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  • #16
    Originally posted by HDVS View Post
    Unfortunately I had only one NAB Isolator that time.
    I will repeat the measurement session with NAB Isolators on both reel plates in the future. Results will be better, of course.
    Yes just wondering if additive or synergistic!
    Myles B. Astor, PhD, Administrator
    Senior Editor, Positive-Feedback.com
    ________________________________________

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    • #17
      Somewhere in the middle...

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      • #18
        I'm at a loss here. How can these NAB isolators reduce wow and flutter by a third? W&F is a function of the tape transport. A well maintained and adjusted R2R deck will have very low W&F eg Studer A80 0.04% W&F at 15 IPS; Technics RS1500 0.018% at 15 IPS. Is it possible to hear a reduction in W&F of 0.006%?

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        • #19
          Originally posted by topoxforddoc View Post
          I'm at a loss here. How can these NAB isolators reduce wow and flutter by a third? W&F is a function of the tape transport. A well maintained and adjusted R2R deck will have very low W&F eg Studer A80 0.04% W&F at 15 IPS; Technics RS1500 0.018% at 15 IPS. Is it possible to hear a reduction in W&F of 0.006%?
          Let me get this straight. Are you disputing Giorgio’s readings? He knows as much about the ins and outs of these machines (and recording too-see the Open Reel Tape Releases) as anyone in the world. You can even see some of the FR’s for machines he repaired and aligned over at the MRL site.

          Second, where are you getting 0.006% figure from? It’s more like 0.029%-0.132% or 0.016%. Or halved.

          Third, yes I heard a difference and it was not subtle. In fact, several others have independently heard similar things.

          Lastly, I hope this post is from you and not a troll that I banned from this site.
          Myles B. Astor, PhD, Administrator
          Senior Editor, Positive-Feedback.com
          ________________________________________

          -Magico S5 Mk.2 speakers with SPod feet
          -cj 40th Anniversary ART300 monoblock amplifiers
          -Merrill Audio Elemente 116 monoblock amplifiers
          -cj GAT preamplifier Series 2 preamplifier
          -Doshi V3.0 phonostage
          -VPI Vanquish direct-drive turntable
          -VPI 12-inch 3D Fat Boy dual pivot tonearm, VPI 12-inch 3D Fat Boy gimballed and SAT LM-12 arm
          -Lyra Atlas SL, Fuuga, vdh Colibri Master Signature, MOFI Master Tracker, Sumiko Songbird cartridges
          -Technics RS1506 with Flux Magnetic heads, Doshi V3.0 tape stage (balanced)
          -Assorted cables including Transparent XL Gen. 5, Allnic cables, Skogrand, Viero, Kubala-Sosna, MG Audio, Audience Au24SX, Genesis Advanced Technologies Power Cords
          -Accessories including Stillpoint Aperture panels, Cathedral Sound panels, Furutech NCF Nano AC receptacles; Silver Circle Tchaik 6 PLC, Symposium ISIS and SRA Craz racks, Audiodharma Cable Cooker, Symposium Ultra and assorted SRA platforms.

          Comment


          • #20
            Originally posted by MylesBAstor View Post

            Let me get this straight. Are you disputing Giorgio’s readings? He knows as much about the ins and outs of these machines (and recording too-see the Open Reel Tape Releases) as anyone in the world. You can even see some of the FR’s for machines he repaired and aligned over at the MRL site.

            Second, where are you getting 0.006% figure from? It’s more like 0.029%-0.132% or 0.016%. Or halved.

            Third, yes I heard a difference and it was not subtle. In fact, several others have independently heard similar things.

            Lastly, I hope this post is from you and not a troll that I banned from this site.
            Dear Myles,

            I did indeed write the post myself. Please excuse my novice understanding of how R2R machines work. I am just rather perplexed, as W&F is a function of the ability to maintain a constant tape velocity over the head. W&F is governed primarily by the speed stability of the capstan and the tape across the idlers, and the rest of the transport mechanism. The other factor is tape binding against the feed reel flange (according to my understanding of John Eargle's Handbook of Recording Engineering).



            It is no different to W&F on a belt drive turntable, where the crucial things are the quality of the bearing, the speed constancy of the motor(s) and the interface between the belt drive, drive spindle and platter. Adding a clamping/isolating device like this is similar to putting a record clamp onto a TT. In my simple mind, I just don't understand how this might work. I don't dispute the measurements per se, but I would be very grateful if someone like Giorgio could explain how this works.

            As for the measurements on W&F, I took the published W&F measurements from the original brochures for the Studer A80 and Technics RS1500 (accepting that these may have been measured in slightly different ways). The quoted W&F for the RS1500 is 0.018% and so 0.06% is one third of the W&F reduction, as you mentioned in your opening post.

            Charlie

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            • #21
              I have a W&F meter. A very long time ago I ran measurements on my machines and found the Wow and Flutter off spec on all of them. I was horrified and tried running a Trident reel instead of NAB with Revox adapters. All machines now comfortably met or bettered the manufacturers spec. At the time I even wrote on some or other forum that I felt the NAB adapter to be the single most significant contributor to W&F on any well functioning machine.

              Not a professional or expert ,just saying what I found.

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              • Tapetech
                Tapetech commented
                Editing a comment
                If an NAB adapter has loose grip on the reel, then wow/flutter can be created as the reel shifts around when turning. For instance if you hear a clucking noise in fast wind, that usually means a loose grip on the reel. Old Revox NAB adapters can have a loose grip, but it can be fixed with a new o-ring that has a slightly larger cross section. Also almost all reel tables have rubber surfaces which are there to aid the grip between the reel table and the reel/adapter. Often due to age, the rubber gets hard and reduces the grip..

              • topoxforddoc
                topoxforddoc commented
                Editing a comment
                That's really helpful. Thank you. I wonder if different OEM NAB adapters perform similarly, or whether say studio Otari/Studer are better than say the plastic/rubber O ring Revox.

            • #22
              Sorry for my late reply, I’m very busy this week and I was away during the last two days.
              Actually I was also surprised by the significant improvement in the W&F value, especially because the recorder used to test the NAB Isolator is an extremely fine electro/mechanical design with highly reactive servo controlled tape tension. Other recorders might give better or worse results of course. Theorically, non servoed recorders should get the highest benefit from this item, but the other parts involved into the degradation of W&F, like capstan motor/shaft/servo, if available, PR, guides etc will also be of lesser quality, so the value could be worse than that measured with the A816. There are good chances that the ATR-100 would show smaller differences, but unfortunately these adapters can’t be used with it at the moment. Another canditate to lower improvement should be the Nagra T, for its extremely precise and strong intercapstan constant tension dual capstan design.
              I think that the comment by Tapetech is exhaustive and nothing needs to be added.
              Thanks also to JDZA for pointing out the problem of W&F with NAB reels. It’s just a matter of tolerances. The Isolator keeps the reel tightly blocked to the reel plate as it was a single piece like an original Cine reel.
              A further improvement could be adding spring loaded balls inside the Cine hole, positioned at 120 degrees each one to the other and looking towards the Cine shaft in order to compensate for plays and eliminate them.
              Last edited by HDVS; 08-21-2019, 10:25 AM.

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              • #23
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                New "Ironman" version for new batch.
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