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Scandalli revoxing and tuning

chj

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Hello! First timer in this forum, as well as an accordionist player and repairman newbie. A situation not without challenges, but fun. I am refurbishing a Scandalli Polifonico Brevetta fisharmonica 13/6, and I have two of them. 1963 and 1959. Beautiful powerful sound for those parts working. Internally alike, but the other one has less register choices. It will end up as one or two Scandallis, dont know yet.

A question to free reed tuning: I have removed vax and reeds in the bass section and try them on a selfmade tuning table. Setting concert pitch to 441 because that is what I measure on the basson when the accordion is mounted, I find that the free bass reeds has a mean tuning value of let's say +8cents. This is in the C3 - C4 range.

I attach two measurement graphs from an excel sheet I made in order to delineate and understand the accordion construction (and as a measure tool).

1. Scandalli 1 (The graph with the many deviations, these are actually reeds with e.g loose rivets or wax gone awry. It seems to have been used VERY much)
2. Excelsior Accordiana 320.

Would someone be able to help me evaluate what the concert pitch of the Scandalli 1 is, when I say the curve is relative to concert pitch set to 441 in the underlying calculus. Is perhaps 441 too low? Is this why I get +8 cents as referenced above?

Back to the +8cents deviation. This is after cleaning them with alcohol, a process which results in a pitch raise of approx 5cents or more, depending on dirt level. Some reads were dark grey with pollution.

The question is if there is a recommended approach for tuning these reeds now; in free air before mounting them again? As I understand it, the lower air pressure outside an accordion will raise pitch, but what is the experienced mean raise in cents? Approx 5cents? Varying with frequency? I.e. I understand I need to subtract a little while tuning in free air, to hopefully avoid re-correcting in the later tuning stages.

Should I find a new concert pitch that cause the +8cents above to be lowered to 0 cents, and then pretune all the reeds to that? I am searching a way to NOT pretune to a faulty value, causing more work in the final "on the block and in the cage" tuning.

I am also searching a PC, Android or iPad tuner app with the option to show mean value. Those I have now have their measured value jumping up and down instantly, making it hard to find a mean value to correct. I.e. an app that calculates mean value instead of instant value. I am aware of Dirk's tuner software which has that as LOCKED, but it is a little expencive in the current situation. Is there a cheaper and well reputed alternative with such a lock?

Final question. See the excelsior measurement. In the lower bass range, there is a notorious pitch lowering. My question if is this is more likely a deliberate tuning from factory, or if it is a result of many years of use (It is a 1973 model in otherwise excellent condition). In other words, should I tune those bass notes back in line with the higher notes, or leave it? (I once read that some instrument has a deliberate lowered bass pitch due to human interpretation making it sound more natural, but I am generally ignorant on that particular effect).

Thanks for any advice.
 

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knobby

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We've just been discussing some of this here:

 

Glug

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I find PitchLab Pro (free version) on my android phone works well, it's got enough 'hold' to make the frequencies readable.

I'm also working on a Scandalli 13/6 from the '60s, it's basically the brevetto without the mutes.
Its been on a shelf for 20 years but I measured the reeds yesterday (before any work) and it seems to be tuned to 442.
 

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