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Tuning Rodgers LTG Oscillators

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  • Tuning Rodgers LTG Oscillators

    So I'm about to go through and tune every one of the oscillators on my Rodgers 925. Is there a special tool that is required to do this? I've heard horror stories about breaking the coils in the oscillators. Obviously this is something that I would like to avoid.

    I figure it will be much easier to voice when it's actually in (relative) tune with itself. Some of the upper work is screaming a bit too much because the mixture ranks are out of tune caused by the out of tune oscillators.

    Also, will tuning it make it sound more sterile?

    Thanks!
    Rodgers Oxford 925 built in 1983
    Kimball K-800 Fascination - Sold

  • #2
    Originally posted by TubaMirabilis123 View Post
    So I'm about to go through and tune every one of the oscillators on my Rodgers 925. Is there a special tool that is required to do this? I've heard horror stories about breaking the coils in the oscillators. Obviously this is something that I would like to avoid.

    I figure it will be much easier to voice when it's actually in (relative) tune with itself. Some of the upper work is screaming a bit too much because the mixture ranks are out of tune caused by the out of tune oscillators.

    Also, will tuning it make it sound more sterile?

    Thanks!
    I can't offer advice about the actual tuning procedure, but can offer something about it being more sterile after tuning. I had a Rodgers analog in the 1980s. There was a forumla for stretched tuning. I no longer have it, but perhaps someone at the forum does. I was pleased with the results because the sound was warmer and easier on the ears.

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    • #3
      I've tuned a ton of Rodgers over 35+ years and never broke a tuning coil. Some tuning caps are easy to turn, some are not. Never loosen the nut on a tuning cap. If you encounter a tight one, you can slide the cap side to side by pinching the cap against the coil body and sliding or rocking it back and forth. In fact, minor tuning adjustments can be made by doing this without turning the cap at all.

      There are three generator sets, Main, Ensemble, and Celeste. The celeste rank is tuned sharp in reference to the main/ensemble.
      There is a guide in the manual,
      Notes;
      1-8 = 16 cents #
      9-20 = 14 cents #
      21-32 = 12 cents #
      33-44 = 9.5 cents #
      45-56 = 7.5 cents #
      57-61 = 5 cents #

      I like to tune these quickly by this table, then fine tune it by ear.

      I've never thought a tuned Rodgers sounds sterile. With 267 individual oscillators it will always have plenty of movement.

      Geo

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      • #4
        Is that table in reference to the oscillators for the celeste stops?
        Rodgers Oxford 925 built in 1983
        Kimball K-800 Fascination - Sold

        Comment


        • #5
          Originally posted by TubaMirabilis123 View Post
          Is that table in reference to the oscillators for the celeste stops?
          Yes, sorry if that wasn't clear.

          Geo

          Comment


          • #6
            Originally posted by Moller Artiste View Post
            I can't offer advice about the actual tuning procedure, but can offer something about it being more sterile after tuning. I had a Rodgers analog in the 1980s. There was a forumla for stretched tuning. I no longer have it, but perhaps someone at the forum does. I was pleased with the results because the sound was warmer and easier on the ears.
            I am interested in the Rodgers " Formula for Stretch Tuning" that you mentioned. I too, have heard of this and want to know what it is. The local Rodgers rep has not been able to help me apart from the table you gave re the Celeste rank of oscillators.
            Surely someone on the forum will be able to provide. It is used to give the analogs a sense of a tuned organ being somewhat out of tune. Or if you prefer a warmer sound!
            Come on folks, somebody, Help.
            And thank you
            EVERY DAY IS SATURDAY!
            ROLAND CLASSIC C-330 IN MY LIVING ROOM

            Comment


            • #7
              Hi,

              I thought I had a document somewhere of what Rodgers recommended for tuning schemes. So far among al the old Rodgers stuff I have, I can't locate it.

              I don't know if Rodgers ever had an official document, but I do know there was a pamphlet written by Allan Van Zoeren, about successful tuning. He used to work for Rodgers. I can't locate that document either. If his tuning concept was anything like his voicing ideas, I likely wouldn't agree with him. I will check next week to see if I can find this document or a Rodgers one.

              AV

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              • #8
                For a year or two I played on a Rodgers 890, which also has three ranks, main, ensemble, and celeste. I remember intentionally tuning them apart for some extra movement in the sound. Best I recall, I simply made up a scheme, something like this:

                "Main" rank, which covers everything from the bottom of the 32' octave to the top of the 2' and mixtures -- tune it exactly to standard pitch throughout its range, or if you wish, tune the two lowest octaves about 5 cents flat so there will be a bit of beating in the pedals when 8' stops are drawn with the 16' and 32' stops. At these frequencies, a difference of 5 cents will produce only a slow beat, not enough to make any unpleasant outphasing waves.

                "Ensemble" rank, which probably is only 61 notes and is used for the great flutes, the swell principal, and a few other stops to provide a tuning offset from the great principal -- tune the lowest octave 5 cents sharp, the next octave 4 cents sharp, then next 3, then 2, then the top octave 1. The effect will be to give a very mild chorusing between the principals and flutes. You need less and less of this as you go up the scale because you don't want any wild beating, which would become very annoying in the higher octaves.

                Celeste rank -- Your celeste pairs will mostly come from beating together the celeste and the ensemble, so you can actually make your celeste rank a tad sharper than the recommended settings since the ensemble rank is a little sharp to standard. You'll also get a more active celeste sound when combining celeste stops with great principal stops. How much sharp? You might start off on the lowest note 20 cents sharp, tapering off to no more than 5 cents sharp on the top note. You can design your own scheme for changing your tuning meter. For example, if you are going from 20 down to 5, you will have 15 steps, so you can adjust your meter by 1 cent after every four notes. This will produce a very smooth and even scaling of your celeste.

                If you feel you have too much or too little celeste with this scheme, try a different one. If you start at +15 and taper only down to +8 at the highest note, you will get a rather different effect. It doesn't take very long to tune the celeste rank, so you can certainly experiment!
                John
                ----------
                *** Please post your questions about technical service or repair matters ON THE FORUM. Do not send your questions to me or another member by private message. Information shared is for the benefit of the entire organ community, but other folks will not be helped by information we exchange in private messages!

                https://www.facebook.com/pages/Birds...97551893588434

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                • #9
                  The Rodgers C32 had two generators that when the Chorus tab was set, it detuned one from the other. I don't know how much the detuning was but it sounded very good.

                  Geo

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                  • #10
                    It's interesting because my 925 has some control called Random Tuning or something like that. It's not the Walker board that Bob Walker would add to the analog organs, but it is on the same board as the volume and filter controls for the Vox Humana. It's just a simple toggle switch on that board. I currently have it turned on. Not sure if it does any good or not, but is that an early attempt by Rodgers to add some kind of tuning randomizer into the signal chain to make things not so sterile?

                    I assume that switch should be in the off position when I start tuning, correct?
                    Rodgers Oxford 925 built in 1983
                    Kimball K-800 Fascination - Sold

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                    • #11
                      Yes, all detuning and choruses off when tuning.

                      Geo

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