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[Scott Holtzman]

Have you ever heard of "pipe resonance"?      Basically the same thing the Blue Man Group uses whacking the ends of PVC pipes with paddles.  Any high aspect ratio enclosure will have an issue unless it is internally baffled to break up the waves bouncing end to end.

Should have mentioned the drivers are sealed back

[Scott Helmke]

I won a box full of really nice 4" drivers on eBay for just about the shipping.  I have over 100lbs of them.   I think enough to make two 6' lines.  Was thinking about cutting PVC pipe and putting in some sort of rail and loading the drivers in.  Just an experiment.

I built a plywood "line" speaker with a bunch of 4" drivers, about 4' total length with 10 drivers. Packed it full of batting to kill any resonance, though there was absolutely no real plan or design simulation. Basically I needed a voice-only system for a reverberant church space (where I go, and we can't install anything), and had a theory that everybody was just stuffing little drivers into skinny boxes and throwing DSP to try to make something out of it.  I also put together a little mixer/amp with a MiniDSP kit stuffed inside.

Damn thing actually works pretty well - definitely covers the space the way I'd hoped.  My theory was correct. 

[Ivan Beaver]

I built a plywood "line" speaker with a bunch of 4" drivers, about 4' total length with 10 drivers. Packed it full of batting to kill any resonance, though there was absolutely no real plan or design simulation. Basically I needed a voice-only system for a reverberant church space (where I go, and we can't install anything), and had a theory that everybody was just stuffing little drivers into skinny boxes and throwing DSP to try to make something out of it.  I also put together a little mixer/amp with a MiniDSP kit stuffed inside.

Damn thing actually works pretty well - definitely covers the space the way I'd hoped.  My theory was correct. 

That is basically it,  Just get them close together and series/parallel them to get the impedance where you need it to be.

About the only "weird wiring" you could do would be a Bessel wring, but that is limited to 5 drivers. to get the radiation pattern of a single driver.

I am not sure if you could "Bessel the Bessels" and use 25 drivers to try to get the pattern of a single Bessel wiring, that simulates a single driver.

It might be something interesting to try-if somebody had a bit to much time on their hands----------

[Hayden J. Nebus]

RCF and other companies are offering similar products.

Danley offers a line of 9"W x 9"D coulmn shaped cabinets with horn loaded coax drivers that really behave like a single coherent source. We have a pair each of the SBH10s and SBH20s. They perform remarkably in a reverberant space.

IMO the SBH line is the smartest buy out there for skinny loudspeakers. I'm not aware of any other columns on the market with broadband directivity that's anywhere near comparable. 

[Jeffrey Knorr - JRKLabs.com]

Danley offers a line of 9"W x 9"D coulmn shaped cabinets with horn loaded coax drivers that really behave like a single coherent source. We have a pair each of the SBH10s and SBH20s. They perform remarkably in a reverberant space.

IMO the SBH line is the smartest buy out there for skinny loudspeakers. I'm not aware of any other columns on the market with broadband directivity that's anywhere near comparable.

We also use a pair of SBH10's in an extremely challenging acoustic environment with very good results.  I wish they had a little more maximum output and low-frequency extension but they greatly simplified what was necessary to expand coverage in our venue.  I would like to try to FIR process them to see if that opens up their clarity even more.

Jeff

[Shane Ervin]

I built a plywood "line" speaker with a bunch of 4" drivers, about 4' total length with 10 drivers. ...<snip>...

Damn thing actually works pretty well - definitely covers the space the way I'd hoped.  My theory was correct. 

Hi Scott,
I bought a pair of similar column loudspeakers from Les Structures Unisson of St. Roch de L'Achigan, QC, about 10 years ago.  He called them "I-Stick", and I bought the variant with 8x 4" drivers.  His design also includes a point source tweeter at the top, and a (lower gain) tweeter at the bottom of the line of mids.

Free-standing, they require no tri-pods, and that's an advantage in many situations.

Although I don't use them often, they're great for house concerts, resto-bar, rest-bar patios, and similar venues where 2-way self-powered speakers on try-pods are usually employed.  (... And of course, those problematic acoustic spaces).

Although processing is required to implement a crossover at ~200 Hz, and a woofer for full-range music, that's pretty easy to do these days (e.g., I use a QSC PLD 4.2).

What's always amazing is how well they keep up with one or two 18".

[Speed Daemon]

I am sure you will get a better answer but it has to do with the spacing.  The drivers have to be a 1/4 wavelength I believe to couple.  At HF a 2" driver is too far apart and will create comb filtering due to the mismatch.

Oh boy, does that bring back memories of high school physics class and the dreaded wave tank. That, and the old Infinity speakers with lots of stacked MF and HF elements.  IIRC the use of interference to aid directionality works great at one specific frequency, but tends to fall apart at frequencies away from the one it's tuned to. I suppose that DSP can help ameliorate the unwanted effects somewhat, but still can't break the laws of physics.  The old Bose 901s came with a box full of EQ filters that tried to make up for the deficiencies of using a bunch of 3" drivers, but all of those filters further colored the sound.

I had the mixed blessing of being the FOH mixer for a band that used a Bose stick-type PA with small subwoofer boxes as the base. With no time to do a sound check, and no monitor system (so the PA speakers were behind the band), feedback was a big problem for me!

[Craig Leerman]

I just did a Road Test on the Turbo IP2000 rig. From what I understand, it's a 4 way system. The sub provides the lows, the lower column does the low mids, the upper column handles the upper mids and the Tweeter does the highs. It's a good sounding rig.

I like column systems. I mainly use a Renkus Heinz IC Live for corporates and bands. While not a traditional column (it's digitally steered and has both cones and compression drivers) it's got a great form factor, sounds fantastic and my clients love em.

I also have a Carvin column rig (TRX 3903s over TRX 3018a subs) That system uses nine 3" full range cones in each box. The Carvin rig sounds the same at all distances and has a nice wide 120 horizontal dispersion.  I would pick the Carvin rig over the Turbo, but the Carvin system costs way more than the Turbo.

[George Reiswig]

Well, I tried it out at home and then at a gig, and it is going back.  I think the description of it as a 4-way system is probably apt, but that means that if there is any column effect of having 17 2" speakers, it is minimal.  The thing totally lacks in low midrange, and feedback is just as bad as with any other speaker. 

I am still struggling to understand the coupling, and in particular how that coupling relates to the center-to-center distance.  For example, I don't know which part of a cone reproduces the highest frequencies most: if that is the center, then it makes sense why coupling can't occur in larger drivers.  But if the edge of the cone produces HF (like when you mic a guitar speaker near the edge and hear more highs), couldn't coupling occur at those adjacent edges? 

Above all, I'm really trying to understand why I had such a positive experience with those stupid expensive Bose sticks...sheesh.

[Speed Daemon]

Well, I tried it out at home and then at a gig, and it is going back.  I think the description of it as a 4-way system is probably apt, but that means that if there is any column effect of having 17 2" speakers, it is minimal.  The thing totally lacks in low midrange, and feedback is just as bad as with any other speaker. 

I am still struggling to understand the coupling, and in particular how that coupling relates to the center-to-center distance.  For example, I don't know which part of a cone reproduces the highest frequencies most: if that is the center, then it makes sense why coupling can't occur in larger drivers.  But if the edge of the cone produces HF (like when you mic a guitar speaker near the edge and hear more highs), couldn't coupling occur at those adjacent edges?

With any moving coil driver you're going to see the fastest rise time, and therefore the most accurate HF response for its passband right at the motor, which is the center ring in a cone type speaker. How well that impulse overcomes the inertia in the rest of the cone is a whole 'nuther story, and one reason why most tweeters are no larger than necessary.

If you aim a mic right at the center of a 10" or 12" guitar speaker driver, you're going to get a good deal of bass boost from proximity effect. Moving the mic to the edge of the cone will reduce bass coupling more than it boosts higher frequencies.

The late Dr. Amar Bose was an accomplished electrical engineer, but his mechanical engineering skills didn't quite match. He managed to force more amplitude out of his little cone speakers, but ignored breakup modes and other things that added much distortion to the extended frequency response. There's no cheating the laws of nature.

If you want good midrange and low mid response, you can't beat a 5" to 8" driver that's optimized for that passband IME. You can get smaller drivers to make noise at those frequencies, but not as melodious as a speaker built for music.

[ProSoundWeb Community]