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Discussion in 'Amps and Cabs [BG]' started by Paul A, Sep 29, 2000.

  1. Paul A

    Paul A

    Dec 13, 1999
    Hertfordshire U.K!
    I'm building a 4x12 cab.When it comes to selecting the right type of speakers.......I'm confused!!
    What frequency range do I go for?
    What efficiency (93db,98db or 103db)?
    what the f*** is resonant frequency?
    (I'll be running it with a 100 watt vintage Selmer valve....sorry,TUBE amp!)
  2. CS


    Dec 11, 1999
    Dont know but I know a man who can.

    THE bloke on this board would be Joris. Try e mailing him.

    If you get no joy try http://www.webervst.com its the home of weber speakers. Theres a chart thing to help you build cabs. Also try the discussion board and go to speakers put Ted in the title, Ted is Ted Weber who knows a lot about speakers funny enough.

    Also havent seen you around much. Happy hunting.

  3. Hi Paul,

    Resonant frequency (fs) is the most important number on a speaker chassis. Preferrable as low as possible. With a 12" 50-60 Hz. Next come Qts, Vas, Xmax etc. etc... Frequency range of the total cab is not important. More important is distortion. The cab mustn't distort in the range you intend to use it. Tune the cab accordingly. efficiency as high as possible. with a 4x12 add 6dB of efficiency compared to one speaker. Anything above 102 dB (total cab) is very good.

    You should really look for yourself which brands and types you can get your hands on. EV, Celestion, Black Widow, to name but a few common US brands. Pick a few of'em and email me their specs. I'll run simulations and pick the best one out for ya!

  4. Hey Paul, where are you man? I guess you're not in a hurry to build that cab.
  5. Paul A

    Paul A

    Dec 13, 1999
    Hertfordshire U.K!
    Hi Joris,
    I'm having a bit of trouble actually getting the parameters of various speakers from dealers over here.Most times they just shrug their shoulders and say 8 ohms......
    The ones that I have been able to get parameters for only handle down to 55hz or so...Is that low enough? ..I don't know.Maybe you could tell me?
  6. I think you should look for a speaker yourself on the Net (start at the brands I listed above), then decide on one, go to the dealer and ask if he can order THAT SPECIFIC SPEAKER. That way you already have the numbers on it (you got them from the NET). If the numbers of a speaker aren't listed, then don't buy it. It's either crap or the numbers are so bad you can't design a proper cabinet for it.

    That's how I see it. No parameters: don't buy it.
  7. Paul A

    Paul A

    Dec 13, 1999
    Hertfordshire U.K!
    Hi Joris,
    Yeah, I think you are right,most dealers I've talked to either don't have a clue .... or something to hide!!
  8. The offer still stands: find a few speakers that you think are good and I'll fire up my design sheets, and select the best one for ya, and maybe even design the whole cab... for me, it's 10 minutes...

    PS. check out JBL too! Maybe the 2206H/J... if it ain't out of your price range.
  9. Paul A

    Paul A

    Dec 13, 1999
    Hertfordshire U.K!
    Hi Joris!
    Finally (I hope) found some suitable speakers.
    How do these sound (pardon the pun!)
    resonance = 51hz (fs)
    freq. range = 50 - 5khz
    sensitivity = 100db
    impedance = 7.25 ohm (Re)
    coil inductance = 0.78 mh (Le)
    electromagnetic q = 0.52 (Qes)
    mechanical q = 5.26 (Qms)
    total q = 0.47 (Qts)
    compliance equivalent volume = 125.38 litres (Vas)
    peak diaphragm displacement = 42.26 cc (Vd)
    mechanical compliance of suspension = 0.3150 mm/N (Cms)
    bl product = 11.75 T-M (BL)
    diaphragm mass (Inc airload) = 30.8 grams (Mms)
    mechanical suspension loss = 1.8804 N*sec/M (Rms)
    efficiency bandwith product = 98.4 (EBP)
    voice coil overhang = 0.8mm (Xmax)
    surface area of cone = 532.36 cm (Sd)
    Impedance at resonance = 80.7 Ohms (Zmax)

    Phew! ...Thats about it! ... hope you can help!
  10. Try out the free software here for plots of cabinet designs with different speakers and cabinet styles.

    The Eminence Beta 12 is in there. I've been eyeing that speaker for my 4x12.



    [Edited by throbbinnut on 10-30-2000 at 11:23 PM]
  11. I'm sorry Paul,

    The Xmax of that speaker is only 0.8 mm. I'm afraid it's not a bass speaker, but a midrange. A 12" bass speaker has at least 4 mm of Xmax (that's the maximum travel of the cone) to move the amount of air necessary for bass.

    Here's what you should look for:

    Qts: 0,25 - 0,4
    Xmax: 4 - 8 mm
    Fs: 40-60 Hz

    Only when you are in these ranges, you can look if the efficiency is right and the high frequency limit is at least 3,500 Hz.

  12. Paul A

    Paul A

    Dec 13, 1999
    Hertfordshire U.K!
    Thanks Joris!
    D'you think I might be better off using 10" speakers?
    They seem to be more readily available.
  13. Excellent info Joris. Could you post some recommended T/S numbers like that for 10's and 15's as well? I'd like to have an idea of what I need for bass with different size speakers.


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