Resources to get started making stompboxes

Getting Started

Someone asked me about getting started building stompboxes, so I thought I’d put it all in a forum post, for your enjoyment and edification.

Become a member of both of these forums. Search, and read what’s posted there. Post your work, and your questions. Lot’s nice knowledgable people.

Probably the oldest stompbox forum around. Really friendly and helpful people. Lots of good info.

http://www.diystompboxes.com/smfforum/

Another great forum, this one has been around for a while.

http://freestompboxes.org/

This forum, ostensibly, caters to the subject Madbean PCB projects, but the people here talk about everything. Not much traffic as the other two forums.

http://www.madbeanpedals.com/forum/

Kits

Probably the best kits out there. This would be a good place to start.

www.byocelectronics.com

Parts

While you were able to get enough parts to make a couple stompbox projects at RadioShack in the past, these you can’t really get more than a cell phone’s there. Sadly there are no brick and mortar stores that cell stompbox parts. Then again you can

Mouser All purpose electronics supply.

SmallBear The original stompbox supply

Mammoth They have everything, good quality, order boxes in colors, and pre-drilled

Pedal Parts Good prices for boxes

Tayda Cheap, good range of parts.

Futurlec Good prices, slow shipping.

Bitches Love My Switches (Yes, that really the name) great prices, prompt shipping. Good for switches, knobs, and jacks.

PCB

After building a few kits try building from just the PCB. You’ll have to source your own parts.

http://www.madbeanpedals.com/projects/index.html

These are very well done PCBs. I have built the the delays.

http://1776effects.com/

http://www.guitarpcb.com/

Here are a few more sources for PCBs, I haven’t tried these

http://lectric-fx.com/

http://diyeffects.com/products.htm

After you make a few projects you might want to try making your own PCB.

http://dirtypcbs.com/

This site is something special. It allows people to upload their PCB designs, and open sources them to the greater community. The prices look good.

https://www.oshpark.com/

Experimenting and making your designs

Get yourself some parts and a breadboard. Build a test rig, and an audio probe, and you’re in business. Besides the forums above, these sites have some information and projects to try.

http://www.runoffgroove.com/articles.html

Download the Stomboxology Article: Going Discreet. This is a great primer on transistors.

http://www.moosapotamus.net/

Sort of the grand daddy of stompbox info

http://www.geofex.com/

 


OSH PARK

This is a really cool service that manufactures open source PCB designs. You can order any of the open source designs on the site. Most of the stuff is not stompbox oriented. It takes a little google-fu to search up stompbox projects. You can also upload your own designs.

You have to order 3 PCB minimum for each board you order. The orders seem to get ganged with other orders so it sounds like your order doesn’t get printed immediately. That said the prices seem very reasonable.

https://www.oshpark.com/

I just placed an order for a few PCBs. I’ll post again when the order comes in…


Good Articles on CMOS Chips in Stompboxes

Here are some good articles on using CMOS chips in stompboxes.

http://www.parasitstudio.se/building-blog/cmos-workshop-part-1

http://www.parasitstudio.se/building-blog/cmos-workshop-part-2-square-wave-fuzz

http://www.parasitstudio.se/building-blog/cmos-workshop-part-3-octave-down

 


Millenium Bypass – Working!

Millenium problesm all solved with the help of R.G. Who kindly pointed out that I probably didn’t have a path to ground on the out put of the effect. Which was exactly right.

After having the Millennium work so well on the SHO, I decided to add one to a Fuzz Face. This Fuzz Face is the First DIY guitar effect I had built. It was built around 2000. Back in the “olden” days it was hard to get 3PDT switches. I seem to remember buying a Fulltone labeled switch from Small Bear, that cost about $13 at the time! So the carling switch was the say to go for DIY.

This is really  Joe Gagan’s Easy Face, which is essentially a Fuzz with variable input cap and Si Q1. This thing sounds pretty good, though I think when I first built it I didn’t get it. Now days I like a lot.

The problems with adding LED to this Fuzz Face is that the circuit is Positive Ground. Nothing a quick Google search can’t solve these days, Of course all paths lead back to the DIYStompbox forum where I found a simple solution using a PNP-2N3906.

Managed to get this working in less than an hour. I used 10K current limiting resistor with and a super bright Blue LED. The Bezel is from Mammoth Electronics. I like these bezels the little stopper is made of rubber and fits into the bezel well.


Millenium Bypass, not so fast

I built this last week, see the previous post. Everything seemed fine on the bench. Today I gave it a test with the band. Seems like it is not working quite right. The LED lights when the effect is on. But, when the effect is off the light slowly turns on over a few minutes. Turning the effect on and off again resets the light. Not sure what is going, need to read the documentation over at GEOFX a few more times…


Millenium Bypass

This is one of those things that has been around for a long time. Back in the olden days when the 3PDT switch was hard to get and cost as much as all of the other parts that went into a box. There was a need for a status LED that could be operated from a DPDT type switch.

Then there was the 3PDT revolution. The blue switches became cheap and plentiful. I had bought a few of the Carling DPDT switches before the revolution. Still having these around I threw one into an SHO clone. I figured I wouldn’t need an LED. Over time I found myself using this more often than anything else. I had built another with a 3PDT and an LED, but I gave this to a friend. You can’t let your friends run around using your products without and LED? They will start saying things to people like: “this thing is great, just wish it had an LED…”

So anyway, I finally decided I’d put an LED in my SHO, and of course I don’t have a 3PDT on hand! Which of course brings us back to the Millennium Bypass. I had  never tried this before. I found a Vero layout, 4 by 5, on DIYStompboxes. Built the whole thing in 15 minutes. Worked like a charm!

The box I had was not originally designed for an LED. So I found some empty space and drilled a hole. I mounted the tiny circuit board from the LED, which was attached to the bezel.

I used a bezel from mammoth electronics. These look like many of the other chrome bezels of similar style. What’s nice about these is they have rubber, rather than plastic, plug to hold the LED in. This makes a nice tight fit and doesn’t leave you thinking it might come loose.

(Note sure what happened, but all of the pictures above seem to have imported upside down?)


Mold Spore Psycho-Scumatic Wah and Ring Modulator

Sounds like something from an old Bugs Bunny cartoon. Though it might have appeared in a Warner Bros. production it could have easily added to a sound track. Looks like it should be on the floor of your custom van, the one with custom paint and interior.

This is the Snarling Dogs Mold Spore Psycho-Scumatic wah. We’ll call it the Mold Spore from here on out. It is a combination wah and ring modulator. Yep, you read that right, wah plus ring modulation.

For those of you who are not familiar with ring modulation a short description is in order.

Ring modulation, also known as balanced modulation, is a process that combines two signals using a mathematical function. The two signals are the input, your instrument, and the carrier frequency. The carrier frequency, in the case of the Mold spore wah, is an audio frequency generated inside the device. The mathematical function is the sum and the difference.

For example, imagine you played the note A 440hz and the internal carrier frequency is 600hz. Feed these both into the ring modulation circuit and it outputs:

1040 (440+600)
160 (440-600)

Generally speaking, this produces a non-musical tonal relationships. The classic sample of ring modulation you may be familiar with is the voice of the Daleks on Dr. Who.

The Mold Spore wah, not only provides typical wah sounds, it also provides ring modulation sounds and it allows you to control the carrier frequency with the treadle. You can actually have the wah and ring going at the same time and control both with the treadle, neat!

The Mold Spore wah sports several controls.

  • Range, with three settings, White Room, Voodoo and Shaft. This sets the range of the wah effect.
  • Preamp, which acts as a boost.
  • Mix, mixes the source with the ring mod sound.
  • Frequency, sets the carrier frequency.

There are two push button switches:

  • Range, which sets the range of the carrier frequency to either a higher or lower frequency.
  • Control which allows the treadle to control the carrier frequency or not.

The enclosure and general structure is pretty well made, very solid. The whole package is heavy and feels very solid.

Inside the wiring and soldering leaves a little to be desired. I’ve had the thing for some years and it still works, but have had to repair it a few times.

Recently, I broke it out for fun, and the ring mod was not working. After opening the box I noticed one of the chips had a hole, which looked to be burned from the inside out.

The chip was a MAX1044, this is a charge pump. The ring mod section probably requires +9V and -9V. The charge pump generates -9V from the regular +9V supply. This allows the mold spore to run off a standard +9V supply.

These chips also cost $2 to $5 ouch! Luckily I had a few in the parts bin. This particular chip was installed in a socket, where the other chips are soldered to the board, which suggests they had problems with this chip, or at list anticipating trouble. This made it easy to replace.

Anyway, I replaced the MAX1044 and the thing fired up immediately. He ring modulator working in all of its sonic glory. Of course the suspicion of something going wrong was in the back of mind. A quick check did not detect any chips showing any signs of over heating.

The Mold Spore runs off a 9V battery, but the charge probably drains the battery pretty fast. best to run this one from a power supply.

Sounds

The wah alone is a very usable. The three settings provide a lot of choice, though I find myself using White Room most often.

The boost is a nice added bonus. I wouldn’t use it just for the boost alone.

The ring modulation is not an effect you will find yourself using often if it all. Then again if you’re in the mood to make dissonant noises it could be just the thing you’re looking for.

As explained above the effect is based on a non-musical function. In general this is true. There are times when the ring mod will produce musically interesting tones. Being able to control the carrier frequency with your foot allows you to ”tune” the effect as you play. Admittedly his is not as easy as playing the wah by itself. The addition of treadle control of the carrier adds a significant dimension to the ring modulation effect.

The ring mod can also produce interesting and musical sounds if he carrier is tuned to a pitch that produces musical tones around a tonal center.

These ideas give you two strategies to using the ring mod. Tune the carrier with your foot, or tune the carrier to a note central to a musical phrase or section.

The ability to control both the wah and the carrier frequency with treadle at the same time adds another dimension. Using the wah with the ring mod works best when tuning the frequency of the carrier and not controlling the carrier frequency with the treadle. Then again controlling both with the treadle sounds pretty crazy.

The wah works well with other effects. I get great sounds putting fuzz before the effect. This creates a really synthy sound with a octave down type fuzz. We’re talking MXR Blue Box type effects.

The Mold Spore’s sounds are both capable and unique. The ability to control the carrier frequency with the treadle adds new dimension to the ring modulator.


Eagle PCB – Autorouter

Obviously it would be great if a schematic would lay itself out. Eagle and other applications have included Autorouters, that do just this, for years. In the case of Eagle this was a feature you had to pay for. Until recently, well recently in years. Of course the computer in this case can not do a better job than a human brain. That said it can do the job much faster.

Read on!


Box of MOSFET

Rock Box!

I was talking to a friend about distortion boxes and the Box of Rock came up. Which got me thinking, I’d never heard one before, and Z Vex always makes good stuff. I found a schematic in the usual place. It looked like a pretty easy build.

The Box is basically two pedals in series, a distortion followed by a booster. The Box has two foot switches, The first switch engages the distortion and the second engages the booster. The controls for the distortion are Gain, Tone and Volume. The booster adds a fourth knob, Gain/Boost.

The distortion section is made of three BS170 MOSFet stages. The first stage is a SHO followed by a Marshall style high pass filter made of a 470p cap and a 470K resistor in parallel. Then come two more BS170s configured gains of approximately 51 and 15.

Next is a BMP style tone stack followed by an extra low pass filter. The low pass filter is exactly the same as used in the BSIAB II. The BSIAB II also uses the same Marshall style, 470p and 470K, high pass filter between the first two stages.

The B of R includes an SHO booster on the output. I had one of these built already so i decided not to build the stock B of R and instead build just the distortion section. I figure I can place my SHO or any other booster after it for different sounds.

Read on!


Ugly face with tone control

The Ugly Face has an interesting set of options. The Threshold knob has to be the most interesting though least useful. Last year I thought I’d add a tone control in it’s place. I wanted to build an Ugly Face and keep it in 1590B sized box. This format makes it hard to fit more than 4 Knobs. I decided to drop the Threshold and replace it with a Big Muff style tone control.

This was a pretty easy project, I already had a PCB and all of the parts on hand. The PCB I had did not have any space for the tone control. The Big Muff tone control requires, besides the pot, fours parts, two resistors and two capacitors. I remembered seeing an article on the Big Muff tone control over at Beavis Audio research where they mentioned soldering all of the parts on to the pot. I thought about this but decided against it. I have been using and planned to use these 12MM pots. Which seemed too small. Plus the box was going to be a little crowded and didn’t want to risk the parts shorting against something.

[picture of 12mm pot]

I decided to mount the tone control on a tiny piece of perfboard.Using small multilayer ceramic caps would make the whole thing fit easily.

[image of perf layout.]

Last was to run the output of the Ugly Face into the tone control before going to the volume.

[Picture the interior of the box]

I decided to do this box in a plush purple fur.


Breadboard test rig

I had been meaning to make one these for a long time. Of course, like so many other things I managed to procrastinate on this simple but practical project for years. Well I finally got around to making the thing.

I started with a length of aluminum L bracket from the hardware store. I had to buy 4 feet of the stuff. So I cut it into 4 one foot pieces and decided to make three test rigs.I drilled a hole every inch starting a half inch from the edge. This gave me 11 holes to work with. After the input, output and bypass switch that leaves 8 holes, which should be plenty for almost any project. I’m going to leave the post out and just install them for what every is currently on the breadboard.

The other parts are not too critical, figure cheap switch and jacks is not a big deal when working with a bunch of parts on the breadboard, better to save the expensive parts for the final build.

I headed to RS to some jacks and a switch. I got a big DPDT toggle switch to switch the effect on and off. I figure this will be easier to use and cheaper that using a stompswitch. I considered adding an LED but decided the extra wiring and hassle wasn’t worth the effort. LED wouldn’t add much anyway since the switch is clearly labeled On and Off.

A small patch of Velcro to hold the breadboard down. For some reason the Velcro was $6 for one foot at the hardware store! Note to self, somethings should not be bought at the hardware store, Velcro topping the list.

Here’s a few pictures of the test rig.


Octave Fuzz Take 2

Here’s an updated version of the octave fuzz. Q1 and Q2 set up a basic NPN Fuzz Face type circuit. While Q3 acts as a phase splitter. Q4 and Q5 act as a frequency doubler each side being fed an inverted signal from Q3.

So far the Fuzz section is working on the breadboard. The octave section is not working at the moment. I suspect the bias is off. Note the voltage around Q3. The collector and emitter voltages should be close to 4.5V. So far they are pretty far off.


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