Synthesizer Build part-60: 4046 WAVESHAPER by Barton Music Circuits

This is the Barton Musical Circuits BMC33, 4046 Waveshaper from 2015. Not to be mistaken for a wavefolder. This module divides and multiplies an incoming signal by x8, x4, x2, x1, /2, /4, /8 and then you can mix these signals back together to create really awesome timbres. It's a Eurorack friendly design.

The finished module

This analog circuit uses a CD4046 PLL (Phase Locked Loop) chip in combination with a CD4040 binary counter to create new timbres and waveshapes. It outputs only squarewaves. It's a really simple concept. You take a VCO signal, turn it into a squarewave by means of an opamp comparator and then multiply the signal x8, x4, x2 and x1 while also dividing it by /2, /4 and /8. Now you have 7 signals each an octave apart and each have a potmeter to set their respective levels which go into a little mixer and are output as one new signal.

It has a Slew switch which changes the capacitor of the filter inside the PLL chip, the CD4046. With higher capacitance the tuning will be more stable (especially at lower frequencies), but the tracking of the notes is slower which you can hear as a sort of glide or portamento effect between the notes. It makes a real difference. Makes it sound more SH101 or Acid like if you rapidly change notes. Some of the sounds it can produce can sound like what you get from a wavefolder although that's a completely different concept. The waveSHAPER can produce a lot of other sounds too.

You can alter this circuit and add CV inputs for each of the controls but I didn't do that. I saw a video by Analog Output who did this and he used little VCA's made with logic chips but that will only switch each channel on or off as far as I understood. Anyway, I'll leave the alterations up to you the builder of the project.

Btw, the output volume or amplitude of the output signal can be quite a bit higher than the input signal but it won't damage anything. You could add a overall level control on the output but that would make the faceplate design too big for my taste.

Here is the schematic I used for my layout design:

There is a PDF file available on the Barton Music Circuits website which contains this schematic plus a lot of extra info. You can download it by --- clicking here ---

If you want to hear what the module sounds like, there are two demo videos further down the article.

LAYOUTS:

Here are the layouts for this circuit. They are verified as always. I used a piece of stripboard that is 24 strips by 30 holes wide which makes it small enough for Eurorack but it will be 6 centimeters deep so it won't fit a Nifty Case for instance.

Wiring diagram:

Stripboard only:

Here are the cuts that need to be made and wirebridges to be soldered in first:

And finally the cuts as seen from the component side. You know the routine but I'll repeat it anyway; mark the cuts with a black Sharpie or Edding felt pen and then stick a pin through the marked holes and mark them again on the copper side. Then you can cut the strips at the marked locations using a sharp hand held 6- or 7mm drill, or whichever method you prefer.

Here is the bill of materials:

PICTURES:

Here are some pictures from the build proces. It was pretty straight forward and the layout turned out to be faultless but I made some silly mistakes when wiring it all up. I had the wire that grounds all the potmeters and sockets soldered to the -12V connection instead of the ground and I had the input and output reversed. Can you believe it? After 60 projects I still make these mistakes. It goes to show never to let your guard down and keep working precise and don't rush it, which was my problem.

Wirebridges put in and cuts made.

Stripboard built up. As you can see I did not include the 10µF capacitors over the power rails. They are in the layout but I usually only include features like that when I have problems with hum or ripple on the voltage lines. With this design you can leave them out. You don't need 100nF bypass caps over the chips either although you can include them if you want. They're not in the bill of materials.

Here's the panel design I made for it. I really got a taste now for using waterslide paper to make these panels. It looks so professional. Only I made a mistake.... 

I made a typo. The plus signs should be multiply signs. Aaaargh!!! Oh well, I'm not making a new one. ^___^  It came out looking great. The faceplate is 10hp or 5 centimeters wide.

Front and backside view:

The module on the test bench. In the image at the top of this article you can see the finished product with knobs on the potmeters. I found these beautiful small aluminium alloy knobs on ebay. Here's a link to that item:

--- CLICK HERE ---

OSCILLOSCOPE SCREENSHOTS:

Here you can see how all these squarewaves of different frequencies are summed together and output through the mixer stage. Note how much higher in voltage the output signal is (in yellow) to the original signal (in blue). Both channels are set to 5V per division.

VIDEO DEMOs:

Here's a good demo video I found on YouTube by username Midiverse - TV. Although playing music inbetween the demo bits is not a good idea in my opinion:

And here's an other one by youtuber: Boogdish:

Okay that's it for article number 60. SIXTY!! I can hardly believe it. This site has become quite an archive for synthesizer projects and a lot of people seem to really enjoy it. Last month we passed the one million all time views!!

If you have any questions or remarks about this project then please put it in the comments below or post in the special Facebook group for this website.