Question on the "double scoop" short throw horn.

[Charley Rummel]

We quickly learned after building our first pair of 4520s how solidly these cabinets need to be built. Cabinet integrity was a concern

Cabinet integrity is one big reason why the design I came up with will weigh in at over 250 pounds. I don't plan to see them used on the road; they will end up in our basement family room. Besides, hauling a beast like that, even with casters, can be a real roady-killer for most.

Regards,
Charley

[dieterj]

Where can i find the Plan for the original 4520 Enclosure?
Who've a Weblink?
Thanks
Dieter

[dancing-dave]

Anyone have this in inches?

http://members.aol.com/xxbase80a/dop....2.15/bau.html

[scott fitlin]

Scoops belong standing upright; at least that was our concensus in the early 1980s. Our woofer of preference was the 2225, which we typically used with bridged Peavey CS800s or CS 1200s. I think that the clipping LEDs were on more than they were off. We pushed our equipment hard, yet averaged about one recone per year. E140s had punch, but lacked that reverberant depth that we also coveted. The 2225s had a combination of both. Our concerns back then were more quantitative than qualitative--it was the "my woofer has a bigger magnet than your woofer" phase of our lives. We quickly learned after building our first pair of 4520s how solidly these cabinets need to be built. Cabinet integrity was a concern when we pondered scaling the 4520 up by 1/5 for the 2240 or the E155. If a 15 inch model weighed 215 pounds, what would an 18 inch weigh? The carcass had to be 1 inch stock. Extra bracing a must. Door frames could present a problem in non-fixed applications. Nobody wanted to do all the arithmetic either. We did not use calculations much back then, or the JBL technical notes. We did things by "feel". Today, if I had the time, money and location, I would build a pair of 18 inch scoops and load them, preferably, with E155s. 2242s might do well also. There are many more options now. There's something to be said for comparative simplicity.

Forgive the non-technical walk down memory lane. Scoops bring back lots of high SPL memories.

Scott

Originally the E-155-8 is what we used in our upsized JBL copies! They were great, the punch, the bass articualtion, and fast transient snap were fantastic! But wasnt the greatest deep bass! The 2240 makes better deeper bottom! If you copy the JBL design the 2242 wont fit, you will have to make the rear chamber deeper, or use spacer rings between the woofer and baffle to facilitate mounting!

As for upright vs on its side, well, according to everything I have ever learned and been told, what happens is that when you have front and rear waves eminating from the cabinet in the same horizontal plane, cancellation arises as when the front and rear waves meet there are phase issues, but when the scoop is upright this avoids that problem as now the front wave is not firing in the same plane as rear, this is what I was always told. My ears tell me they just sound right standing up! Similar to stacking theories!

Scoops are not technically subwoofer cabinets, dont have a long throw, and shouldnt work, but I use them as corner loaded subs, and they DO work! On top of this, they happen to sound great! Clean and audible definition coming directly off the cone, and the extra oomph and grumble from the rear loaded horn! Everybody likes my corner stacks with the double 18in scoops! On an RTA I have usable response down to 30Hz, it actually is flat down to 30, and I can squeeze some response to 25hz, but not alot, but it gets down low pretty well, and while this isnt really 20Hz, most music I play doesnt have any info that low anyway! But it sounds good, its round and punchy. Conversely, I have had dual ported direct radiators in here, with proper power and subwoofer drivers, and found that although they posess deeper extension, the tradeoff for this extension was punch in the bass and upper bass region! They did more way down deep, but not enough between 60Hz to 100Hz! So it wasnt as lively and propulsive sounding! To me this is exactly where science and whats technically correct go out the window, and art takes over! I have also had inverted W bins in the corners, and they offer more upper bass punch, but even less deep bass extension, so back to the scoops with the JBL 2240,s it was, this offers me a decent balance of fairly deep bass extension, great punch, and a nice sounding, round bottom end! Yes, Im partial to a punchy sounding bottom, even if its not technically 100% correct!

It works, and everybody likes them, including me!

[mikebake]

That is exactly what I always said/liked about scoops; one word. Punchy. And I agree, whatever the drawbacks were said to be, I always like 'em.

[Earl K]

The first bass bins I owned were 4530s with 2205a woofers.

They were everything that has been described above.

Nice punchy, round, musical, bass reproduction .

<. Earl K

[subwoof]

Ah the memories...I have built hundreds of single and double scoops for all kinds of projects. And while they are no longer in favor ( due to amp / speaker / size issues ) there is NO way to duplicate the punch of bass for dance club installations. I couldn't tell you how many times over the years a BR cabinet was spec'ed, installed and while it sounded OK at sound check, put 300 sabin-suckers on the floor and the bass got lost in the sauce.

Toasted woofer coils, amps burnt from 100% dutycycle ( aren't compressors good for that! ) and overall "where's the bass I paid for" all went away when the 4520's were swapped for the BR boxes.

Our boxes incorporated interior pathway improvements to smooth out the response and correct structural weak points and a couple of times were made of 3/4 plain-sliced oak plywood and were trimmed out ( flushed in the walls ) during construction. One DJ liked to mess with people by putting a car dimmer switch ( the old high-current stomp kind ) in series with one that was hidden near the bar. Of course the bottom of that cabinet was waterproofed from the spilled drinks...

In reference to a post, we did ( and still do ) make a 4520 variant that uses a single 18 and this is a REAL popular box for the rave crowd.

There was a company in upstate NY ( rochester ) that made a single 12 scoop but it had no advantage over a BR 12 due to the short horn.

sub

[scott fitlin]

This has to be one of the very few threads where everybody posting agrees 100%!


As for size and weight issues, if it goes into a club, where its never going to have to move around, and go from venue to venue, whats the difference? It stays where it plays, and " If it dont weigh enough, it cant play enough " !

[paragon]

Agree,

The 4530 with his old 2205A standing in the corners in my little "listening" room
working down under 50 Hz and sounds very good.
Eckhard

[House de Kris]

Wow, glad to have found this thread. When I first got my double-scoop cabinets sans drivers, I searched around here but found little discussion about them. Anyway, I got them with the intention of carting them around to gigs. Boy, was I wrong. A guy offered them for free because he wanted to reclaim real estate in his garage after storing them for 25 years. He had inherited them from some old-time JBL guy who had also stored them in his garage for nearly as long. At over 200lbs each EMPTY, I quickly decided not to use them on the road, like when I was unloading them to put in the garage for the first time. I says, "well, these things are never going to move again."

Mine came with some wierdo protruding front baffle to angle the drivers allowing deeper drivers to be installed. I've always wanted to have a bunch of blank front baffles made to facilitate messing around with them. One of the wacky ideas I'd like to try is to have three 10" drivers across the front. The two outside ones would be longish throw with the center one with, perhaps, an accordian surround. Actively cross them over at 150-200Hz, depending on where the mid comes in at, to have each section covering about two octaves. A bi-amped woofer, if you will. Another crazy idea is to have 16 5" drivers per cab in a 5-6-5 array. You may be scatching your head asking, "why?" Well, um, er, you got me on that one. I dunno, I just like fooling around with insane ideas.

Anyway, my double-scoops stand ready and waiting for whenever I get around to pulling zany stunts. Until then, they will have to suffice with being a nice home for some mice underneath them.

[paragon]

Simulation 4520-4530

[Ian Mackenzie]

Interesting thread.

Some people in the Hi End Hi sensitivity driver scene still use rear loaded scoops for drivers like the Coral Beta 10 & 8 driven by low powered SE amps.

The transient performance is amazing.

Ian

[scott fitlin]

Interesting thread.

Some people in the Hi End Hi sensitivity driver scene still use rear loaded scoops for drivers like the Coral Beta 10 & 8 driven by low powered SE amps.

The transient performance is amazing.

Ian

I have seen cabinets like the ones you describe! For the Lowther drivers, too!

Goes back to what I always say, some things work well, and sound right to the ear, in spite of not being textbook correct!

[whgeiger]

Scoop Builders,

Have scoop designs for the following drivers made by Precision Devices (Old Harmon Company in England):

Super Scoop for PD-1850 (Back Loading Version, 18" Drivers)

Magnum Scoop PD-2150 (Front Loading Version, 21" Drivers)

Drawing files are available in both .gif and .dwg (AutoCAD) formats.

Send me an e-mail for copies.

Regards,

WHG

[paragon]

There are a lot of scoops builded for smaller drivers like Lowther, Fostex, Coral and others.
LF output of these is limited at 70-80 Hz.
Years ago i heared a Lowther Auditorium Audiovector (rear and frontloaded) with a Klipschorn Sub.
Great !!

Eckhard