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Cabinet design help....Celestion BN15-400S

Discussion in 'Amps [BG]' started by jongor, Feb 3, 2013.

  1. jongor

    jongor Supporting Member

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    I'd like to design as small an enclosure as I can for this driver to fatten the low end on my rig.

    I've downloaded Winisd but can't seem to get anywhere with several issues...access violations when closing the program, no help file installed, after adding the driver to the database I can't select it....etc.

    I don't have a lot of power to give, running an older Eden Traveller that's 400 watts at 4 ohms, or an MB200 which 200watts.

    I would be running that speaker, as it's 4 ohm, alone with the MB200 or under an Epifani 112 with the Eden.

    Don't really know what frequency to design for, I play 4 string but use an octave pedal occasionally.
  2. 5 Wire

    5 Wire

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    What are the TSP's on the driver(s)?
    Design accordingly.
  3. jongor

    jongor Supporting Member

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    What are TSP's?....and I don't have a working design program.

    I don't know much of anything about designing cabs.

    This is the driver.
  4. 5 Wire

    5 Wire

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    Find one. TSP's (Theil Small Parameters) or SST's (Small Signal Parameters) are the electromechanical specs for a particular driver. Without this information design programs don't work and ignoring it will most likely cost you the driver.
    Do some research/homework.

    Vas - 171.9lt/6.07ft3 is what it is most comfortable in. That's a huge box man.
  5. 1958Bassman

    1958Bassman

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    If he can't get WinISD to work, what do you want him to do with the parameters? Make up his own formulae????????????????
  6. 1958Bassman

    1958Bassman

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    YOU do some homework. Vas isn't the size of the box that's needed, it shows the 'equivalent volume' of the driver.
  7. subbasshz

    subbasshz

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    this man has it correct.
  8. 1958Bassman

    1958Bassman

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    This link has explanations for all of the parameters.

    http://en.wikipedia.org/wiki/Thiele/Small#Small_signal_parameters

    They describe the electro-mechanical characteristics of a particular driver and are used to calculate the box dimensions, damping, resonance frequency, etc. Everything has a frequency that makes it vibrate most easily- that's the resonance frequency. I'm sure you have been near a large window when a big truck rolled past and wondered if it was going to shake itself to death. The Vas describes how easily the cone assembly moves when pushed- if you have handled a lot of speakers, you may have noticed that some move very easily and some are stiffer. A small Vas is stiffer and a large one is very loose. Instrument speakers aren't usually very loose.

    Anyway, getting back to the problems with the program, if you downloaded WinISD Pro, remove it and install it again. It may have a problem with the download. If it still doesn't work, look for the Beta version and try that- it's not as full-featured, but it's also not going to be as confusing. The Pro version needs/wants/uses a lot more data that may not be available from the spec sheet and may not be offered by the manufacturer. I think Linear should come up with a version that's somewhere between the two, so the power handling can be determined.
  9. jongor

    jongor Supporting Member

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    Oh...I know what the parameters are used for, just didn't recognized the acronym.

    I now have the beta version, will give it a try.

    thanks
  10. fdeck

    fdeck Supporting Member

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    Disclosures:
    HPF Technology: Protecting the Pocket since 2007
    In my view the Pro version of WinISD is the only version that can be used for bass cab design, as the Beta version doesn't allow independent adjustment of the box volume and port dimensions.

    I've created a box modeling program in the form of an Excel spreadsheet:

    http://personalpages.tds.net/~fdeck/bass/speaker.xls

    Beware that my program is not for the faint of heart. I intended it to accompany the documents that I wrote on speaker design theory. And I have relatively little practical advice to offer on speaker design because I've really never designed anything to satisfy anybody but myself.

    My impression is that the Celestion driver is not a good choice if you're looking for more low end. It has an Xmax of 2.5 mm, which means it is probably obsolete for bass use except perhaps in a low powered combo amp. There are 12" drivers that move more air for the same price.
  11. pie_man_25

    pie_man_25

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    ^ that is definitely a serious program, I think I'll be looking it through. I've been given a lot of troubles with the prop version of WinISD, only the beta version seems to want to work without any hassle, but it doesn't give me exactly what I want, this could be different though.
  12. astack

    astack Supporting Member

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    Yeah WinISD pro is what you want. It's finicky to get started with, for sure. But kudos for trying!

    Like fdeck said, the xmax of this speaker limits it's ability for bass.

    Things to look for when quickly comparing drivers (before going through the hassle of inputing the data) is the displacement volume, Vd. If it's not listed, you can calc it by multiplying the surface area (Sd, or roughly use the surface area of the nominal size, i.e. pi*15^2/4) by the Xmax (piston travel distance before weird things happen :)). That will give you an idea of how much low freq it can dish out, relative to others. A premium 15" can do 400cc no problem. That one is closer to 250cc.

    Another thing I like to check quickly, is wether it's suited for a sealed or ported boxes. Find the EPS = fs/Qes. If it's 80 or less, sealed all the way. Over 120, ported all the way. Around 100, could go either way. You'll notice this driver is suited for a sealed box. That doesn't tell you a lot unless you care about which design to use though. But it will keep you from trying to fit a square peg into a round hole, type thing.
  13. rpsands

    rpsands

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    Not interested in entering that into Winisd really, but that woofer is suited for a ported box.

    I'd start at 3 cubic feet and 45hz tuning and jiggle it around from there.
  14. lhoward

    lhoward Gold Supporting Member

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    I noted that this driver is available in 4 and 8 ohm impedance. There is some variance for the T/S parameters for each one, so the OP needs to determine which he will use. From my point of view, I would not use either one for bass instrument applications as the x-max is 2.0mm and 2.5mm for the 8 and 4 ohm models, respectively, and I don't why the design engineer decided on such a minimal x-max for a bass driver. I'd look elsewhere for a more suitable driver.

    Take a look at Fdeck's very nice design spreadsheet, although you may need to enable macros in your spreadsheet's security settings in order to fully use the document. It may help gain some knowledge in this area if you don't want to purchase the full version of WinISD. You can also do a web search for “loudspeaker designing” and study the references found. 1958Bassman's link will also help educate you in the mathematical nature of the design process if you don't mind doing some number crunching on your own.

    Both the design and construction aspects are enjoyable ventures. Have fun!

    Attached Files:

  15. rpsands

    rpsands

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    Look at the ratio of xmax (2mm) to xlim (10mm) - it's a design decision to increase distortion.
  16. fdeck

    fdeck Supporting Member

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    Increased distortion and weak bass are two sides of the same coin.
  17. rpsands

    rpsands

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    Yep, but plenty of guys like that sound, and you can often get enough lows. And you can get more sensitivity that way.

    All part of the balancing act, but I wouldn't call it a blanket stupid decision so much as a design decision.
  18. 5 Wire

    5 Wire

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    There is a formulae. Pretty simple with a calculator. All it takes is a little homework like, i dunno, looking up the equations?
    Wow, you can use Google. I did the homework - you do it and tell me what size box you come up with.
  19. pie_man_25

    pie_man_25

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    I honestly have not even thought of that, I just gave them a pass based on the low xmax, so maybe they'd be good drivers for somebody looking for a "classic" type of sound?
  20. BogeyBass

    BogeyBass

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    I agree it wont handle to much power
    so a small box and tuning it close to (Fs)

    so 3 cubes at 41/45 hertz sounds good to me.

    but i dont understand why you would want to mate this with a single 12, and dont understand why with a 4ohm
    hope your amp is 2 ohm stable

    what is the load of the 112

    plus i really would not waste time with this speaker
    sorry...it is what it is.

    for the price range a kappa 15lfa would handle much more power
    not much highend but i guess that is what the 12 is for
    the kappa could go into 4 cubic and same thing tune to the Fs of the driver

    but just build your box to match your 12" width wise
    and then make it deeper to get 3 cubic feet

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