For all of those running old (say older than 2006) 3 way ATCs...Mid Dome concerns - Hi-Fi Stereo & Home Cinema forums | ATC Forums

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  • For all of those running old (say older than 2006) 3 way ATCs...Mid Dome concerns

    Hello all,

    Wanted to share a recent conversation I’ve had with Pete at ATC. Yesterday I noted that one of my mid domes was starting to make a ‘tizzing’ noise with piano music. I’ve heard this before, prior to my speakers going for a major service in 2018. Back then pre service, both my classic 100As from 1996 (now ASLs with ATC tweeter) were really rather poorly, both mid domes ‘tizzing’ and or distorting, especially with piano music.

    The short version of this story; based on increased incidence of mid domes manufactured on or before roughly 2006 coming for service, ATC now recommend a full mid dome replacement rather than re cone. Mine were re coned in 2018 and have otherwise been fine until yesterday.

    The longer version and I quote from Pete;

    ‘We have been reviewing how best to approach servicing on these older middome drivers, and have come to the conclusion that the best policy is to actually offer replacement drive units for units made before 2006, approximately.
    We are doing this for two reasons:
    1: increasing incidence of issues with corrosion and fragmentation of plating in the critical gap area, particularly on drive units from the 1990's and early 2000's. We are seeing this more and more on older drive units coming back, and believe it be partly due to usage/storage conditions and the plating quality, as suppliers and materials changed over time. There is a high risk that more debris will break away and damage the cone/coil assembly. I think this may well be the case with your current drive unit problem.
    2: On middome drive units manufactured pre-2006 the final alignment of the cone coil assembly is carried out with tone, monitoring at quite high levels, prior to gluing the assembly in place, and this has been deemed a long term heath/safety issue. Current issue metalwork permits easier servicing, and exchange of cone coil kits, as it incorporates stepped metalwork allowing self-centering of cone/coil assemblies. In the long term this has proved to be the best solution for servicing, especially in the field.
    For these two reasons it won't be possible to recone your middomes with any degree of reliability, so would strongly suggest that you purchase current issue replacement middomes at this point.’


    So to summarise - for those running old (2006 or older mid domes) that have been re coned recently, you might need a complete replacement mid dome unit.

    Right now the mid domes are not sounding terrible it’s really only on one speaker and certain piano music that excites the ‘tizzing’ type noise.

    At least with ATC there are options in order to keep these older speakers going and I am booked in for next year!

    Alastair

  • #2
    Thanks a lot for sharing your experiences!

    Comment


    • #3
      Alastair - are you able to give an indication of the cost involved per replacement midrange driver? Precise cost isn't necessary, but an indication of approximate cost would be very useful.

      Incidentally, I'd be prepared to bet that the way in which an individual pair of speakers has been used will have a very large influence on this. I would expect that speakers that have spent their whole lives in a domestic environment are unlikely to be badly affected, while those that have been used and/or stored in damp environments are likely to be much more seriously affected. Have your speakers only been used domestically?

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      • #4
        Originally posted by Antifon View Post
        Alastair - are you able to give an indication of the cost involved per replacement midrange driver? Precise cost isn't necessary, but an indication of approximate cost would be very useful.

        Incidentally, I'd be prepared to bet that the way in which an individual pair of speakers has been used will have a very large influence on this. I would expect that speakers that have spent their whole lives in a domestic environment are unlikely to be badly affected, while those that have been used and/or stored in damp environments are likely to be much more seriously affected. Have your speakers only been used domestically?
        Hi, yes each mid dome unit is about £500 each. I am pretty positive it’s something a non expert can do ie switching out old for new but I await feedback from the factory.
        I am 100 percent sure mine have only been used domestically and I am the 3rd owner. The first owner might have stored them in a damp space, given the report from ATC when they serviced them, the second owner certainly had them in a dry homely space.



        Comment


        • #5
          Thanks for the info.

          Agreed - it should be a DIY job. When I had a (just factory serviced) Cyrus Mono go 60VDC on the output and damage the bass driver in one of my SCM40's, they were happy to re-cone it and send it back for me to refit, which was good, as it's always a worry sending a whole floorstanding speaker back via courier! As you may know, they will probably insist on you using their factory packaging to return a driver and each of those is relatively expensive, but worth it for the protection.

          Until recently I had been considering buying an early pair of active SCM50's, but this adds an element of risk that I'll probably choose to avoid now...

          Comment


          • #6
            Hello Alastair
            Thank you for that information.

            Comment


            • #7
              Hi Alastair. I bought some new ATC SCM100ASLs in 1998. My dealer at the time mentioned that there had been issues exactly as you describe with the mid-range unit, and that ATC weren't sure what caused the problems. Right enough, a couple or so years later, one of my mid-range units started to tizz. It was most noticeable on piano. The dealer arranged for a new mid-range unit to be sent FOC from ATC, and turned up to to fit it, but as he started work it was evident he did not really have the competence to do the job. I phoned ATC, and they said that in any case the whole speaker should be sent back as the crossover might need re-aligned. I had the packing, so I procured a pallet and got the speaker sent back and fixed. A hassle, but I couldn't live with the tizz. Some while later ATC upgraded the mid-range surround and the bass port and I needed to get the amps re-capped so I sent the pair back for the upgrade and re-cap, this time in a pair of flight cases that ATC provided. I might've had the domes replaced as well, I can't recall. IMO it is pointless having a speaker of this calibre in any less than perfect condition.
              Last edited by AndyU; 01-11-2021, 02:15 PM.

              Comment


              • #8
                Originally posted by AndyU View Post
                Hi Alastair. I bought some new ATC SCM100ASLs in 1998. My dealer at the time mentioned that there had been issues exactly as you describe with the mid-range unit, and that ATC weren't sure what caused the problems. Right enough, a couple or so years later, one of my mid-range units started to tizz. It was most noticeable on piano. The dealer arranged for a new mid-range unit to be sent FOC from ATC, and turned up to to fit it, but as he started work it was evident he did not really have the competence to do the job. I phoned ATC, and they said that in any case the whole speaker should be sent back as the crossover might need re-aligned. I had the packing, so I procured a pallet and got the speaker sent back and fixed. A hassle, but I couldn't live with the tizz. Some while later ATC upgraded the mid-range surround and the bass port and I needed to get the amps re-capped so I sent the pair back for the upgrade and re-cap, this time in a pair of flight cases that ATC provided. I might've had the domes replaced as well, I can't recall. IMO it is pointless having a speaker of this calibre in any less than perfect condition.
                Hi Andy, yes the tizzing once heard can become irritating and I hate knowing that mine are not performing 100%. That said, the issue is much less worse compared to the sound pre service, concerning Piano replay.

                My pair are now not going to the factory but new mid units are being sent soon. I just decided that I might as well do both. Pete has given me some clear instructions of how to, it reads as easy, it’s more about safely (meaning not damaging you, a component or the cabinet) removing the bass driver, in order to drop through the mid unit, through the bass unit gap. I am sure in the factory this is a 5 min job per speaker for the pros but it will take me longer I am sure!

                Comment


                • #9
                  Hi all
                  I haven't been on the forum for a while, but this looks like an interesting thread.
                  My 100 Anniversaries are at ATC at the moment ostensibly to have the tweeter upgrade, but Pete did mention that the midranges might also have to be done. It's taken me a looooong time to get the shipment organised (they sent crates last month) and I now hear they've been sitting in a queue at the factory over Christmas, as they are overloaded in production, I guess because of Covid. At least my tweeters have now been built, so let's see what else needs doing when they finally get round to the cabinets.
                  Alastair - I guess they sent you the units to fit, otherwise it would just take too long a turnaround. I originally booked mine in over a year ago, and finally pushed them to get something sorted. I'm living with Genelecs at the moment, but it's not the same

                  My advice to anyone now, is not to send their speakers to ATC until they sort themselves out, otherwise you may be without music for a long time!

                  Comment


                  • #10
                    Hello John, good to see you here. I waited at least 8 months for the 100s to get in, had quite a few emails and calls with Pete to try to persuade him to get them in! So I have sympathy re your long wait. I’d suggest swallowing and doing the mids if it comes to it, especially as they are at the factory.
                    Yes I think they preferred shipment of mids to me due to the current work volume plus COVID on site restrictions.

                    I’ve actually also put in a request pre Xmas for my C6 sub to have a once over but I can’t see that happening until or after the summer.

                    Comment


                    • #11
                      Hello all, just a quick update here. After nearly 4 months I finally got my new mid domes! I only needed one for my tizzing right speaker but took the view that replacing both would help with the longevity of the pair.

                      Getting the bass unit out was a pain, locking and lifting with an Allen key was a bit hit and miss for me. Also make sure if you do this that you clear the speaker of all the acoustic waste material, otherwise you could end up with a fluffy mid (!) as you pass the mid through the bass hole and up into its proper mid position.

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