diystompboxes.com/smfforum/index.php?topic=30707.0

Actually would you be in a position to try it and let us know?

[Paul Marossy]

My clone hardly crackles at all. I have always wondered why he designed it like that, though.

[soggybag]

That is a small layout. Looks good for a pot mounted board. Which make for a nice assembly.

Here's my alternate version: http://www.super-freq.com/?p=214 This doesn't crackle. I'm not sure if this gain pot arrangement makes a difference in tone.

The crackle had never bothered me. It's really pretty minor. It's not like I'm turning the knob while I play. It never sounds like it might damage my speakers or something.

[earthtonesaudio]

My clone hardly crackles at all. I have always wondered why he designed it like that, though.

It has to crackle, otherwise the "crackle okay!" knob makes like zero sense whatsoever.  CMON.

[Paul Marossy]

My clone hardly crackles at all. I have always wondered why he designed it like that, though.

It has to crackle, otherwise the "crackle okay!" knob makes like zero sense whatsoever.  CMON.

Doh! Why didn't I think of that? 

[El Heisenberg]

its like that because the old stuff crackled. It's just a gimmick, am I right?

This is what I've read.

[PRR]

> crackle like grandpa's 78's

All the time? Or just when you turn/touch the knob?

Real pots (specially cheap pots) don't like what this does: flow large DC through the wiper of a pot that also affects audio. Whacha call Bad Practice.

Good Practice leads to a much more complex or less flexible result.

Get a better pot. Get a different pot. Try a little pot-lube. Or just live with it.

[El Heisenberg]

I did hear that he purposely designed it to crackle when the volume is turned. Like older stuff.

[soggybag]

It's just the design of the thing. If it could have easily been set up Crackle free it would have been done. Figure if you've got a great sounding thing made with fewer parts, with a minor drawback, it's not worth it to add a lot of parts or reduce the sound quality to remove the drawback. The SHO sounds pretty good as is.

The crackle is such a minor thing, the marketing of of the crackle has proven a triumph!

Good point about the Crackle wearing out the pot. This could be possible.

Someone posted a variation with a 1M pot on the input as a gain control. I haven't built this but it's sans crackle.

[bumblebee]

He would never have sold as many units had it not crackled!

[zyxwyvu]

I just built a SHO for a friend, using my super compact layout below. Nice boost, but it does indeed crackle like grandpa's 78's. Might seem like a daft question, but why not just ground the source, remove to resistor to ground at the output, and use a pot configured as a voltage divider at the output for a volume control? Or am I missing something?

By grounding the source, you'll ruin the high input impedance the SHO has. At minimum gain, the input impedance is quite high - hence the typical 10M bias resistors. As you turn the gain up, not only does the bias shift, but the input impedance goes down. Also, with no source resistor, you'll probably get clipping unless you attenuate the input. Personally, I think the crackle is an acceptable price to pay for such a cool little circuit.

[frequencycentral]

Good answers guys, thanks. My pot only crackles when I turn it. I'll go with it stock, as that's what the guy I built it for wants. Though if I was doing it for me I'd look at the crackle-free alternatives.  

Wow, that is really compact. It could even easily go into a guitar control cavity. Not bad for a "Cyborg Perf Boy from Outerspace".  

I'm still a cyborg, but I've stopped doing perf layouts now, it's easier for me to do a PCB layout but still build it onto perf. That way the traces are easier to see, you can colour code the ground, +ve and vref................and the PCB is there for others if they want it.

[cpm]

By grounding the source, you'll ruin the high input impedance the SHO has. At minimum gain, the input impedance is quite high - hence the typical 10M bias resistors. As you turn the gain up, not only does the bias shift, but the input impedance goes down. Also, with no source resistor, you'll probably get clipping unless you attenuate the input. Personally, I think the crackle is an acceptable price to pay for such a cool little circuit.

fix dc, but ac bypass source with a cap, more like the fuzz-faces do.

[aziltz]

the input impedance of the stock sho goes down as the gain is turned up anyway.


here's a good explanation of how it works and how to make a no-crackle variant.

http://solgrind.wordpress.com/2009/01/08/crackle-not-okay/

[moose23]

I've found the crackle sounds great as part of my noise rig. I'm also starting to think they should all come with a master volume pot like the super duper.

[Paul Marossy]

I'm still a cyborg, but I've stopped doing perf layouts now, it's easier for me to do a PCB layout but still build it onto perf. That way the traces are easier to see, you can colour code the ground, +ve and vref................and the PCB is there for others if they want it.

Man, I haven't done a PCB layout in years. It's probably been about four years since the last one I designed.

[bumblebee]

Some people complain about the crackle, personally I like it as its such a clean boost it lets me know if its actually on on the minimum setting *there's no mistaking it being on when its turned up) just by moving the knob a little. No, I generally don't put LED's in my builds as I don't have much use for them aside from in phasers and delays etc, if its fuzz or distortion I usually just omit the LED's.

Anyways, whether it was designed to crackle or it is a design flaw,I like it.

[80k]

the crackle didn't bother me. However, the circuit seems to pop quite a bit when I stomp the stompswitch. I built a superduper-2-in-1 (two SHOS with a master volume).

Also, my RE-20 (Boss Space Echo) picks up some noise from the MOSFET circuit and you can hear a faint whooshing sound even when the RE-20 is bypassed, so there is a weird problem with the combination of the SHO circuit and the RE-20.

After some time, it seems the AMZ MOSFET Boost is more suitable for my rig (little to no popping and the RE-20 does not whoosh any noise from the MOSFET).