DIY Speaker Cabs for Tannoy DCs - Advice Wanted

Discussion in 'DIY Discussion' started by Uncle Ants, Oct 21, 2004.

  1. Uncle Ants

    Graham C

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    Lordy mama - where to start? First off, your graph and analysis are spot on..as you said, you can either have a 'bit more' at the very bottom - and lose a few dB @ 45Hz or have a 'maximally flat' curve to use the jargon. Not a lot gained is also how I would describe it
    The trouble with modelling the passive bits is too many unknowns.

    If you use their x-over, you would start by measuring the DC resistance of the inductor that feeds the bass driver, then add the resistance of your speaker wire. It might come to say 1 ohm..

    Re = 6.3 ohm [datasheet] + 1 ohm = 7.3

    7.3/6.3 = 1.159

    1.159 x Qes = 0.5005

    Qms = 5.32 [datasheet]
    [ 1/.5005 ] + [ 1/5.32 ] = 2.186

    1/2.186 = 0.45746

    This is the new Qts and has gone from 0.4 to now 0.457 which sounds trivial but isn't. If the Q is above about 0.5 you will never achieve a curve like your 150 litre box line because the Q is too high. Try making a new driver model in WinISD with the new Qes and Qts [ call it DC 200 + 1ohm] and see how the new curves need much bigger boxes
     
    Graham C, Nov 22, 2004
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  2. Uncle Ants

    MarkS

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    Hi Dev!

    I don't have params for the 2558 driver as I never had a pair to play with...bit thin on the ground. I was going to recone a pair of 2588's but never got round to it - sorry.

    Mark
     
    MarkS, Nov 22, 2004
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  3. Uncle Ants

    MarkS

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    Try Electro Voice and you will change your mind. :D

    Mark
     
    MarkS, Nov 22, 2004
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  4. Uncle Ants

    themadhippy seen it done it smokin it

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    i have( the sx200's are a pretty good alrounder),along with meyer,jbl,martin yamaha and sevral other manufacters offerings and still stick with the cougars
     
    themadhippy, Nov 23, 2004
    #44
  5. Uncle Ants

    Uncle Ants In Recordeo Speramus

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    Dear Graham,

    Many thanks - maybe we should have a new Forum - "Speaker Design 101"

    I plugged the new figures in and it came back with a 135 litre box (quite a difference) and the port tuned to just over 26 Hz. The curve looks a lot better too - we've magically gained 5 Hz at the bottom end (see attachment, pink = 87 Litre box, green equals +1ohm and 135 Litre box).

    Now I'll just have to get the real measurements for resistance (actually find someone who can do it for me - I wouldn't have a clue) and plug in the real figures.

    As an aside - this small change to the paramaters has made a big difference to the optimal box size and port tuning - given that part of this change is down to the resistance of the speaker cable, could this be why speaker cables might make a difference? (no I don't want to start that old debate again, but it seems logical).
     

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    Last edited by a moderator: Nov 23, 2004
    Uncle Ants, Nov 23, 2004
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  6. Uncle Ants

    MarkS

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    Well I guess that makes you a happy man...

    Enjoy.

    Mark
     
    MarkS, Nov 23, 2004
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