Actually, mentioned in my 'recycled muso' thread on the P/A, is another technique, that once again, the experts decry - in fact beginners are specifically warned to NOT do this as it stops you getting a clear constant tone! :-)

The trick of one who thinks that they have 'mastered' an instrument, is to know HOW to do this, and WHEN to use it, especially when to NOT use it....

ANY unwanted movement of the player, will, especially on the larger boxes, often introduce a 'wobble' in the sound.

What happens is that if the bellows structure wobbles, it affects the steady flow of air, producing a pulsing effect.

So...

When doing one of my other 'tour de force' pieces, I can either produce a steady flow of air, or I can 'tremolo' individual notes. It shows up strongest and is easiest to learn when playing with minimal bass reeds and a single note and reed on the keyboard, but it works, once achieved, with the full sets of reeds on both sides.

I place a finger on a key, then shake/wobble that finger - not in teh in/out direction of a 'shake', but at right angles 'along the line of the keyboard face'. It looks a bit like a violin players wobbling finger on the string, funny enough... :-)

Simple - it then causes the energy to be absorbed in the air in the bellows, causing a pulse - you can then 'drive' this pulsing to get a whole range of pulsing speeds, from a slow 'wow' to a rapid 'flutter', even doing so while holding a single note.

This IS NOT really 'bellows shake' as defined, it's also a lot more subtle and less energetic.

Attempted illustration:

Da da da~~~~~~~ da da da da~~~~~


I think that concertinas could use this too...