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MOS Celeste Tuning

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    MOS Celeste Tuning

    I have never played a MOS-1 with the analog celeste, but have heard others talk about how warm and nice it really is. One of the organs I'm charged to play has such a beast, and I wasn't all that impressed. Wasn't very celeste sounding at all.

    I recently got a hold of the celeste tuning page, so to the organ I went with my strobe tuner. I checked the computer tuning first. It was +1 cent and I adjusted back to A440. Then went to the celeste. Not sure why but the celeste was only about 3-6 cents sharp across the compass. I adjusted the tuning to what Allen suggested which if you don't know is graduation from 20 cents sharp at the bottom to 6-7 cents at the top. It was a drastic improvement! I left the regulator wheels alone for now - the volume is even and seems to balance with the string stop.

    There were two pitches were I could not get the pitch raised D#3 and F3. I rotated the wheel and could get down to -40 cents but after about 1/2 cw rotation, it stopped raising the pitch at only +4 cents. It's odd to me that it just quits raising the pitch. I assume the wheel is just a voltage regulator. Is it like a dirty pot and just needs to be rotated back a forth a few more times, or is there some part that needs to be replaced?

    I'm thrilled with how the rest of celeste sounds and can't believe it was tuned so dry. I don't notice lack of celsete on the two notes unless I play them individually. I just though if it's simple, I'd fix, if not I'm ok too.

    Taste in the difference between the unison and celeste tuning varies from one organist to another--I suspect people who have "perfect pitch" prefer little or no celeste, but that's just a guess,

    Allen's analog oscillators only had a limited tuning range, and if you needed to go farther than what the range provided you had to change a tuning capacitor. Sometimes these capacitors were on binding posts with knurled nuts for easy change. To go more flat, use the next size larger capacitor (or parallel a capacitor of about 10 to 20% of the existing capacitor), to go more sharp, use the next smaller size capacitor. Mylar, polypropylene, or other foil & film capacitors of about 15 to 25 working VDC are appropriate.