Advice re spacers in adjustable bass reflex port..

Discussion in 'Hi-Fi and General Audio' started by Doctor Jeep, Jun 12, 2007.

  1. Doctor Jeep

    Doctor Jeep

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    Hi guys,

    I've just acquired some Castle Conway 3 floorstanders for a second system and they don't come with any hints on how many spacers may be needed to raise the speaker above the plinth and thus adjust the reflex port. I'm aware this may be a room thing and that it alters the 'damping' factor but beyond this I'm stumped. OK I understand that trial & error may be the best way forward here but I just wondered if there was a more scientific method? It's a real tricky job fitting the spacers and I would rather get it right on the first go if at all possible! Do I go for two or shall I try three? :confused:
     
    Doctor Jeep, Jun 12, 2007
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  2. Doctor Jeep

    SteveC PrimaLuna is not cheese

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    No-one else has answered, so I'll guess a bit. I suppose the only objective way would be to measure the frequency response you are getting and adjust the port damping (spacing) to help correct any objectionable bulges you're getting. You could accomplish this by borrowing mic and gear such as Behringer DEQ 2496 or Velodyne SMS-1 to get a graph of your bass response. Or you could do it the laborious way with a downloaded CD of sine tones over a range of frequencies, a sound level meter and a spreadsheet.

    But in practice I'd be inclined to set them up with middling spacers and just move them around the floor a bit. After all, many people that get ports supplied with optional bungs face the same problem but I never heard of anyone doing it properly "scientifically".

    Maybe you've got the reverse "what the eye don't see the heart don't grieve over" syndrome: the adjustment is there so one feels one has to use it. But OTOH this is such an uncommon option that it can't be that critical can it? Maybe even experiment with greater or lesser bungs if it's a pain actually to change the spacers.
     
    SteveC, Jun 12, 2007
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  3. Doctor Jeep

    Snoo

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    Your best bet is to give Castle a bell and I'm sure they'd give you a swift response.
     
    Snoo, Jun 13, 2007
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  4. Doctor Jeep

    Doctor Jeep

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    Cheers chaps.
     
    Doctor Jeep, Jun 15, 2007
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  5. Doctor Jeep

    pvslab

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    I read a review that says with 3 spacers the port is effectively tuned to 50 hz, and 45 hz with 2 spacers.
     
    pvslab, Jul 14, 2007
    #5
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