DIY Sub Problem

Discussion in 'DIY Speaker & Subwoofer Building' started by csx, Apr 2, 2001.

  1. csx


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    Just made a sub woofer based on following design :-
    85L Vented enclosure from 25mm & 50mm MDF
    Fully braced sealed and 80mm tuned vent.
    Driver Peerless 850140CSC 10" 150W 8 ohms
    FS=25.6, Xmax=6mm, QMS=3.39, QES=0.39,QTS=0.35, VAS=136L

    I Designed it using WinISD giving me an 85L box for Tuning Freq=29.5Hz.
    Box lightly lagged and quite square in dimensions (on castors)
    However on powering it up im not happy in fact my mates stereo Boss 10" speakers gives more tighter power output. I will attempt to explain what it does and doesn't do :-
    At low levels seems nice and low in frequency and good quality with tight bass and no distortion. When I crank the amp right up the bass goes sort of boomy because the driver cone seems to be going wildly in and out (vibrating). It seems the driver cant handle the high volume low bass.
    The box is built like a brick **** house, vibrations of the enclosure is very minimal even at high outputs.
    I was expecting this thing to make my guts rumble and my ornaments dance but no way. others on the newsgroups tell of such things with subs no bigger than mine.

    Whats wrong ?? Please help. I spent 4 months reading up and designing this thing and im not happy. Normal listening levels is fine low and tightish, but at high volume its not awesome its disappointing.
    Things im gonna try
    1. Running it in longer at its only had about 3 hrs under its belt
    2. I have about 15mm of insulation on all but the front inner face, I will fill 50% with loft insulation.
    3. If all else fails buying a 12" Shiva driver and Vent from Adire and putting that in my box based on their 85L design.

    Any suggestions welcome.

  2. Ramius

    Well-known Member

    Oct 13, 2000
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    It looks like that the Peerless driver is more of a 'woofer' than a true 'sub-woofer'.
    A high excursion 12" such as Adires Shiva will give you the results you're expecting.

    That 29Hz tune is too high and this is causing the driver to unload below Fs (all that flapping business).
    Try tuning to around 20Hz. This will mean a longer vent- 20Hz tuning, 80mm diameter vent, will require a length of 377mm, will this fit in your enclosure?
    You may want to even try completely removing the port and going for sealed. The driver can be used for a sealed application according to WinISD.

    And make sure your enclosure is leak free.

    As I'm sure you've read before- 'Bass is all about moving air' unfortunately your Peerless wont be cutting it compared to a Shiva or similar, if you want that gut wrenching bass you may have to bite the bullet and get the Shiva for your enclosure. [​IMG]


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