Bose L1 buster?

[Jack Gilvey]

Any ideas as to how to cop this general idea?

http://www.musiciansfriend.com/product/Bose-L1-Model-II-System?sku=600095

Sounds like just a vertical array of 24 extended range drivers on a slim baffle. Not concerned with the 2 x 5 1/4" "sub", of course. I want to use this to amplify a guitar modeling processor, not for hifi as such. Need reasonably extended range and good dispersion.

[JonMarsh]

Many ways you could do this, Aurasond has a nice 4" extended range (NS4-255-4D1/8D1) with underhung VC if you only need 8 kHz clean; they also have a 3" extended range which I believe Macintosh uses for their column type systems that's very wide range, useful output to 18 kHz, 3 mm Xmax. Of course, it's not very sensitive with just one, but pile them on and that improves; its the NS3-193-4A/8A (available also in 4 ohm and 8 ohm versions).

Any full range design like this will probably still need an appropriate BSC circuit even though it doesn't have a crossover per se.

Others will probably have different ideas for small full range drivers, it's not an area I follow closely.

[joecarrow]

I've heard these Bose sticks in a store before, and it's interesting that you can kind of tell a point where the character of the sound changes based on distance. There's something to them that lives up to the hype, but I'd say mostly in small rooms.

Bose isn't known for using the very best drivers available, so it seems like the key thing to optimize here is cost and ease of assembly. Here are a couple at Parts Express that could be made to work out:

http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=299-015

http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=290-010

Maybe not as nice as the ones Jon mentioned, but if you're buying 25+ drivers you'll appreciate the cost difference between a $7 driver and a $15 driver.

[JonMarsh]

I've heard these Bose sticks in a store before, and it's interesting that you can kind of tell a point where the character of the sound changes based on distance. There's something to them that lives up to the hype, but I'd say mostly in small rooms.

Bose isn't known for using the very best drivers available, so it seems like the key thing to optimize here is cost and ease of assembly. Here are a couple at Parts Express that could be made to work out:

http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=299-015

http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=290-010

Maybe not as nice as the ones Jon mentioned, but if you're buying 25+ drivers you'll appreciate the cost difference between a $7 driver and a $15 driver.

Oh, most certainly a $7 may be more practical- I was hoping you or someone else would chime in with some ideas based on what they're familiar with.

[cjd]

Ironically, PE just posted some new buyouts that look VERY scarily like the drivers in that image!

Nice price on them too.

C

[joecarrow]

Oh, most certainly a $7 may be more practical- I was hoping you or someone else would chime in with some ideas based on what they're familiar with.

Experience? Gosh... I guess I've experiences a couple.

The Aurasound NS3-193-8A is decent, and I use it as a surround. It has impressive excursion and decently clean sound, but is really not very efficient. For something like pro sound, I would look for something more efficient, even if you used a ton of them. You get something like 3 db from every doubling of drivers (I think it's really less than that), so if these things have 80 db efficiency, it would take 32 drivers per side to add 15 db and get to 95 db efficiency. You'd have 500ish watts of power handling, so the peak SPL should be in the neighborhood of 120 db at one meter, perhaps falling off more slowly than usual if the line array is effective. This could be a clean way to go if 8-foot columns are your style, and $500 in drivers per speaker doesn't bother you. If you used 16 of these per side, your power handing and sensitivity would both go down, and then I'd be less willing to consider it for concert use.

Another one I had experience with was the venerable "NSB". This was a 4" paper cone "full range" driver that Parts Express sold for what seemed like a couple of years. They were supposed to be from Pioneer, but the maker's mark had been removed. They were sold for between $2 and $0.49 each, and a lot of people have done line arrays with them. I played around with a few and made open baffles, shoe box speakers, etc, just to try out some of the acoustic concepts I was reading about, and they were surprisingly pleasant sounding for the price. They needed a tweeter if you wanted to be serious, and their bass might have been even more limited than the NS3-193, but you couldn't beat the price. Many of us who are frugal or just enjoy trying crazy projects without risking much money are waiting for that kind of situation to come along again.

[jonathanb3478]

The OP indicated he wanted "good" dispersion. By this I assume he means "wide" dispersion.

Do line arrays do that? I thought they were similar to the electro statics like Martin Logan in their dispersion (excellent performance in their sweet spot, but a small sweet spot to work with). I don't know, line arrays aren't my thing. Based on my (very possibly incorrect) understanding of strict line arrays (not the point the drivers all over the place - Bose fashion), they are not wide dispersion speakers.

???

[joecarrow]

Actually, line arrays have very tight dispersion in the vertical plane, but dispersion similar to a point source in the horizontal plane. When done properly, they produce a cylindrical wavefront, compared to a point-source's spherical wavefront.

When you go to a rock concert, you're very likely to see a pair of arrays hung from rigging. Pro arrays are more sophisticated than this, with the ability to cover different depths from the stage with different sections of the array, and multi-amplification allowing different levels and effects for various sections of the array. As far as I know, their high frequency radiation pattern is (in the horizontal plane) dictated by the horn tweeter.

If you had a line array with just a short line of tweeters in the middle (some people do this, probably to save money), and if you go from sitting to standing then the highs are deranged.

I believe Jim Holtz has a big line array in his home as well, and could comment a bit on this.

[Jack Gilvey]

Thanks, guys.

The OP indicated he wanted "good" dispersion. By this I assume he means "wide" dispersion.

Yup...wide is good.

Actually, line arrays have very tight dispersion in the vertical plane, but dispersion similar to a point source in the horizontal plane. When done properly, they produce a cylindrical wavefront, compared to a point-source's spherical wavefront.

Yeah, that's the idea. A typical 12" guitar speaker gets horribly beamy at the top of its range, something I'm tired of. The amp modeler I'm using, a Vox TonelabLE, can simulate the response of amp and cabinet, so a flat,full-range system (a PA, basically) is best to reproduce its output. If such an array also maintains output with distance better than a point source, it can also be better for avoiding feedback on stage by reducing volume at the source. Not too concerned about bass (subs are easy), but I would like to go above ~10kHz cleanly as I don't want to augment the modeled rolloff
I'd look to try a small "proof-of-concept" first.

[joecarrow]

Can you estimate your SPL requirement? If not, perhaps a known speaker can/can't exceed your need, and can give us an estimate. Whether you're looking for a studio monitor, a stage monitor, or a PA for an audience of hundreds makes a big difference.

For a while I was playing around with cloning a flown PA formula that involves a huge stack of boxes with a horizontal MTM on each, really close spacing between drivers and between the top/bottom of the box and the driver edge, and a low crossover to a horn tweeter. With a pair of 8" or smaller midwoofers per box, and a decent compression horn, you'd be able to get into the 130+ db neighborhood cleanly for under $3k, in stereo- just add lab horns. I mostly played around with that idea back when my old fraternity received a $million+ offer on its property, and was going to buy a masonic lodge to renovate as the new chapter house. A $5k budget didn't seem unreasonable, and it would have been cool to have a setup worthy of national bands.

As it happened, they got put on double secret probation, I moved into the land of tiny apartments, and now none of us are seriously looking at building big.

[Jack Gilvey]

Not too bad as far as SPL requirement, Joe. I don't have a number, but right now I'm looking at studio/stage monitor just for the guitar.

[Mark Seaton]

Hi Jack,

I've been playing with a variety of wide-range, micro-drivers lately. It is quite a departure from big subs, but fun and challenging. While not available to DIYers, let's just say it's really cool to see a 50mm driver move +/-4mm!

There are two ways you can design the system you are talking about... One is to pop it up, off the ground on a stick, the second is to make it a full height column, even if it separates in 2 pieces for transport. I suggest the latter of a full height column. I would stay at 3" nominal or less in driver size to keep HF dispersion wide enough.

My 10min look/quick pick?:

http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=264-809

$8.88 each is a steal, and TB usually has very good suspension travel that means the 0.5mm Xmax for this underhung design should be able to tolerate the occasional peak above that. I'd use 16-24 stacked vertically with 10-25W per driver with a small rear chamber of 0.375-0.75L per driver. Only plan on using it above 150-200Hz, although some quick LF EQ in front of it would probably make it work very nicely for acoustic/light duty guitar in a smaller space.

I would have to model it up to see if there was any tinkering worth doing with a very simple passive filter for smooth directivity, but with the line coupled to & mirrored by the ground, I think it would work quite well without much effort.

If it were me I'd then make a subwoofer form the stand for this. Use 2 opposing (L & R firing) drivers so you can make the box lighter while not shaking the towers. Add a 2ch amp that with some simple DSP and you're rockin.

Hmmm... Thanks for the quick mental exercise on this one. I spawned a cool idea for a completely different app!

[Hank]

In addition to TB, I've considered Hi-Vi for a column. For a 3":
http://www.partsexpress.com/pe/pshow...Number=297-427 OR:

http://www.partsexpress.com/pe/pshowdetl.cfm?&PartNumber=297-428

Too bad there's not a square frame version. For that convenience, there's this 2":

http://www.partsexpress.com/pe/pshowdetl.cfm?&PartNumber=297-432

[Jack Gilvey]

Good stuff guys, thanks.

I may have to give those little TB's a go at that price, Marky Mark. How would a dipole line array of those work?

[Mark Seaton]

Hi Jack,

I wouldn't think the dipole radiation would be desired for this purpose, where I'd think a deeper "U baffle" with some stuffing in back might be more fitting, but ultimately larger in size and not the direction I would want to go with these lower excursion drivers. The small sealed chamber also gives you better handling of power in the ~160-350Hz range. A simple high pass of maybe 2nd order around 150Hz would work well to a woofer underneath and you could drive them with a real 100-400W total without much worry. The HiVi drivers are interesting, although generally don't have as well behaved nor extended a high frequency as the TB drivers we're looking at.

[Jack Gilvey]

Thanks again, Mark. Would there be a minimum number you'd think worth trying this with at low levels? An array of four, perhaps, to get an idea of dispersion, balance, etc? I'd roll in a sub below 200Hz or so.

[Mark Seaton]

I'd suggest 8-12 as a nice size, with a gross height of about 36" with 8 drivers to be a good starting point. The issue is where the vertical directivity goes away and how high off the ground you want the column. I'd prefer to keep the top of the column less than 2x the height of the column itself, although I haven't modeled it yet to examine the effects. My suspicion is that a standing height of somewhere around 1.5x the column height is more ideal. I also expect that you can improve behavior by applying some passive low pass filter at high frequency to the upper most drivers. This is more for the group delay effect than it is for frequency shading.

When you go to a shorter line that is relatively far from the ground as compared to its height, you get back into a realm of a suspended speaker with a ground reflection, and you have to treat it more as a separate entity rather than a speaker that can be designed to beneficially interact with the ground as a boundary.

my 2c anyway...

[Jack Gilvey]

Thanks Mark!