So I promised I’d write up what we were up to at the Bluedot Festival this weekend and while I won’t be able to recount everything we did, I hope the following gives you all some idea, this was all done right underneath the amazing Lovell Telescope
The basic idea is that we hooked up a Mass Spectrometer (MS) to a modular synth and turned physical materials into audio!
If you thought Eurorack power requirements were difficult the MS makes them pale in comparison, I think I remember correctly in that there are 6 different power sources, one for each stage of the process, some of them reaching as much as 4,000V. Believe me when I say I was checking the voltages we were using with a multimeter before they got anywhere near my modular
Anyway, it just so happens that the voltages output by the MS that represent the materials analysed are 0-10V. A little bit of hardware hacking and this voltage was exposed via a mini jack socket so it could be taken directly into the modular.
Here’s a brief overview of how it all works it is a single quadrupole LC/MS which stands for Liquid Chromatography Mass Spectrometry. It is used to analyse solutions of molecules using electrospray ionisation
- sample must be in solution could be ibuprofen dissolved in methanol
- sample goes into a syringe pump that squirts it really slowly into the electrospray probe which starts the ionisation process
- electrospray probe consists of a very very small tube inside a small a tube connected to about 4000 Volts
- The sample is squirted through the inside tube, nitrogen gas flows through the outer tube so the sample is nebulised from the probe. The droplets produced are charged due to the 4000 Volts
- Around the outside of the probe there is another flow of nitrogen gas which is heated, this helps to evaporate the solvent from the droplets
- Once all the solvent has evaporated (droplets get smaller) the charge is left on the ibuprofen molecule and turns it into an ion (an ion is a charged molecule or atom)
- Ions due to their charge can be moved by electric or magnetic field
- The mass spectrometer must operate at very high vacuum almost like being in space, this is generated by turbo molecular pumps which look like small jet engines
- Ions are sucked into the mass spectrometer
- The ions then fly through the quadrupole mass analyser and hit a detector
- in very simple terms when a low voltage is applied to the quadrupole the low mass ions can fly through and hit the detector. when a high voltage is applied to the quadrupole the high mass ions can fly through and hit the detector.
- The quadrupole is scanned from low mass to high mass to generate mass spectra
- The output from the detactor will also be used to play music and generate visuals
Using the voltages for control signals was the original idea, but as the data tends to form spikes quite a lot of processing was required to bring the signals into a usable range. However, we also realised that we could use the output as a direct audio source in a single cycle waveform oscillator and because each material produces a different waveform, we should get a different timbre for each material.
As you will probably know already, the ER-301 is perfect for this kind of audio manipulation!
Here’s a photo of the output from the MS displayed in the analytical software on a computer:
And the same waveform recorded into the ER-301 (keeping gear clean in a field is challenging!)
Injecting the MS with a solution of Ibuprofen:
Turning it into music:
And here’s the audio, a nice evolving drone accompanied by Beth playing her Melodica:
We are planning to do more events using this technology as the response was absolutely fantastic, so many people came by and couldn’t believe what we were doing. Being able to show both the MS and modular waveforms on an oscilloscope and manipulate the audio in real time in response to the materials being analysed in a meaningful way kinda blew peoples minds
Only other thing I would like to say is a huge thank you to the Bluedot festival - a very family friendly and civilised festival with an incredible array of stunning musical performances - Orbital were out of this world!!