Large stereo bass line-array only system...

Chops · « **on:** 24 Dec 2008, 03:55 am »

As the title says, I'm wanting to build a line-array, but only for bass. These will pretty much be stereo subwoofers for my 2-ch system which will consist of a pair of fully modified Fostex FE206eN drivers from Dave at Planet10-hifi. The modded Fostex drivers will be going in a pair of Sachiko double mouth horns. These horns and drivers alone will get down into the mid-30's easily, possibly even the upper 20Hz range, given the right room. The Fostex drivers are getting the full mod treatment as we speak. The horns have yet to be built.

The thing is, yeah, sure, the Fostex in the Sachiko horns can get low, but with an Xmax of 1.5mm, they can't provide the physical impact and slam needed for large pipe organ, orchestra and some modern music that I listen to. I'm sure they'll do perfectly fine for jazz, blues, chamber music and such on their own, but for the large scale music, probably not so much.

The reason I want to go with line-arrays is because of the much added efficiency, much lower distortion, and multiple small drivers which will remain very quick and tight... A perfect match for the efficient, ultra-light Fostex cones and strong motor structures. Drivers 10" and above will simply drag behind and sound sluggish compared to the Fostex drivers.

The reason I want to go with the Dayton DC160-8 drivers is because I know what ONE of them sounds like in the BR-1 kits. A pair of these little bookshelf speakers are quite capable of producing some seriously low, solid, clean bass that some large floor-standers would be a shamed of!

My plans are to go with somewhere between 8-12 Dayton DC160-8 drivers per channel in line-arrays. Their Fs is 34Hz and I know they sound excellent and extend well in .55cf enclosures which I think are tuned to 40Hz as in the BR-1's. They will be crossed over at 70Hz. I actually wish I could cross them lower but my Rane AC-22B crossover only goes as low as 70Hz.

Now my problem... I don't know how large I should make the chambers in the line-array and where I should tune them in order to get down TO or BELOW 20Hz. I know they can do it, it's just a matter of proper designing and planning.

Danny, if you're out there, I'm sure you remember my "Massive Line-Array" thread towards the beginning of the year. However, that thread quickly ran off course, not fault of yours of course.

Anyway, if you guys could point me in the right direction, I would greatly appreciate it.

Many thanks in advance!

EARGASM · « **Reply #1 on:** 24 Dec 2008, 07:11 am »

Removed by member.

Danny Richie · « **Reply #2 on:** 24 Dec 2008, 06:21 pm »

Hey Chops,

I like your line of thinking.

The DC-160-8 needs an optimal ported box of .34 cubic feet. In that box it will hit a -3db of 48Hz.

Pushing it to a .5 cubic foot box (ported) will take away some power handling but that won't be too much of a problem with 12 per side. It will push the -3db to 42Hz.

Then with the collective gain you get from the length of the array you should see a true -3db on the low 30's.

Eric is right though. The servo subs will eat them up. Nothing beats those things or even comes close. Plus, they play flat to below 20Hz and are completely adjustable. There is even a built in EQ to fix any peaks or dips in the room response.

BillB · « **Reply #3 on:** 24 Dec 2008, 06:51 pm »

I'd really like to see a 6-7" servo sub with a lower powered amp.

arthurs · « **Reply #4 on:** 24 Dec 2008, 06:58 pm »

Quote from: EARGASM on 24 Dec 2008, 07:11 am

I think a line of them, maybe 6 per side, or so would certainly look very, very impressive. 'Might have to try that...

Might?! Might?! Will!!!!!

Happy Holidays E!

EARGASM · « **Reply #5 on:** 25 Dec 2008, 01:08 am »

Removed by member.

arthurs · « **Reply #6 on:** 25 Dec 2008, 01:51 am »

Quote from: EARGASM on 25 Dec 2008, 01:08 am

It's going to be a great 2009!

The greatness of my 2009 is in your hands buddy...

Chops · « **Reply #7 on:** 25 Dec 2008, 04:33 am »

Hmm...

So about these servo subs, what options would I have and what do you think would be a good match to the Sachiko horns? Using the servo amps with them, I would only be running the subs from say 40Hz and below. Heck, at that point, I probably wouldn't even need to do stereo subs. Although, it couldn't hurt.

HT cOz · « **Reply #8 on:** 25 Dec 2008, 03:46 pm »

You could try the OB subs mono placed in the middle of your two horns. That way you could get a taste and not be fully comited to stero subs. Who knows you could be satisfied witht the initial setup.

I bet those drivers would be happy to give up trying to play the realy low notes.

Chops · « **Reply #9 on:** 25 Dec 2008, 04:44 pm »

Now that's something to consider.

Also, I was wondering... Would any of the GR 12" drivers be suitable for a folded horn, or would that be way too huge?

Keep in mind my room is only 10' x 13' and I'm going to already have huge Sachiko horns in there.

Danny Richie · « **Reply #10 on:** 25 Dec 2008, 04:52 pm »

I just hope that those horns can keep up with the GR servo subs.

That room is not very large. A single SW-12-04 in a sealed box will be fine.

I don't see any advantage in horn loading these. Horn loading is a good way to increase SPL through compression and if done right add a little more low end extension.

These already play flat to below 20Hz and plenty loud.

You can always use a pair of the SW-12-08's on a single amp to increase output levels and lower distortion even further.

If you wanted to do open baffle then keep in mind that they will need to be at least 3 feet or more into the room. I don't know if your room will support that or not. If so, then you can run two or even three of the SW12-16FR's on one amp.

Chops · « **Reply #11 on:** 25 Dec 2008, 05:09 pm »

Well this system's one and only purpose is purely 2-channel audio, and I want it to be as simple as possible with the least amount of components.

My main system resides in the larger family room/theater room which consists of a pair of x-statik's and an x-voce supported by an SVS PB12-Plus/2 V12.3. That room is still kind of small-ish at 13' x 17'.

Since it would be impractical to run OB subs in this smaller 10' x 13' room, how about a ripole sub or even a single SW-12-04 with a PR?

I'm just trying to feel out all my options.

Chops · « **Reply #12 on:** 25 Dec 2008, 06:02 pm »

Actually, I just remeasured this room as it's been quite a few years since I had and it is only 11' x 12'. Just as bad either way.

Danny Richie · « **Reply #13 on:** 25 Dec 2008, 06:20 pm »

No need for the PR in this application.

With a room that small, a single sub should do it for you.

Chops · « **Reply #14 on:** 25 Dec 2008, 07:45 pm »

Detail wise, how do you think a single sealed servo sub would compare to the servo OB subs? The reason I ask is because I'm quite aware of OB bass and how it sounds.

In fact, in one of your other threads, you mention how great the OB servo system does drums. I know exactly what you heard as I felt the same way with my huge twine dipole subs (total of FOUR 15" drivers in large 24"W x 24"D x 36"H H-Frames and 300 watts each) while watching the movie "Drumline". At the time, I was also running a pair of Klipsch Cornwall's. The ONLY other time I had ever experienced drums like that was back in school when I'd hang out with some friends during band practice. I was actually in orchestra, 1st chair bass for 6 years straight.

Danny Richie · « **Reply #15 on:** 25 Dec 2008, 08:54 pm »

The sealed version does just as well. The advantage of the open baffle version is less room interaction.

Chops · « **Reply #16 on:** 25 Dec 2008, 11:10 pm »

I'm sold! LOL

Honestly, that sounds like the most reasonable and sensible way to go in this room. And since the servo amp allows a crossover point as low as 40Hz, I will no longer be limited to the 70Hz limit on my Rane crossover.

BTW, a bit off topic, but I'm also working an a sound quality system in my SUV and have been having a rough time figuring out what sub to use. I need it to be sealed and use as little air space as possible. The amp I have is a JL 500/1v2 which is rated at 500w from 1.5 - 4 ohms but has been bench tested at a solid 650w. It also has a fully adjustable PEQ from 20-80Hz. I would also be using an AudioControl Epicenter that takes the bass harmonics and digitally recreates them an octave lower. This would not be used all the time, but it would be used nonetheless.

To get to my point, would I be able to use the SW-12B with success? I see it's Pe is only 200 watts which concerns me. What about the servo subs? Can they be used on regualr "non-servo" amps?

Bill Baker · « **Reply #17 on:** 26 Dec 2008, 03:02 am »

I have been toying around with a massive OB sub tower to compliment some of the speakers I have arond including some GR OB-7s. I have a few ideas drawn up on paper. Eric....care to take a look at em'

My idea is take 6 GR Servo subs in a single, yet two piece tower powered by two dedicated servo amps. I'm pretty sure that will fill my room with some bass

These are NOT simply a large baffle with 6 holes in it.

EARGASM · « **Reply #18 on:** 26 Dec 2008, 05:00 am »

Removed by member.

Chops · « **Reply #19 on:** 26 Dec 2008, 05:42 am »

Quote from: EARGASM on 26 Dec 2008, 05:00 am

Hey Chops,
Hook yourself up with a (2) driver GR Servo Kit in a sandbox and get a seatbelt for your chair, dude! The OB setup is really killer, but it's much happier way out in the room. I'm likely to revert to sealed units, as soon as I get some time.

You get so much "room gain" in a car, and the Epicenter only contributes to [the perception of] that. I think the GR subs will do your bidding handily. Keep it sealed and you wont have excursion problems. I think if space limitations are your thing, an isobaric alignment is the way to go. You know how the Epi is great at bouncing voice colis, I'm sure. The current will help your cause on that JL badboy, but you'll have the gain way down I think.

Hi Eric,

So you think I should go with 2 servos in my tiny room? Danny thinks one would be more than enough. BTW, how large should the sealed enclosure(s) be for a single servo anyway? I don't think I've seen the answer to that anywhere yet. I'm also starting to wonder how a couple of these servo drivers would compare to my big SVS PB12-2/Plus in the theater system. It sounds great with movies but still seems a bit "heavy" and sluggish with music. Hmm...

As for my mobile audio system, you think the SW-12B will be alright with the Epi behind it and 600+ watts on tap? What about the servo subs? Aren't they simply normal DVC drivers, only that one coil is used in the servo circuit of the servo amp?