"Box in box" speaker designs?

K

kristianjohnsen

Senior
Mar 13, 2011
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Lillehammer, Norway
www.partyfabrikken.no
Hello all.

I have been wanting to start another carpentry project for quite some time now and I have found out what I want to build: I have fallen in love with the idea of a compact speaker system where the top cab travels inside the sub.

I have only ever seen two designs like this:

One is the Outline Kangaroo:
http://www.performing-musician.com/pm/sep08/articles/outlinekangaroo.htm

It's nice but way to high quality and expensive for what I'm aiming to use these speakers for.

The other is a folded horn bass design by FBT where the top travels in the void of the big horn. It's big, heavy and I might have seen some T-rex clawmarks on the one I last saw, so not really what I'm looking for.

The quality I'd be aming for would be JBL Eon15 quality and higher for the top, with a reasonable low end foundation for corporate playback, etc.

So what do you think? Buy a kit with plans and hardware and recalculate the boxes so that they fit inside eachother yet still have the intended internal volume - and then make that? Buy stock subs, make a hatch, and just try to fit a stock top speaker in there? Other ideas?

PS: I have never calculated and built something properly. I have made speaker boxes before, but they were either a shot in the dark or a copy of something else. I did OK at the carpentry stuff.

Thanks for your input if you have any :)

PPS: My dream system would probably have a reasonably powerful 15 inch sub with a built-in amp module and a 10 inch coax top that's powered off the sub.
 
Re: "Box in box" speaker designs?

Kristian,

Although you haven't designed and built anything like this before, I would highly recommend going through the entire design process for the sub. Standard bass-reflex subs are not that hard to build, and you can fudge it quite a bit and still have something that is highly usable if you get it a little wrong.

The advantage of designing and building it yourself is huge. You will learn so much that you can apply to the rest of your system. That is invaluable.

The top cabinet is a different matter though. Building the box is easy enough, but building a passive crossover is serious business. Anybody can get mediocre performance with a crossover they built, but to get that superb response that you and I are accustomed to takes LOTS of skill, patience, and trial and error. I would suggest building the top from plans, OR build the top and send it to a pro to have a crossover designed.

Sounds like a great idea! I bet you'll have a great time building it.

Besides this forum, you can hit the LABsub Section on the PSW, but the best resources on the net seem to be, http://www.freespeakerplans.com/ as well as http://www.speakerplans.com/ and also http://www.diyaudio.com/ Although this is slanted more to the HiFi market, there is a ton of solid info on the diyaudio forum.

Good luck!
 
Re: "Box in box" speaker designs?

I have some you can rent from me, Lab subs with two QSC HPR112 in them ;)

On a more serious note, there are some DYI-tops available if you need something to start with and redesign them to fit your needs. The guys over at speakerplans.com have a lot of different designs, you could check them out. And if you need some cheap 18" drivers, I have six I don't use anymore for sale.

Good luck :)
 
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Re: "Box in box" speaker designs?

Hi K,
You might be able to figure out something using a 3 channel DSP powered plate amp, such as this:

http://www.dsp4you.com/downloads/PWR-DSP3 Datasheet.pdf

That would give you enough power for the sort of application you describe, and plenty of DSP to save you from needing a passive crossover design. You'd have to make a powered loop out for channels 2 and 3 to the top box, but that's easy enough.

The coaxial will keep things nice and small, and there are some great sounding coax drivers available in recent years.

Re the sub, if you are planning on a 10 inch coaxial and are hoping to run the sub into higher frequencies to help support the tops, be aware that folded horn designs can start to sound poor once you get into the range well above 100Hz. It's sort of a "smearing" that happens as the frequency increases.

The Outline Kangaroo design is very cool. One challenge would be ensuring a tight seal on the area which opens and closes for storage of the top box, as a bad seal could significantly affect performance. Using a horn mouth for storage would be much simpler, but with its own caveats.

Best of luck, an interesting idea for sure. Keep us updated on your thoughts moving forward.

Jeff
 
Re: "Box in box" speaker designs?

Tim Weaver said:
Jeff, that's a really cool plate amp.
Click to expand...

Yes, that is a really cool plate amp!!! I see the spec sheet says that they are using the Pascal amplifiers. That is pretty awesome because Pascal is affiliated with CAMCO. So, yes, these plate amps should be very cool critters if they have added a decent DSP platform to the Pascal amps. I'm left wondering what DSP platform they ended up using.

Anyway, yes, that is a very cool find, Jeff!
 
Re: "Box in box" speaker designs?

Hello Kristian,
I have some thoughts on this.

First, to the Yorkville, it seems this is a wonderful powering system, but not the transport/fit inside idea that fits the OP.
Coda has some similar amp/processor, built into the sub to power the tops also, but would not fit the money side of it.
At least as expensive as Outline is my guess. (And not fit inside the sub.)

My own that I am working on is a double 18" reflex, with BMS 18's, natch, and a 4594 (coaxial 1.4") on a large horn that would have no enclosure.
The trick is fitting the mouth of the horn in the box, (large mouth to go low enough to meet 18") but by the time you get to the throat/driver there is much more room to fit around the 18" speaker.

Again, this would not fit the needs of the OP.

One of my posts of a couple of years ago was for a source for coffin locks, and was for this purpose.
To go all out I am making the cabinet of aluminum and expandable foam. I have some aluminum cut, but am over a year side tracked.

I also have a trailer stage with a built in sound system.
There is one chamber on the deck of the stage, between the two double fifteens built into the deck, that has a trap door to access the monitors, mics, stands and cords.
VII was going to have the lows with a removable, lockable top, with these accoutrements inside.
But I am already past that thought and on to subs with horn chambers, and not enough room for anything to fit inside.

About five years ago I was working with Bassmaxx to have a single 15" horn loaded sub, to specific dimensions, with this same thought in mind.
But instead of my wants/needs it kept getting side tracked to their flavor of the month, or ignored completely so I gave up.

I have another wild idea that takes yours one step further and one step back.
What I call the Rickshaw system. Which is a LF cabinet which is also a trailer, and holds everything, except stands that are strapped to the bottom, and is pulled by a bicycle.
I have more wild ideas than I do gigs, so this one is on a very slow track. But it will have 8" coaxial tops, and 5" coaxial monitors, and be good for a solo or duo folk group.
I am picturing a (no longer made) Ederol board, a couple of mics. One version in my mind has it shaped like an egg, with the 8" coaxial tops the *caps* of the egg, that clamp on for transport.

I think that the FBT design is the way to go. The mouth should match up quite well with what you want to do for the top. And after the initial build, would be easier to use, and you wouldn't have to worry about keeping the cabinet seal every time you set up. I also like the coaxial tops. One thing, you will not need the top cabinet to be near as big as the 15" Eon, to outperform it. As in, you will not need the space for LF, using it with a sub, and with out the separate horn/cone, a lot of space will be saved. I use my CIARE/BMS hybrid in a .66 cubic foot box, stand alone, for monitors, and talking heads.
(Don't take this as Eon ragging, I think that for what it was 20 years ago, its price point, and sound, it was a wildly successful speaker.)

I am picturing something like the Danley 15" sub, but w the speaker inside, instead of outside the horn.

A 10" or 12", maybe even 8" coax, should be perfect. Any of the Euro companies will be a step above the original Eon. CIARE, BMS, B&C, 18 Sound. I am guessing that the FBT uses CIARE or B&C.

A good way to get started is with Google Sketchup (free) 3D cadish drawing software.

I have been really impressed with pictures/descriptions of Welter Systems designs. Because Art designs the system with so many factors in mind, such as stack height, van/truck packing, the venues they would generally be used in, his clients, etc.

And this is really where a proprietary system can shine. Large systems are designed for standard (North American here) truck packs, but when a company does a system this size it is a very generic offering. You have the advantage of starting with what size and weight you want/need, and working from there. First off to fit your trailer, or a specific trailer you might want to do jobs like this.

The forementioned Danley 15" is a pretty good overall offering for North American transportation, and fairly ergonomic too. A much better design that his first go with the former company, the td-1 that had almost unusable handles.

Whew, wind me up and let me go. Look forward to more good discussion on this.

Regards, Jack
 
Re: "Box in box" speaker designs?

Jack Arnott said:
I am picturing something like the Danley 15" sub, but w the speaker inside, instead of outside the horn.
Click to expand...

The problem is that is that you just can't "put the driver inside the horn. The throat area needs to be small. That is why the driver is "outside" the horn.

Now a very different design could be done-just not like the Danley products
 
Re: "Box in box" speaker designs?

Ivan Beaver said:
The problem is that is that you just can't "put the driver inside the horn. The throat area needs to be small. That is why the driver is "outside" the horn.

Now a very different design could be done-just not like the Danley products
Click to expand...

Yep, I was not quite clear. But the cabinet size, and mouth size are kind of what I was alluding to.

Regards, Jack
 
Re: "Box in box" speaker designs?

kristianjohnsen said:
Hello all.

I have been wanting to start another carpentry project for quite some time now and I have found out what I want to build: I have fallen in love with the idea of a compact speaker system where the top cab travels inside the sub.

I have only ever seen two designs like this:

One is the Outline Kangaroo:
http://www.performing-musician.com/pm/sep08/articles/outlinekangaroo.htm

It's nice but way to high quality and expensive for what I'm aiming to use these speakers for.

So what do you think? Buy a kit with plans and hardware and recalculate the boxes so that they fit inside eachother yet still have the intended internal volume - and then make that? Buy stock subs, make a hatch, and just try to fit a stock top speaker in there? Other ideas?
Click to expand...
Kristian,

The Kangaru approach is easy to do in concept, as most bass reflex sub cabinets have plenty of room to hide a top cabinet inside.
The devil is in the details, all the felt guides, a latching system that does not rattle and is airtight, that type of stuff increases the complexity of the build and set up time.

Back about 1994 I built four ported 15" with removable bottoms, two 10" & tweeter top cabinets could fit in each.
The bottom used a weather gasket around the perimeter, the weight of the cabinet and tops made for a good seal.
Made for a heavy cabinet when loaded.

Going back to Minneapolis in the 1970s, there was a fairly popular front horn design by Steve Hall, Mike Justin named it the "Cruncher".
The Cruncher was a two part cabinet, the compression chamber and the horn, many bands filled the horns with monitors, lights or whatever would fit. Same thing happened with W bins.

Tapped horns are chock full of wood inside, there is not an adequate area to put a decent size top in.

The ultimate would be a telescoping bass reflex design with an interior linear actuator, plug it in and the small cabinet would grow in volume by a factor of four (more or less) and elevate the top cabinet portion above head height. This type of design could actually reduce the whole package to about half the size of a normal ported sub. It would look kind of like the Empire State building :^).

That said, used equipment prices being what they are, the most cost effective approach would be to buy used subs, make a hatch, and fit the top speaker in...

Art
 
Re: "Box in box" speaker designs?

Hello all.

Thanks to anyone who has replied.

I have gotten a few good ideas, some that I would like to implement, but again I'm too busy for carpentry.

I have since discovered an interesting pre-made product (funnily enough by the speaker brand I use the most at the moment, HK Audio) that would pretty much fit the bill for the corporate uses I discribed before even if the physical design is quite unusual and different from what I was thinking of when I started this thread. For smaller concerts, etc, something bigger would be necessary I think.

At any rate, I'll leave the project on the back burner for now. Thanks to those who replied, I got some really good info here :)

Here is a link for anyone interested in the HK Audio speaker system I mentioned:

Videos - SOUND CADDY ONE - HK Audio
 
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