[sdiy] Cheap frequency counter for oscillator calibration

[Florian Anwander]

Hello Terry

> Just for fun, Ever try using a tuning fork and your ears? It is a bit of a
> work but the voicing is so much better on a piano.

The tune fork comes in when you want to setup the absolute tuning of the 
oscillator.

But in regard of the workflow of setting the octave width a tune fork 
has the same problem as the frequency counter. David Brown described it 
very well as "you're just chasing your tail as both frequencies shift". 
While setting the ocatve spread you have to concentrate on the relative 
tuning in the (multi-)octave jump. This can be controlled very good by a 
trained ear.

Though I have a really good hearing (I can tune a piano by ear quite 
well), my experience is that adjusting the octave width a polyphonic 
synth is extremely much faster with the described method using a 
chromatic guitar tuner.

While a piano basically is already at the right coarse tune, the VCO can 
slip through three or four notes when setting the octave spread. This is 
a completely different strain to the hearing than listening to a detuned 
piano.

Florian