oscillator

Sound Lab Ultimate Notes and Photos

I’ve finally completed the MFOS Sound Lab Ultimate and despite the scattered moments of irritation over the past 8 months all-in-all I think it’s come out great. I’ll assume folks reading this are familiar with DIY projects so I skip the detailed build notes and move directly to some key points that I think will help anyone who is considering building this project.

1. Read all the instructions before you start. This is a classic ‘rule-of-thumb’ and no matter how many times I ignore it, I am always reminded through costly errors that I should have followed it. For example, after spending many hours putting together my own parts list in Mouser for this project and bitching to myself that Ray Wilson should have a parts list link on his site I finally discovered that he in-fact does. Putting together a project parts list is easy when you only need 20 parts, but given the size of this project you don’t want to go through the painstaking process of doing it yourself.

2. If money permits, buy all 1% tolerance resistors. The design calls for some which are 1%, and some which do not need to be 1% but some of these are the same valued resistors. You don’t want to realize that you just soldered twenty 10k 5% resistors down which should have been the 10k 1% resistors. It’s an easy mistake to make. And I made it. Speaking of mistakes, double check your work before plugging in. notice anything peculiar in the photo below? I’m glad i spotted that error before plugging in the power supply.

3. Also, if money permits, spend some coin on good knobs. It makes a huge difference in the look and feel of the finished project. If you do use the knobs suggested in the project plans purchase extra. Many of mine arrived missing the mounting screw rendering them useless.

4. Also double check the shaft type of the knobs in the parts list. After receiving my order and setting up the control panel I realized half of them were D shaft and half were full round shaft. Mounting regular knobs on d-shaft pots makes the knobs rotate in an elliptical fashion and, although not critical, it’s a detail that just frustrates the hell out of me.

5. I struggled with what to do about an enclosure but I found this gem at hobby-lobby. It’s a painter’s box or rather “a wooden artist’s case”. Either way, it was 19.99 and I had a 40% off coupon so it was a score. The MFOS SLU fits perfectly into it with only slight modifications. The one pictured on the website looks way nicer than the one I picked up but I’m not sad. Hobby Lobby saved the day again with cheap pre-fabricated boxes for any project.

6. On the wiring side it’s a toss-up. On the one hand, solid core saves you a ton of time when tinning the ends of your wire and it’s easy to bend into shape. But when you have to run approximately 120 hook-up wires stranded may be the way to go for flexibilities sake. Your call. I’m happy w/ the solid core.

7. If you’re willing to risk it, I think it might be possible to forego the process of hand matching your transistors. I originally hand matched a couple dozen xxxx transistors and they needed it. However, I matched another handful of xxxxx and they were all within .002mV as per the specs. Perhaps it was a fluke, but building the circuit, and then actually testing the transistors took all night one evening.

Workshop Osc Machine (W.O.M.)

An excellent thread detailing a build of the ‘Workshop Oscillator Machine’ (WOM) via Bugbrand. The WOM is a tone generator/oscillator designed around an NXP Hex Inverter and an NXP Hex Schmitt Trigger. What i particularly like about this kit is that it’s designed with the intent of usage in workshop and educational events and includes all required parts. Although i have not personally built this kit, I suspect by looking at it that it’s a nice balance between ease of build and functionality. And if you were so inclined Bugbrand includes the schematic on their site so you could always wire one up on your own, sans pcb, and see what happens.

WOM - Bugbrand

Music From Outer Space – WSG mods completed

MFOS WSG
Usually I will just post a couple images with brief descriptions of the process behind a project I post. But with the completion of my mods to the MFOS Weird Sound Generator I wanted to offer up a couple of the dos and don’ts I learned while working on this.

Dos

  • Do buy an Alesis Quadraverb on eBay for 10 bucks and use the 1 space rack case instead of buying something new.
  • Do save the seemingly useless Alesis front panel because you never know… you might need it (and I did).
  • Do take the time to measure twice, three and four times.
  • Do be prepared to find out that your measurements might still be wrong.
  • Do go with your instincts and spend the extra cash to make it look nice.
  • Do use pre-tinned solid wire (and save a lot of time).
  • Do drill or punch starter holes.
  • Do look up parts you’re unfamiliar with in Mouser’s four inch thick hard-copy catalog. It’s far easier to get an idea of what your actually buying sight unseen.

Don’ts

  • Don’t waste three weeks comparison shopping at on-line front-panel design shops. You spend a lot of time learning stripped down versions of proprietary CAD tools that can be enormously frustrating and in the end the price difference isn’t that significant.
  • Don’t do anything less than 2mm on the width of the front panel.
  • Don’t ever go back to stranded wire.
  • Don’t pass by the $20 Quadraverb and waste two and a half weeks looking for a better deal. 18 days is worth the extra $10 bucks compared to the money you save from buying new.
  • Don’t rush.

And lastly, Don’t do this:
MFOS WSG

When you can do this:
MFOS WSG

This is a nice shot of the whole unit which shows the excellent work the folks at Front Panel Express did on this. If you’re considering spending the coin on a custom front panel and on the fence about it I can say without reservation that my expectations were exceeded and I will never doubt that it was money well spent. Just make sure you have your measurements right. I made a couple mistakes which I was able to work around without major issue but it was at the expense of several days time figuring out alternative solutions.
MFOS WSG

You can see more images of the final build on Flickr here…

MFOS – Weird Sound Generator

Sometimes you don’t want to have to spend hours researching designs and finding parts to build a project… sometimes you just want to buy everything you need at once, solder it up, and have fun without the worry of troubleshooting your design. At those times a kit is perfect and in this case that’s just what I did.

I’ve posted about MFOS before. They manufacture a number of kits from entry level to advanced synthesis kits. I decided to go with the ‘WSG’… or Weird Sound Generator. Ray Wilson has some excellent designs that are really fun to put together. I managed to get this up and running in a weekend without any hassles and it sounds great. It’s basically two squarewave generators with LFOs and a resonance filter. If your just starting out this is perfect… and even though I’ve been doing this for a while it was still a ton of fun. Ray’s taken all the hard work out of the process and made DIY synthesis simple, straight forward, and well documented.

He provides all the documentation you could need including wiring diagrams, pcb templates, schematics, block diagrams, and parts lists so I won’t duplicate that here. I’ll just add some comments on the build and a video of the finished project at the end of the post…

Here we have the parts list laid out…

Most of the components have been soldered to the PCB at this point. All the parts are included in the kit and none were missing.

The finished PCB sans ICs.

I used a aluminum enclosure from an old broken gemeni turntable mixer I bought off of ebay. I’ve had great luck finding things like this for 10 bucks or less sometimes and they’re perfect when you need spare knobs, op amps, or enclosures. I just flipped it upside down and took of the rubber feet. Holes were drilled using a step bit (these are a must have for drilling good holes in aluminum enclosures).

Here is everything wired up.

This is the PCB finally wired up. One complaint about this is that the holes on the PCB for all the wiring are placed all over the PCB which makes for really messy wiring. I found that extra care was required to make sure the wiring didn’t bend too much and come detached from the PCB. It seems like using headers would be a much easier way to go about this the next time around.

When I put this together I first soldered the hookup-wire to the board, then to the components on the panel which makes it really difficult to keep things neat and tidy. Next time I will wire up the panel first, then complete the board, then make my connections to allow for a cleaner layout.

Just a tip for beginners… don’t shrink the heat shrink tubing until you’ve tested your work and are certain it works. It’s a major irritation to have to remove heat shrink tubing after you’ve already… well, shrunk it.

Jürgen Haible – Tau Pipe Flanger

Jürgen Haible from Germany redesigned the Tau Pipe flanger and documented the test and build in great detail at his site http://www.jhaible.de.

His site has more information than you could ask for when it comes to synth and audio effects DIY.  He includes schematics, block diagrams, design and test notes, high resolution pictures, mp3s, external links to resources, formula calculators, spreadsheets, etc.   He does this for over 25 projects.  It’s truly impressive.  Take a look at the images of his Tau Flanger/Phaser redesign…

Tau Flanger/Phaser Redesign by Jurgen Haible

Tau flanger/phaser redesign by Jurgen Haible

Ryan BoCook – Synth DIY and A Victoreen Geiger Counter

I happened across Ryan’s excellent DIY synth and immediately recognized the housing he used for it.  It’s a Victoreen Radiological Survey meter.  You can find these in abundance on eBay for pretty cheap (which is exactly what I did).  Hats off to Ryan on this really cool modification.  You can find images and more about Ryan on his site Pickleinn.com

Ryan Bocook - Victoreen Synth

PAIA Theremax Theremin

Because of a lack of new content I’ve resorted to posting old projects. This is one of the first builds I completed somewhere around 1995, a PAIA Theremax Theremin. PAIA has been around since 1959 and has been making DIY kits for musicians for decades. In addition to several analog modular synthesizers, Reverbs, EQs, a vocoder they also have their twist on the Theremin, the Theremax.

From PAIA’s website:

…In addition to the traditional mellow sine-like tone, Theremax’s Timbre control can mix in a harmonic rich square wave to produce a signal that’s ideal for use with external filters and processors. And to control outboard units, there are Pitch and Volume Control Voltage outputs.


But the features that really set Tmax apart as a gestural controller are it’s Velocity Control Voltage (proportional to how fast you increase the Volume) and Gate/Trigger outputs. A convenient foot switch input allows muting the internal tone source without disabling the CVs…

Panel controls:

  • Pitch & Volume Trim – these control provide a vernier null of the reference and variable heterodyneing oscillators in the Pitch and Volume control circuitry.
  • Pitch CV – controls the range of control voltage produced in response to hand proximity to the vertical pitch antenna on the right side of the instrument. Clockwise rotation increases range up to a maximum of 6 Volts. This control does not effect the sensitivity of the internal pitch circuitry.
  • Timbre – controls the brightness of the internal tone generator. At full counter-clockwise rotation the output is pure sine wave. At full clockwise rotation the output is a square wave. Intermediate settings produce a mix of the two.
  • Velocity – controls sensitivity to rate of change of volume level. At min, there will be no velocity response no matter how fast volume is changed. Rotation toward max produces increasing response. At max, the Velocity Control Voltage output will produce a 4 Volt change in response to the quickest possible hand gestures. This CV is a transient with a time constant on the order of a second. Internally, this CV biases the VCA for asymmetrical distortion, with no distortion at the min setting.(asymmetrical, transient distortions are responsible for some of the perceived “punch” in natural instrument) This control also sets Gate/Trigger sensitivity, at max sensitivity the gate will respond to very slow movements of the Volume hand.
  • Volume – adjusts the sensitivity of both the internal VCA and external Volume CV output to hand movement relative to the Volume antenna. Output level is adjusted here, but more importantly this control is capable of driving the VCA into symmetrical distortion. (symmetrical distortions are responsible for much of the “loudness” of instrument when played fortissimo)

Jacks

  • Mute – a foot switch, or S-trigger to this jack mutes the internal pitch producing circuitry. CVs are not effected.
  • Pitch CV – Control Voltage proportional to hand proximity to the Pitch antenna as ranged by Pitch CV control.
  • Volume CV – Control Voltage proportional to hand proximity to the Volume antenna as ranged by Volume CV control.
  • Velo. CV – Control Voltage proportional to how fast a hand is moved in proximity to the Volume antenna as ranged by Pitch CV control.
  • Gate/Trigger – This TRS jack provides a 5 V. gate signal at the “tip” when Velocity exceeds a threshold. The “ring” connection is an S-Trigger compatible closure to ground. The LED lights to indicate a triggered condition. (note that the gate responds to change in volume, i.e. how quickly the volume control hand is moved, not the static location of the hand)
  • Audio Out – Output level is adjustable with the volume control but is nominally -10 dB.

I didn’t have the cash for the nice wooden desktop enclosure so I built my own out of spare wood and used metal shish kabob skewers for the antennae (not pictured). The Theremin still works well to this day although I’ve always had a little bit of a problem with the volume control. The 9v DC power supply is hard wired into the unit which was a poor decision on my part. An easy fix if I ever get to it. I’ve used the gate output to trigger an old Alesis D4 with good effect. The voltage control outputs are perfect for controlling various parameters of an analog modular synth.

If you’re comfortable around a soldering iron this is a great kit, an easy build, and for just the electronic kit it’s only $115. Money well spent considering what you’re getting.

16 Step Sequncer & Synth: An Update

This is a follow up to my original post on the 16 step sequencer/synth that I posted several months ago. It’s taken some time to get moving on this but I finally ordered up 32 pots to test my design and make sure everything was working. The overall concept is to have a 16 step sequencer where each step allows you the flexibility to adjust the VCO, LFO, envelope, noise generator, and filter on each step. The sequencer will allow you to switch, for example, the VCO from individual control on each step to a global setting. This would hold true for all parameters. The sequencer will step forwards, backwards, and allow you to select how many steps to make (1-16). Each step will have an optional output that bypasses the main output when used. Finally, the sequencer section will have a speed or rate control. I’m still debating if I want to figure out how to make this sync to a midi clock or display a BPM reading. When it’s all finished it will have over 80 dials, 50 switches, and plenty of flashing LEDs for those late evening explorations. Video to follow soon…

Also, I’m getting to the point now where I need to consider what type of enclosure all this will go into. I’m looking for carpenters, machinists, and artists to talk about unique ideas and options. If you interested shoot me an email.

Synth - Sequencer

Here we have 32 pots temporarily wired up on a piece of cardboard. This was the cheapest and most reasonable way to wire up the amount of pots for just a test circuit. I do this frequently when I need a quick mock up for controls. These are 1M linear taper pots and they’re all wired with a common ground and then each one is individually wired to a multiplexer input. I should be able to just take these out of the cardboard and drop them into the finished control panel when it’s completed.

Synth - Sequencer

This is full shot of the prototype prior to some sequencing enhancements. You can clearly see the leads from the pots coming into the 4067 multiplexer. It’s only necessary to run one set of 16 leads to the multiplexer, each additional row of pots can be wired to the previous with only the addition of one unique lead to the control input of the sn76477. A 555 timer is wired as an astable multivibrator for the clock and is sufficiently stable for my purposes. Although difficult to see in the image the sn76477 has a regulated 5V DC output to drive your logic ICs regardless of what your power supply voltage is. The group of black leads with green shrink wrap brings over the 4 bit binary count to the second multiplexer. In this image the binary counter is a 4520B dual binary counter. The original plan was to utilize both counters and a comparator to set the sequence length from 1 to 16 steps. The three switches at the top of the rightmost breadboard are for selecting the mix channels of the sn76477. through a combination of these switches you can include a VCO, LFO, decay, noise generator, and filter as well as bypass the sound completely. Like the pots these will be added for every step in the sequence for tailored sounds on every step of the sequence.

Synth - Sequencer

In this photo you can see some changes have been made. I swapped out the 4520B dual binary counter for two SN74LS193N pre-settable up/down 4 bit binary counters. The output of one counter is wired to the multiplexers and controls the sequence and then flows into the 4063B 4 bit comparator. The second counter is manually stepped manually with a push button switch and also feeds the comparator. Count A > count B a high signal is sent to the master reset of the sequencer counter and the sequence starts over at the beginning (0). The two switches off the side of the leftmost breadboard are required to allow for running the sequence in reverse. They serve two functions 1) to switch both counters from up to down counting and 2) to send a preset to the sequence counter on reset. Normally the counters reset to 0, but when going in reverse you want it to reset to 15 otherwise your sequence gets stuck on 0 indefinitely (due to the comparator condition always being met). Make sense?

Synth - Sequencer

This is just a close up of the hectic wiring going on. I only have yellow and white wire so it makes for a confusing time tracking down and correcting problems. In the left-middle you can see the 555 timer obscured by a couple yellow wires. Currently the frequency of the clock is variable with a duty cycle of 50%. One of the next steps is to include another timer so I can retain adjustable frequency and adjust the duty cycle to something much higher like 90%. This won’t impact the sound but it will make the LEDs flow from step to step smoothly… a totally superficial enhancement. On the lower right is a 3 input multiplexer to handle sending the reset number to the sequencer clock when running in count down mode. Another next step is to add an analog switch to replace my two toggles to switch from count up to count down mode.

Jakob Lysgaard and the Dub Siren

JakobLysgaard

Jacob Lysgaard recently contacted me while he was working on building the Dub Siren I posted here and on Flickr. His documentation and description of the required parts, where he bought them, his findings, troubles, and experience while building it is far more informative than my images and flagrant plug for Bastard Jazz.

I’m happy to see someone has not only successfully built the dub siren but is finding use for it in their performance. All the best to Jacob.  You can find the post on his blog here:  DYI Dub Siren – the complete rubdown.

Dub Siren


This little monster is a Dub Siren I made for DJ DRM (Aaron Schultz) of Bastard Jazz Recordings. If you’re unfamiliar with what a dub siren is you might guess by its name that it sounds like a siren. There are many varieties and a good deal of folks make their own:

One
Two
Three

But the tying thread is that they are usually just square wave oscillators with minimal tone and a couple controls to vary the speed and pitch of the siren. Check the sound samples at the bottom of the page for an example of this one.


This dub siren revolves around a couple of 555 timers and has four main controls. A speed control which changes the speed of the siren, a pitch control which changes the, well, pitch of the siren. A range control which changes the siren’s range and lastly, a modulator which, when engaged, alters the smooth sweep of the siren to a more asymmetrical ambulance type siren. There are two LEDs: one that flashes in synch with the clock cycle so you can see the speed in the dark and another that oscillates gently when the momentary switch is engaged. Both RCA and ¼” jacks are available and the RCAs are only active when there is not a ¼” jack plugged in. This was to prevent ground noise from accidentally coming into the circuit by inadvertent contact with the jacks. Check the full build on Flickr by the link below.

More photos, comments, and the schematic can be found on Flickr here:

SupersetSiren

Sound Samples:

Dry, without Effects

Wet, with effects