Synthicase and Softrock timelapse build video

I finally got around to throw my synths in a suitcase. It is a injection moulded case (Pelicase copy). The case consists of a x0xb0x bass synth, a Sonic Potions LXR drum machine, a Shruthi-1 synth, a MFOS noise toaster, and my DIY modular mixer consisting of mostly MFOS modules. The devices are mounted with velcro tape.

The LXR is not subjected to the best fit in the case, since I do not have right angle phono and MIDI cables.

I created a first tune with my Synthicase using the x0x as the master MIDI clock and the LXR sequencing the Shruthi. The x0x bass tune is a classic theme, probably heard before. Ok, here it goes, DJ DIYcrap in action:

By the way, the video shows me building the Softrock RXTX HF Transceiver. The video is shot using my DIY time lapse device and a Nikon D90. In other words, this video is truly DIYcrap.

DIYcrap audio mixer #3. FV-1 Reverb

This is part 3 of "building an audio mixer with effects". For part 1 go here, and for part 2, go here.

The mixer is working fine, and already has got two PT2399 circuits for delay. But now it is time to add some reverb. For reverb I decided to use an FV-1 based design. Experimental Noize has some nice small boards built around this chip, preprogrammed for different purposes. I decided to go for the SKRM-C8-R02 Mono-In/Stereo Out reverb and delay module.


I wanted to use a rotary switch to select between the different programs. The SKRM data sheet proposes to use a 74HC148 8 to 3 Line Priority Encoder for this purpose. Hence, there is a need for a small PCB to mount the SKRM and the 74HC148 (in addition to some additional components). Although I have used KiCad and OSH Park for PCB production previously, I wanted to test Fritzing for this small project.

I drew a quick diagram in Fritzing, swithced to PCB-view and the auto-router took care of the rest (at least most of it).

After a about ten days the card arrived in my mailbox.

The board came out quite nicely. Although I am very satisfied with the result, I do not think I will use Fritzing for my next project. OSH Park and other alternatives are way cheaper, and I think the Fritzing software is a bit limited compared to Eagle or KiCad (and even if the Fritzing-software is very simple to use, Eagle and KiCad are not that difficult to learn). The files are available at the Fritzing-site in case you are interested.

It took about 10 minutes to add the few components :-). It is only a 74HC148, a capacitor and a pull up resistor network.

Then I slammed the SKRM on top of it, soldered the connectors, and started jamming with some heavy reverb. But wait, I forgot one thing, namely to securely mount the PCB inside the mixer. A simple solution is to screw standoffs to the front panel, but the screws would interfere with the front panel design. I could also glue the standoffs to the front panel, but I just hate to glue things together when there is a slight chance that I might want to dismantle it later.

Hence, I created a plate to screw the PCB standoffs to, that is fastened with the rotary switch. It is designed in OpenSCAD and 3D-printed.

The above picture show how it looks like inside the mixer. Notice that the plate (in pink) is fastened together with the rotary switch.

The above picture show how the mixer looks like inside. The SKRM is driven by a LM7805 which is connected to the +12V rail (the blue heatsink can be seen on the bottom part of the picture). The circuit draws about 170mA, even if the data sheet states it should be less than 75mA. The reason? I do not know.

DIYcrap mixer. Now with reverb.

Building an enclosure for Mutable Instruments Shruthi-1

About a year ago I ordered a Shruthi-1 PCB and a Four Pole Mission PCB from Mutable instruments. After sourcing the components, it was a quick and enjoyable build. The synth has, however, been sitting in my drawer for a long time waiting for an enclosure.

First, I thought of buying the metal enclosure from Mutable Instruments. Besides the fact that the metal enclosure costs ¢55 (not a bad price, but still), I had, due to financial reasons, used different buttons than those recommended my Mutable Instruments. Since I had no intention to change those, I had to make my own enclosure.


Before bragging about my design I have to inform you that there is an excellent downloadable enclosure out on Thingiverse:284637. I tried it, but I just could not get it to print nice on my small RepRap Huxley.

I used OpenSCAD since it is Open Source and pretty nerdy. The box is pretty simple (and boxy), but takes only a couple of hours to print and consists of only three parts.

I created small cylinders for the LEDs. In this way they are highly visible on the front panel although the PCB is about 10mm below the panel. The cylinders also ensures that there is no light leakage from one LED opening to the next.

The final case looks ok. However, the Shruthi is not the easiest synth to use, at least when none of the buttons are labeled in any way. Therefore, I waned to create a panel with labels on.

Using the command "projection(cut=false)", the 3D drawing of the front panel can be converted to 2D. Then it is possible to export a DXF-file which can be imported in Inkscape. I learned this technique from this blog.

Once imported in Inkscape, I can create some text and stuff on the front panel. I used the same approach as I did on my mixer, and printed the front panel on some piece of colored thick paper.

Before laminating the paper, I cut out the opening for the display with an exacto knife and punched 3mm holes for the LEDs with a drill bit.

I had to extend the buttons with some Sugru to make the hight appropriate for the front panel. Looks a bit strange, but it works surprisingly good.

This is the final unit. You can download the design files on thingiverse if you like, and hack the heck out of it. The OpenSCAD-file is parametrized and it should be fairly easy to alter the design for whatever buttons you might have.


Here goes some additional pictures.

The front panel is secured with the nuts on the five potmeters.

The back plate is secured with the plastic nuts on the audio jacks.

DIYcrap audio mixer #2

This is part 2 of "building an audio mixer with effects". For part 1, go here.

The mixer is coming along quite nicely. Thanks to the excellent documentation on the Music From Outer Space web site and the professional quality on the PCBs, I had no problem soldering the four boards together.

The DIYcrap audio mixer

The picture above shows how the mixer looks. The different features of the mixer will be explained as we go. First, lets take a look into the assembly of the mixer.

Testing how the jack plugs and the knobs fit the front panel layout

As explained in part 1, I created the layout in Inkscape. I printed out a test on normal paper, just to check if all the knobs and plugs fitted nicely.

Running the paper through the laminator

After a few minor errors had been sorted out, I printed out the overlay on a piece of orange paper (I wanted the mixer to look a bit vintage and a bit seventees), and laminated it. This is the method proposed by MFOS and is by far the most economical approach to making synth front panels.

The panel is glued to the aluminum Bud-box

After the front panel was sorted out, it was time to fit the PCBs.

The PCBs

The PCBs are mounted on the back-plate of the Bud-box. From left to right in the above picture: Power supply, MFOS auto panner, two MFOS Echo FXXX (on top of each other), and MFOS panning mixer.

MFOS auto panner

Two stacked MFOS Echo modules

The MFOS panning mixer

All the MFOS-components are now mounted in the mixer cabinet and works flawlessly. The stuff that remains are, the SKRM FV1 reverb unit, a highpass filter, and a distortion unit. 

Testing the mixer with a function generator and oscilloscope

Thats it for now. The next part will (probably) cover installment of the the SKRM FV-1 module i purchased from Experimental Noize.

DIYcrap audio mixer #1

Introduction

During the last year I have built four synthesizers: a MFOS Noise Toaster, a x0xb0x, a Shruthi, and a Sonic Potions LXR drum machine. Hence, now I have an urgent need for an audio-mixer, and I have decided to build one, DIYcrap-style.

Modules

The mixer is based on the MFOS Stereo Panning Mixer. This circuit board uses TL071 and TL072 opamps and gives four mono input channels each with panning two effect send loops. In addition there are two stereo inputs, a headphone amplifier and stereo out to drive an external amplifier or recording unit.

I also need some built-in effects. The first effect is the MFOS ECHO FXXX. This is a PT2399-based delay module, and I am going to use two of these. Hence, they can be used in parallel (for awesome stereo effects), in serial (for super-long delays), or individually on two different mono-sources.

The second must-have effect is Reverb. I will use the SKRM-C8-R02 Reverb/Delay from

www.experimentalnoize.com. This unit is based on the Spin Semiconductor FV-1 and comes preprogrammed with a few stereo reverb and delay effects. With some additional circuitry it should fit nicely with the stereo mixer.

The last effect I am going to add is distortion (or fuzz). I have yet to create this module but i might try out the MFOS fuzz module to begin with.  The fourth module is also from MFOS and is a Stereo Auto Panner. Hopefully, this unit will provide some cool effects. Lastly, since delay and reverb does not fit nicely with low frequencies, I am going to add a variable high pass filter for the effect out part of the mixer. I might give this variable 20-200Hz filter a try.

Panel

One of the biggest challenges with the mixer is to create the front panel. Inspired by the latest Soundlab MkII from MFOS I decided to use the BUD-box AC-423. It is a 17x7 inch box in aluminium.

The status now is that I have soldered most of the boards and I have created the first version of the front panel in Inkscape.

First prototype of the layout (some text is missing)

The design is inspired by other MOTM-style synth-panels, like this one.

I also got useful tips about creating front panels in Inkscape here. Schaeffer is a popular choice for manufacturing the front panel. A more DIY-ish solution is to use LazerTran. However, I will probably just laminate an A3 paper and glue it to the AC-423 in the first version.

This project is still work-in-progress, and I will use this blog as my build log and as a place-holder for all the links I collect. 

Building a x0xb0x synthesizer

I just finished my x0xb0x synth. It is a Roland TB-303 clone which was originally developed (or reverse engineered) by Limor Fried at adafruit. The kit I built was from willzyx.com.
The timelapse video below shows the complete build. It took me about 10 hours to complete the synth, and luckily it worked straight away.

I am sorry about the rubbish soundtrack in the video. It was just about the first sound coming out of the box recorded and produced live in a really amateurish way (in other words, it is DIYcrap).

Anyway, it was a really fun kit to build. Although the kit consists of more than 500 components, it is fairly simple to build as long as you keep everything in order. All parts came in clearly labeled bags and not a single piece was missing from the kit. Willzyx is highly recommended!

Noise Toaster

A couple of months ago I purchased the book  Analog Synthesizers by Ray Wilson. I was intrigued by the book and quickly decided to build the beginners kit of a DIY Analog Synthesizer presented in the book, the Noise Toaster.

I already had a plastic enclosure and a bunch of components, so I decided to order just the PCB from Ray Wilson, and not the whole kit. Ray Wilson is sort of a DIY analog synth guru and runs the web page http://www.musicfromouterspace.com/. The web page consist of all the information you need to build the Noise Toaster. However, I highly recommend to buy the book. It is well written, and I think the guy deserves some extra dollars for running his highly informative web-page.

 

The Noise Toaster consists of about 150 components, and is a fairly easy build. The only thing i forgot while ordering parts was that the design uses a lot of E24 resistors (which I did not have) and some bipolar capacitors (which are hard to get). Besides that, the components are fairly standard.

The only problem I had after the assembly was that the white noise generator did not work at all. I traced it down to the 2n3904 transistor Q5 which was not actually generating noise. I recommend to breadboard the white noise generator to make sure you select a 2n3904 which generates sufficient white noise. Two of the transistors I tried did not actually work as white noise generators. After soldering up the PCB and mounting the switches and pots, I fired it up and enjoyed the nice sound of the synth with all its squeals and noises.

The Noise Toaster runs of a 9V battery, which must be mounted securely inside the box. I downloaded a design for a 9V battery holder from Thingiverse, printed it on my 3D-printer and "glued" it to the bottom plate with sugru. For the speaker, I drilled a 50mm hole and mounted the speaker (again with sugru).

Since my plastic enclosure was way smaller that the design presented in the book, I had to design my own front panel. I did this in gimp based on Wilsons design. As I do not have a laminating machine, I printed the front panel on a 20x15cm photo paper and cut it to its proper size. It is not scratch-safe, but seems to work just fine.

The next step is to build some additional synth boxes to accompany the toaster. Together they will rule the world of noisy analog music.