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Building speaker cabinets -Long Throw encloseur

U

urb

Dec 8, 2012
28
0
#1
I just acquired a Peavey 118 speaker and have nothing to put it in. Unless an 18" cabinet falls from the sky and lands in my yard I am forced to make a box.
I am interested in the longthrow design. I spent a few minutes searching info about them, didn't come up with too much.
If you have any experience with them , know some pro's vs cons .Please clue me in. Should I use plywood or particle board? Stuff like that I need to know. Thanx , Shane.
 
#2
long throw? Do you mean a folded horn/W-bin cab?

What model Peavey 18" do you have? You'll need the Thiele-Small parameters to do your modelling for the cab.

Birch or arauco 1/2" ply are you cabinet woods of choice, not MDF or gawd-forbid particle board :D
 
#3
its a pv 118. so the guy who sold it to me said. Tell me about the Thiele-Small parameters.
 

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#5
urb said:
Tell me about the Thiele-Small parameters.
Click to expand...

The Thiele-Small parameters describe various aspects of the behavior of the woofer primarily at low frequencies, and are used to evaulate the suitability of a given woofer for a particular application, and then to design a proper enclosure once the woofer has been chosen. Eminence has a very good introduction to T/S parameters and other data on their website:

http://www.eminence.com/support/understanding-loudspeaker-data/
 
#7
would be helpful to know exactly which Peavey 18" model you have. Like any other style cab, you can't throw in just any driver into a W cab and expect it to work properly.

Also, they have poor response above 500 to 800 Hz depending on the exact design so you'd have to add a midrange driver.

W cabs are rather complicated to build in comparison to a ported or sealed cab and generally take up a lot of room. That may or may not be an issue for you, though :hmm:

Not trying to discourage you, but if this is the first time you're building a cab from scratch you'd be better served going with the more common sealed or ported boxes. I've built large horn cabs in the past and they can be pretty challenging.
 
#9
Single low frequency speakers are not "long"- "mid"- or "short"- throw. Or any "throw" at all, actually.

Any sealed, vented, bandpass or horn enclosure will follow the same SPL vs distance loss rule. As long as the radiating surface (the surface of the enclosure) is small compared to the sound waves it will reproduce it remains mainly omnidirectional.

To control radiation pattern of the sound waves, the surface area must be large enough to prevent waves to "sneak away" in the unwanted direction. So bass speakers must be either very large (several meters) or stacked in groups to control the direction of the deep bass frequencies.

You might still want to build some kind of horn enclosure but I recommend you do a bit of studying before you start the power tools or you might end up with a design very far from your tonal goals.
 
#10
I own the PV W horns mentioned earlier in this thread. I love them, but they're a handful.
Recommendation: Google "Andy Lewis on horns", read this thoroughly and understand what he's saying before you start a project.
I had a 18" Cerwin-Vega fall into my lap, and pursuant to a fellow TB'ers advice, built a generic 8 cu.ft. box, featuring 3/4 ply. Also included were 4 4" ports ( about 6" long) across the bottom. Also cut the lower back corner at a 45 deg. to accept two 4" heavy duty casters from the home center.
The box could be 6 to 8 cu. ft.
Anyway,I built this monstster, and I am quite happy with its performance.
Good Luck with your project...
PS, here's a friggin horn...
 

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#11
One advantage to a folded bass horn is how it filters out Doppler distortion from cone movement.
At first listen, they sound like something is missing (it is), and they don't have the thump of a direct radiator.
A 100 Hz crossover does not filter Doppler distortion at all, because it is produced by the cone and not the input signal.

The audible strength of a bass horn becomes very obvious at some distance back from the stage.
My last encounter with the cops a few years back, was due to complaints about bass.
The person complaining was very far away from the outdoor venue.
The cop said he could here the subs plain as day, and followed the noise.

I was doing a Relay for Life event with a stack of T39s.
 
#14
I was kidding. There's no such thing as Doppler distortion. Some people think that because a speaker is producing low frequency waves as well as high frequency waves the higher waves are undergoing "distortion" just like how a police car siren is higher pitched when approaching than when driving away. Meanwhile our ears are doing the exact same thing, picking up low frequency waves with the same eardums we use to pick up higher waves.... It's a conspiracy!!!

I was referring to Marshall McLuhan, who is a far more interesting read than Christian Doppler.
 
#15
I used a couple Peavey 1810 cabinets for years, and with one, I cut off the 2X10 section, and covered the exposed wood with the tolex from the section I cut off. The speaker cab, after removing the 2X10 was fairly compact, yet performed pretty well, although I still used a mid cabinet with it, with the 500Hz crossover in the mid cabinet.

The dimensions of the 18" cabinet are 21"H X 24" W X 18.5" D, with the baffle inset 1.5" from the front edge. There are two triangular ports at the bottom corners that are about 4.5" X 4.5" X 6".

The 1820 cabinet, also a 1X18" with 2X10" speakers is similar, but a few inches deeper.

As far as folded horn cabinets go, the Peavey was similar to an Acoustic 371 cabinet and DIY 361/371 cabinet plans can be found on line. BUT in all the discussions I've read about the Acoustic folded horn cabinets, a PV Black Widow 18" was spoken of as a bad speaker for this enclosure.

I would seriously consider EV TL plans. There are two such plans for an 18" speaker, the TL505 (7.1 cubic feet) and the TL405 (13 cubic feet.) I would use the 505 plans as it is a much more manageable cabinet. Here is a link.

http://mypicsonline.net/archive/arc...es/EV/Builders Plans/TL505 Builders Plans.pdf

Here's the much larger TL405 plans...

http://mypicsonline.net/archive/arc...ves/EV/Builders Plans/TL405 Builers Plans.pdf

I will say that modern 15" speakers can far outperform my old Black Widow 18's. I have a couple TL 15" cabinets, one with an Eminence Kappa Pro and the other with a 500 watt MCM 15 that are louder, punchier with more low end than the 18's I have. I still pair my 18's up with my Acoustic 370 head for fun.
 
#19

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