Rear Loaded Horn?

Discussion in 'Amps and Cabs [BG]' started by Tom Crofts, Feb 4, 2002.

  1. Tom Crofts

    Tom Crofts

    Mar 15, 2001
    Hi, I'm making a bass guitar speaker cabinet for my AS Tech project and was wonderig if anyone knows anything much about rear loaded horns? I am thinking of making a 2x12 horn as this should give extended bass response due to the horn and good mids with the 12s (is this right?). Does anyone make one commercially? I've never even heard one before, what does it sound like? Apparently it's kinda honky or something (that's what dr. decibel from celestion told me).

  2. gweimer


    Apr 6, 2000
    Columbus, OH
    I assume you mean speakers when you say horn. I don't know if they still make it, but Gallien-Krueger used to make a rather odd cab - 4x10 rear-mounted w/baffle and 2x12 front-loaded. Rear-mounted cabs aren't all that rare, and I would guess you'd be able to find a design spec somewhere - JBL might be a good starting point.
  3. Tom Crofts

    Tom Crofts

    Mar 15, 2001
    No, I don't mean the speakers. I've seen a photo of a rear loaded horn and a couple of descriptions but never actually seen or heard one in real life. It has 1 or 2 speakers at the top at the front then there is a kind of folded horn at the rear of the speakers taking the out of phase waves from the rear and around to a huge horn below the speakers (apparently they are also known as sugar scoops but that's because it's a really old book). This is supposed to only let the longer wave bass frequencies through and they should come out in phase with the front waves (I think).
  4. That isn't how they work.

    Before you get into a horn, understand they are ruled by basic laws of physics. One of them being the cutoff point is a function of the length and mouth diameter. The smaller the horn dimensions, the higher up it cuts off.

    If you want low E from a horn, you'll need a 12 x 12 foot (!) mouth, and approximately 27 feet of internal length. Horns can be built for true low bass reproduction, but they are not practical for moveable equipment due to their size. This is a definite reason why bassists are not using bass horns. Otherwise, you'd see them everywhere.

    Link to Horn Design and Theory

    [ edit ]

    Since this is for a project, consider either a sealed or vented cabinet. The sealed is easier to make but won't go down as low. The vented requires more design work, but can be tuned with an inexpensive volt meter and a few Radio Shack parts. If you choose your driver correctly, either of these will result in a very satisfying and successful project.
  5. I used to use an old sugar-scoop. They are really loud and efficient, and big as hell. :D Mine was a big 4'x2'x2' refrigerator-looking box with an 18" Pyle driver in the top, and what looked like a skateboarding 1/4 pipe shaping the horn in the bottom. There was also a vent shaping board which went from the bottom of the speaker baffle back up into the cabinet at a slight angle. It kind of seperated the horn part of the cabinet from the upper half, and I'm sure it helped tune it by creating a rectangular port at the top of the quarter-pipe. Really cool sound big old low sound, but since the speaker was front-firing, it would chunk-chunk with my Rickenbacker. It allowed me to play in bars with a 100 Watt Ampeg V4-B tube head, against (3) other guitarists, each with 4-12's and 50 or 100 Watts. I was always heard, no problem. I never turned the Ampeg up above 11 o'clock on the Volume knob. I traded the cab to a guy for some Altec Lansing woofers. It was too big to move for fun, and I'm not gigging with roadies.

    I will tell you this: Whenever I've tried to build a speaker cabinet, I have failed miserably. Good luck. :D

  6. I had a look at the link, but didn't see any references to Paul Klipsch, widely recognized (at least on this continent) as the father of the horn-loaded loudspeaker... strange...

    I met him once - back in the 1980s - interesting (but slightly eccentric) guy!

    - Wil

    Later: OK - I stand corrected! I took a closer look - there are some references to his work (interesting links - thanks!)
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