Question about Alesis M1-Active MkII Main / Stereo Speaker

1 Answer

Fried Woofer I turned on my speakers and there was no signal being sent to the amp. very strong smell of buring. Thought it was a power supply (wall wart). Then saw smoke coming from the speaker cab. Woofer fried. Took both cabs apart and did check on speakers. Dead speaker showed .7ohm. Good speaker was about 7ohm. Tried to test amp by hooking good speaker to it. Bad move - fried the other woofer. Looks like something has failed on main board and sending high voltage to speaker. very pissed off with this as the units are just over 1 year old. Cant believe that Alesis has designed a board that has very little protection for the speakers. have been thinking about repairs and buying new woofers but can anyone tell me if this problem will keep happening. If anyone knows what part of the board needs replacing please tell me. But - even if the amp circuits are repaired what are the chances of this happening again? Anyone got a circuit diagram? Thanks for any help. Mezzy

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  • mezzy Nov 29, 2008

    thanks for your help - but ended up throwing them away. did not wish to try repair for same thing to happen again. the spares are 2 expensive. going for a better make instead

  • mezzy Nov 30, 2008

    Hi again,



    The small parts are, as you say, not that expensive and I was going to repair the electrronics. But what put me off was the cost of the speakers. They are a silly price. OK - I would have paid the price if I had faith in the electronics. But my speakes died after just 13 months - just out of warranty.



    I decided that the protection for the speakers was rubbish and that it could easy happen again. If the circuits fail then full power goes to the coils and burns them out. It is a very poor design. I cant believe that there was no safe guard to stop this happening.



    For a few pence more a fuse or some other device could have been added to the speaker supply making certain that if excess power somehow got past the other stages then it would not ruin the speakers.



    When I do get new units I shall be looking for non powered ones.





    Thanks for your help. Hope that other owners of these speakers do not have the same problems.

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The problem are worsen that before. It is wisely to replace both left and right amplifier
IC, but make ensure that the power supply feed a good amount of voltage to amplifier,
Also a strong good signal. Be sure to measure it.

r_ic7

Posted on Nov 29, 2008

  • Rick Foster
    Rick Foster Nov 29, 2008

    Im so sorry ! the common problem in your area like that parts are true expensive

    Example : 2pcs of TDA 7294 IC for the left and right power amplifier ?

    But doing the job is so easy ?and the thermal protection is the fuse and heat sink.

    Base on my experience its better to replace them both rather than to made it cheaper

    by replacing one by one to get rid of happening again.

    I foresight the the future and the warranty period of the job.if well done

    Thank's thats all.



    r_ic7

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