A philøsøphical expløratiøn øf cøntent related tø synthesis, synth DIY, and øther music technøløgical pursuits. Written and møderated by yøur very øwn resident turd-ferg: Røsnald Fensch.  

Interstellar Radio

I joined Eric Schlappi of Schlappi Engineering for an evening of synth noodling, heavy nerding, and discussion about his forthcoming module: Interstellar Radio. At the beginning of the evening, Eric's neighbor came outside for a brief chat. He offered us some snacks which set the perfect headspace for our conversation throughout the evening. The audio clip beside has more info. 

Here's a shot of Eric Schlappin' some 0603's onto a PCB

Here's a shot of Eric Schlappin' some 0603's onto a PCB

R: What is your background in electronics?

E: I'm an electrical engineer. 

R: You've been a professional in the field, yea? 

E: I've worked in the field for 5 years. I went to school for audio recording and worked in studio and live sound which really sucked. I saw people making more money doing easier things than me so I went back to school and got my EE degree. I did that for a few years which also sucked. 

R: How much of your education applied to synthesis and audio? 

E: About 10% of it. 



R: Were there skills from the other 90% that apply to what you're currently doing? 

E: Sure, electro magnetics and physics are always useful. If I ever get back to doing digital stuff, there's a lot I learned in that department too. I took a fuckload of classes on DSP. There weren't a lot of classes for analog electronics. 

R: So where did you work? 

E: (laughs) well I um.....I worked for the defense industry for three years....I don't really like to talk about it.

R: Can we talk about it? Can I write about that on the internet or allude to it? 

E: Sure yea (laughs).

R: Were you working on weapons? 

E: Well...test equipment for weapons. A lot of my life decisions have been really ill considered. That job was from a period as a graduate where I had the mentality of !APPLY APPLY APPLY! at two in the morning while drinking whiskey. I don't even remember applying for that job. 

R: Don't worry, I'll frame it in a way that makes you look cool and not evil. What was your position? 

E: I was an electrical engineer in systems testing. We needed to test how off the shelf parts interact on a particular unit and needed the process to be automated. Naturally, that required multiple pieces of very expensive test equipment. There was a massive rack where each piece of test equipment was a separate card. This machine cost two or three million dollars in total. Each piece of equipment was around $5,000. The format was probably related to what Eurorack originally started out as. I spent months making absolutely perfect drawings. This company didn't actually make anything, they just made a shit ton of drawings and got another subcontractor to make the actual thing. There was one thing I was working on that got held back for six months because of a drawing dispute. Everything I drew had to be reviewed by a bunch of senior engineers. The head engineer was this guy who hadn't done engineering in like 10 years. He insisted that I wasn't using a squircle right. 

R: What the fuck is a squircle? 

E: So on engineering drawings the material call outs are a number inside a thing thats a square/circle shape called a squircle. He thought I was using them wrong and rejected all my drawings. I read all the squircle standards and figured out I was right and brought them in to show him. We got into a yelling match during a meeting about the use of squircles and then my boss was like "don't worry about it, no one likes him he'll be fired in six months." The project was held back six months because we couldn't agree over a standard on how to label a drawing for a cable. I don't want to work for a place like that again. We spent thousands of dollars arguing over a cable! A simple cable! That's how defense contracting works. 

R: Your first release is Interstellar Radio. Have you put stuff out in the past? 

E: This is my first release. There's a certain part of me that felt I should follow the traditional path, you know clone some stuff and release some kits. Maybe do that for a few years and then eventually put something out. I don't have time for that right now. I made a thing I think it's pretty cool, let's just build it and see if people like it. 

Proud papa

Proud papa


R: Amen to that dude. What inspired you make it? 

E: I was working for this medical company prototyping this device that smashes kidney stones. It used 20 kilovolts at 9000 amps to achieve this task. There was an issue with electro magnetic interference everywhere and machines would just break. I had to design a bidirectional voltage to optical pulse converter so voltages could be sent optically without having the grounds of different parts of the system connected. During this process, I found this circuit called a "voltage to frequency converter." I realized that if I eliminated the optical transmission and played with the sample rate I might have something useful for audio. I thought it would be more like a bit crusher but it isn't. I actually want to do more contract work that's outside of synthesizers for this reason. I think you get good ideas by doing work that isn't related to audio. 




R: What's the basic signal flow of Interstellar Radio? 

E: The input gets converted into a high frequency pulse train in a synchronous manner which gives you control over the pseudo sample rate. This gets fed into another synchronous voltage to frequency converter wrapped in the feedback loop of a phase-locked loop which demodulates the signal. If you use a PLL by itself it is essentially a phase comparator and an oscillator. The internal oscillator latches onto whatever frequency you feed into it. You don't have to use the internal oscillator, however. You get different control laws If you wrap other oscillators into that PLL loop. It's a simple device that creates really weird complex things becaues the way it locks onto a signal is kind of magical. 

R: Sounds like a mouthful. 

E: It's only semi scientific. It started in a scientific place but once I started trying to make it for sounds, it's less like the thing it is theoretically supposed to be. After the adjustments, it's more fun to use in what I believe is a musical context. Whether or not that works for anyone else's musical taste I don't know. 

R: So it's not a radio? 

E: No, it's not a radio. 

Ross FishComment