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MMC20 Genetic manipulations…

Home Forums Bang & Olufsen & Your Computer Bang & Olufsen / PC MMC20 Genetic manipulations…

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  • #35639
    orava
    BRONZE Member
      • Topics Started 5
      • Total Posts 23

      Anyone (Chartz?) happend to know how MMCx000 series is build? Is it glued together  and is there a way to disassembe it?

      #35641
      Glitch
      BRONZE Member
        • Topics Started 15
        • Total Posts 302

        I’ve run some similar experiments using the same dirt cheap replacement cantilever/stylus…

        My approach is a bit different than matador’s. Instead of using an “internal” wire to connect the new cantilever to the old cross, I reamed out the new cantilever to fit over the collar on the cross. This (theoretically) has a performance advantage of only having one interface connection (i.e. where glue is needed) instead of two.

        FrankenCartridges_lowres

        The picture above shows a couple examples of the FrankenCartridges compared to the original.

        The FrankenCartridges track a record groove just fine and make music. I’ve noticed some distortion in the high frequencies. My initial thought was that this was caused by a bad suspension in the donor cartridge. I’ve since repeated the experiment on a few other cartridges to try to identify a pattern. My sample size is admittedly small, but the two “best sounding” cartridges that have nearly identical distortion. I also have cartridges where it is obvious that the suspensions are shot. Based on this, I’m guessing that the distortion is caused by bad tip geometry, bad interface connection (currently just using a friction fit), or that the new pink styli are simply crap. I’m not ruling out all three ;-).  Does anyone have any theories?

        I’m not sure what I’ll try next. Has anyone tried this with a better quality replacement cantilever/stylus?

        Glitch

        #35644
        Glitch
        BRONZE Member
          • Topics Started 15
          • Total Posts 302

          Derek:  Thank you for posting the video. I was able to pick up at least one tip as well as confirm that some of the methods that I already figured out are on the right track.

          Martin: Yes, the tracking angles in the first picture are pretty unsatisfactory, especially the FMMC2. The FMMC20 isn’t nearly as bad. I didn’t do a good job at lining up the cartridges for the picture. For the first attempts, I didn’t try any adjustments to the geometry. I was just happy to complete the transplant without destroying either the replacement cantilever or broken cartridge. 😉

          Here are today’s results that include adjusting the tracking angle and better cartridge alignment for the picture.

          FrankenCartridges_lowres_2

          The tracking angle in the top left was purposefully altered. The bend in the bottom right is a result of damage from the reaming process in one of my earlier attempts. I’ve learned that it is pretty easy to damage the components while working on them.

          One advantage to Matador’s approach is that it should be easier to adjust the tracking angle simply by bending the inner wire.

          Glitch

          #35642
          auric
          BRONZE Member
            • Topics Started 14
            • Total Posts 83

            Hi:

            There is a short video interview of Axel Schürholz plying his craft. Some of the footage shows his approach:

            Derek

             

            #35643
            Dillen
            Moderator
              • Topics Started 3
              • Total Posts 590

              Sure you got the tracking angle correct?
              I think it looks very steep.

              Martin

              #35645
              Glitch
              BRONZE Member
                • Topics Started 15
                • Total Posts 302

                FMMC_TA_on_Record_lowres

                The latest experiment was to make several cantilevers with different tracking angles. The picture above is the one that, by eye, has the best geometry. The bad news is that all of the candidates exhibit a very similar distortion. The good news is that my cantilever bending jig seems to work and I found a record track where the distortion is easy to hear (i.e. the issue is easily repeatable).

                Please let me know if you are interested in hearing a recording of the distortion, would like to see any other views of the cartridges, or have any suggestions of what to try next. Thanks.

                Glitch

                #35646
                Glitch
                BRONZE Member
                  • Topics Started 15
                  • Total Posts 302

                  The latest (and last for now) Franken-MMC (FMMC) experiment. The donor cantilever is aluminum with a conical, bonded diamond stylus.

                  FMMC14_TA_on_Record_lowres

                  FMMC14_TA_on_Record_closeup

                  My cursory evaluation of the cartridge performance on a 1 to 20 scale, where 1 through 5 map to B&O’s MMC1 through MMC5, respectively, and 20 is something put together from sewing needles and twigs…

                  The FMMC with the $2 pink ceramic stylus is about a 17. The grafting is relatively easy to do, but the playback is muddy and suffers from distortion on some recordings.

                  The FMMC with the conical, bonded diamond stylus is about a 12. The playback distortion exhibited by the pink ceramic FMMCs is gone. In general, the highs and lows are there, but the fine detail is not. It sounds like a tired, inexpensive cartridge. This isn’t surprising since it actually IS a tired, inexpensive cartridge.

                  My overall conclusion is that this type of DIY grafting isn’t very practical. There is a learning curve where one will certainly destroy some donor cantilevers and/or target cartridges. The overall performance could certainly be improved upon by buying a higher quality donor cantilever/stylus. However, the risk/reward ratio just isn’t there. Botching just one reasonably nice donor cantilever and having to replace it puts the overall price in the ballpark of a new SMMC4 (that has a fresh suspension).

                  My future plans are to use the grafted cantilevers for evaluation of cartridge suspensions. I have a handful of cartridges with missing cantilevers. I got these with various used turntables and have no idea of their history. If I happen find a suspension that still has life in it, I’ll be remotivated and graft it. Maybe some sort of nude elliptical?

                  Yep, none of this made sense. Wound I do it again? In a heartbeat!

                  Glitch

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