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Rear loaded horn

Discussion in 'Amps and Cabs [BG]' started by fbleagh, Mar 1, 2002.


  1. fbleagh

    fbleagh Guest

    Mar 1, 2002
    Hmmm any of you guys ever played on a rear loaded horn rig ?

    I tried one at a friends place and damn that is some serious bass extension.

    cab stood 5'6" loaded with a 12" JBL driver.
    Powered by a 200W homemade MOSFET amp, with a basic solidstate pre-section.

    all homemade and rather excessive :0

    but i would love one for my room - ( i dont like my neighbours )

    I was thinking of rear loading an EV 15" and driving it with a 400W amp i have around.

    This will not come into fruition for a quite a while - hense my previous thread about a chaeap amp :)
    but it food for thought and something ive been wondering about.

    :)
     
  2. bizzaro

    bizzaro

    Aug 21, 2000
    Vermont
    I would bet it is a"folded horn" like in a bass bin design. I would further guess with the horn facing the wall, the whole wall sort of acts like a huge cab and reflects the sound back which also would reduce the distance necessary for a folded horn to be effective. Just a guess.:)
     
  3. gweimer

    gweimer

    Apr 6, 2000
    Columbus, OH
    Most folded horn cabs involve a sound baffle that forces the sound wave to travel a length much greater than the actual cabinet size, allowing (as bizzaro states) the lower frequencies to develop more completely before they leave the cab. It usually translates to more rumble in a smaller space. If you use one of these in a loud club, you will learn very quickly to play by FEEL (literally) rather than by tone!
     
  4. Tom Crofts

    Tom Crofts

    Mar 15, 2001
    If it was a REAR LOADED horn then the mouth would have to be about 12ftx12ft to allow you to play an E without the bass having rolled off somewhere higher...
     
  5. bizzaro

    bizzaro

    Aug 21, 2000
    Vermont
    I don't claim to be a techy, but I think you should check your facts. I have never seen a bass bin with anything close to a12x12 foot horn. And the folded horn design is used, but I don't think you'll find too many in the dimensions you state are necessary to be effective. I realize you said rear loaded horn, but still I can't fathom it. I guessed the wall behind the horn would shorten the "throw" of the horn? Anyone familiar with this design:confused:
     
  6. Tom Crofts

    Tom Crofts

    Mar 15, 2001
    a rear loaded horn isn't the same as a folded horn. It has the speaker(s) at the front above a big horn mouth and the waves from the rear of the speaker(s) move through a long folded horn out to the mouth at the bottom. I don't know how big it has to be for a normal folded horn... Sorry for any misunderstanding.
     
  7. bizzaro

    bizzaro

    Aug 21, 2000
    Vermont
    Hey, I really don't know about cabinet design and I appreciate your patience. This is beyond any knowledge I have concerning cabinets. It just sounded beyond reason to for a horn to have to be so big....ie where is the payoff? Why even develop it like that if it isn't usable?
     
  8. Tom Crofts

    Tom Crofts

    Mar 15, 2001
    Well if it did have a 12x2 mouth then it would be VERY powerful and produce a hell of a lot of bass. So it could be used in a PA system for a club or something I suppose... This is what I wrote about the rear loaded horn for my tech project I'm doing at the moment (building meself a cabinet). I got it from a number of books but there was nothing relevant that I could find on the internet.

    Rear Loaded Horn

    The rear loaded horn takes the waves from the back of the speaker and directs them in a 180° semi circle out the front. The waves from the front of the cone are radiated directly forward. In most systems the rear loaded horn produces a relatively high percentage of bass (because the shorter high frequency waves cannot follow the bends in the horn as well), and it is considered to be well suited to rooms where fidelity is the primary consideration.

    The horn flare can be generated from the rear of the driver, folded to conserve space and opened out at its mouth to the front baffle for the bass frequencies only. The front of the driver can then operate as a direct radiator for the mid and high frequencies. However, for the horn to reproduce an E (41Hz) the mouth of the horn would have to be 12ftx12ft.
     
  9. bizzaro

    bizzaro

    Aug 21, 2000
    Vermont
    so with a rear loaded horn, does the opening have to seal around the back of the driver, or is thier space between the beginning of the horn and the driver? and the shape of the horn is just a return from the rear of the driver in a half circle to the front of the driver??
     
  10. Tom Crofts

    Tom Crofts

    Mar 15, 2001
    Well I think it can either be a big huge 180 degree thing like the hedlund (i think) try searching for rear loaded horn on google and it's one of the first ones... Or I think it can be folded up like a maze type thing inside the top bit. Here's the only pic I've ever seen of an instrument specific one in an old guitar book.