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TPS-L2 The missing link?

Discussion in 'Best Threads' started by sotza, Jun 17, 2017.

  1. sotza

    sotza Active Member S2G Supporter

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    Hi to all,
    This is an exact adaptation of my topic from the old forum ,fully detailed dialogs of fellow members were included for the sake of completeness but avatars, text etc are not corresponding to any links to this forum .
    Of course you can comment from here on. :)

    First posted January 31, 2015 9:06 AM :

    This is a commemorative photo from 1989 for the 10 years of Sony walkman:


    Among all these walkmans,ranging from entry level to top models,there is one that looks a bit peculiar,this one:


    At first glance it looks like a wm 3EX with oversized headphones but its not,if you notice at the top left corner you'll see something that looks like a tape counter.

    So what it is?

    Probably a prototype based on this:



    The Sony BM12.

    We know that TPS-l2 derived from TCM-600 but probably that's half the truth because TCM-600 was mono on the other hand BM12 was not:



    But why this may be a prototype in the photo and not just a BM12?

    Because although the photo is not clear, it can be clearly seen that the large recording button of the BM12 ,on the top of walkman, is missing .

    You might argue that the button is pushed down but again the top seems pretty clear without shadows.

    There is also a rectangular color difference , in relation to the BM-12,to the outer right top corner suggesting a different part on that corner (hot line mic ?) .

    TCM-600 has to be excluded also because of the narrower plastic portion that contains the controls:

    a_005.jpg 2_003.JPG
    TCM-600 BM-12

    To the best of my knowledge BM-12 stopped being produced in 1978.

    And last but not least why it is in an anniversary photo with the large stereo headphones around it?

    1/31/15 9:46 AM

    Thank you for this interesting post.
    You have observed very sharp.

    I think it is the legendary prototype from March 1979.
    Look at the control on the headphone.

    Like Reply (3 Likes)


    1/31/15 10:41 AM
    Ha, love it.

    This is interesting actually, clearly a prototype, a bit more history here...


    Like Reply (1 Like)


    1/31/15 11:10 AM
    The official Sony prototype photo (or the prototype in the anniversary photo)must be either another or a modified prototype,there are two subtle but important differences,one already mentioned (rectangular color difference) A) and a small slot(B) that can barely be seen:


    One can't be certain but I think the difference is obvious.

    The headphones seem to be the same.

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    1/31/1512:12 PM
    Looking the magnified photo seems that the (B) difference (small slot) is just the door that is misaligned revealing that small slot (probably for the head alignment),but the (A) difference between the two prototype photos is there.

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    1/31/15 8:09 PM

    S2Go solves mysteries like this guy!


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    2/1/15 8:32 AM
    Thanks guys glad you liked it! icon_smile.gif

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    2/2/15 5:38 AM
    Sotza i like the way you unfold the story which
    is behind on how the TPS-L2 was brought by Sony
    to consumers. icon_smile.gif

    Like Reply (1 Like)


    2/2/15 7:36 AM
    Thanks Dimitri,just tried to resemble the research I've done only in fast forward! icon_smile.gif

    Check your PM. wavey.gif

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    2/5/15 2:09 PM

    Part 2 DNA Decoding

    This time under the microscope (sort of) is the prototype you can see at the Sony website (photo from renzgi and link from AO, above).

    This prototype photo is tiny and has very low resolution.

    Magnifying the photo and raising the contrast the result was this:


    Not a pretty sight but some interesting things revealed:


    The text in fact is one disturbed black line, under the Sony logo,but that's exactly the point ONE line:

    This photo is from the front side of a Sony BM-12,only BM-12 had one row text under the Sony logo.

    The TCM-600 had two row text...


    ...and the identical TCM-100 had two row text also.

    Raising the contrast revealed this lighted rectangular area that looks like a cover plate:


    In this region Sony BM-12 has this:

    The start button. Great for dictation but not needed on a stereo player.

    Here is a direct comparison of the prototype with a Sony TCM-100:


    And one by one:

    The prototype.


    Among the details spotted ,to the prototype,identical to the BM-12 there is also a small semicircular indentation near the edge of the door common to both (probably a cup for the head alignment screw).

    The Sony TCM-100.

    There are two unique details on the prototype:

    A) There is a protrusion, at the bottom, that looks like an adjustment screw .

    and B) The location of the headphones jacks at the bottom in the area where should be the DC IN on the BM-12.

    For comparison the bottom of a SONY bm-12:

    In conclusion, the Sony BM-12 looks almost identical to the prototype with the exception of the start button that is not in place but this area clearly seems covered,the similarity with the BM-12 is also internal,as can be seen at the first part with the "4 track two channel recording system".

    The Sony TCM-100/TCM-600 on the other hand has major and obvious differences from the prototype externally but also internally being a mono.

    It just doesn't seems logical ,if you want to build a portable stereo cassette tape player only and in your laboratory you have from the existing production line a BM-12 and a TCM-100/600 to choose the latter to build a prototype.

    A Sony BM-12 is on the way for comparative tests with a Sony TPS-L2 until then,

    Like Reply (2 Likes)


    3/28/15 2:38 AM
    Hi sotza

    Thanks to your post I have buy such a BM-12 for my TPS-L2 variants-collection. icon_thumbsup.gif

    Now a question about yours unit.

    What did you for a serial number.
    Is on the serial number sticker only the number or text "SERIAL No."and number?


    Like Reply (1 Like)


    4/4/159:31 AM
    Hi Renato,

    I'm very glad that you added a BM-12 to your collection icon_smile.gif

    Sadly my BM-12 never came through mail so I'm looking for another one icon_frown.gif ,that's why I didn't post any tests,just for the record it had a serial number sticker with the words "serial No" on it.

    It would be very interesting to hear what is your impressions of BM-12 in relation to the TPS-L2. icon_smile.gif

    Like Reply (1 Like)


    7/10/15 6:48 AM
    Back in Business Machine again!

    After a long long delay before I could finally get my hands on a BM-12 and an even longer delay before I could replace my laptop I can share with you some interesting new info ,photos and tests .

    I couldn't figure out what "BM" stands for until I saw this photo:


    Simply business machine..

    The most interesting aspect of BM-12 is the "4 track 2 channel system" ,carefully chosen words: "2 channel" but not "stereo" ,that's because you need 2 channel to have a mono cassette recorder with E-IDX system but that doesn't make it stereo.

    What the hell is E-IDX system ? I hear you say,it simply means Electronic InDeXing system, Sony explains:


    The above is from the owners manual ,the pdf I found is interrupted at that page (15) but you get the idea.

    I couldn't find a service manual to see how exactly the system works but in general the second track is used to record a signal to certain points of the recording , chosen by the user ,that signal is recognized by the "secutive" system to stop the tape at these prerecorded points :


    Here you can see the tape head of my BM-12,it looks stereo but is two channel:


    ...and front side :

    I haven't tested how that system works in practice yet but I was amazed by the sound quality even from the internal speaker with crisp and clear sound clearly on another world in comparison with my TCM-600B, although ,to be fair, this BM-12 looks almost unused contrary to TCM-600B which is heavily used.

    I found myself enjoying listening BM-12 from its internal speaker with a strange feeling to listen to something that looks like a TPS-L2 without headphones or external speakers !

    Sony BM-12 was a technically advanced evolution of TCM-600 with the addition of E-IDX system and that in turn brought BM-12 closer to the TPS-L2 concept with its two channel tape head.

    I hope to find a BM-12 service manual to find out what else is common with TPS-L2 internally.


    Like Reply (1 Like)


    7/18/15 3:27 PM
    Thanks for the additional contribution.

    I am pleased to see, you've buy the boxed BM-12 from West Haven. icon_wink.gif

    The disadvantage of the BM-12 is that it is not suitable as a music player.
    You can hear in stereo recordings only the right channel.

    And records of the BM12 listen on stereo player only on left channel.
    Left you can only hear the beeps of the Index.

    Like Reply (1 Like)


    8/20/15 3:46 PM

    Originally Posted by renzgi:

    The disadvantage of the BM-12 is that it is not suitable as a music player.
    You can hear in stereo recordings only the right channel.

    And records of the BM12 listen on stereo player only on left channel.
    Left you can only hear the beeps of the Index.

    Thanks renzgi icon_smile.gif

    That's right BM-12 is not suitable as a music player ,it can be used as a monitoring player or, if someone has recordings on mono boomboxes or mono cassette recorders shouldn't miss anything except of course the stereo feature .

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    8/20/15 5:08 PM

    Part 3: The Final Evolution

    It was all the time in front of us and all of us, subconsciously, had noticed but it was Tim Jarman and Nick Jarman from the wonderful WALKMAN CENTRAL site that put it down in words:

    "The WM-D6 used a very similar mechanism to that of the TCM-600 and the TPS-L2. The similarity is evident in the layout of the controls and tape transport components. However, to raise the quality to the high level demanded, the mechanism was upgraded by fitting a disc drive capstan servo similar to that of the TC-D5. "

    You can read full article here :http://www.walkmancentral.com/products/wm-d6

    This is an ad from 1982 of the famous Sony WM-D6 :


    Above is the first model (notice the green lettering under WALKMAN logo) of a long running production that lasted until 2002.

    In other words the WM-D6 had an evolution from 1982 until 2002, 20 years, but that's another interesting story.

    As far as TPS-L2 is concerned the first WM-D6 could be considered as its final evolution but the concept that started with the 1978 Sony TCM-600 and lasted with the 2002 Sony WM-D6C had a lifespan of 23 years, remarkable for a consumer electronics product.

    The only industrial product with uninterrupted , long running, production/evolution and close to the original concept that comes to my mind is from the automotive world with the Porsche 911 which by the way was born in 1963 the same year that Compact Cassette was introduced.

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    Last edited: Jun 17, 2017
  2. walkman archive

    walkman archive Administrator Staff Member

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    Great thread and great re-living. Thanks Sotza!
    bronco, deech and sotza like this.
  3. sotza

    sotza Active Member S2G Supporter

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    Thank you Hugo ,really appreciate It !
    bronco and deech like this.
  4. Boodokhan

    Boodokhan Active Member S2G Supporter

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    Enjoyed reading it
    nowadays most of the BM-12 models being repainted and sold like TPS-L2
  5. buzbox

    buzbox Active Member

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    That is true. Seeing so many on ebay.
  6. sotza

    sotza Active Member S2G Supporter

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    I'm not at all surprised.
    bm12 (2).PNG

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