Building a Z.Vex SHO clone from scratch

In my previous post I had some great success building a very simple boost circuit, the Electroharmonix LPB-1. While learning all about that particular circuit I kept coming across discussion surrounding the Z.Vex SHO; mostly questions of tonal comparison. So I decided to build one of those too, and was greatly excited to find this thread, which spelled it all out for me in simple terms. Here’s the circuit in a simple schematic form (I made it in ExpressSCH (on a Linux box)), then a diagram with some options. And finally one with external components that you’d find on a typical pedal schematic:

My own SHO schematic, with bill-of-materials

My own SHO schematic, with bill-of-materials

ZVex SHO circuit

ZVex SHO “diagram”

Z.Vex SHO schematic

Z.Vex SHO schematic

As you can see, it’s very simple. So much so that a fair few forum members decried it as “too simple” and in fact “retarded”. But I admit to wanting to know how Z.Vex can sell one of these circuits in a pedal for more than $150.

ZVex SHO Updated - from Zach schematic-762360Layout

As with the LPB-1 I wanted to attempt a layout myself, and do it on veroboard. This genuinely was quick easy as this really is a simple circuit. My approach as to keep the relative positions of the components on the schematic. It practically wrote itself. It turns out my own layout was wrong, and non-obvious, so I’ve replaced it (on the left) with a decent layout from Mark at Guitar FX Layouts.

Soldering was simple, and went without drama. I was able to test the circuit within the hour. It worked! When I built it I didn’t have all the hardware, so as you can see from the picture, I used a trim-pot rather than a full-size potentiometer.

SHO clone on veroboard

SHO clone on veroboard

Enclosure

Then the fun part, the enclosure! I’d been wanting to do a decent custom enclosure for quite some time, but never got around to it. This time I decided to make the effort and do something special. First step was to take some good measurements of the enclosure. I had ordered the enclosure from Small Bear, and started by spraying it a lovely fire-engine-red, using Rustoleum paint. That stuff goes on really well and I had no issues with drips or runs.

Decal

Then it came to the decal. I’m not a great designer, or at least not one dripping with amazing ideas for these things, so I looked around at other pedal manufacturers for inspiration. In the end I went for a cheesy tribute to Nigel Tufnel in the spirit of his ‘one louder’ philosophy. With my measurements in hand I used Inkscape to create a set of guides so I would know where all the hardware was going to go on the face of the enclosure. Then I made a simple panel-oriented design that would hopefully go well with the red enclosure. I had deliberately chosen the decal paper that had a white backing to it, so I knew that the upper panel would appear white. I also knew that the gap between them would contain the on/off LED, so that was intentional.

Decal shown in Inkscape

Decal shown in Inkscape

Application

Then it was a case of printing out the design on the water-slide inkjet paper (also purchased from Small Bear). Prior to printing it on the (expensive at $2 per sheet) paper, I did some trial runs on plain paper, just to check for size. You can see in the picture below how the ink looks nice and bold on the real paper compared to the plain paper.

Once printed, I then sprayed a reasonable coat of Rustoleum clear onto the inkjet waterside paper, to seal the ink without letting it run. I was surprised that even after drying for 12 hours the paper was still flexible. Next, I cut out each panel with small, sharp scissors, and made sure it all fit nicely. Finally I soaked each panel in water for about 30 seconds so that the decal was ready to slide off the backing paper. It was simple to apply the decal to the enclosure and get it lined up with the edge. It was most pleasing that my measurements were good, and also that the printer was accurate enough to obey my measurements. After smoothing out the decal with a bit of tissue I left it to dry overnight.

Decal ready to be applied

Decal ready to be applied

Finish

The next day I got things setup to shoot some clearcoats onto the enclosure. I planned on applying 5-6 coats, or until I got bored. This proved easy as long as I kept within the one hour time limit. If I waited longer than that I’d have to wait a further 23 hours to apply another coat.

Assembly

Well, it’s all assembled, and it is fully functional, but I’m not magically happy with the finish. It looks great, but it’s really really soft. It dents easily, even with cloth and finger prints. Maybe this means it will hold up really well to abuse because it won’t chip? Time will tell.

I am however pleased with the LED lenses, which I got from Mouser. Fulltone use a fresnel-type lens on their pedals, which I liked immediately. And to be honest I’m tired of the standard ‘chrome plated cone’ type that I’ve been using up until now. These ones are made by VCC and available from Mouser…try part 593-3210C (tall, like on this booster) or 593-2800C (flatter)

The finished article

The finished article

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26 thoughts on “Building a Z.Vex SHO clone from scratch

  1. SLW says:

    It looks great Simon! It is indeed a very simple circuit but I think it sounds good.

  2. Eric says:

    What are the red dots on the layout?

  3. AP says:

    Hey,

    great diagram… I may just be being stupid, but where exactly does the Output, 9v and Ground wires actually connect to? (with emphasis on the output, as I assume the 9v and ground are the holes directly next to the wording?) Also, (again, probably being a complete noob), but which resistors are which please?

    Hope you can help me out, I really want to get cracking!

    • simonallaway says:

      You’re right, I missed those on my layout. The output can come from any of the holes on the top row, where the 100k resistor meets the 10uF cap. 9V power can go into the far right hole on the second row. Ground can come from any hole on the bottom row. I promise I’ll do a better layout soon :) Thanks for pointing out my errors.

  4. Reid says:

    Hey,

    I’m a little new to pedal building. Currently, I’m working on a SHO clone of my own. I followed your layout to the “T”, but I’m encountering a problem. When I engage the pedal and turn the “Pot” there is no Boost, the signal remains unchanged. I tried troubleshooting it (replacing the transistor/ making sure everything is soldered correctly) but nothing seems to be working . The pedal acts more like a buffer than a boost at this point. If you have suggestions I would greatly appreciate it. :)

    • simonallaway says:

      The first thing I would ask is ‘what are the voltages measured at the pins of the transistor?’. This will essentially ensure the power supply is set up correctly. Let me know what you find, and we’ll take it from there.

  5. Will says:

    Hey, this is my first time at DIY. Is there any chance you can make a diagram of how to connect the DPDT to the circuit board, as well as the input and output jacks? Just a little confused as to how to do it, unless I’m missing something.
    Cheers!

    • simonallaway says:

      Hi Will! The internal wiring can be confusing as it’s not immediately obvious what’s going on, so I know what you mean. I’ve always relied on one particular diagram from the Beavis site, which is about as clear as they get:
      http://www.beavisaudio.com/techpages/StompboxWiring/

      Luckily it’s all pretty standard across nine out of ten pedals. Good luck and let me know how it goes.

      • Will says:

        This is exactly what I was looking for! Cheers! :)

      • Will says:

        The DPDT that I’ve got has 6 terminals, could I follow that same diagram but just ignore the top row of terminals? Thanks again for your help!

      • simonallaway says:

        Well, no. The wiring diagram I posted earlier uses 2 of the poles for doing true-bypass with the input and output. The third pole gets used for the LED. So you have to decide whether you want true-bypass OR an LED indicator without true bypass. I’d suggest you just buy a 3PDT and be done with it.

  6. Michael McAdams says:

    I’ve never built a pedal, but this seems like an easy enough first build, but I have no experience nor expertise in this field, but I want to do it right. Could you possibly email me a parts list with exact names and values for the parts, and maybe even where you got them? I say that because most DIY pages will have things like “.01uf capacitor”, but there is literally hundreds of”.01uf capacitors” out there, and thats not even including what material the capacitors are made of. Any help would be appreciated. Thanks! Michael

  7. juan garcia says:

    I dont know if someone will reply but: the bs170 can be replaced with what fet from here? http://www.steren.com.mx/catalogo/category.asp?c=1213&s=transistores-jfet&search_type=prod IAM FORM MEXICO THAT’S WHY IS IN SPANISH

    • simonallaway says:

      According to Jack Orman, who designed this largely similar MOSFET booster: http://www.muzique.com/schem/mosfet.htm

      “The BS170 mosfet is specified in the schematic though a 2N7000 or similar device could be used. Other alternates include the NTE490, VN10LP or Zetex ZN3306A, and the IRF511 sold at Radio Shack even works…”

      The page you posted does not contain any of those, but look at the specification sheets to see if they are similar. Or see if you can find the suggested substitutes from another store.

      Good luck Juan.

  8. captian dragon says:

    one of your diodes is backwards on your layout

  9. Dirk says:

    Why are the two cuts in the 5th row of the SHO clone layout? There is nothing else on the row, except the link from transistor to poti between the two cuts. Doesn’t it make more sense to get rid of the cuts and make the connections to the poti at the border of the board?

    The lower diode in the layout isn’t in the same direction as in the schematic/diagram.

    Can you explain how you replaced a 5k rev log poti with a 100k lin poti? Seems like quite a difference to me.

    • simonallaway says:

      You’re right about the first two points. I really should fix the layout and post a better bitmap.
      I replaced substituted the pot because I wanted to use a trimmer, and mount the while thing inside an already built pedal, and I only had a 100k. I’ll correct that too, to suit the actual pedla build I did.
      Thanks!

  10. Sam says:

    Hey, I’m a noob when it comes to building pedals. I built this more closely resembling your picture rather than your schematic. I switched the second diode around the way it appears in your picture. However, I only get clean sound, and the pot doesn’t seem to affect it. A couple questions:

    1. What voltage should I measure between the Drain, Gate, and Source of the FET?
    2. Are pins 1 and 2, or pins 2 and 3 of the pot connected to ground?
    3. I see a jumper in your picture from rows 6 to 7, is that just to line up the pins on your line trim, or something more important?

    Thanks in advance

    • simonallaway says:

      I will measure this evening and post my results. I actually gave away the pedal you see in this post, but I ahve another one inside the Box of Rok clone I made recently.

    • simonallaway says:

      So, answers…

      1) Voltages measured at the pins of the transistor.. Drain: 5.2v, Gate: 2.6v and Source: 0.4v
      2) Lugs 1 and 2 of the pot go to ground.
      3) You are right; that linkage was for the sake of the trimmer pins. Nothing more important.

  11. Vanessa Bruno Soldes

    Building a Z.Vex SHO clone from scratch | Hot Bottles

  12. […] Project : hotbottles.wordpress.com/2012/03/29/building-a-z-vex-sho-clone-from-scratch […]

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