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Cab design help needed. JBL 2204H driver

Discussion in 'Amps and Cabs [BG]' started by jock, Apr 10, 2005.

  1. jock


    Jun 7, 2000
    Stockholm, Sweden
    I´ve got a JBL 2204H in a SBB4 tuned cab right now and it sounds great. The deal is that I´ve got a 1x15 Glockenklang on it´s way to me right now :hyper: and I will only need the JBL to give me some mids on bigger club gigs while the Glock will be used on it´s one in smaller settings. The SBB4 cab is made of MDF so it´s really heavy and I´d like to build a new cab from birch or pine plywood. I just thought that it would be a good idea to make a sealed cab for the JBL and add some lowcut filter. This way I can make a smaller/lighter cab which is my goal here (27 liters sealed vs. 47 Liters in SBB4).
    So is this a bad idea? Should I just build a lighter SBB4 cab? And how would I make a lowcut filter for this config? Is it even needed?
  2. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    30l sealed will give you an f0 at 200Hz, f3 at 100. HP filter the JBL with a 80mfd electrolytic paralleled with a 20mfd poly.,assuming you don't want to pay $20 or more for a 100mfd poly. You might also want to LP the 15 at 1kHz, as above that it's only beaming anyway, with an output from the JBL box filtered with 1.3mH.
  3. 6L6


    Apr 7, 2005
    If the job of the JBL is to give you midrange,
    i think your'e better of with 2 x 10" system.
    OR a 1 x 12".
    Still, is there anyway you can use a 2 channel amp ?
    One channel for The bottom and one ch. for mid.
    And a electronic crossover. ?
  4. jock


    Jun 7, 2000
    Stockholm, Sweden
    The 2204H is one 1x12 speaker. :meh:
    I use it with a mono amp and dont want to carry a big stereo poweramp.
  5. Petebass


    Dec 22, 2002
    QLD Australia
    Yep 30 litres sounds good for a tried and true Qtc of 0.707 (B2 Butterworth). Interestingly the 20L sealed yields very similar F3 figures. It pushes the Qtc out to aprox 0.8. There's nothing to worry about there.

    As a rough guide, the smaller the sealed box (higher Qtc), the better the transients but you may end up with something that's overdamped and a bit taught sounding in the bottoms. That said, sealed cabs are far more forgiving to changes to cabinet size, and you've got the Glock 15 to take the lows. So far so good.

    Now the bad news (maybe). Your biggest problem is going to to be making a 20l box that cab fit a 12" driver. It's going to have to be quite shallow. I'm not sure how deep a 2204H is, but if it's any deeper than 170mm, you may have a problem. For this reason alone the 30l cab might be the better option. It's unlikely the 2204 is more than 240mm deep, and it's still a very small cab!