Can I build a sub with 6 Line Source woofers??

freerider · « **on:** 26 Sep 2010, 10:29 pm »

I have a few extra (broken) XBL^2 M130 woofers lying around that are damaged from auction shipping.

I was wondering if it was possible to build a subwoofer using 5 or 6 of these, rather than tossing them in the garbage.

I pulled these stats from another thread...I'm assuming they are for these woofers.

Samples for the 6.5" woofers to be used in the line source designs have the following parameters:

"Title: Measured Data"
"DCR mode: Fixed (3.28 ohms)"
"Area (Sd): 137.07 sq cm"
0.601 "RMSE-free Ohms"
34.544 "Fs Hz"
3.280 "Re Ohms"
40.114 "Res Ohms"
5.419 "Qms "
0.443 "Qes "
0.410 "Qts "
0.603 "L1 mH"
1.057 "L2 mH"
9.412 "R2 Ohms"
29.609 "Vas(Sd) liters"
18.918 "Mms(Sd) grams"
1122.068 "Cms(Sd) æM/Newton"
5.513 "Bl(Sd) Tesla-M"
90.102 "SPLref(Sd) dB"

Danny Richie · « **Reply #1 on:** 26 Sep 2010, 10:46 pm »

Sure, minus 3db for 6 of them will get you in the upper 20's range.

freerider · « **Reply #2 on:** 27 Sep 2010, 03:02 am »

Cool! Now I just need to figure out all the other details!

I think they are supposed to be in a box of some sort....

chlorofille · « **Reply #3 on:** 27 Sep 2010, 05:13 am »

The drivers model nicely in a 25L ported enclosure per driver, tuned to 32Hz via 50mm port, 180mm long.

How are you doing the wiring ? All 6 drivers in series/parallel to form an equivalent 6Ohm load ?

freerider · « **Reply #4 on:** 27 Sep 2010, 02:13 pm »

Danny,
Can you confirm the T/S parameters on these LS6 woofers? The ones above are from a 2006 post, that said they were preliminary.
http://www.audiocircle.com/index.php?topic=21141.msg238696#msg238696

I also had a couple questions about the parameters:

I was wondering if the 90.102 "SPLref(Sd) dB" parameter was dB-SPL at 1 meter for a 1 W input, or is it 8ohms (2.83 volts RMS input)?
What is the Le? (or what frequencies are L1 & L2 measured at?)
What is Z?

freerider · « **Reply #5 on:** 27 Sep 2010, 02:20 pm »

Quote from: chlorofille on 27 Sep 2010, 05:13 am

How are you doing the wiring ? All 6 drivers in series/parallel to form an equivalent 6Ohm load ?

I don't know the pros and cons of these options yet. I'm also might consider 8 woofers, if I can get a lower F3 for the design.

Danny Richie · « **Reply #6 on:** 27 Sep 2010, 02:42 pm »

Here are the parameters of the final version.

"Area (Sd): 137.07 sq cm"
36 "Fs Hz"
3.36 "Re Ohms"
5.17 "Qms "
0.46 "Qes "
0.42 "Qts "
0.62 "L1 mH"
1.08 "L2 mH"
27.04 "Vas(Sd) liters"
18.92 "Mms(Sd) grams"
1025 "Cms(Sd) æM/Newton"
5.6 "Bl(Sd) Tesla-M"
84.8 "SPLref(Sd) dB" (2.83 volts)

Le is inductance (use .62 mH).
Z is nominal impedance (4 ohms).

freerider · « **Reply #7 on:** 27 Sep 2010, 02:57 pm »

Thanks Danny!

Quote from: chlorofille on 27 Sep 2010, 05:13 am

How are you doing the wiring ? All 6 drivers in series/parallel to form an equivalent 6Ohm load ?

I got to thinking about this...if I used 8 woofers, I could make an 8 Ohm load using series and parallel configurations. Looks like 6 Ohms is the best option for only using 6 woofers (2 series sets of 3 in parallel). 6 would make a nice pattern in a rectangular enclosure. 8 would present more problems, and I might have to look at mounting woofers on multiple sides (4 front and 4 rear firing, or something).

Danny Richie · « **Reply #8 on:** 27 Sep 2010, 03:02 pm »

Two groups of four woofers will give you 6.6 ohms. That will be great.

Put all 8 of them in a line and lay it flat on the floor or stand them up and take up very little floor space.

freerider · « **Reply #9 on:** 27 Sep 2010, 03:39 pm »

Thanks for the advice. Unfortunately, I am restricted by the WAF, and only have one possible location for the 2nd sub, which is next to the couch. I have an MFW-15 on the other side of the couch already in the corner. This new sub would replace the hex side table in the picture. It will also be restricted to the height of the couch's armrest.

corndog71 · « **Reply #10 on:** 27 Sep 2010, 05:03 pm »

That's an unfortunate layout. And having the speaker jammed in the corner like that...

Just saying.

poseidonsvoice · « **Reply #11 on:** 27 Sep 2010, 05:17 pm »

Quote from: corndog71 on 27 Sep 2010, 05:03 pm

That's an unfortunate layout. And having the speaker jammed in the corner like that...

Just saying.

Yes. The problem here isn't subwoofers. It's the room/layout. Most likely you are getting some serious destructive interference (i.e. SBIR) since the LS-6's are very capable of decent bass. Early reflections are bound to be an issue as well. You should get some advice from Danny about this, since I know the low end of the LS-6's can be tweaked. Not just that, your seating position is right against a wall...translation -> no imaging/depth of the soundstage. I feel really bad for you. Honestly.

I wouldn't spend any more money on this setup until those aspects of the room are modified. The LS-9's need room to breath. Lots of room. Read this for more info.

Good luck

Anand.

jtwrace · « **Reply #12 on:** 27 Sep 2010, 05:20 pm »

Put your speakers on either side of the fireplace and your TV over the fireplace and set the sofa in a near-feild setup so you can have access behind it to the other room. I think the WAF will actually go up with this. Your equipment rack (new) would go in the LF corner .

You also bring the fireplace back as the focal point of the room rather then really large line array's that the Mrs. hates. Tell her your online audio interior designer said so.

Just a thought...

freerider · « **Reply #13 on:** 27 Sep 2010, 05:29 pm »

Thanks for the input. I appreciate all critiques, as my goal is to make what I have, sound as good as possible, so it's great to hear what is wrong with my setup.

I wasn't an audiophile when I bought this house... or I wouldn't have bought the house.

I don't have a built-up pair of LS6's yet...they are just empty cabinets in my garage. Polk RTi12's are in the room right now, but they are not benefiting from being stuffed in corners either.

So I'm planning on adding as much room treatment as my wife will allow. I can pretty much treat the whole wall behind the speakers as needed. Behind the couch is more difficult. I'm going to put bass traps in the corners, and sound absorption behind the speakers.

I'm only building the sub, because I don't have anything else to do with the pile of busted LS6 woofers I have. I'm certainly not putting them in the LS6's.

A few years down the road, I'll sell this place, and get a proper daylight basement to turn into my audio room.

freerider · « **Reply #14 on:** 27 Sep 2010, 05:33 pm »

Quote from: jtwrace on 27 Sep 2010, 05:20 pm

Put your speakers on either side of the fireplace and your TV over the fireplace and set the sofa in a near-feild setup so you can have access behind it to the other room. I think the WAF will actually go up with this. Your equipment rack (new) would go in the LF corner .

You also bring the fireplace back as the focal point of the room rather then really large line array's that the Mrs. hates. Tell her your online audio interior designer said so.

Just a thought...

Thanks! Unfortunately, the TV is a 65" rear projection. The above picture is accurate to within an inch, so there's no way it can go above the fireplace (a rear projection is not mountable, and it would look awful up there). Plus, in order to keep the TV, my wife made me wrap it in wood, which costs 2.5 times as much as the TV!

Beatcoaster · « **Reply #15 on:** 27 Sep 2010, 05:39 pm »

Freerider don't get discouraged on your project from poseidon and corndog's posts. Yes it is an unfortunate room layout, but I have the exact same issue and my living room is only 13'(f/r)x15'(side to side) - ridiculously small. My LS-6's still sound amazing even with my WAF factor not allowing any bass traps or wall treatments and my sitting position is right against my back wall as well. If I crank it up the reflections are there, but it still needs to be ear bleeding for them to become really bad. We can all only hope to live in another house someday and envision it to have an adequate mancave for all our toys devoid of the WAF factor and geared toward pure tonal bliss - that's why we build and buy what we do now! I need to have you come over sometime and listen to my setup, it will motivate you more than you know.

freerider · « **Reply #16 on:** 28 Sep 2010, 05:07 am »

I'd be up for some motivation!

Danny,
Do you know the Xmax on these woofers?

Trying to design a box for these is not going to be easy (unless I copy the LS6 minus the Neo8 enclosure). There are not a lot of resources for a multiple driver subwoofer.

JohnR · « **Reply #17 on:** 28 Sep 2010, 06:12 am »

Quote from: freerider on 28 Sep 2010, 05:07 am

There are not a lot of resources for a multiple driver subwoofer.

I think you should be able to do it for one, then multiply the box volume by 6 and the port area (not diameter) by 6 also.

dvenardos · « **Reply #18 on:** 28 Sep 2010, 03:33 pm »

So you don't have to wait to get a new house just a new TV or projector.

Quote from: freerider on 27 Sep 2010, 05:33 pm

Thanks! Unfortunately, the TV is a 65" rear projection. The above picture is accurate to within an inch, so there's no way it can go above the fireplace (a rear projection is not mountable, and it would look awful up there). Plus, in order to keep the TV, my wife made me wrap it in wood, which costs 2.5 times as much as the TV!

Danny Richie · « **Reply #19 on:** 28 Sep 2010, 03:55 pm »

Quote

Do you know the Xmax on these woofers?

By the numbers it is 7.8mm each way, but the surround limits it to about 6mm or so.

You need 6.76 cubic feet or air space for all 8 of them (optimal) and 8 2" flared ports that are 6" long. That will tune it to 33Hz and give you a -3db down point in the mid 20's for most rooms.