[tjbmi]

Having built a new house a couple of years back, I am now getting around to finalizing my great room and its audio system.  I have long been an electrostatic fan but my new room arrangement (and WAF) does not allow for proper placement of my Quads.  The agreed upon solution is to integrate some speakers into a custom built-in entertainment/bookshelf wall unit.  After alot of reading and investigation, I have decided that I should use a line array.

Material on well researched DIY designs is scarce.  I believe that the use of ribbon/planar tweeters would be a good substitute for the open and accurate sound of the electrostatic units that I am so fond of and they can be run monopole which is required in my plan.  Due to width constraints, my first plan was to use a B&G RD75 with a row of 6-7" woofers, crossed over in the 500-800 Hz range.  I read some very good things about the RD-75 but also some valid shortcomings.

Searching further, I did find some good info concerning GR Reasearch's LS6 & LS-9.  The design and review comments seem to match my goals.  The LS's idea of using several Neo8's (PDR modified) seems to address the sensitivity and high end roll-off problems of the RD-75 but does introduce the possibility of lobing and reduced horizontal dispersion.  I also like the idea of the allowable lower crossover in the 800-1000 Hz range.

I understand that integrating a line array into the wall unit will require some compromises.  The open sound due to rear wall reflections may disappear.  There may be edge diffraction problems due to adjacent shelf units and the proper spacing and toe-in (if required) will
have to be predetermined.  I have read the thread http://www.audiocircle.com/index.php?topic=46858.0 "On-wall Line Array" with great interest. The difference is that my design will consist of a full wall unit (depth to be determined) built up against the wall with the speakers integrated rather than individual speaker units attached to a flat wall.  Sonically, maybe there is no difference.

My current idea would be to just purchase a LS-9 kit when available and integrate the basic design into my wall unit, but the LS-9 utilizes rear vented enclosures.  What I need is to duplicate this excellent design idea with sealed enclosures.  Possible?  That's where my questions come in.

- Are the "specially built woofers in the LS6/9 the same as the M165X woofers sold by GR Research?

- If so, can they be used in a sealed enclosure and if so, what is the recommended volume?

- If not, the M165X seems like a good substitute.  Has anyone used the M165X woofers in a sealed enclosure with good results?

Further, my idea is to build these units and see what kind of low end is obtained in my room.  If more bass reinforcement is required, I will build a transmission line sub woofer with the driver and port in the bottom of the wall unit with the t-line extending through the floor into the basement between the floor joists.  Did I mention that the room has a 17ft flat ceiling!? 

Any comments would be greatly appreciated because I need to get this project designed and started (that WAF stuff again!)

[Danny Richie]

I read some very good things about the RD-75 but also some valid shortcomings.

The real limitation in using them in a line array is the sensitivity issue. They really only hit about 85 to 86db with 1 watt and getting a line of woofers to match that is not likely.

my first plan was to use a B&G RD75 with a row of 6-7" woofers, crossed over in the 500-800 Hz

500Hz is too low. It gets into the critical midrange that is in the 300 to 500Hz range. I'd stay in the 800Hz to 1,000Hz range.

using several Neo8's (PDR modified) seems to address the sensitivity and high end roll-off problems of the RD-75 but does introduce the possibility of lobing and reduced horizontal dispersion.

Actually just the opposite. The 5/8" wide playing surface of the Neo's will give you better horizontal dispersion than the larger RD series drivers. Also, with the LS series line sources, the low crossover point and steep acoustic slopes of the crossover allows for great horizontal coverage with no lobbing errors. In this regard it is better than any other lines sources ever introduced for sale. Even out to 40 degrees off axis in either direction they still maintain a consistent response.

My current idea would be to just purchase a LS-9 kit when available and integrate the basic design into my wall unit, but the LS-9 utilizes rear vented enclosures.  What I need is to duplicate this excellent design idea with sealed enclosures.  Possible?  That's where my questions come in.

For that application I'd use them in a sealed box configuration. Fortunately the bass management system incorporated into that design will allow for the adjustment gained from the wall reflections. In fact a lowering of the inductor value in the bass management system will allow the adjustment to reach a little higher up in range. That would help some too.

Are the "specially built woofers in the LS6/9 the same as the M165X woofers sold by GR Research?

No, the M-165 is completely different.

If not, the M165X seems like a good substitute.  Has anyone used the M165X woofers in a sealed enclosure with good results?

That woofer works great in a sealed box. I even use it in a kit design that uses a sealed box. But the sensitivity is way too high to get it to match with the line of the custom Neo-8's.

The custom woofers used in the LS series are a 3 ohm, low sensitivity design. This allows many to be used in series, keeping the output low enough to match the 91db level of the tweeters.

Any comments would be greatly appreciated

Build LS-6's or LS-9's in a sealed box version. Then add some of the direct servo subs as needed for additional first octave output.

[tjbmi]

Danny-

That woofer (M165x)works great in a sealed box. I even use it in a kit design that uses a sealed box. But the sensitivity is way too high to get it to match with the line of the custom Neo-8's.

If I were to use an active crossover - then the sensitivities could be matched, right?

Build LS-6's or LS-9's in a sealed box version. Then add some of the direct servo subs as needed for additional first octave output.

Or for utilizing the kit with the LS woofers - Do you have a suggested volume for this woofer(s)?  Estimated f3 point for x-over with sub?

Without tryimg to pin you down, are we talking days, weeks or months before the LS kits are available?

[Danny Richie]

If I were to use an active crossover - then the sensitivities could be matched, right?

Yes, active crossovers and of coarse multiple amps.

Or for utilizing the kit with the LS woofers - Do you have a suggested volume for this woofer(s)?  Estimated f3 point for x-over with sub?

.38 cubic feet per woofer. For a single woofer the -3db is 65Hz. For 8 of them in a line it will be about 57hz and for 12 of them in a line it will be about 55hz. Then factor in the XBL factor gain and room gain and drop it another 10Hz.

Without tryimg to pin you down, are we talking days, weeks or months before the LS kits are available?

I have been trying to nail AV123 down on when more drivers are due in for a long time (I am piggy backing on order with them and taking driver from their next order). My guess is that it will be a couple of months if I'm lucky.

[AUDFILE74]

Without tryimg to pin you down, are we talking days, weeks or months before the LS kits are available?

I have been trying to nail AV123 down on when more drivers are due in for a long time (I am piggy backing on order with them and taking driver from their next order). My guess is that it will be a couple of months if I'm lucky.

 so the ls-9 kits are still available?

[Danny Richie]

so the ls-9 kits are still available?

They will be as soon as I can get some more drivers in here. I have a good handful of people on waiting lists.

[tjbmi]

Have you established an approximate price for the kits when they become available?

[Danny Richie]

Same prices... LS-6 kit is $1,995. LS-9 kit is $2,695.

[tjbmi]

If I choose to use the M165X or another woofer, do you have the Neo 8.8's (since they only come from Las Vegas) and other misc parts available now?  Neo 8.8 cost?

[Danny Richie]

do you have the Neo 8.8's (since they only come from Las Vegas) and other misc parts available now?  Neo 8.8 cost?

I am out of the Neo 8.8's. The come from BG in Carson City. Cost is the same as the standard Neo 8. I do have everything else in stock though.

[AUDFILE74]

so the ls-9 kits are still available?

They will be as soon as I can get some more drivers in here. I have a good handful of people on waiting lists.

  thanks for the good news danny!

[tjbmi]

Danny,

What are the T/S parameters for your LS woofers?

[Danny Richie]

From an earlier post:

"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"