Sjoeberg Table Quirks

Good afternoon!

I have some questions for Kinya about the Sjoeberg tuning table. I acquired a master table back at the beginning of our lockdown in Canada, and I've been spending a fair bit of time tinkering with it and getting the hang of how it works.

I'm blanking out the "master" section on the back for now, as I am only occasionally cloning one of my better harmonicas over to a new one.

What I've noticed is that activating reeds on the drawplate with a draw, results in a note that is pretty darn close to how the note sounds when the harmonica is reassembled. However, activating reeds on the blow plate with a draw, as the table does, tends to result in a note that is as much as 15 cents sharper than the note will sound when reassembled. The end result is that my blow notes all end up flat when reassembled.I've created a spreadsheet that I use to calculate my "blow offset". So while I might tune the draw plate to A4=443, the blow plate will get tuned to something like A4=405.05 so that the two plates end up sounding in tune.

However, I've also noticed that this effect, across both plates, is amplified as you move up from the low reeds to the high reeds. It appears to be somewhat logarithmic.

So on any one plate, if I tune all the reeds nice and evenly to a tenth of a cent, when I reassemble, the reeds will start in tune and become progressively flatter as I move up the harmonica. (From low to high on the draw, and from high to low on the blow plates)

I'm thinking this has something with the size of the air cavity inside the Sjoeberg, and the distance between the air intake (on the far left of the table), and the notes being tuned on the far right.

I've seen some comments about using the "black valves" to simulate nasal breathing and smoothing things out, but the model of table that I have does not have that feature. It only has 10 valves. I'm considering testing out a new blanking plate with a tiny "air hole" drilled for each hole, just to let that tiny bit of backpressure out... not sure what effect that might have. I have also contemplated attaching a regular old reedplate onto the "master" side of the table that has all the holes taped over except for a tiny hole that I can adjust...

I really like the table, and it definitely has the potential to speed up my workflow. But having to make mathematical adjustments to each hole takes time, even if my software tuner can be programmed to account for those percentages automatically. It also means that I can't "trust my ears" when I hear a nice clean chord with no beating on the tuning table. Because once it's off the table, those notes shift relative to one another, and I end up having to touch them up again manually on the comb.

In any case, any thoughts or feedback you might have on this process would be greatly appreciated. I would be DELIGHTED to discover that I'm just doing something wrong, and this can be fixed by correcting my technique. I'm still relatively new at this, so I feel there's a 90% chance that this can be chalked up to "operator error". :)

Cheers!

Rob Laferriere

Russell, MB, Canada