Time to Rebuild / Upgrade

Discussion in 'Archived Threads 2001-2004' started by Rich Coffey, Mar 11, 2003.

  1. Rich Coffey

    Rich Coffey Auditioning

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    Hi all,
    I have been reading this forum for a while and have a few
    questions and would appreciate your input.

    I have a pair of 23yr old M&K Volkswoofer Subwoofers that are showing their age and many parts for them are no longer available. For those not familiar with thes Subs, they are 2 cubic foot sealed cabinets with a 12" driver and a 60watt servo feedback type plate amp.

    I was thinking that with the technology available today I might be better off gutting the cabinets and upgrading the
    plate amp and driver.

    After reading the many posts here and checking the few things that I understand of the specs I am thinking of using either the PE 250 or the Rythmik 350 watt plate amp and possibly the Titanic MKII driver.
    I am not locked into these individual amps and drivers and
    other suggestions and explainations would be welcome as well.

    At this time I am only able to use one of the subs due to space restrictions.

    I am looking for suggestions to get the most kick and bottom
    end from this cabinet while maintaining the sealed cabinet.
    I listen to about 60% HT and 40% music.

    I am trying to learn as much as possible about this project but there seems to be much to learn.

    All suggestions and explainations would be welcomed.

    Thanks in advance
    Rich
     
  2. JohnOwens

    JohnOwens Agent

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    The driver that comes to mind in a small sealed box like that is the Adire DPL 12.

    It has a -3db (F3) or around 30 Hz - much lower than most.
    The sensitivity is not very high (around 84db @ 1/W I think) so the Rhythmic would be the way to go if you want to get a boost of about 2-3 db compared to the RE 250w amp.http://www.adireaudio.com/diy_audio/...dire/dpl12.htm
     
  3. ThomasW

    ThomasW Cinematographer

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    The Titanic MKII are nice drivers. However the Vas is a little high for use in your boxes.

    If you can wait for the Stryke AV12 second preorder, those would be a good 'fit' for you M&K boxes.

    Or if you want something readily available the closeout BP-1203's are quite good.

    With either the Stryke or BluePrint look a higher powered amps and possibly using a Linkwitz Transform circuit to get good deep bass. Both of those drivers are rugged enough to handle the extra power that the use of an LT circuit requires.
     
  4. Rich Coffey

    Rich Coffey Auditioning

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    Thanks for the info John and Thomas.

    I have been trying to learn a bit more with modeling software but seem to know less now than I did to begin with.

    I have been working with WinISD and Unibox but really don't know if I am inputing the proper info to get results like I have seen in other posts here and in the Speaker forum.

    Thomas, you mention that I would probably need more power
    with the Stryke or Blueprint. I was wondering how much
    power would be necessary for good results? Would the Rythmik
    350 be enough or are we talking something in a totally different power range. I would like to stay with either the Rythmik or PE 250 plate amps if possible.

    John, I was wondering how the Adire DPL 12 would compare with the suggestions that Thomas made.
    Could either of you give me an idea of what the low end capability would be for the various drivers?

    The specs on the original M&K system if accurate were:
    Anechoic measurement of 18 to 100HZ + - 3db with a roll-off
    below 10Hz to help eliminate rumble and near DC infrasonic noise.

    I don't necessarily understand all the info that I have been
    collecting lately but am doing my best to learn. The only reason I mention the specs of the M&K is that I would like to compare what I had with possible replacements.

    Please bear with me as I am new to this and trying to learn
    on the fly.

    Input from any other forum members would also be appreciated.


    Thanks again
    Rich
     
  5. ThomasW

    ThomasW Cinematographer

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    I have a dozen of the Adire DPL-12's boxed up in the basement. They're certainly very nice drivers. Although certainly usable in a standard sub, it isn't a 'mondo' woofer like the BP or AV are. Also for your use the DPL-12 offers no significant operational advantage over it's less expensive cousin the Shiva

    The low end capability of any driver is a function of box size and the 'tuning'. Note that tuning for a ported design is the size of the box combined with the size of the port. A sealed box is 'tuned' only by the size of the box. The bigger the box the lower the tuning.

    Since you have a 'fixed' box size, there really isn't much point in modeling it's performance. If you were going to rebuild the box or scratch build something then the modeling programs would be beneficial

    BTW, I don't use WinISD, I much prefer Unibox. Regarding Unibox you enter the T/S parameters of the driver along with the net box size(box volume with driver displacment subtracted)you want to model. The only variables you can enter are those in blue. The program creates the red ones. You then tell the program to 'update' and it models the performance of the design.

    For a reference here's a Unibox model of a BP-1203 is a ported 70L box. Obviously your box is smaller (58.6L) and sealed. This model is one I had already uploaded to my server for another project

    [​IMG]

    As far as amps go I recommend getting the amp that will deliver the most power to the driver you choose.
     

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