Reply To: Reed tuning table

Antonio Freixas

Daren, good luck with your tuning bench!

I’m going to make some comments that are based on theory and not practice. The best advice, of course, would be from someone who has successfully built a tuning bench for a melodica (I wouldn’t assume a tuning bench for an accordion would work equally well for a melodic–it might; I just wouldn’t assume it would).

My physics site has languished as I’ve tried to come up to speed on the fluid dynamics. I’ve created a few models of reeds and run them in SimScale to check on air pressure and velocity.

When you are playing a single note, the amount of air that flows through a reed is equal the amount blown in–not more, not less. However, one can “shape” the airflow by trading velocity for pressure and vice versa. This could affect the pitch of the reed.

Using the wrong “shape” may cause reeds that are perfectly tuned on a bench to be off pitch when mounted in the melodica. While I don’t have any practical experience with this, I have run into some accounts where people noted having this problem. I wish I could give you a citation, but I’ve done a LOT of reading in the last few months and I’m not sure where I saw this.

Back to theory: it would seem that the most successful tuning bench would be one in which the airflow mimicked that of the melodica as closely as possible. The big problem with tuning with the reeds in place is that one needs to install a lot of screws in order to test the tuning. Perhaps a good melodica tuning bench would use an air chamber that could be quickly sealed and unsealed. I could imagine a system where a lever could be used to lower a cover and seal a chamber containing the reed. So: file, lower the lever, blow, check tuning, lift the lever, file, repeat.

OF course, if you build a simpler tuning bench and you find that, say, the notes are consistently sharp by a predictable amount, you could just tune them flat by the same amount.

Good luck with the tuning.

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