There seems to be a lot of questions about oscilloscopes and how they work with audio.  Heck, I didn’t even know really what one was for a long time until the good ol internets helped me gain a better idea of what they really do.  It’s simple. They allow you to “see” audio signals or voltage rather.  This gives the viewer or artist an idea of how clean the sound they are producing is.  

Simply doing an internet search for an oscilloscope can be daunting to say the least.  You will end up with everything from hospital articles, to CRT (Cathode Ray Tube) discussions and even forums dedicated to what they do. 

To say the least, I was intrigued.   By its sole definition, an oscilloscope is an instrument used to display and analyze the waveforms of electronic signals,  In other words, it draws an electronic graph of signal voltage as a function of time. 

Now, with all this being said, I have a dire love for modular synthesizers and found myself doing more and more research on modules and how they are used.  I found one that allowed an oscilloscope to be hooked up directly to the module so that your waveforms could be viewed right there on the spot.  Now, why would one want to do this or use this in their rack?  The simple answer is to make sure the waveform (sound) or CV (control voltage) is “clean” or free of noise.  Confusing eh?  Think of it this way… if you have extra glitches in your audio, the audio can sound more garbled or distorted (and not in the good way).  

After seeing all this and reading about oscilloscopes, I decided that instead of investing in the eurorack module to take up more space in my rack, I would just build an external oscilloscope to plug it in when I felt I needed to.  I found myself scouring the internet once again for DIY kits and cam across the DSO0138 Oscilloscope kit.  I picked one up off of eBay and began my journey into a whole new world of sound analysis.  

First let me say this… the build itself was difficult to say the least. The instructions were not very clear about what went where and what was what but, with the help of another DIY kit I previously built (transistor/resistor/capacitor tester), I was able to figure out what resistance each of the resistors were.  I took the time and tested every capacitor, resistor and made sure to keep track of them in a compartmentalized case so that the build would be easier in the long run.  After popping in all of the components, I soldered them all to the board and continued ahead, one piece at a time… double checking each step along the way with the terrible schematics that were sent along with the kit.  I did a couple of YouTube searches and found similar builds that I could reference, as long as I continually paused.  

All in all the build went smooth.  I had to contact the company that sent it to me because a few missing pieces to attach the LCD screen were missing, but they quickly sent them right over within a few days.  Upon getting everything installed, double checking my work and purchasing a 9v power supply, I plugged the scope in and to my surprise, it booted up immediately.  Confused?  Well I was. I didn’t know really what I had just done or built besides knowing the basic concepts of a scope.  I went through the calibration process and next thing you know, the scope was calibrated and ready to let me see the beautiful waveforms of the audio I had been making for all of these years. 

Update:  After spending time to get to know the DSO138, I can say that I am impressed by its simple design and functionality.  I did buy an acrylic case for it and have ordered a couple adapters to make testing a bit easier with different audio sources.  One thing I can say is that its been fun and I felt very accomplished by completing this build.  I had built many modules before, but this one was a bear for someone still considered new to the soldering world.  I do recommend that one buys quality soldering tools and has the correct setup to complete a build like the DSO138.  This would include: 

  • Solder w/flux 60/40 – .08m 
  • Soldering Iron 
  • Desoldering Pump
  • Helping Hands or some sort of PCB board holder
  • Magnifying glass with light
  • The YouTube app – this was essential in the build. 
  • Patience
  • Transistor/Resistance/Capacitor Tester 

If you are an iOS user and you want a quick and easy scope to get to know, do a search for SoundBeam on the App Store and you can have your very own iOS version of one to mess around with.

If you would like more view high res photos of the DSO138 build and some of the tools I used in the build, please check out the gallery below. 

~ fiN