RunOffGroove 22/7 Build

Here is another 22/7 build. It’s a Big Muff variation. This unique circuit replaces the transistor stages of the classic Big Muff with CMOS inverters. It’s a unique flavor of Muff. CMOS inverters have their own unique flavor of distortion and have been used in many classic pedals like: Craig Anderton’s Tube Sound Fuzz, Way Huge Red Llama, Blackstone Appliances MOSFet Overdrive.

The 22/7 was created by the unstoppable genius over at RunOffGroove.com. They have a lot great stompbox designs and great information, be sure to check out their site.

Build your own

I designed the PCB and created a project over at OSH Park. Check out my build Docs to read more about the circuit and learn how to make your own! The PCB is designed with the the pots, switch and LED mounted to the board for ease of assembly.

Build post here for parts and PCB: http://www.super-freq.com/22-7-on-osh-park/

Build Process

For this build I used a powder coated enclosure and milled the labels and logo through the powder coating with a desktop mill. This process works for me and I can do everything myself at home with no chemicals and little set up and clean up. I want to give UV printing a try in the future, I’ve seen a lot great results! I’ll be writing a blog post about it in the future.

What’s it sound like?

Sounds a lot like a Big Muff but with its own character. The hex inverters have their own flavor but the strong clipping inherent in the Big Muff architecture dominates the sound giving it the characteristic Big Muff sound. I suspect you hear hex inverters as the last inverter is overdriven by the rest of the circuit. I’d say you get the classic Big Muff clipping sound but you don’t get the over saturated sound you can get with a Big Muff when the input is too hot or the sustain high.

The 22/7 has a switch that changes the range of tone control through three different ranges. This changes the range and sweep of the tone control to match other big muff models. There is a Classic option which is described as an average tone model of classic Big Muff models. A Flat option which creates a flat tone response removing the mid scoop of the classic mode, this is a well known mod. Last is the Scoop mode which creates a deeper mid scoop, I compare this to the sound of the original Way Huge Swollen Pickle.

I like the last mode on its own, but the flat mode sounds better with the band. writing this in 2021 I’m spending all of my time playing at home so all the modes sound great!

This has been my favorite Big Muff of late! It’s got a good sound and the tone control hits a very usable range.

Haunting Mids Reflection

The goal of this project was to build three Haunting Mids, keep one and sell the other two, hopefully coming out ahead!

This post covers the original Haunting Mids Fuzz. Note! This is not the JHS pedal with the same name.

What is Haunting Mids?

Haunting Mids is a Big Muff variant. Besides careful choice of resistors, capacitors, and diodes the biggest change to the circuit is dropping the tone stack and the output buffer. This offers the sound of a Big Muff but with more hair and volume. It’s really loud. You hear the raw distortion from from the two clipping sections unfiltered.

In the original the Sustain control is meant to be an internal trim pot, set and forget. With only the volume control on the outside of the box. I decided to put the sustain control on the outside of the box for convenience.

The original is a must have for people who like single knob boxes!

I found this PCB for Haunting Mids while searching for DIY projects on OSH Park.

https://oshpark.com/shared_projects/JtR27cHU

It’s a well laid out PCB for a 1590A sized box. I ordered three of these and built them successfully. This board works well I would recommend it. The switch is mounted to the board which saves trouble wiring.

A little History

The Haunting Mids Fuzz was developed around 2005 by a group of DIY pedal fans who set up a private forum, which I’m guessing was dedicated to the development of the Haunting Mids circuit. I say “guess” because I was never a member though I had heard of the forum.

Not sure when but the Haunting Mids forum died and went away. Go figure, an anti social site is going to have growth issues. That said there is something pleasant about discussions with a small group of like minded individuals rather than everyone and their friends and family.

It seems that Haunting Mids has gone through a couple iterations. The board linked above is labeled v3. You can search Haunting Mids and you’ll find several versions. To my knowledge all versions are based around the Big Muff sans tone and output buffer.

At some point JHS made a commercial pedal with the same name. I’m not sure why they did this. I suspect it was joke, or some sort dig at the original Haunting Mids group, or they just wanted to get a media boost by piggybacking on the name. I wish they hadn’t done this since it makes researching the circuit more difficult.

What’s it sound like?

Sounds like a big muff! It also has its own character like all of the other Big Muff variants, which the world of pedals is full of. But the two cascaded clipping sections guarantees you get the classic Big Muff character. Without the tone stack you hear the clipping section raw and unfiltered! It like a big muff with all the hair and grit.

This demo compares five different DIY Muff variants. Haunting Mids is in the center.

Here’s is another demo of the Haunting Mids:

Build

I built three of these. The parts were were all easy to find. You can get everything at Tayda. I chose to build mine with two knobs and put the Sustain/Gain control on the outside of the box.

I like having the sustain/gain control but the range is not that usable, or maybe there is some less useful range. With the gain up all the way there is too much gain. On reflection I see the reasoning behind making this control an internal set and forget option. I think I might go this route for future builds!

The PCBs from OSH Park are designed for a 1590A enclosure. I decided to build two in 1590B enclosures because I like these better than the small A sized boxes. I did build one in an A sized box.

Costs

This is a pretty cheap box to build. None of the parts are expensive or hard to find. You can source everything from Tayda and order boards from OSH Park.

Ordering the boards from OSH Park requires that you buy three boards but the cost is $14.85 which is about $5 a board. Making the board the most expensive part unless you get a fancy enclosure. The overall cost was about $25 for all the parts to build a single box.

I built three and managed to sell two on Reverb. I kept the last for myself. They sat on Revered for a month or two but eventually sold for $220 (both) not including tax and shipping. Reverb took their cut which left me: $202.50. I spent roughly $75 to build all three so I cleared $127.50.

Boss Muff

I love Boss pedals, they are bomb proof, have a great form factor, work well, and look great. They don’t make a couple effects that I like. For example you can’t get a Big Muff in Boss. I had the idea to rehouse some effects in Boss enclosures. Here is the Boss Muff.

The Boss Muff is a Green Russian Big Muff in DS-1 enclosure

Sourcing enclosures

I couldn’t find empty Boss enclosures for sale anywhere so I had to recycle. Boss pedals keep a good resale. It’s hard to find these for less than $40. Often used Boss pedals go for $100 or more. I didn’t want to pay $40 for an enclosure but I wasn’t going to pay $100, especially for something I might want to keep.

After some research on Reverb I found the Boss DS-1 was cheapest. Typically they go for ~$40. The historical prices show sales a range of $25 to $45. Reverb says the estimated price is $25 to $35.

Check out historical sales on Reverb here: Boss DS-1 Distortion (Silver Label) 1994 – 2021

Note! New Boss DS-1 and Boss SD-1 go for about $50. If you have a discount or see a sale it might be good to buy a new pedal since places like Sweetwater offer free shipping.

Watch the shipping! People will ask $15 on average which is really high for something where the asking price is $40. Typically I can mail a pedal for $6 to $10 USPS.

This is the donor DS-1 for ~$40 from Reverb.

The enclosure and parts

The enclosure is great, it’s pretty spacious, pre-drilled, and it comes with some usable parts. It’s even partially pre-wired!

It comes with jacks, LED, battery clip, a momentary SPST switch, knobs, and some pots. It also comes with a DC power jack but, this was mounted to the original PCB, there will be nothing to anchor it to when I replace the board so I couldn’t use it.

The contents of the DS-1 and the replacement boards.

The Jacks are useable and the wiring can be repurposed. There’s nothing special about these jacks. It is interesting the way they fit the enclosure. You don’t need hold them from the inside when you tighten the nut.

The LED is mounted to a small board. I used the LED and board. I just replaced the wires because I needed a little more length. The LED is a typical red 3mm type. Nothing special here.

I usually don’t use a battery but, since the clip was there and partially wired it was easier to just keep it! I wired up the battery snap for this build.

I went with a relay switching system, more on this below, the existing switch worked well for this! I left the existing switch in place along with the wires.

The pots from the DS-1 were B100k, B100k, and B20k. Since I was building a Big Muff I needed 3 x 100k pots. I kept two of the original pots and replaced the 20k pot with a A100k pot. The two B100k pots were 16mm and B20k was a 9mm pot with pins at 90 degrees. It looks like you could fit 3 x 16mm pots but I didn’t test this theory and just brought another 9mm pot.

Pots from the original DS-1 mounted to the new PCB with the original ribbon cable.

All of the pots had a small PCB with a ribbon cable running to the main PCB. I used these small boards and the existing ribbon cables.

Note! The ribbon cables use thin solid core wires. These seem like they would break easily but Boss glues both ends to their respective boards with some kind of industrial glue, maybe epoxy. I took their lead and glued the end of the ribbon cable to the PCB with some gorilla glue. The glue anchors the end of the wire where it’s prone to breaking.

They did the same with the DC jack, this type of jack is prone separating from the board on other pedals, I’ve fixed a few of these in the past. Not on Boss pedal! The jack is soldered then glued to the board! I’m surprised other manufacturers haven’t caught on to this.

I reamed the enclosure to fit a standard DC jack. I used a couple of those plastic washer to keep the jack from extending too far out of the enclosure.

The knobs are nothing special. They use splined knobs rather than knobs with a set screw. I kept the pots so I kept the knobs. I had to get a new knob for the replaced 9mm pot since I couldn’t get a 9mm pot with a splined shaft or at least a 9mm pot with 90 degree pins with a splined shaft.

Switching

Boss uses an electronic switching system paired with a buffered bypass. Seems like you could use this some how. This might be a future project…

For this project I decided on something I could more easily understand. I went with a relay switching system. This is an electronic DPDT that includes a circuit that also handles the LED. The system uses a Microcontroller that tracks the SPST, powers the LED and switches the relay.

Madbean Softie (left) and Rabbithole (right) PCBs

I went with the Madbean pedals Softie system. It has some good features. It is also true bypass. The effect path through the relay is essentially a wire connection all the way through. A nice feature of the Softie is if the power goes off it switches to bypass. The relay has an estimated failure of 100k clicks so it should outlast a stomp switch.

I chose the Softie 2 board. Madbean offers three PCB versions 1, 2, and 3. The Softie 2 is made for 1590B sized boxes. I thought this would good but I wasn’t thinking in 3D. This board mounts parts on both sides which makes it taller even though the footprint is smaller than the other boards. I still made it work but, a wider flatter board, with all the parts on one side, would work better in this enclosure.

The Softie works well. Assembly is easy. Some of the parts you’ll need to order from Mouser so it won’t be as cheap as a 3PDT switch. Wiring is easy. Overall I’d recommend this for other projects.

Cost estimate

ItemCost
Used Boss DS-1$40
Madbean Rabbit Hole PCB$6
Madbean Softie PCB$4
Relay 80-EC2-4.5NU$2
Other parts$5
total estimate$57
Cost estimate to build a Big Muff in a Boss enclosure

But What about the finish?

I didn’t paint the enclosure. This would have added a lot of time, cost, and effort to the project. Admittedly it would have looked far more amazing when it was finally finished. I was not super excited to try and peel off that rubber pad on the foot switch and glue it back on. You might be able to mask this. Also sanding the enclosure did not inspire me.

I think I might just slap a label on this to remind me what’s in the box. As it is the existing labels: Tone, Level, and Dist work for the Big Muff. Though the arrangement is not what I would have done. The small center knob is Level. Intuitively I reach for the upper left when I want to adjust the Volume. Sounds!

Here is a short video clip of a stock Boss DS-1 next to the Boss Muff. I built the Boss Muff to the spec of a Green Russian Big Muff. Not sure if I made a mistake or if it’s the nature of the green Russian but it has lots of bass. This would be great for bass.

Conclusion

So was it worth it? The whole process was easier than I thought it would be. The cost was higher than building other projects but not as high as I thought it might be. Reusing parts from the DS-1 saved on costs for pots, jacks and knobs which are some of the more expensive parts.

I could have shaved the costs down if I could have traded for a Boss pedal or watched Reverb for a couple weeks looking for a deal. I just bought the cheapest DS-1 I saw and paid the asking price. Besides waiting for a $25 DS-1 to show up on Reverb and then see $15 shipping is a little anticlimactic.

Overall the experience was informative. I think I enjoy having the rehoused Big Muff. I’ll probably use this pedal. The process revealed some of the tech used by Boss in their pedals. I’m definitely going to do a follow up…

Check out this Make Guitar Podcast where we talk about building the Boss Muff:

Haunting Mids project

What’s Haunting Mids?

Haunting Mids is a Big Muff variant. In a nutshell it’s the input buffer, and first two clipping stages from the regular Big Muff circuit. It drops the tone control and the output buffer of the original circuit. There are a few other changes in part values but the the circuit is otherwise the same.

Haunting Mids Fuzz is not to be confused with JHS pedals Haunting Mids which is a completely different circuit that came later.

I created this PCB layout from version 3 of the original Haunting Mids. I made small change by moving the sustain/gain control to the outside of the box. The original circuit used an internal trim pot with only the volume accessible from the outside.

this video compares 5 Big Muff Variants, Haunting Mids in is in the Middle


Another demo of the Haunting Mids



PCBs

The PCB was designed in Eagle PCB. You can order boards from OSH Park for fairly cheap but you must order three. You can order boards here:

https://oshpark.com/shared_projects/Wu8UpzQE

Build

this should be a pretty easy build. Without the tone control and output buffer there are fewer parts than the original Big Muff. Pots and LED are mounted to the board. And most of the off board connections are lined up along the bottom of the board for easy wiring.

The parts are standard and easy to find. You should be able to order all of the parts at Tayda.

Capacitors
C1220n
C2470p
C3150n
C4150n
C5470p
C6470n
C7150n
C8470p
C9470n
C10220n
C1147µ
Pots
VOLUME A100k
SUSTAINA100k
Diodes
D11n4001
D2 LED Red 3MM
D3 LED Red 3MM
D41n4742
D51n4742
D6 LED
Transistors
Q1BC337
Q2BC337
Q3BC337
Resistors
R133k
R282k
R3120r
R4470k
R518k
R61k
R78k2
R856k
R9100r
R10470k
R1110k
R128k2
R1382k
R14120r
R15470k
R1618k
R17RLED


Haunting Mids Fuzz schematic


The circuit shows BC337 transistors but these don’t seem to be so special. You should be able to replace these with just about any NPN device. The usual suspects 2N3904 and 2N5088, or maybe 2N5089 if you want more gain.

The diodes are the same. You can probably experiment with anything for diodes in this circuit. The choices here are interesting definitely try them. But if don’t have these parts or can’t get them use what you have!

Wiring

Work in progress

I always get into something for a while, then need to take a break. There are a few hobbies I always seem to come back to. Pedal making is one of these!

I dug out a few of the boards I started before the last break, and ordered a few more. Sat around soldering the last couple days and here we are!

PedalPCB Parentheses Fuzz

Here are three PedalPCB Parentheses Fuzz. I made a few of these before and they sound really great. This is a clone of the EQD Life pedal with a couple mods. If you’re looking for one I’m going to sell these when they are done. Currently I’m wringing on parts. That mini four position switch is hard to get. Seems like PedalPCB is the only place that has these.

assorted PCBs in progress

First are three Fuzz Factory boards. Next are three Haunting Mids Fuzz. This is the first version of a PCB i designed. I’ll post a project for this once I’ve tested it. First on the bottom row are two Nobels Overdrives. These are AionFX Andromeda PCBs. Next is a left over Vulcan, and last is a Big Muff board from Madbean. I’m going to build this using the green Russian spec.

22/7 on OSH Park

Built and test this second version of the 22/7 by RunOffGroove.com. Sounds good. This is a great alternative for Big Muff fans. The OSHPark project is public and verified.

22/7 is a Big Muff built around CMOS inverters in place of the transistors used in the traditional BMP circuit. The CMOS inverters have a tube like sound when over driven.

Order PCB here: 22/7 PCBs on OSHPARK

Parts List

Capacitors
C1        100µ
C2                   33n
C3            100n
C4             220p
C5               150p
C6                150p
C7             100n
C8              100n
C9                  3n3
C10                6n8
C11                 10n
C12                10n
C13               100n
C14               150p
C15     100n
Diodes
D1-4    1N914
D5              1N5817
D6           LED
IC
IC1       CD4049UBE
Resistors
R1      100K
R2                 470
R3       1M
R4       1K
R5      33K
R6       1M
R7        33K
R8       1M
R9        39K
R10         27K
R11                  1M
R12      1M
R13               330K
R14           100K
R15         RLED
Switch
RANGEON OFF ON 
Pots
SUSTAIN A100K 16MM 
TONE    B100K 16MM
VOLUME   A100K 16MM
Parts

Wiring

If you don’t want to build your own this one is for sale on Reverb.

Haunting Mids Fuzz (clone)

This Haunting Mids clone is on sale on my Reverb shop. If you haven’t heard of Haunting Mids, this is not a clone of the JHS Pedal with the same name, it’s DIY community variant of the Big Muff. It has a great sound and stands on it’s own in the field of BMP clones.

The Haunting Mids Fuzz uses the first three transistor stages of the original circuit but drops the tone stack and output buffer. It also changes up the regular diodes for some more carefully chosen diodes in the clipping stages. What you hear is the raw distortion from the circuit without any filtering.

The original circuit uses a single volume control with an internal trimmer where the Sustain control would go. This was meant to be set and forget. I’ve moved this to outside of the box to give you a little more control and variety of sounds.