Info on non-rectangular cab design?

Mattosaur · #1 09-15-2011, 07:55 PM

My google-fu has been a little weak and hasn't turned up anything useful yet... does anyone have any information on building non-rectangular cabs? I'm specifically thinking about trapezoids. I imagine non-rectangular cabs have different issues when it comes to porting and tuning, but I don't really know enough about cab design in general to know what they are.

I very much would like to learn though. So, anyone have any experience building non-rectangular cabs? What are the cons? What do I need to understand to balance the risks and design something that isn't going to sound awful?

I wasn't sure if it wasn't done often because technical reasons. Thanks for any info you can share.

**JxBass** · #2 09-15-2011, 08:07 PM

http://www.billfitzmaurice.com

billfitzmaurice · #3 09-15-2011, 08:24 PM

Quote:

Originally Posted by Mattosaur

I wasn't sure if it wasn't done often because technical reasons.

It's not often done because it's more difficult to construct and offers no advantages, while packing them is a PITA.

Rick Auricchio · #4 09-15-2011, 08:24 PM

Building a non-rectangular cab costs much more than building one with 90-degree outer corners. That's why no manufacturer of bass cabs bothers.

PA companies, on the other hand, need to supply line-array cabs, which fit together nicely with trapezoidal cabs. And there's lots more money in the big-PA market.

Mattosaur · #5 09-16-2011, 12:07 PM

Thanks for the responses, guys. I thought there must have been some technical aspects of speaker box design keeping people from experimenting with more unusual box shapes. For stuff that sits up on a stage with people staring at it, I'm surprised more people don't try to get creative with interesting looking speaker cabinet design.

I definitely get why they're impractical for construction, storage, and travel, but I'm glad they're not fundamentally flawed at a physics level. I wasn't sure if the volume of air inside needed to be equally distributed or something.

BTW-- I was talking trapezoidal from top to bottom, not front to back (like trapezoidal PA speakers). I'm not sure if that makes a difference.

dhsierra1 · #6 09-16-2011, 12:20 PM

I've experimented making PA and bass cabs out of those cylindrical cardboard concrete molds used to cast rebar pillars and such. I have to concur w/the above comments, specifically PITA to both build and schlep and they offer no real advantages over standard rectangular shapes. But they did look pretty cool

Mattosaur · #7 09-16-2011, 12:28 PM

This thread brought to you by this box of Ritz crackers:

Alex1984 · #8 09-16-2011, 02:25 PM

Well, not many people tried that. GK did try a front to back trapezoid thing, which I personally don't like, and Trace had that funny shaped 3x12.

BassmanPaul · #9 09-16-2011, 02:41 PM

Quote:

Originally Posted by Mattosaur

For stuff that sits up on a stage with people staring at it

In my mind I think the audience should be staring at me while I perform not at my speaker cabinet!!!

Mattosaur · #10 09-16-2011, 02:48 PM

Quote:

Originally Posted by BassmanPaul

In my mind I think the audience should be staring at me while I perform not at my speaker cabinet!!!

Sure, but using that logic we wouldn't see things like funky lights or backdrops at shows either. I think adding a bit of creative design to cabs can add something, if that's your thing.

gerryjazzman · #11 09-16-2011, 02:52 PM

Well not a trapezoid, but... I'm dating myself for remembering this from an old Pop'tronics magazine:

http://www.audioxpress.com/magsdirx/...drainpipe8.pdf

BassmanPaul · #12 09-16-2011, 03:10 PM

Quote:

Originally Posted by gerryjazzman

Well not a trapezoid, but... I'm dating myself for remembering this from an old Pop'tronics magazine:

http://www.audioxpress.com/magsdirx/...drainpipe8.pdf

Nah Gerry, not dating yourself! I have that magazine - in fact I have them all!!!

BillF is in it a lot and even I have had a small item published in it.

srxplayer · #13 09-16-2011, 03:10 PM

Rocktron used to build 1X12 ported guitar cabs that were trapezoid shaped. They called them Velocity cabs. They looked like a small PA cab. "They claimed something about the design eliminated mid-range notching"??? I used to own one and ran a Crate Power Block amp into it. It worked okay and sounded decent but it it was awkward to carry and you couldn't put it on an amp stand. I bought it because they were pretty inexpensive and looked interesting but turned out to be pretty impractical using it live. I'm guessing that probably has something to do with cabinet makers not building them. The extra expense of the non-rectangular design along with with the extra materials involved in tuning, bracing, porting and damping a bass cabinet probably makes it cost prohibitive for the market.

Correction...Rocktron still makes the S112 cabs. I just saw them on the Rocktron website.

chaosMK · #14 09-16-2011, 03:18 PM

I've wanted to make a cab that is spherical in shape and suspended from the ceiling or and apparatus like a punching bag stand. It would be easy to roll to gigs.

MarkA · #15 09-16-2011, 04:43 PM

Quote:

Originally Posted by JxBass

http://www.billfitzmaurice.com

I've got no direct experience with any Bill Fitzmaurice cabs, but I've considered them. This looks like it might make an interesting, unobtrusive, small gig cab, if used as a standalone.

Jeff Scott · #16 09-16-2011, 06:55 PM

Here you go:

Rickenbacker Amplifiers - Transonic Series

Mattosaur · #17 09-16-2011, 08:02 PM

Quote:

Originally Posted by Jeff Scott

Here you go:

Rickenbacker Amplifiers - Transonic Series

Bingo. Thanks!

teemuk · #18 09-17-2011, 05:25 AM

One more...

Needless to say, you can always turn the insides of a traditional box-shaped cabinet to trapezoidal since it's all about just trying to minimize standing waves and parallel surfaces inside the enclosure. Heck, I've seen box shaped (HiFi) speaker cabs where the internal enclosre is actually shaped like a sphere and Acoustic made "tube" cabinets which externally looked like a traditional speaker box but the internal enclosure was shaped like a cylinder.

will33 · #19 09-17-2011, 09:59 AM

Someplace on here a few years ago, somebody posted a link to somebody doing cabs out of bass drum shells. Pretty neat idea......until you have to stack 'em.

Bassflute · #20 09-18-2011, 03:07 PM

MUSIC SWOP SHOP ONLINE

Only online pic I could find.

Cheers,
Cameron

Quote:

Originally Posted by Mattosaur

My google-fu has been a little weak and hasn't turned up anything useful yet... does anyone have any information on building non-rectangular cabs? I'm specifically thinking about trapezoids. I imagine non-rectangular cabs have different issues when it comes to porting and tuning, but I don't really know enough about cab design in general to know what they are.

I very much would like to learn though. So, anyone have any experience building non-rectangular cabs? What are the cons? What do I need to understand to balance the risks and design something that isn't going to sound awful?

I wasn't sure if it wasn't done often because technical reasons. Thanks for any info you can share.