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?
(http://i210.photobucket.com/albums/bb292/frequencycentral/SHOPCB.gif)
(http://i210.photobucket.com/albums/bb292/frequencycentral/SHOPnP.gif)
Wow, that is really compact. It could even easily go into a guitar control cavity. Not bad for a "Cyborg Perf Boy from Outerspace". :icon_wink:
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?
My clone hardly crackles at all. I have always wondered why he designed it like that, though.
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.
Quote from: Paul Marossy on February 20, 2010, 09:44:53 PM
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.
;)
Quote from: earthtonesaudio on February 20, 2010, 10:26:59 PM
Quote from: Paul Marossy on February 20, 2010, 09:44:53 PM
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? :icon_lol:
its like that because the old stuff crackled. It's just a gimmick, am I right?
This is what I've read.
> 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.
I did hear that he purposely designed it to crackle when the volume is turned. Like older stuff.
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.
He would never have sold as many units had it not crackled!
Quote from: frequencycentral on February 20, 2010, 08:35:25 PM
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.
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.
Quote from: Paul Marossy on February 20, 2010, 09:25:19 PM
Wow, that is really compact. It could even easily go into a guitar control cavity. Not bad for a "Cyborg Perf Boy from Outerspace". :icon_wink:
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.
Quote from: zyxwyvu on February 21, 2010, 06:33:26 AM
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.
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/
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.
Quote from: frequencycentral on February 21, 2010, 06:47:33 AM
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.
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.
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).
"Newer SHO units have a diode protection circuit to keep the transistor from blowing"
So is that the 1n4148's in my layout?
........and why does the Sho have three 1/4 inch sockets?
Quote from: frequencycentral on February 23, 2010, 05:09:55 PM
"Newer SHO units have a diode protection circuit to keep the transistor from blowing"
So is that the 1n4148's in my layout?
........and why does the Sho have three 1/4 inch sockets?
bump
Quote from: frequencycentral on February 23, 2010, 05:09:55 PM
"Newer SHO units have a diode protection circuit to keep the transistor from blowing"
So is that the 1n4148's in my layout?
........and why does the Sho have three 1/4 inch sockets?
There's a single 12V or 9.1V Zener protection diode in some of them. From the centre leg(control G) to ground. 12V in the SHO and two 9.1V in the Super dooper. The third 1/4 inch socket is a second output.
when you say center leg (control G), what do this mean? It seems like a simple fix, just need to know where to put it.
To answer my own question.
The versions with the two diodes are the older version and it's easy to blow the mosfet by plugging in an input cable while its powered on.
ZVex modified the later ones with a 9.1v zener diode between source and gate, and removed the other two diodes. Zener cathode connected to the gate.
Quote from: frequencycentral on February 25, 2010, 01:47:11 PM
The versions with the two diodes are the older version and it's easy to blow the mosfet by plugging in an input cable while its powered on.
ZVex modified the later ones with a 9.1v zener diode between source and gate, and removed the other two diodes. Zener cathode connected to the gate.
Do you have a schematic for this so it will be a bit more clear? I don't quite understand what changes to make...
Quote from: BoxOfSnoo on February 25, 2010, 02:04:23 PM
Do you have a schematic for this so it will be a bit more clear?
It's the same as how the zener diode is connected on this http://www.muzique.com/schem/mosfet.htm (http://www.muzique.com/schem/mosfet.htm)
And it's safe to get rid of the other two diodes entirely? It's confusing me I guess 'cause it's location is fairly different. I suppose electrically it's almost the same thing?
Edit: Looks like it! I found a layout on the other site, looks very simple. I gotta try this now.
I notice some people use a lin pot instead of a rev log - any comments on that?
I also notice different pot values are used - does the value matter, as long as it's the same value as the drain resistor?
The version II seems preferable, ie a zener instead of the two 1n4148 - I also notice some people just use a LED instead of a zener - any LED? Comments on LED vs zener?
Thanks!
I built one with a linear pot and all of the gain is bunch up at the end of the pot travel. Definitely use a reverse log pot.
The gain is roughly Rd divided by Rs.
I put an LED across the gate and source of the MosFET because the RunOffGroove guys did it. Hey if they jumped off a bridge I'd follow them, and often it would sound great. I was just copying the Peppermill: http://runoffgroove.com/peppermill.html There are some notes on this here.
Quote from: frequencycentral on February 20, 2010, 08:35:25 PM
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?
(http://i210.photobucket.com/albums/bb292/frequencycentral/SHOPCB.gif)
(http://i210.photobucket.com/albums/bb292/frequencycentral/SHOPnP.gif)
Question, in the pic showing parts layout, are they shown on the solder side or the component side? Hate to sound like a noob, but the pic is a little confusing.
Quote from: krhnyc on February 27, 2010, 05:34:56 PM
Quote from: frequencycentral on February 20, 2010, 08:35:25 PM
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?
(http://i210.photobucket.com/albums/bb292/frequencycentral/SHOPCB.gif)
(http://i210.photobucket.com/albums/bb292/frequencycentral/SHOPnP.gif)
Question, in the pic showing parts layout, are they shown on the solder side or the component side? Hate to sound like a noob, but the pic is a little confusing.
No the picture is fine. The overlay when put on a pcb is correct. When you flip it over, it matches the layout. You put your parts in on the non copper side corresponding with how the graphic looks.
It's confusing, but that particular layout software allows you to do everything from the top side of the board. Which is way less confusing than having to rotate everything in your head.
I can't get this layout to print at the right size for the life of me. What are the dimensions supposed to be? Do I have to scale it down?
i gotta ask this cause i had a thread about this pedal awhile back and never really felt i got a straight answer.
i dont have the proper diodes. i only have 1N400x's and a a few 12v zener diodes. any way i can build this thing without frying it?
1N400Xs will do the job.
Quote from: TimWaldvogel on March 27, 2010, 03:33:14 PM
i gotta ask this cause i had a thread about this pedal awhile back and never really felt i got a straight answer.
i dont have the proper diodes. i only have 1N400x's and a a few 12v zener diodes. any way i can build this thing without frying it?
......or use your 12v zener thus:
Quote from: moose23 on February 23, 2010, 05:54:09 PM
Quote from: frequencycentral on February 23, 2010, 05:09:55 PM
"Newer SHO units have a diode protection circuit to keep the transistor from blowing"
So is that the 1n4148's in my layout?
There's a single 12V or 9.1V Zener protection diode in some of them. From the centre leg(control G) to ground. 12V in the SHO and two 9.1V in the Super dooper.
Quote from: frequencycentral on March 27, 2010, 05:00:18 PM
Do I need to do anything special to get the your layout to print the correct size?
Quote from: therecordingart on March 28, 2010, 12:43:47 AM
Do I need to do anything special to get the your layout to print the correct size?
http://www.diystompboxes.com/smfforum/index.php?topic=80316.0
Quote from: quarara on March 28, 2010, 04:33:31 AM
Quote from: therecordingart on March 28, 2010, 12:43:47 AM
Do I need to do anything special to get the your layout to print the correct size?
http://www.diystompboxes.com/smfforum/index.php?topic=80316.0
No access to Photoshop. I'll shoot someone a few bucks if you can get this to the correct size and put it in pdf form for me...or any way that it'll print correctly. I've been printing different sizes and trying to fit parts but can't get it right.
Quote from: therecordingart on March 28, 2010, 10:51:45 AM
Quote from: quarara on March 28, 2010, 04:33:31 AM
Quote from: therecordingart on March 28, 2010, 12:43:47 AM
Do I need to do anything special to get the your layout to print the correct size?
http://www.diystompboxes.com/smfforum/index.php?topic=80316.0
No access to Photoshop. I'll shoot someone a few bucks if you can get this to the correct size and put it in pdf form for me...or any way that it'll print correctly. I've been printing different sizes and trying to fit parts but can't get it right.
If you don't have PS you can always download GIMP instead. It's freeware and really similar to PS. I would do you the scaling for free, but I'm not at home at this moment.
Quote from: therecordingart on March 27, 2010, 09:58:22 AM
I can't get this layout to print at the right size for the life of me. What are the dimensions supposed to be? Do I have to scale it down?
It's the same size as a 5 x 8 hole piece of perf, so 13mm x 20mm approx.
http://www.mediafire.com/file/jjhzmdmwnmt/sho.pdf
I've done a pdf file. I think I did it alright.
I've got a SHO on the breadboard (again). This time I set up the crackle knob like a FF fuzz knob, lug 1 to source, lug 3 to ground, lug 2 to ground via a 10uF cap. No crackle. Discuss?
Quote from: frequencycentral on March 29, 2010, 10:43:48 AM
I've got a SHO on the breadboard (again). This time I set up the crackle knob like a FF fuzz knob, lug 1 to source, lug 3 to ground, lug 2 to ground via a 10uF cap. No crackle. Discuss?
you get the mosfet hiss at maximum level on all the pot range
Quote from: frequencycentral on March 29, 2010, 10:43:48 AM
I've got a SHO on the breadboard (again). This time I set up the crackle knob like a FF fuzz knob, lug 1 to source, lug 3 to ground, lug 2 to ground via a 10uF cap. No crackle. Discuss?
Fixed bias helps keep the crackles out.
Quote from: frequencycentral on March 29, 2010, 10:43:48 AM
I've got a SHO on the breadboard (again). This time I set up the crackle knob like a FF fuzz knob, lug 1 to source, lug 3 to ground, lug 2 to ground via a 10uF cap. No crackle. Discuss?
We don`t know how you number your lugs, but most probably you are not sweeping the DC. You most likely just sweep an AC degenerative feedback in and out of the circuit. Result: no crackle. Like in a Fuzzface and others.
I seem to recall reading ages ago that if you switch the battery voltage from the output jack, you won't have the issue of possibly blowing the mosfet in the SHO.
What if you let this circuit with a jumper (or a small resistor) to ground at the source and put a "level" pot at the out?
There was a post by Z somewhere where he talked about the cap to ground off the source. This removes the crackle. But he said it cut the max gain by a small amount. He figured players wanted that extra gain. He gave some numbers also. I think he said he could a gain of 50 or 60 with a pot to ground. The cap reduced this.
Quote from: quarara on March 28, 2010, 12:45:21 PM
http://www.mediafire.com/file/jjhzmdmwnmt/sho.pdf
I've done a pdf file. I think I did it alright.
I didn't end up using this. I really appreciate the help, but I ended up using a piece of vero. Your PM was completely unnecessary.
Quote from: MetalGod on March 30, 2010, 11:08:47 AM
I seem to recall reading ages ago that if you switch the battery voltage from the output jack, you won't have the issue of possibly blowing the mosfet in the SHO.
The amount of voltage required to blow the MOSFET is something like 20V between gate and source. A 9V battery can't make that happen.
However, static discharge can. It only takes a minuscule amount of current at high voltage to punch through the gate.
The danger comes from inserting the cord. The battery is unrelated, so it doesn't matter which jack you use. On the other hand, if you customarily unplug to disconnect the battery, then using the output jack will help, by reducing the number of times you plug a cord into the input jack.
There is an extremely cheap thing you can do to vastly improve the ESD immunity: add a resistor in series with the input. It doesn't have to be large, 100 ohms should be plenty. This will dissipate the current and protect the MOSFET.
Vex'x own schematic, the zener goes to ground: http://www.zvex.com/module_instructions.pdf
Interesting stuff about the blown transistor business--I haven't run into that problem. My SHO is pretty much completely stock, and I love it. I actually prefer the crackle--I've used it with a looper for some interesting noise creation to overlay with my guitar playing :)
Quote from: frequencycentral on February 20, 2010, 08:35:25 PM
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?
(http://i210.photobucket.com/albums/bb292/frequencycentral/SHOPCB.gif)
(http://i210.photobucket.com/albums/bb292/frequencycentral/SHOPnP.gif)
I don't know anything about electronics (though now that I've finished school I want to learn) but I can read a schematic and put stuff together. I just don't know why it works. Anyway, where would be a good place to slap an LED in there? I like my pedals to glow.
Hey, I have a problem, it doesn't sound.I have all grounds connected to the enclosure(I checked with a multimeter and yes, all grounds are connected). I get about 8.8v at the pad which is right to R1(source?) But then I get 0.0 v in gate and drain.What can I do?
Oh by the way, I have the positive of the c2 down, I mean, the positive of this cap is connected to the output.
What does " D G S" mean?
Im confused. I think the zener protection diode goes anode to ground, but frequencycentral said it goes to S. Could anyone clear this up for me?
There's a link to Zvex's own schematic in reply #51, it does indeed go to ground. However, the AMZ Mosfet Booster and ROG Peppermill have the zener between G and S. I don't think it makes much difference, certainly none to the tone. The important thing is to protect the G.
Cool. Ill use a 12v zener anode to ground
The inventobox module SHO schem has other differences...a .01 cap and 1k series combo at the input. ...?
With the zener to ground, large negative inputs could cause the diode to conduct in the forward (non-zener) direction. Whereas with the zener to source, and the gain control NOT at maximum, there is a higher resistance path for current to flow so clipping with the same input signal will be reduced or eliminated.
Regarding the other differences, I think .01 is the standard size for the input cap on the SHO. The 1k resistor in series with the input is not something I've seen in a Zvex pedal, but it would be beneficial to the SHO because it will reduce the chance of ESD damage significantly. Of course the input should still be capacitively coupled, so in the final build you'd have cap+resistor in series going into the gate.
Quote from: El Heisenberg on October 27, 2010, 01:25:19 AM
The inventobox module SHO schem has other differences...a .01 cap and 1k series combo at the input. ...?
I already built mine point to point on top of the 5k pot and hot glued everything in place. Zener to ground. I used a .01 cap but no 1k resistor.
Alright, I need some help. I followed the OP's pcb layout except for leaving out the D1 diode and for D2 I used a 9.1 Zener diode. I have everything wired up and it has a bad hiss pretty much on any volume. I don't know much about building pedals so any help would be appreciated. Also should I put a 1N4148 diode for D1 or should I leave it out? Thanks in advance.
If I wanted to add a stomp switch... Where would that go in the circuit? I know it would probably go near the power supply however will signal still go through when it is bypassed? Trying to make a pedal... This is going to be my first project. Seems like a relatively simple one and a great addition to my pedal board.
Thanks!
If you want to know how to wire a stomp switch to bypass an effect, here are the different options:
http://www.tonepad.com/getFile.asp?id=76 (http://www.tonepad.com/getFile.asp?id=76)
Quote from: guitari89 on April 12, 2012, 01:11:54 PM
If I wanted to add a stomp switch... Where would that go in the circuit? I know it would probably go near the power supply however will signal still go through when it is bypassed? Trying to make a pedal... This is going to be my first project. Seems like a relatively simple one and a great addition to my pedal board.
Thanks!
Here's another good description of wiring the switch and LED:
http://www.generalguitargadgets.com/diagrams/switch_lo_3pdt_ig_dcjack.gif?phpMyAdmin=78482479fd7e7fc3768044a841b3e85a
Quote from: frequencycentral on February 23, 2010, 05:09:55 PM
"Newer SHO units have a diode protection circuit to keep the transistor from blowing"
So is that the 1n4148's in my layout?
........and why does the Sho have three 1/4 inch sockets?
2 outputs jacks and 1 input
Wow, didn't realize that!
What's the difference between the two outs?
I'm looking to this circuit as the next building.
To either run to two amps at one time or one amp and the tuner as well Hope this helps and it's a great build. I recommend doing the zener diode version or the one with the no crackle mod