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Thread: ECM8000 Mods

  1. #101
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    Marik,

    It may be similar to the pics you posted on page 2, but the variations required enough modifications to the PCB to regard this as "version III".

    What I have just noticed is that either (or both) the larger 22uf electrolytic near the XLR connector and the 152 ceramic next to it have been generating enough heat to start to fuse the two together as they were virtually in contact. On my other ECM, even though there is a gap between the two caps, there are signs that heat is causing changes to the cap surfaces.

    Gus,

    The two small ceramics at the connector end are 222. The other two are both 152. The larger electro is 22uf 35V. The small electro in that group I can't identify other than it is 50V. The larger blue electro is 47uf and the small one next to it appears to be 22uf and the last electro at the capsule end is possibly 10uf. The polyester at the end is 332J.



    The transistor is marked .... S9014 C 331, and the IC is A1349.

  2. #102
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    <It may be similar to the pics you posted on page 2, but the variations required enough modifications to the PCB to regard this as "version III".>

    Ausrock,

    I meant the schematics is the same, just different PCB layout.

    <The two small ceramics at the connector end are 222. The other two are both 152. The larger electro is 22uf 35V. The small electro in that group I can't identify other than it is 50V. The larger blue electro is 47uf and the small one next to it appears to be 22uf and the last electro at the capsule end is possibly 10uf. The polyester at the end is 332J.
    The transistor is marked .... S9014 C 331, and the IC is A1349>

    All the values are the same as on my version, except of coupling small electrolitics, which are changed to SMs on mine. On one of my boards the transistor is BC118, on another--BC331--same as yours. The A1349 is a 2SA1349 monolitic dual transistor.

  3. #103
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    Originally posted by ausrock
    What I have just noticed is that either (or both) the larger 22uf electrolytic near the XLR connector and the 152 ceramic next to it have been generating enough heat to start to fuse the two together as they were virtually in contact. On my other ECM, even though there is a gap between the two caps, there are signs that heat is causing changes to the cap surfaces...
    This is very strange. I've never heard of caps heating up like that - unless you happen to be holding a soldering iorn to them.

    Are you sure they weren't just glued together?

  4. #104
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    Tim,

    That was my first thought, so I opened up my second ECM and found that the two caps in question were totally separated but two others were almost touching and showing similar signs. It is always possible that a small quantity of a solvent based liquid has splashed on them and caused some minor damage. I can't imagine flux retaining sufficient heat to do this although the residue around the "melted" surface could be a flux deposit........maybe. Remember, what I am seeing is only a couple of mm square if that and only where the caps are VERY close together.


  5. #105
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    Here is complete schematics of the stock one:
    Attached Thumbnails Attached Thumbnails behringerecm8000schema-jpg  

  6. #106
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    Originally posted by ausrock
    ...Remember, what I am seeing is only a couple of mm square if that and only where the caps are VERY close together...
    Ha! I know what happened - they were touching each other when they were being soldered to the board. The heat from the soldering iorn (or flow machine) was just enougn to cause some melting.

  7. #107
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    I'll accept that explanation...lol.


  8. #108
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    OK folks,

    Hope I did not bore you to death with this one and you are still interested in this project...
    The mic is ready to go.
    As I wrote before, I tryed a lot of different circuits and made at least five prototypes. I gave up WM60 capsule for two reasons. First, it is more noisy, and second, it is out of production.
    The easiest mod would be to change it for WM61 with Linkwitz mod, and to throw away transistor in the circuit with associated parts. Apart of some noise and SPL handling improvement, the sonics are also better. The output will be the smae as a stock one.
    Scott Dorsey's mod, as somebody advised, did not work well with this capsule--bass was noticably rolled off.
    Finally, I made a circuit based on JFET source follower as a buffer, with constant current source. If you are interested I can draw schematics (right now it is in my head only). I am wondering if I use this circuit for Oktava 012...
    I am getting very busy, as I am preparing for major recording of mine. Meanwhile, for this recording I made a new tube preamp, based on Kevin Carter's phono pre, and now working on my new ribbon mic coupled with omni capsule.

    Harvey kindly agreed to check the modded ECM8000, so around mid March I will send it to him for review.

  9. #109
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    Thanks, Marik. I think we are still very interested in your work on this mod and others. Good luck on your recording project.

  10. #110
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    Wow, great work, Marik. I'd be verrrry interested in the schematics!

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