For this year’s Gaussfest I decided to make a dub siren and connect it to Odin.
A dub siren is basically a very simple analog synth used to make sound effects for dub reggae. The original ones were a simple circuit with two 555 timers, but there are all sorts of variations on the theme. I was especially impressed by the Rigsmith GS1, which seems to contain some sort of toy sound effect IC.
I’m sure I had something similar mounted on the handlebars of my Raleigh Chopper in the 80s. How hard could it be to build one?
After some Googling and searching eBay, I found a surplus dealer selling some promising looking chips: the HK620 and HK623.
To make my dub siren I copied the data sheet application circuits almost exactly. The only change I made was to replace the timing resistor (“Rosc” in the datasheet) with a 1M pot in series with a 47k fixed resistor. I also added a 3.3 volt regulator so it could run off the standard 9V guitar pedal supply.
It sounds identical to the Rigsmith! Have they been shopping at Budgetronics too? 😀
My Tesla Guitar video has got quite a lot of views lately, so I’ll try and address some of the comments people have made on it here.
1. Yes, the sound comes out of the sparks. There are no other amps or speakers involved.
2. Yes, it sounds pretty harsh and horrible, no matter what pedals I try. It also needs a different playing style than you would use with an ordinary amp, and even then it sounds awful! Any chords more complex than octaves or fifths just sound like noise.
This is a consequence of the way the signal is processed into pulses for driving the Tesla coil. I’ve not figured out a way to improve the tone without losing the lightning-like look and large size of the sparks.
It works much better with bleepy waveforms from a monophonic synth, which is why the other famous musical Tesla coil sounds better. The only part of the video when you can actually hear a melody, is when I played a lick that I’d found to work well with guitar synths in the past.
I think some Youtube poster suggested a hexaphonic pickup and six channels of processing, one per string, and he is right, this would help a lot. But I don’t really want to build another five channels of electronics and recharacterize everything for EMI all over again. Anyway, the terrifying distortion might even be useful in some kinds of music!
3. What pedals did I use in front of it? For the video, a Marshall Shredmaster distortion pedal. It actually makes no difference to the tone, but adds sustain, which it was sadly lacking otherwise.
4. It is possible to mic it up safely, I’ve done it!
5. I’m still waiting to hear from Trent Reznor and Muse :-<
It’s not the easiest or safest instrument to practice with, but I’m working on improving the sustain and adapting my playing style to it. Watch this space for a better sounding demo!