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Author Topic: Malcolm, a SEOS12 Center (Middle?) Channel speaker  (Read 12129 times)

Offline bwaslo

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Malcolm, a SEOS12 Center (Middle?) Channel speaker
« on: March 31, 2012, 09:31:10 PM »

Here it is, an Ewave type center channel, dubbed "Malcolm".  It uses a SEOS12 and (currently) one of Erich's "less good" clone drivers. 

Weather was good tonight and I had a little time to set up outside and take some pattern measurements.

Woofers are 4x DS-115-8, cleverly (or so I think) arranged as a shaded horizontal line source.  Near crossover, the middle pair plays dominantly to match the SEOS12 pattern, with the outer pair cutting in a few hundred Hz lower and continuing directivity like a 20" driver.  The effect is rather good constant horizontal directivity down to about 500Hz, in a box only 12" high and 21" wide.  8" deep.  The speaker cabinet looks a lot better than it appears in the camera photo (the flash does funny things inside the waveguide contours).  The crossover mess on top, though, is every bit as ugly as it looks here -- needs to be put on a board and mounted inside.

The box is ported, tuned to 60Hz and has an F3 of about 57Hz when mounted against a wall (above or below an LCD monitor is the intention).

Here are the Horizontal curves, unsmoothed.  0 to 60degress in 7.5 degree steps-

Pretty good, huh?  Check it out in the usual 1/6th Octave smoothing (0 to 90deg):


These are some color polar plots of the horizontal performance (map and cylinder formats):



In the vertical, the waveguide can only control directivity down to about 3kHz or so and the woofers (being only 4"ers) don't control it at all.  But the very close 5.5" CTC keeps the curves smooth and useful so what does go vertically off axis is at least well-behaved.  Vertical Upwards, 0 to 60, unsmoothed:
\
Vertical Downwards:


And here's the high-tech measuring "lab", including speaker precariously balanced on a ladder with a sheet of MDF clamped below to try to simulate an LCD screen.  The whole arrangement is about a foot from the door behind it, so bass wasn't as good as it should be.
« Last Edit: April 16, 2012, 05:03:20 PM by bwaslo »

Offline bwaslo

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Re: Malcolm, a SEOS12 Center (Middle?) Channel speaker
« Reply #1 on: April 16, 2012, 04:58:39 PM »
Here is schematic and partslist for Malcom 1


266-552  Qty 2   1.5mH
 255-044  Qty 1   0.8mH
 255-026  Qty 2   0.25mH
 255-038  Qty 1   0.55mH
 
 027-940  Qty 1   22uF
 027-406  Qty 1   0.47uF
 027-438  Qty 1   25uF
 027-427  Qty 1   6.2uF  (use for 6uF)
 027-410  Qty 1   1uF
 027-364  Qty 1   150uF
 027-354  Qty 1   50uF
 
 015-.5  Qty 1     0.5 Ohm //  Combine with 1.0 ohm to make 1.5 ohm
 015-1.0  Qty 1   1.0 Ohm //
 
 //These two could be replaced with an L-Pad if adjustment is wanted:
 015-3.0  Qty 1   3.0 ohm
 015-12   Qty 1  12 ohm  (use in place of 13 ohm, close enough)
 
 015-10   Qty 1   10 ohm
 016-1.2  Qty 1   1.2 ohm
 015-1.8  Qty 1   1.8 ohm
 015-3.3  Qty 1   3.3 ohm
 
 260-407 Qty 2  1.5"D Ports (shorten each by 1").
 
 295-424  Qty 4   4" Designers' Series woofers
 SEOS12 Waveguide Qty 1 (get from Erich)
 Horn driver:  Qty 1.  Designed using "lesser" clone from Erich. "Better" clone will work nearly same (slightly smoother).  B&C DE250 (294-605) will work as well also, though expensive.
 
 Box made with 0.5" ply, baffle is 3/4" MDF.  Outside dimensions are 21" wide, 12" high, 8" deep.  Woofers spaced with 0.5" between edges.  Box has internal window brace (with cutouts to allow air flow) between top section and woofer section.  More bracing might be a good idea.


____________

BTW, there has been a Malcolm2 version made.  And it was a complete flop!  I used 4 of the Aura6 woofers, mounted on top of the short, wide, box so that they were up against the back wall, really well-made plywood box, no pieces had to be remade, I should've known something was wrong.  I miscalculated the distance beween the woofers and their "reflections" on the wall,  The center-to-center of those was about 6.5" and the listener is getting the wave from the reflection delayed by about 0.5msec, making a BIG suckout right at the 1kHz crossover point... oops.  So that really nice box is firewood.  I have a plan for a Malcolm3 but that will have to wait until I have time again, whenever that happens.....
« Last Edit: April 16, 2012, 05:01:48 PM by bwaslo »

Offline PassingInterest

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Re: Malcolm, a SEOS12 Center (Middle?) Channel speaker
« Reply #2 on: April 17, 2012, 05:42:34 PM »
You da man, Bill!  Thanks for your tireless efforts with the designs.
Malcom in the Middle.  You really crack me up!

Offline Maxjr

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Re: Malcolm, a SEOS12 Center (Middle?) Channel speaker
« Reply #3 on: April 25, 2012, 02:47:22 AM »
This is great!  Love the horizontal line array, bwaslo.  I'm looking forward to Malcom 3.  Is there any chance of a version using 2x NS6 drivers instead of 4 as a small surround?

Offline Kagey

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Re: Malcolm, a SEOS12 Center (Middle?) Channel speaker
« Reply #4 on: April 25, 2012, 01:02:49 PM »
How did the Malcom 2 behave when pulled out from the wall?

Offline bwaslo

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Re: Malcolm, a SEOS12 Center (Middle?) Channel speaker
« Reply #5 on: April 25, 2012, 09:47:57 PM »
Bass falls off, as you'd expect.  It counts on boundary reinforcement.

Offline DS-21

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Re: Malcolm, a SEOS12 Center (Middle?) Channel speaker
« Reply #6 on: April 29, 2012, 02:24:44 PM »

IMO, this speaker is the most interesting thing yet to come out of the SEOS project.


Very creative, Bill. And it looks like a very room-friendly way to get a properly identical front trio of mains.


How do you think the response would suffer if it was scaled up a bit, to say 4 NS6's in your shaded array. (Something about the idea of all NRT motored drivers - NS6's, NS-series subs - from ~1kHz down seems just "right" to me. And unfortunately Madisound seems permanent sold out of the old Ford GT/McIntosh blue-coned Aura 5" drivers.)


Would that really need an SEOS15 (and higher price, because they're only available in fiberglass) or would an SEO12 still work, and get the kind of on-axis response and polars you're getting with the DS5/SEOS12 combo?

Offline bwaslo

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Re: Malcolm, a SEOS12 Center (Middle?) Channel speaker
« Reply #7 on: April 29, 2012, 03:27:21 PM »
Thanks, glad you like it.

If you want to use the same design for side channels, too, you'd need to put something below them for boundary reinforcement.  Something behind them would be a good idea, too. 

The one above the monitor will be against the wall and facing forward, but the ones on the sides really need to be toed-in (otherwise, IMO, you're just wasting the effects of using a waveguide -- see http://www.diysoundgroup.com/forum/index.php?action=articles;sa=view;article=1).  Toe-ing in will bring them away from the wall, which is probably not a great idea (though EQ may be able to deal with it).

You should be able to use NS6 drivers, but the speaker will get taller, nearly square-shaped.  Not too consmetically appealing above an LCD screen, but maybe something can be done with grille cloth?

Offline DS-21

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Re: Malcolm, a SEOS12 Center (Middle?) Channel speaker
« Reply #8 on: April 29, 2012, 07:30:09 PM »
The one above the monitor will be against the wall and facing forward, but the ones on the sides really need to be toed-in (otherwise, IMO, you're just wasting the effects of using a waveguide -- see http://www.diysoundgroup.com/forum/index.php?action=articles;sa=view;article=1).  Toe-ing in will bring them away from the wall, which is probably not a great idea (though EQ may be able to deal with it).

I'd probably just build angled cabinets for the side speakers, so they're all close to the front wall. I've been a believer in "overtoeing" and since some DIYA posts by Dr. Geddes convinced me to try it.

You should be able to use NS6 drivers, but the speaker will get taller, nearly square-shaped.  Not too consmetically appealing above an LCD screen, but maybe something can be done with grille cloth?

I was thinking of mounting the LCD a bit high, so the front trio could be at an identical elevation below it.

At any rate, it'll probably look better than this:



Or, prior to the Nathan Funk cabs, this:



A single guy can get away with that. Dr. DS-21, wonderful as she is, just won't let me next get away with it next go-around. :)

So I gotta figure out a way to get decent front mains in an aesthetically appealing package. (Though until your Malcolm design got my brain moving my leading idea was to put my existing Tannoy-based speakers on wall-mounts up high and run a thin drape across the top.)
« Last Edit: April 29, 2012, 07:33:03 PM by DS-21 »

Offline bwaslo

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Re: Malcolm, a SEOS12 Center (Middle?) Channel speaker
« Reply #9 on: April 29, 2012, 08:39:51 PM »
Ceiling hugging waveguide speakers maybe?  There was a discussion of that in the "hey guys" thread at AVS.  A sketch, too.  Put the NS6s against the ceiling, the seos beneath.   If I have time I may try that.

Offline noah katz

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Re: Malcolm, a SEOS12 Center (Middle?) Channel speaker
« Reply #10 on: April 30, 2012, 12:55:12 AM »
Bill, do you even use a center?

Offline bwaslo

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Re: Malcolm, a SEOS12 Center (Middle?) Channel speaker
« Reply #11 on: April 30, 2012, 05:15:27 AM »
No, not yet.   Have it built, but need to come up with a way to hold it above the screen.  Don't really feel a strong need to get on with it, the phantom center works very well with the toed wgs on the fronts.  But I did the Malcolm because people kept asking about ewave centers.  Sometime I'll make up a bracket or something to hold it up.

Offline maxmercy

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Re: Malcolm, a SEOS12 Center (Middle?) Channel speaker
« Reply #12 on: May 01, 2012, 06:18:50 AM »
bwaslo,
 
I have an idea for a SEOS/E-Wave center, but it involves a smaller SEOS, like the SEOS 6.  Use two 10" high sensitivity 16 Ohm woofers run in parallel up to 500Hz, (Eminence Delta10B, or pricier Faital Pro drivers), flanking a 6" high sensitivity pro midrange, with SEOS 6 or similar (maybe a Denovo?) waveguide above.  12" tall, 28" wide, 95+ dB sensitivity, and able to reach reference with only receiver power.  Catch?  Can only be tuned to ~65Hz and highpassed, unless you use pricier drivers. 
 
Stack the drivers vertically, and you have a main/center solution for non-acoustically transparent screens.
 
Another option would be using a coaxial in the center, like the JTR offerings that can be placed vertically or horizontally.  I have not seen a DIY version that I know of.
 
I have yet to experiment with CBT solutions to see if reference is do-able with receiver power in a slim package, but I plan to this summer.
 
JSS

Offline iconrl

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Re: Malcolm, a SEOS12 Center (Middle?) Channel speaker
« Reply #13 on: August 21, 2012, 10:49:30 AM »
Bill & MM,
Any new progress on these center channel designs?
Donít let your ego write a check your character canít cash.

Offline bwaslo

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Re: Malcolm, a SEOS12 Center (Middle?) Channel speaker
« Reply #14 on: August 21, 2012, 11:54:37 AM »
Yeah, I'm trying to cajole Erich into making me a Malc olm-like cabinet with 4 six inchers.  If he gets to it, I'll work  up a crossover for it.  Should get nice directivity and bass spl