First build of 2022! This is a 4069 version of RunOffGroove’s 22/7. The original uses the 4049 hex inverter. This the same circuit using the 4069. Both chips contain 6 inverters but the they differ in format and layout. The 4049 is a 16 pin DIP and the 4069 is a 14 pin DIP. One is a drop in replacement for the other.
While it’s possible to make an adapter I decided to make a a new PCB based on the 4049 board I had already made since the board will be more reliable and make a better build than using an adapter. Now days it’s cheap and easy to have boards manufactured. The cost is around $20 for 10 boards is money well spent if you consider the time invested make boards from scratch. I had these boards made at PCBWay.com. They service is pretty cheap and easy to use.
Build your own 22/7
You can order these boards and build your own! Order from the shared service at PCBWay here. Then follow the 22/7 Build Guide.
Does the 4049 sound different from the 4069? Not that I can tell. But discerning ears might detect a subtle difference. I’d like to hear your opinions. The best thing about this project is that it this is a a great sounding circuit and it gives me a place to use this bag of 4069 chips!
You can see it has 16 pins with 6 inverters. There is a power Vdd pin 1 and ground Vss pin 8. And two unconnected pins 13, and 16.
The 4069 is essentially the same chip. Here is the 4069 data sheet. Here is a picture of the chip:
The 4069 is a 14 pin chip with 6 inverters. Pin 14 is power and pin 7 is ground. There are no unused pins.
The two chips should be the same and interchangeable. Of course we of discerning audio tastes can sometimes hear subtle differences in devices. So of course we have to build both and see what they sound like!
RunOffGroove.com has notes on building an adaptor. You can check out the instructions here.
I had the PCB designed for the 4049 already and PCB manufacture these days is pretty inexpensive. I updated my 4049 design and had some boards made. It cost about $25 for 10 boards. I figure that’s worth the couple hours time it might have taken to make the boards myself, and I get high quality boards! Manufactured boards have two sides, are pre tinned, and have tighter tolerances which allow you to get more in a smaller space. I used PCBWay.com low cost prototyping service to create these.
I updated my 22/7 PCB. I had these boards made at PCBWay.com. These boards are great quality. Very cost effective. I’m a fan of OSH Park.com. They are good when you want only three boards, are in the US and need quick shipping. The PCBWay boards are very clean, they offer a range of colors, and their design rules support smaller trace sizes. If you need three boards and need them quick OSH Park is good. If you need more than three boards and can wait for slower shipping PCBWay is the better deal.
The 22/7 is a design by RunOffGroove.com. It’s a very innovative take on the Big Muff. It replaces all of the transistors with CMOS inverters. This version uses a 4049UBE hex inverter. I’m working on a version that uses the 4069UBE. Look for that in the future!
Hex inverters have been used in many popular pedals. These have a great amp like over drive. In the case of the 22/7 I’d say the magic happens in the first and last invert stages. Looking at the schematic you can see the second and third stages use the hard clipping from the Big Muff. The first stage can be over driven from the input and the last stage can be driven from the preceding stages. I think this keeps this circuit from getting that closed off over saturated sound you can get with a Big Muff when the input is too hot or the gain is too high.
I designed this board with the power at the top and other off board connections at the bottom of the board. I used the style from PedalPCB.com. I think everyone should do this. It makes for a clean and easy to assemble board. I didn’t even have to look any the wiring diagram as. I built this one.
With the pots, switch and LED on the board assembly is a snap. It also makes it easy to remove it all from the box if necessary. The clean assembly makes for fewer errors also!
I built this one in a love green powder coated box. I had some of these knurled aluminum knobs. I really like these knobs they have a great grip and the size is good. If the line was on the top they would be perfect.
Reading an interview with the guitar player Wata. It mentions the Hizumitas, her new signature pedal from Earth Quaker Devices, being “A painstaking recreation of the Japanese alt-rock icon’s beloved Elk BM Sustainar.” I had to look this up.
Turns out the Big Muff Page has me covered with some background history and a schematic! Looks like this version of the Big Muff is most the standard circuit. The one biggish exception is that it uses PNP rather than NPN transistors.
Here is what the Big muff Page has to say about the ELK Big Muff Sustainar:
ELK BIG MUFF SUSTAINAR / SUPER FUZZ SUSTAINAR – Among the many Japanese Big Muff clones, one of the first on the market was the Super Fuzz Sustainar, a nearly exact clone of a 1972 era Big Muff made by the Hoshino Gakki company (early units possibly made by Miyuki Ind. Co.) sometime around 1973. It was housed in an identical enclosure to the V1 Big Muff with very similar graphics. These were sold throughout the 1970s, and not long after its introduction, Gakki shamelessly changed the name from Super Fuzz to Big Muff. The pedals marked Electro Sound are the earliest, and those marked Elk Incorporated or Elk/Gakki are the later made production.
The circuit is identical to a PNP triangle circuit from 1972, almost identical to the PNP circuit shown above. The only change made was the high pass cap in the tone section at C9. Typically .004µF, it was changed to 330pF in the Sustainar. This had the effect of retaining treble when the tone pot was turned to the bass side, making the bass range more useful. When fully in the bass position the overall volume level is significantly higher than other tone settings as well.
The transistors used were NEC A733. I looked these up. They seem pretty standard but lower gain. The data sheet I read shows typical HFE of 90 to 200. Looking online I found 10 for $8.65. That’s $0.87 a piece for some meh transistors. Looking in my parts bin I found a bag with some PNP types in similar gain range.
Speaking of Big Muffs with low gain transistors, I think these sound really good. My favorite Big Muff is a clone of the Way Huge Swollen Pickle Jumbo Fuzz. It uses a transistor array that has four low gain 2N3904 transistors in one device. These transistors are in the same range Hfe range ~200.
Using the PNP types would mean the circuit would have a positive ground. With the consequence of using a daisy chained power supply being all of the noise from your other pedals would be going through audio of this pedal. It would be possible to use a charge pump to generate a negative voltage from a positive supply but this seemed more work than it was worth.
Looking through my parts I found some NPN transistors that measured about 200 to 285. Which seemed in the ballpark. I decided to use these. I can use a standard power supply, and no battery.
Now I need a PCB. This would be a good test for my MiG Buff board. This board is printed with the part numbers uses by all of the schematics on the Big muff Page! I had a board and some transistors it was time to get started!
Order some boards, find a schematic on the Big Muff Page, and follow the instructions here to build your favorite version of the Muff.
Built the board on one my BMP PCBs. I had a run of these made at PCBWay.com. You can order this PCB from their shared service here.
I soldered up the boards and used what I had on hand. It was great not having to order parts. The transistors were 2N2222A types in these little metal cans. They look super old school.
Next I found a Black glossy powder coated 1590B enclosure. I setup the mill and milled the box. I spent a little time in Sketch setting up the art.
I fit the PCB, pots, and LED into the box and soldered it all up.
Then I wired it up and tested!
How does it sound? Sounds like a Big Muff! It also has some secret sauce that gives it it’s own unique flavor of the Big Muff sound. The tone Stack is has a different feel. Part of this is because the pedal uses Audio taper pots. The change in C9 also is noticeable. When you get the dial around to the bass side. The lower gain transistors provides that singing sustain and a bit of note bloom, especially when you play with a light touch.
Next to nothing. I was able to build this with parts that were laying around and left over from other builds.
Does the world need another? I wanted to do a Big Muff using those 9mm pots. These seem like they might be a good build option. I also wanted to setup this PCB to use the same part numbers that appear on all of the schematics not the Big Muff Page. This way it would be possible to easily build any version from the many schematics there!
This is a Big Muff built around MOSFet inverters in place of the Bipolar transistors used in the standard Big Muff. This is a great sounding Big Muff. If you’ve built Big Muffs in the past you should try this one.
The tone control deserves a look. It has three modes: standard mid scoop, flat response, and mid focus.
Here is a build of the Morbid Fur fuzz. There were a few errors in my first version of this PCB. All my fault. I had these boards manufactured at PCBWay. com. They do great work and have many options to choose. Like solder mask color. I wrote about their service in more details in a previous post.
This time through everything worked well. This board went together well and fired up the first try!
I followed the off-board wiring scheme used by PedalPCB with all LED mounted to the board, power at the top and the rest of the wiring on the lower edge. All of the wires that go to the switch are on a neat row where the wires can all run parallel to the switch. This arrangement makes wiring a breeze and the layout neat and tidy.