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Thread: Interesting Chinese field coil 13" driver.

  1. #11
    Join Date: Feb 2013

    Location: W Lothian

    Posts: 44,801
    I'm Grant.

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    Quote Originally Posted by Barry View Post
    That one has bothered me for some time. I assume it is historic, as permanent magnets then were not powerful enough (i.e. could not produce sufficient flux density).

    However the power supply has to be very well smoothed, otherwise any residual mains hum would modulate the audio signal. Traditionally they ran off 100V and consumed a fair bit of power.

    The only advantage of field coils I can see is that you can vary the energising current, and hence the damping.
    How about back emf has less effect on magnetic field integrity and therefore is more accurate under normal operation.?? dont know, just asking
    Regards,
    Grant ....

    I've said it before and I'll say it again: democracy simply-doesn't-work
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  2. #12
    Join Date: Feb 2008

    Location: Middlesex, UK

    Posts: 3,287
    I'm Alex.

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    Quote Originally Posted by Barry View Post
    That one has bothered me for some time. I assume it is historic, as permanent magnets then were not powerful enough (i.e. could not produce sufficient flux density).

    However the power supply has to be very well smoothed, otherwise any residual mains hum would modulate the audio signal. Traditionally they ran off 100V and consumed a fair bit of power.

    The only advantage of field coils I can see is that you can vary the energising current, and hence the damping.
    I suppose that one could Turbo the field coil, over voltage the coil, probably shorten it's life too.
    Spendorman

  3. #13
    Join Date: Apr 2012

    Location: Southall, West London

    Posts: 35,214
    I'm Geoff.

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    Quote Originally Posted by spendorman View Post
    There is a 12" Magnavox field coil speaker in a very very old radio here.

    Is there any advantage of field coil units?
    I can't think why there should be. I think fans just like the 'aura' of a sort of exclusivity.

  4. #14
    Join Date: Apr 2016

    Location: souf east for work

    Posts: 950
    I'm paul.

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    Quote Originally Posted by walpurgis View Post
    The other products from this maker are well worth a look.
    Yes some nice kit, I have too many projects lined up already and not enough time.
    Sony STR 6055 Denon DP80 Stax UA-70 Shure Ultra 500 Zu omen

    Office system, DIY CSS fullrange speakers with aurum cantus G2 ribbons Najda dsp as dac Akai AM-U02 Jvc QL-A51 direct drive turntable
    SAE1000LT leema sub. JVC Z4S cart is in the house

    Garage system another Sony receiver, cassette deck and full range drivers in free air


    System components are subject to change without warning and at the discretion of the owner.

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