Sony WM-D6C slighty unbalanced Channels

Discussion in 'Tech talk' started by mclovingr, Oct 17, 2021.

  1. mclovingr

    mclovingr New Member

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    Hello folks,

    i got a nearly Mint D6C this Week and it works perfectly fine. But then i hooked it up on my Computer via Lineout to digitize some tapes with Audacity and noticed that the Channel Levels and slightly off. Left Channel is about 2-3db louder than right channel. I also tried the Headphone output and it shows the same results.

    Then i recorded some static noise with it and the recorded Material also has also the 2-3db difference between the channels. The levels are the same when the recorded tape is played on another machine. I already cleaned the head and the Capstan with isopropyl alcohol and demagnetized the Heads but it didn't do anything.

    In general, i wouldn't notice it if i only listened to external speakers or my Headphones but i would like to know, if this small unbalance is normal or common on this Model.

    Thanks in Advance!
     
  2. Valentin

    Valentin Well-Known Member

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    From my experience, most SONY devices (not just the D6C) have an imbalance between their Dolby (playback) levels. When I adjust with a proper Dolby level tape (200nWb/m ANSI), one channel always needs more adjustment than the other to make them equal.
    My conclusion is this is caused by a combination of 2 factors:
    - incorrect DIN calibration tape used at the factory (this is confirmed by tapeheads.net members);
    - the fact they used needle based analog AC milivoltmenters which compared to modern digital ones are not very accurate;

    If you don't want to use Dolby at all (which would be a pitty given the Dolby C functionality), this small imbalance would not cause any issue. However, Dolby decoding (especially Dolby C) will not work right.

    There are 2 options for solving this problem: get yourself a Dolby level tape and calibrate the unit yourself (you also need a decent TrueRMS multimeter or digital scope) or send the unit to me for a full calibration, including playback levels, rec levels and bias.
    The rec levels and bias can be adjusted for a particular tape that you want. For more details please send me a private message.
     
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  3. mclovingr

    mclovingr New Member

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    UPDATE:

    My WM-D6C was fully restored by @Valentin and now works without any issues! Levels are balanced in Playback and also on Recording. I'm listening to a Tape right now while I'm writing this.
     
    Last edited: Nov 12, 2021
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  4. gkajaia

    gkajaia New Member

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    I have a question if it won't bother you, I recently bought Sony D6C on ebay for around 550$ and changed belts cleaned head and demagnetized it but the sound is not good at all :( There is no wow and flutter issue. The thing is that all recordings even factory recordings sound quite muffled with treble going up and down, even my cheapest FX303 sound much better then D6C. Also recordings from D6C sound the same on the same D6C but sound awful on my Pioneer double deck as well as on FX303. I have made recording using PC line in from both D6C and FX303 and D6C is not good at all. Any advice how or even can I fix this ? :( Or it should sound like this ? :( I am uploading examples one from D6C one from cheap FX303
     

    Attached Files:

  5. TooCooL4

    TooCooL4 Well-Known Member

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    If you are saying the recordings made on the D6C sounds good on the D6C, but sounds bad everywhere else and all recording made elsewhere sounds bad on the D6C? Then it looks like you have an azimuth issue.
     
  6. gkajaia

    gkajaia New Member

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    No I meant recordings made on d6c sound the same dull as prerecorded ones. :( Please listen to audio files one is played on d6c second oncheapo fx303. which will explain how d6c sounds :(
     
  7. TooCooL4

    TooCooL4 Well-Known Member

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    I see, I'll check out the files in a minute. Personally I have never recorded anything with any of my D6C's, as I have a much better home player / recorder. I only ever use the D6C for playback.
     
  8. TooCooL4

    TooCooL4 Well-Known Member

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    Okay sounds like it could be dropout or the tape is moving up & down on the head, on the playback from the D6C anyway.

    Saying that, you need to get the unit to a good tech for a complete overhaul. They may be plenty of issues that just changing the belt & cleaning the heads did not fix.
     
  9. Valentin

    Valentin Well-Known Member

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    @gkajaia I listened to your recording and indeed it does seem that the azimuth is changing during playback, possible due to a bad pinch roller.

    Changing the belts on these D6C is by far not enough to make the new again. While those belts do need replacement, there are many other things that need to be done.
    I have a thread covering the majority of these things, so please go here for reference: https://stereo2go.com/forums/threads/sony-wm-d6-d6c-buyers-guide.7801/
    You can check the link in my signature for other D6C related sutff. Indeed the unit will need a complete overhaul, as all D6Cs do need at this point in time.

    Another aspect that I must say, especially for other people that will be reading this thread, is you should never expect to buy a D6C and be perfectly functional just because the seller says so.
    Sellers (especially on ebay) want to get the maximum price possible, trying to tell you it's working exactly as when it was new, etc. etc.
    My advice is you can always assume these will need an overhaul, even if they do work. Muting modules and EQ modules will fail intermittently, giving the impression it works perfectly.
    Rubber is all old and needs replacing, not just the belts but the capstan ring, the 2 idlers and the pinch roller are always in need of replacement.

    Of course it is prefferable to buy a fully overhauled unit, but if you do that you must know what has been done on it before commiting. Otherwise, many can call a belt replacement "overhaul", when in reality it's not.
    I, for example, provide a service report with everything that has been done and measurements (including the wow&flutter).
     
  10. Costa32

    Costa32 Member

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    My D6C sounds dull too but it doesnt have that rollout over the head, my suspition is a bad pinch roller as stated here. Just do a video of it for us to try to help you better.
     

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