WM-D6C - very high treble and buggy NR.

Discussion in 'Tech talk' started by flash_the_84, Nov 8, 2018.

  1. flash_the_84

    flash_the_84 Member

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    Hello, the title says it all,
    On this D6C unit I have, the Dolby tracking seems a bit... late and slow, both on tapes that it records and on the tapes that it plays back, even from other machines; the level seems to jump a bit and is generally a bit glitchy. You can hear it quite good on the attached mp3 (Axel F by Harold Faltermeyer), especially when the hi-hats start appearing at 16 seconds, although the high noise on there is because of utter incompetence of me while capturing the audio.
    The second issue is the treble, the tapes that it records all have very high treble, wether it is Dolby NR, or no NR, type I or two, lower/higher biases (the bias required for TDK D, Sony UX-S, and Maxell XLII are all different, all of the tapes i tested are brand new). This D6C NR struggles a bit with tapes recorded with other players but the sound is overall quite bassy on tape not from this device (probably alignment mismatch, not the problem here). You can also hear it on the mp3, again don't mind the noise, it was when capturing.

    Overall : The NR is a bit jumpy, and the recordings are very high in treble (tested with white noise), and i do not think it is because someone changed the bias (tested with different bias tapes).

    Thank you for reading this and i hope there is a solution, it just doesn't sound quite 100% right here.
    Got any question or detail you want to know, just ask.

    Thank you!
     

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    Last edited: Nov 8, 2018
  2. flash_the_84

    flash_the_84 Member

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    Again, sorry for the background noise on the recording, but you can clearly hear something isn't right with that Dolby C decoding.
     
  3. Jorge

    Jorge Well-Known Member

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    Heres the tip: Do Not Use Dolby-B/C!!!
    Unless @Deb64 kicks in you are on your own of pain'n'suffering of going thru the SM and reading between the lines...
     
  4. flash_the_84

    flash_the_84 Member

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    Thank you for your helpful tip, but it doesn't resolve my problem !
    I like to use NR.
     
  5. Deb64

    Deb64 Active Member

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    I'm not the best person to ask about Dolby as I haven't used it since the early 1980s. I have never used Dolby C. When Dolby B was developed in the late 1960s cassette tapes were very noisy and the Dolby reduced the hiss considerably. By the 1980s cassette tape formulations had improved a great deal and the noise reduction no longer made such a difference. So I concur with @Jorge on Dolby.

    It's difficult to tell what your problem is without hearing both the source recording and your WM-d6C recording (not in compressed MP3 format). I had a listen to your recording and it doesn't sound too bad, apart from the background noise.
    I think you may be asking a lot of your WM-D6C. They are good playback machines for their size, but are not especially noted for their recording performance, when compared to full sized decks. If you want to produce high quality cassette recordings, with a high level of detail, then you would be better off getting a 3 head full size deck, with adjustable bias, for recording. I would suggest asking on here for recommendations for a suitable deck for your budget and what you want to use it for.

    You have admitted that the noise on the recording is down to "utter incompetence of me while capturing the audio." (your words, not mine!).
    Recording onto tape is not as easy as some people make it look. You need to try different tapes and recording levels and find one which suits you best.
     
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  6. flash_the_84

    flash_the_84 Member

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    The recording noise was introduced because I set the headphones volume way too low and the line level input on my PC very high. (I cannot record the Line Out using this particular computer for some reason)
    I know there is a problem because i've had a perfect working D6C before and it didn't sound that bright. For this D6C (the one that has problems), I have late 90s repair bills that state "distorted audio while recording" on two different repair jobs and i think the former owner just forget about it because the store couldn't fix it (it even got the CX chip replaced by that store back then, for distorted audio!). Maybe it could be with the two Dolby ICs (I do have two parts machines i could source them from) but I do not know for sure, and my IC soldering skills are non existent.
     
  7. dotneck335

    dotneck335 Active Member

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    SONY WM-D6/D6C calibration tutorial | Stereo2Go forums
     
  8. Valentin

    Valentin Well-Known Member

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    Listening to the recording I don't hear what I expect given the description.
    You stated you confirmed the very high treble with white noise test. Can you attach a spectrum measurement ?
    How exactly did you measure the frequency response and concluded there's a treble peak ?
    Assuming this is a plyabck issue (not just rec), how do you know it's not the other way round ? Consider the old one may may have had a worn head or misaligned azimuth.
    Distorted audio while recording can be due to incorrect bias adjustment. If the bias is set so the 10kHz response is much higher than the 315Hz, the SOL will be very low and tape will distort very early.

    So please clarify: does this treble peak occur only during recording or playback also ?
    It's also unclear what the MP3 recording is about: it's a tape recorded by this unit, by other recorder, a prerecorded tape ? Is it recorded with NR or without NR ? Seems to be played back without NR.
    To give an opinion about NR mistracking, we need a playback sample of a properly recorded cassette (bias, level adjusted for that tape) played back with the NR type it was recorded with.
     
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