Synthesizer Build part-60: 4046 WAVESHAPER by Barton Musical 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.

This project will work on both dual 12V and dual 15V.

Here is the schematic I used for my layout design:

There is a PDF file available on the Barton Musical 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 if you fit it vertically behind the faceplate, so it won't fit a Nifty Case for instance. If you use a 14hp (7CM) wide faceplate you can mount it flat and then it'll be just under 4CM deep.

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. I put in 1µF caps over the outputs because I misread the schematic at first. The dot before the 1µF on the schematic is very difficult to see but it makes no difference for the working of the module; they're just DC blockers here.

As usual I didn't include 100nF bypass caps over the chips, 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.

Synthesizer Build part-34: TRIPLE WAVEFOLDER.

A wavefolder with three folding stages which produces amazing sounds and it's very easy to build too!

I came across this project on YouTube when I watched a video by YouTuber Adamski A. called "DIY analog synth project part 18 - The Wavefolder".

So I set about building it and it came out very well so I asked Adam for permission to write an article for my website, based on his project, to which he very enthusiastically replied in the affirmative so here it is; The Triple Wavefolder.
Like I said, it's a very simple design and in my experience those work the best. This wavefolder produces sounds that I would describe as sharp or hard and accurate. In some settings it almost resembles a Harpsichord or an electric piano. They can be real speaker rippers too. If you watch Adam's video (see link above) you can listen to the wavefolder in action. The latter part of the video is full of sound samples in different settings. I also made a little demo video myself which is at the bottom of this article. The sound is very different from that of the filters we've become so used to, with their resonance and cut-off frequency. It sometimes almost sounds like an FM synthesizer. That's why this is a very useful addition to any modular set-up because diversity in sound is what we all want don't we?
Now, I built the Yusynth Wavefolder after first building this because I thought that this triple wavefolder was more of an experimental thing and the Yusynth one would be the official implementation to go into my synthesizer. But the Yusynth one only has a single folding stage and eventhough that sounds amazing too, I found that this one actually sounded even better. So I made a panel for it and mounted it in my synthesizer. The voltage it runs on has an influence on the number of folds you can get so changing the value of the 22K resistors going to the emitters of the transistors influences the behaviour of this circuit.

This wavefolder works best with Triangle or Sawtooth waves or even Sinewaves but Squarewaves pass through almost unchanged. That's convenient because squarewaves are best used for conventional filters because of their harmonic content.

Adding CV control to the parameters:
This wavefolder has in it's original form only three controls; the input level or 'Amount', the Dry/Wet control and a Saturation control. As an experiment I added voltage control to two of those, the Amount and Saturation by means of two self-made Vactrols connected between pins 2 and 3 of the respective potmeters.
These vactrols are made up of a bright white LED, a Light Dependent Resistor (LDR) and a 2K2 current limiting resistor connected together with some heat-shrink tubing that seals it off from any light from the outside.
These Vactrols both have their own level potmeter too so you can dial in the effect it has very accurately. I've had questions about what LDR's you should order for these and I really can't tell you. I had mine in stock for ages. A while back I ordered a batch of 5 x 10 LDR's from China. 5 different values with 10 of each value. They all have a dark-resistance of at least 100 Mega Ohm and a full light resistance around 1 Kilo Ohm or lower. That's all I can say. You can also buy Vactrols ready made like the VTL5C3 which should work fine here.

Even better than a Vactrol, at least for the Amount parameter, is to use a VCA on the Wavefolder input, That way you can control the level and thus the Amount by sending a Control Voltage into the VCA. This works much better and it's what Adam also demonstrates in his video. (See the 'Metalizer' project elsewhere on this website. That is in principle a quadruple wavefolder with a VCA on the input.)

In the video demonstration the vactrols didn't have that much effect but I had forgotten that the potmeters for Amount and Saturation need to be set a good way counterclockwise for the Vactrols to take full effect. And in that sense you could in principle do away with the CV Level potmeters because the Amount and Saturation potmeters have that function too for Control Voltages. But you must not forget that this module was built first and foremost as an experiment that I didn't think I would publish. 

Anyway, you could decided to leave the CV inputs out alltogether, it's up to you.

THE GAIN CONTROL:
The other thing I addressed was the fact that the Amount control is also the Amplitude or Volume control so turning it up increases the volume and turning it down decreases it. For that reason I added a Gain potmeter to the output opamp which increases the volume by a factor of 2 to 22 times!! This option is a game changer for this wavefolder especially with this much Gain! This gives you the possibility to really boost the sound output and it sounds awesome I can tell you. You can really boost the lower and mid ranges of the Amount potmeter to match the high output level when Amount is fully open. I even found that opening up the gain helps to level out the output amplitude across most of the Amount potmeter throw without really clipping the output. But even if it does clip, it adds a very musical sort of distortion to the sound. It's never unpleasant to listen to.

Here's the schematic drawing of the Triple Wavefolder by Adamski A. I have re-drawn it and added the Vactrols to it. I mention on the schematic that you can also use BC transistors instead of the 2N transistors I used, but that will influence the sound or the number of folds you get because BC transistors have a greater multiplication factor. You can of course experiment with that by setting up the circuit on a breadboard first. (Btw, the BC548 and BC558 can also be BC547 and BC557 types.) The CV-Level control potmeters are not included in the schematic. This is because I added the CV control as a bit of an after-thought to see how it would work out. Like I mentioned before you don't have to include the Vactrols and CV level controls. I leave that up to you.

(Last revised: 11-July-2020: Changed GAIN potmeter from 20K to 100K.)

Here's the stripboard layout. It's verified because I used this for my own build. All potmeters are viewed from the front side with shaft facing you!
(Wiring diagram):

(Last revised: 11-July-2020: Changed GAIN potmeter from 20K to 100K.)

Print only. Note that pins 5 and 10 of the TL084 are connected underneath the chip!!:

Bill of Materials.

15V vs 12V and de-coupling:
As you can see a very simple and easy to build project and it sounds amazing so I can really recommend trying this one out. The circuit is meant to work on a dual 15V powersupply but I tested it on 12V and it works just fine but changing the voltage does influence the number of folds you get so it sounds a bit different but it still works fine, trust me =)
I did not include any de-coupling capacitors in the schematic because I didn't use any but if you need to have those included just put a 100nF from plus to ground and a 100nF from ground to minus and place them as near to the TL chip as possible. Should you have problems with hum, you can also add a few electrolithic caps (22µF or 33µF) on the plus and minus rails like the other caps and you can also try putting Ferrite Beads in series with the plus and minus power supply input, or if you don't have them, a few 10 Ohm resistors. There's plenty of room on the stripboard for that. But you only need to do that if you're having problems with hum or noise in the audio output.

Here's a picture of the finished panel:

Here's a look at the stripboard: I see from these pictures I added an extra opamp to the output but because I actually built this module a while ago I can't remember why I did that. Probably to have more room to experiment with the output and add the Gain potmeter. Anyway, it works the same so you don't have to include that.

And, to close off this article, I made a video demonstrating the different settings and the sounds they produce. As you can read in the article, I recently changed the GAIN potmeter from a 20K into a 100K one giving a total gain of up to 22 times. This gives the option of boosting the middle range of the Wavefolder which sounds really awesome!!

Here's a video that's also posted in the "Sample and Hold" article. It's a triangle wave going through the Triple Wavefolder and then through the Steiner-Parker filter, fed by random notes from the Sample and Hold connected to the CV-2 input of the VCO.

Okay that's an other project done. I hope you enjoyed it. Check out Adamski A. 's youtube channel. It is full of awesome synthesizer projects and electronics tutorials. It's an enormous source of inspiration for anyone interested in building synthesizers.

As always, any questions or remarks, please put them in the comments below or post them on the new EB Projects Facebook Group.