Need advice on troubleshooting Martin Delta 4050 speakers

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  • BlueBrat
    Junior Member
    • Jul 2014
    • 5

    Need advice on troubleshooting Martin Delta 4050 speakers

    Hi everyone, I messaged an admin on where to post this and he suggested here or DIY. I'll try here first, if it should be moved that's cool. :T

    I have a pair of Martin Delta 4050 speakers. I've recently purchased a Pro-Ject Debut Carbon turn-table and did some comparison listens through two of my older amps, a Harman/Kardon Citation 22 and a Hafler DH-220. It was during this evening when listening and comparing the two amps that I noticed the speakers are not sounding exact.

    I found the DH-220 to be a the better sounding amp and set up the Citation 21 pre-amp to mono output and tested each Martin tower. They do not sound remotely similar! One sounds "muffled" without much distinction in timbre, and as I discovered, one of the adjusters for the tweeters apparently does nothing! The second speaker appears to sound louder, but has a very harshness to its sound.

    All speakers appear to be producing sound, so nothing seems completely blown. So here's where I am starting to need advice.

    Are these worth the effort
    Even before continuing, are these speakers worth troubleshooting and fixing or should I look elsewhere?

    If yes, should I be looking at replacing all the drivers or re-coning the mids?

    Troubleshooting
    My big concern about simply replacing cones or speakers is determining if the crossover in the cabinets is still good. Is it possible the electronics are producing the discrepancies I'm hearing? Is there any guides out there on determining this?

    I wouldn't mind upgrading the drivers with something more quality available today if it's worth the while. I'd rather not just trash the speakers in general even if they aren't near good quality, I'm sure someone would appreciate them. As it is right now, anything I play through them results in me picking out all sorts of issues, limitations and slight distortions. Grrr.

    Thanks for any advice and help, it's appreciated!

    (photo is from my previous place, they're in a much larger room and not connected to a tv, craptastic stereo, etc, but you get the idea)

  • Alaric
    Ultra Senior Member
    • Jan 2006
    • 4143

    #2
    I don't know the age of your speakers , but examining the cone surrounds for signs of decay/separation would be a pretty easy task. Depending on age , they may well benefit from new capacitors , etc. , in the crossovers. he best part of that is most speakers don't have a lot of parts , so upgrading the caps to Sonicaps , Elna's , or even some nice Mundorfs (!) isn't near as costly as something like an amplifier would be.
    A quick internet search didn't turn up much for me , but I'm now guessing they have been around since the 70s? A recap would certainly not go amiss there , and throw in some resistors while she's on the table! PM sent.

    Oh! And Welcome to the 'Guide! Feel free to take your shoes off and stay a while!
    Lee

    Marantz PM7200-RIP
    Marantz PM-KI Pearl
    Schiit Modi 3
    Marantz CD5005
    Paradigm Studio 60 v.3

    Comment

    • John Holmes
      Moderator Emeritus
      • Aug 2000
      • 2703

      #3
      Just curious, has your setup always been in this location? I ask because, with one speaker in the corner and the other seemingly having open room to one side; I would expect the two to sound different. If you have always had them in this location and are just now unhappy with the sound, Alaric gave good advice on correcting the problem/s.
      "I have come here, to chew bubblegum and kickass. And I'm all out of bubblegum!!!"

      Comment

      • Alaric
        Ultra Senior Member
        • Jan 2006
        • 4143

        #4
        Thanks for the kind words , John. I missed the set up the first time , but I think the OP mentions they are in a different room ?
        Also , Bluebrat , did you try switching the speakers left-to-right , just to make sure it isn't an amplifier problem ? Silly question , I know. But sometimes it's easy to miss the obvious. One more question-did you check the speaker for fuses ? My old A/D/S L1530s had one fuse externally , but behind a small cover , by the binding posts , and another fuse inside the cabinet. I don't know if that was a 70s thing or an A/D/S thing , but worth checking while you have a driver out checking the capacitors. Please let us know what you find out. I'm hoping it is something simple and cheap !
        Lee

        Marantz PM7200-RIP
        Marantz PM-KI Pearl
        Schiit Modi 3
        Marantz CD5005
        Paradigm Studio 60 v.3

        Comment

        • madmac
          Moderator Emeritus
          • Aug 2010
          • 3122

          #5
          First off, those are really nice looking speakers!. If one or some of the drivers have been replaced, that could be one cause of your problem. However, I suspect the electronics (Adjustment knobs I see on the front) to be the likely problem. I would suggest bypassing them altogether. Just let the crossover send the raw signals to the respective drivers. That should be a relatively simple process.
          Dan Madden :T

          Comment

          • Hdale85
            Moderator Emeritus
            • Jan 2006
            • 16075

            #6
            If they are designed to have the adjustment knobs (likely potentiometers which adjust the resistance of some part of the crossover) bypassing them would be a bad idea as then the resistance wouldn't be there at all.

            Comment

            • John Holmes
              Moderator Emeritus
              • Aug 2000
              • 2703

              #7
              Yup, I somehow missed they were in a different room.ops:
              "I have come here, to chew bubblegum and kickass. And I'm all out of bubblegum!!!"

              Comment

              • Kal Rubinson
                Super Senior Member
                • Mar 2006
                • 2109

                #8
                I could find no significant information on them other than your contributions and the specs I did find were not particularly informative. If you did like them, I suggest that you trouble-shoot them by swapping drivers/components between the two until you found the culprit(s) and try replacing/repairing those. I would not put much money into them.
                Kal Rubinson
                _______________________________
                "Music in the Round"
                Senior Contributing Editor, Stereophile
                http://forum.stereophile.com/category/music-round

                Comment

                • BlueBrat
                  Junior Member
                  • Jul 2014
                  • 5

                  #9
                  Thanks for the advice. I have been looking into rebuilding the crossover which is a whole learning thing in its own right. Will look into those caps.

                  Comment

                  • BlueBrat
                    Junior Member
                    • Jul 2014
                    • 5

                    #10
                    Originally posted by John Holmes
                    Yup, I somehow missed they were in a different room.ops:
                    Heh yep! In the new house they're placed in opposing corners. It's a vaulted-ceiling room and the acoustics are surprisingly pretty good and didn't need too much acoustic padding.

                    Comment

                    • BlueBrat
                      Junior Member
                      • Jul 2014
                      • 5

                      #11
                      Originally posted by Hdale85
                      If they are designed to have the adjustment knobs (likely potentiometers which adjust the resistance of some part of the crossover) bypassing them would be a bad idea as then the resistance wouldn't be there at all.
                      Good point and it makes sense. I haven't taken them apart yet to find out the why to what's happening with that bypass.

                      Comment

                      • BlueBrat
                        Junior Member
                        • Jul 2014
                        • 5

                        #12
                        Hi everyone, so here's an update. I finally opened up the casing to get specs on the crossover to start a rebuild of it. Unfortunatly in the process of doing so, on one of the larger drivers, the wiring clips that holds the wire to the driver on the frame to allow the wire on the back of the cone to safely pass through the metal frame came loose. In fact they both just fell off. The condition of the cones are pretty rough with some mildew or something, and the cone frame has a white rust-like powder flaking off when you touch it.

                        So already I am thinking about possibly reconing the drivers, again, if someone wouldn't mind looking at the attached photos, is it worth doing so? Replacing the drivers would mean a new crossover as well, something I'm not beyond doing, though it does bring up the point of the overall dynamics of the cabinet into consideration and possibly ruining the balance of the original design. There is a cavern created by a board running down the middle of the cabinet, so there is airflow direction involved.

                        The problem that happened is apparently a short occurred after my meddling, causing my halfer power amp to no longer produce sound to either channel even after unplugging this one speaker I opened up. I'll have to examine that later, but the easy-access fuses on the outside are fine. I will connect the H/K Citation I have to see if the pre-amp is still good. In the meantime I need to really service this speaker and undo whatever I fouled up.








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