Classic Synthesizer: The Minimoog - temperature stability
So you thought tuning your synth was a thing of the past? Indeed, how wonderful it is just to be able to switch on and play without having to check your tuning every time you want to do a bit of recording or present your musical wares to the public.
Poor old guitar players still have to do it, but those clever tuning checkers are a real help and should be made compulsory for all string pluckers.
The problem with analogue circuitry is that it is inherently unstable. Take a common or garden transistor for instance. Its output current is dependent on the input current and guess what?
The transistor, which is the building block of virtually all analogue circuitry, is affected by temperature to a significant extent. So, even with all manner of compensating techniques, any transistor based circuitry is bound to be prone to the effects of temperature changes, and oscillators, which ideally should be accurate to at least one part in a thousand, are first up for producing noticeable problems.
Now you might suspect that tuning an analogue synth is as easy, with the aid of a stable pitch reference or a tuning checker, as tuning any other instrument. Not quite, because not only do you have to check the tuning, you also have tomake sure that the scale is correct.
If the scale was incorrect, then you would find that one note would be in tune but the rest would be out, which is easily checked by playing the note an octave above. So the first thing you have to know about any Minimoog is that these things need to be checked and adjusted if necessary, otherwise you might lay down a track that is impossible to overdub to in tune, even by retuning or using varispeed.
Hopefully, the scale tuning of the Minimoog that you find yourself sitting at will be very close to perfect, but if it isn't then you have a job on your hands. Since this is far from being a current instrument it would be a public service to describe how to perform the tuning procedure so that those Minimoogs that have drifted beyond usability may be fully rejuvenated. Full details shortly...