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[Terry Smith]

     i am starting a sub project to be used outdoors, and mid-to-large indoor event capable.  i recently purchased the build plans for a clone of the jbl 4520 2 x 15" double scoop.  i am using 3/4" birch to build these with, and add extra bracing when needed.  nothing unusual here...just nice solid cabinets.
    at the moment, i am planning to use an unusual choice for speakers.  they were originally used for dbDragracing, but were later illegal to use in their competition.  i have access to 8 of these drivers for cheap; enough to fill 4 of the 4520's (4 cabs is the goal).  these speakers are made by a company called atomic (i think...), have four 4ohm voice coils, can take 1500 watts per voice coil (6000w total), have a 3INCH total excursion, and are field re-buildable.
    and for the third part of my evil plan, i am planning to power EACH driver with a crown ce4000 in 2ohm stereo mode, wiring each driver into two pairs of 4ohm voice coils.
    i want these cabs to be "quasi-cannons" with very high, long throw, output.  i know there are easier ways to do this, but i am wanting to come up with something different.  running sound back in the mid '80s, i developed a soft spot for the jbl 4520's, 4530's (half of a 4520), and the 4560's which i considered to be the high end cabs of the day, especially at the level i was playing in.
    ok...that's the plan in a nutshell...i can build these, including drivers, hardware, and finish, for under $1500 per cab...what ya' think?
   

[Mac Kerr]

I think if these speakers were originally intended for dB drag racing they were probably designed to be loaded by the small sealed volume of a car. Mounted in scoop type cabinets, with only the loading of the horn in the back, they will likely launch themselves out the front of the box the first time you fire them up in anger. Not to rain on your parade, but taking a box that may have the shit in the '80s, and loading it with drivers meant to be in cars, doesn't necessarily make a good combination.

There are quite a few people in this forum building subs of various configurations, you may want to rephrase your question and ask what people think might be a good box design for those drivers.

Mac

[John Halliburton]

So far, I don't think much of this plan.  For that kind of money, you can build two LABhorn subwoofers, which have a known record around here for well documented performance.
Sorry to sound rather impolite, but I would not want you to make such a potentially expensive mistake.
That said, it would also help a lot if we had more(a lot more) info on the drivers.  Is this the company:

http://www.atomicspeakers.com/

If so, can we find out what model driver you are looking into?
And, I don't think of scoop style cabinets as "long throw".  I also would use something more robust than a CE4000 in 2 ohm stereo mode on something like this.  You also can't use an amp in "2 ohm stereo mode" on a pair of 4 ohm drivers.  The amp would be rated at 1200 watts/channel into 4 ohms(each channel).

Some sorting out of amps and design can be clarified once we have paramters on the driver(s).  After skimming over the site I listed, it looks like you'll have to ask for them, they only publish recommended alignments for their drivers.  You need the "Thiele/Small" parameters, as well as "large signal" parameters(ie, power ratings).  Part of the isssue too is that these drivers are oriented for autosound, and may not translate well into pro sound designs-it remains to be seen.
Hopefully Atomic has all the paramters available.

Best regards,

John Halliburton

[Chris Jensen]

Learning is why we are all here.  All the answers are here for any type of incredible sub system.  That being said you could build a couple of labs for cheep maybe even 4 and blow the crap out of a place for way less power.  After all power is expensive.  I mean 6000 watts, and is that per driver or per cab, are you meaning to put 12000 watts max into a box?  Look into an amp that puts that out and see if it is worth it.  Much less find a distro for it, you are getting into some pretty heave stuff.  I mean for 1500 a box you could get 4 EAW la400's.  I would love to have 4 of those.  I made the mistake of getting an la218 over an la 400, for the same price the la218 needs WAY more power that is very very expensive, for the same if not less performance.  What I'm really getting at is why are you going to build a new sub?  Is it to learn?  If so then learn on, that is the beauty of DIY.  Getting the plans to some clone box isn't learning it's mimicking.  And that box was built with a certain driver in mind.  Probably not the one you are looking at.  The first thing to remember is that you are dealing with a system!!!  System meaning everything works together and is designed with like goals in mind.  The lab is for sub bass, it wont do 250hz, why try, if you want it to do that then you redesign the horn and use the proper drive, you don't just stuff a new driver into it.  

Not to grill you because you are far past me on getting started with a design, but if you want some advice on your project it would be good to start with a few design goals.  You must work backwards from what you want to attain.  You know the size of the venue, mid to large, does that mean a 1000 people because on the scale of things a large venue could mean 80,000 people in the middle of a field.  What is the desired spl, what kind of program are you dealing with?  Knowing even just how loud you want the system to be at a certain freq you can model the speaker and box combo and see what it will roughly do.  Look a few posts down there is a good post in a thread by Mr. Danly using only math saying that certain things are completely un doable.  It can be very expensive to just use trial and error.  Otherwise your sitting there with 8 blown drivers, a bunch of cut up wood non reusable wood, some smoking amps, and a possible angry client.  

Im not trying to offend you, but these are the most basic parts to creating a system.  That is why systems costs as much as they do.  Good luck and just consider every little thing possible.


Chris

[Ivan Beaver]

You might want to add that bragging about how much power you can push (or your speaker MIGHT be able to handle???) is like bragging how little MPG you car gets.

The end result is SPL (or speed as the case may be)-not watts.  Design with SPL in mind and sensitivity.  A 3 dB increase in SPL is worth waaaay more than a driver that will handle twice the power, and will probably sound better (all things being equal-which they are not).

[Terry Smith]

ok...so far, so bad...i know this project is a bit of a stretch, i'm just trying to think "out of the box".

ok...so let's pick it apart:
the enclosure...
a box that may have the shit in the '80s
is the 4520 THAT outdated of an enclosure?  the one's i've heard over the years, set up right, sounded GREAT.  punchy with a bite.  i also realize that a lot of these setups had no dedicated sub system, and a lot of these boxes were required to play from about 350hz, or so, and below.
    I don't think of scoop style cabinets as "long throw".
i believe the "scoop" IS designed for medium to long throw applications, just not extremely long throw.  i think they would work great outdoors (i my head...)if they are capable of doing what i hope. and without trying to sound too sophmoric, i think they look COOL!  with the right drivers, and dubious amounts of power, does the 4520 have the potential of becoming a high-output, good-sounding, sledgehammer-hitting sub?

the driver(s)...
these drivers are oriented for autosound, and may not translate well into pro sound designs-it remains to be seen
taking a box that may have the shit in the '80s, and loading it with drivers meant to be in cars, doesn't necessarily make a good combination
there are fundamental truths in both these comments that i quite agree with.  auto sound speakers, per se, are not proven performers in the pro audio world.  with that being said, i would like to rant on what seems to be a popular misconception, imho, about "auto sound" and "pro" drivers.
to put it rediculously oversimplified, a speaker is a speaker.  autosound and pro drivers share the same basic design; you have baskets, some type of magnet, voice coils, spiders, cones, surrounds, yada-yada.  i take exception to the thought that ALL autosound drivers are sub-par (excuse the pun...)when compared to pro drivers.  in probably about 95% of the time, this is absolutely true.  but there is some gear out there that i believe is the exception to this rule.  i know their parameters are designed for a given usage, and used outside this niche there are no guarantees, but i think the auto-smirk that comes with talking about possibly using these products in alternative ways is unwarranted.  look at the quality of workmanship on quality qutosound subs...stiffer cast baskets instead of the standard stamped steel...some are multiple voice coil such as the one i mentioned in my original post...gold connectors at the driver...surrounds that look like half of a charged firehose...extremely long excursions...take LOTS of power...field rebuildable.  theile-small parameters are needed to engineer a proper enclosure for any given driver whether it be pro or autosound.  good physics is good physics...i'm just saying keep an open mind, and don't auto-smirk when an alternative approach is considered.  rant done.
    think if these speakers were originally intended for dB drag racing they were probably designed to be loaded by the small sealed volume of a car. Mounted in scoop type cabinets, with only the loading of the horn in the back, they will likely launch themselves out the front of the box the first time you fire them up in anger
this is a DISTINCT POSSIBILITY!  i overlooked this possibility; you would probably have to equalize the load on the front and the back of the driver, or it might look like a stinger missle launch battery!  i realize that this probably I'SNT the right driver for the right job.  i AM more interested in finding a driver with LOTS of excursion, and LOTS of power-handling capabilities.  is there such a beast?  which driver would YOU recommend?

powering the monster...
in my op, i spoke of using the atomic sub because they were quad 4ohm voice coils.  i also spoke of using a ce4000 per DRIVER.  two drivers per cab = two ce4000's per cab.
 I also would use something more robust than a CE4000 in 2 ohm stereo mode on something like this. You also can't use an amp in "2 ohm stereo mode" on a pair of 4 ohm drivers. The amp would be rated at 1200 watts/channel into 4 ohms(each channel).
i might not have been clear enough on the connections.my initial idea was to tak two of the 4ohm voice coils and wire them in parallel for a 2ohm load.  with each driver having 4 voice coils, you can get two 2ohm leads from each driver. the reason for doing this is in case you have problems with a vc pair, or an amp channel, you can still use the setup, just shut down the problem channel.  this is done 2x (two ce4000's) per cab.  again, i realize this probably isn't the right speaker for the job, but i do want the driver to be capable of handling A LOT of power.
well, there it is again in a nutshell...i AM going to build the 4520's regardless...even if they don't do as i hope.  i'll just build me a nostalgic old school pa with the 4520's, some 4560's as mid-bass, and come up with a mid/horn combo for upstairs.
just trying to keep idle hands busy...
keep the opinions coming...      
   

[Terry Smith]

sorry,,,i tried to highlight selected quotes from thread posters, but it didn't work...how do you do that anyway?  i'm still learnin' the forum's ropes...

[Ivan Beaver]

I think you are waaaaaay to hung up on the ower issue.

Typically high power auto woofers are at least 10-13dB (or more)or so less sensitive than pro audio drivers.  That means you will have to put 10-20 time the power into them to get them just as loud!  As an example if you compare a pro 500 watt driver to a "typical" auto speaker-you will have to put 5000-10,000 watts into the auto one to be just as loud.  Now look at all the money you have spent on amplifiers-distro-racks-cabling (and possible wiring errors)-truck space etc.  Why not get a high output pro sub?  It will be cheaper-smaller (overall) less expensive and louder.

[Mac Kerr]

Terry Smith wrote on Thu, 29 December 2005 22:43

ok...so far, so bad...i know this project is a bit of a stretch, i'm just trying to think "out of the box". ok...so let's pick it apart: the enclosure... a box that may have the shit in the '80s is the 4520 THAT outdated of an enclosure?  the one's i've heard over the years, set up right, sounded GREAT.  punchy with a bite.  i also realize that a lot of these setups had no dedicated sub system, and a lot of these boxes were required to play from about 350hz, or so, and below.     I don't think of scoop style cabinets as "long throw". i believe the "scoop" IS designed for medium to long throw applications, just not extremely long throw.  i think they would work great outdoors (i my head...)if they are capable of doing what i hope. and without trying to sound too sophmoric, i think they look COOL!  with the right drivers, and dubious amounts of power, does the 4520 have the potential of becoming a high-output, good-sounding, sledgehammer-hitting sub?

A "scoop" is not only not "long throw", it is not medium throw either. It is a short throw mid bass box. It is not a sub of any kind.

Terry Smith wrote on Thu, 29 December 2005 22:43

i would like to rant on what seems to be a popular misconception, imho, about "auto sound" and "pro" drivers. to put it rediculously oversimplified, a speaker is a speaker.  autosound and pro drivers share the same basic design; you have baskets, some type of magnet, voice coils, spiders, cones, surrounds, yada-yada.  i take exception to the thought that ALL autosound drivers are sub-par (excuse the pun...)when compared to pro drivers.  in probably about 95% of the time, this is absolutely true. SNIP i'm just saying keep an open mind, and don't auto-smirk when an alternative approach is considered.  rant done.

Nobody was maligning autosound speakers. We were pointing out that they are designed to work in different ways. A speaker designed to fire into a small tightly sealed enclosure like the cars used in dB drag racing will probably rip itself to shreds when used in a cabinet that does not provide that degree of driver loading.

Terry Smith wrote on Thu, 29 December 2005 22:43

regardless...even if they don't do as i hope.  i'll just build me a nostalgic old school pa with the 4520's, some 4560's as mid-bass, and come up with a mid/horn combo for upstairs. just trying to keep idle hands busy... keep the opinions coming...

I have to wonder why you asked in the first place. You got several considered responses explaining why it would be a bad idea, and your reaction was to say we are smirking about auto sound gear. You also say you are going to go ahead and build them anyway. There may be more than marketing involved in the fact that no major artists are touring with scoops and horns anymore. Since you seem determined to build these boxes, at least find drivers with the right characteristics to be used in those boxes.

Mac

[Ivan Beaver]

[quote title=Mac Kerr wrote on Thu, 29 December 2005 23:23 Since you seem determined to build these boxes, at least find drivers with the right characteristics to be used in those boxes.

Mac[/quote]
He could go with JBL 2226's and get the drivers and cabinets for "free" by not having to buy all the extra CE4000's he is talking about-not to mention all the other "stuff" needed-as already mentioned.

They would probably be louder than what he is talking about-but then again he wouldn't have the "bragging" rights about power-that he is so hung up on.

Performance is obviously not what he is after (look at what he is talking about for mids/highs)  it is all about the "look" and the "power".

Hey- I used to use tons of the 4560s along with single and double scoops back in the 80's, but that was 20 yrs ago, and I have learned quite a bit since then.

Many of the newer designs are louder-sound better-and are smaller than what I used to use.  I wish I had them then.