At last, the SEOS12 Measurements - AVS Forum
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post #1 of 66 Old 10-29-2011, 04:45 PM - Thread Starter
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ErichH and I had great weather today for doing outdoor measurements of some waveguides and other stuff. Weather was great for people running their leaf-blowers and lawnmowers, too, but we managed to work around them.

First, a shot of our 21st century test setup. That's ErichH trying to hide behind the SEOS18. If you look close, you can see the chalk marks on the concrete indicating the measuring angles. The control console is a laptop computer sitting on an upturned rubbish can. We used an old Advent speaker sitting on a folding table to raise the test subjects well above ground.


Here are some curves of SEOS12, using a DE250 driver. Measured at 2m distance, about 5' off the ground.
Horizontal patterns (measured in 7.5 degree steps, 0 to 90 degree range, curves unsmoothed):




Vertical patterns:




Harmonic distortion (at around 90dBSPL, 2m):

red is 2nd Harmonic, pink is 3rd, green is 4th, light blue is 5th, dark blue is total. Ripple is from ground reflection (since measuring at 2m distance)
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post #2 of 66 Old 10-29-2011, 04:52 PM
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wow, that looks really nice. strikingly good off-axis frequency response. no on-axis hole either!

which harmonics are those?

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post #3 of 66 Old 10-29-2011, 05:15 PM - Thread Starter
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Quote:
Originally Posted by LTD02 View Post

which harmonics are those?

Looks like you were replying while I was editing -- see redone last line of previous post.
-bw
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post #4 of 66 Old 10-29-2011, 05:24 PM
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Very nice.

I'm asking out of genuine interest. Why measure outside? Inside would be quiter, and you were only 5' off the ground. When I measure outside I usually hike it up over 8'. And usually only bother for sub-500hz interest. Is there still an advantage doing it outside like you've done? Thanks.
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post #5 of 66 Old 10-29-2011, 05:25 PM
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ah, the dark blue (total) is the one that was throwing me off, as i've never seen any harmonics overlay like that. again, nice work; nice horn.

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post #6 of 66 Old 10-29-2011, 05:29 PM - Thread Starter
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Someone was asking for the FRD file for the SEOS12, it's here -
SEOS12.frd
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post #7 of 66 Old 10-29-2011, 05:35 PM - Thread Starter
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Quote:
Originally Posted by tuxedocivic View Post

Very nice.

I'm asking out of genuine interest. Why measure outside? Inside would be quoted, and you were only 5' off the ground. When I measure outside I usually hike it up over 8'. And usually only bother for sub-500hz interest. Is there still an advantage doing it outside like you've done? Thanks.

Measuring outside so as to get data down to around 500Hz (my living area is too cluttered for getting really clean data down there). Need a lot of area to deal well with getting polars. It can be done inside, but not as easily.

Also because distortion testing is annoyingly loud and others are indoors (and not terribly appreciative of the sweeps... like my neighbors are )
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post #8 of 66 Old 10-29-2011, 05:45 PM
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That's great, Bill asks me to get things lined up.......then goes at tries to take a photo while I'm moving it around! You know that's a big waveguide if it can hide my meat head!

It looks like we're right in line with the house, but it's actually moved up more than the photo shows.

By the way, I think that's over 5' off the ground.....or I'm shrinking!
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post #9 of 66 Old 10-29-2011, 05:54 PM
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Ah, makes sense. Especially trying to get polar inside. I've been there. Even 30 degrees starts reflecting off walls.

Last edited by tuxedocivic; 06-20-2014 at 07:54 AM.
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post #10 of 66 Old 10-29-2011, 07:33 PM
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Bill,

Are you using a version of Omni not available to the public as of yet? I just upgraded to the latest version from PE's site and see no mention of the polar information, either from a new tab or from the help information. Thanks.

James
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post #11 of 66 Old 10-29-2011, 08:18 PM - Thread Starter
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Quote:
Originally Posted by exojam View Post

Bill,

Are you using a version of Omni not available to the public as of yet? I just upgraded to the latest version from PE's site and see no mention of the polar information, either from a new tab or from the help information. Thanks.

James

Hi Exojam,

Parts Express has the newer version and should be putting it up on their website shortly. Till then, you can get it here: OmniMicInstall.exe

If you are doing polars, it would be a good idea to look at the Help. There is an auto-filenaming feature now, which makes it easier to generate a set of frd files to form polars from. Essentially, you set up for measurements and then right-click in the freq graph and choose the "Configure Auto-increment" function with a dedicated directory for each set, a basic file name (or use the default), a starting angle, and an increment value. Then to save successive measurements at each angle, you only have to right-click in the graph again, then hit enter twice, it will save the file with the angle embedded in the file name, for a successive series of files. To show the polar graph all together, use the "Curves Add" menu and select all the files in the set, which will show the fanout of all the curves. Then click on the "polar" button (an "advanced function") and you get to the polar maps and radar plots -- for those you probably want to normalize the curve to the default curve where it would be EQ'd flat. Unless you are measuring an already-equalized and crossed-over speaker, that is. Anyway, it's pretty easy after you finally get how to do it.
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post #12 of 66 Old 10-29-2011, 08:21 PM
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Wow, those look great!

Even the first horizontal polar graph, which doesn't seem to agree with the second.

The former shows that directivity, as evidenced by equal spacing between the curves, is held down to ~1200 Hz, where they start to converge, but the latter (sonogram?) doesn't seem to start to expand significantly until ~800 Hz.

If I'm not misunderstanding how to read these, which one is right?

Noah
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post #13 of 66 Old 10-29-2011, 08:24 PM - Thread Starter
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Quote:
Originally Posted by noah katz View Post

Wow, those look great!

So good in fact that I don't understand.

Why doesn't the directivity decrease more as freq goes down?

It does, when you get down to where it loses control (below 800Hz). Or in the vertical curves, where the directivity drops gradually all the way through...

As for how it worked out that way, you'll have to ask the guys who really designed it (I only participated to vote on size and outside shape issues). Head back into the early pages of the "Hey guys..." thread here on AVS. Of course, following in the footsteps of Geddes and Keele.
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post #14 of 66 Old 10-29-2011, 09:18 PM
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Quote:
Originally Posted by bwaslo View Post

It does, when you get down to where it loses control (below 800Hz).

Am I mistaken that the first horizontal plot shows directivity decreasing at 1200 Hz?

To my eyes they're painting a very different picture.

Noah
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post #15 of 66 Old 10-29-2011, 09:55 PM
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"Am I mistaken that the first horizontal plot shows directivity decreasing at 1200 Hz?"

you kind of have to pick an off-axis spl where you want to call it at. most choose something between -6db and -12db. in this case that gives you a result of 750-850hz in the horizontal.

the off-axis at 90 degrees does begin to collapse around 1200hz, but that sound is down around 25db or more vs. the on-axis, so it really doesn't matter.

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post #16 of 66 Old 10-30-2011, 12:04 AM
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Quote:
Originally Posted by LTD02 View Post

you kind of have to pick an off-axis spl where you want to call it at. most choose something between -6db and -12db. in this case that gives you a result of 750-850hz in the horizontal.

Thanks, I see that now; as the sonogram flares more at larger angles.

This WG seems to cry out for at least a 15" woofer.

Noah
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post #17 of 66 Old 10-30-2011, 06:06 AM
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Yep, my build with the TD15M's now has another piece

JTR Noesis 212HT x 3 (LCR) powered by Lab Gruppen 10000Q amp
CHT SHO-10 x 4 (sides and rear) powered by Denon 4311
JTR S2 x 2
CHT 18.1 x2
Oppo BDP103D bluray player/Sonos/PS3
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post #18 of 66 Old 10-30-2011, 06:16 AM
 
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I'm still trying to wrap my head around reading these measurements. Does the 12 look smoother than the 15?
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post #19 of 66 Old 10-30-2011, 07:15 AM
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Great work guys. Thanks for the effort. Nobody's time is free and setting up for polars takes time.

These measurements look great. They are smooth out past 45 which is nice and they will be even smoother on an wide baffle or rounded over baffle.

These will cross great to a 15 but better to a 12. It isn't doing much in the vertical below about 1500hz. That is hardly a deal breaker when crossing to a 15 around 1100-1200hz, but not as good as the SEOS-15.

If a cheaper version is made available, I'd be comfortable with it being the SEOS-12. It wouldn't be the uber-performer that the SEOS-15 or 18 will be, but it will be pretty damn close and allow for a more normal sized box. I would guess that the actual audible differences will be small.

Any SEOS-18 measurements?
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post #20 of 66 Old 10-30-2011, 07:53 AM - Thread Starter
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Quote:
Originally Posted by coctostan View Post

Any SEOS-18 measurements?

See the separate thread on that one, http://www.avsforum.com/avs-vb/showthread.php?t=1369783
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post #21 of 66 Old 10-30-2011, 12:18 PM - Thread Starter
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Quote:
Originally Posted by mikey15 View Post

I'm still trying to wrap my head around reading these measurements. Does the 12 look smoother than the 15?

SEOS12 Horizontals:

SEOS15 Horizontals:


SEOS12 Verticals:

SEOS15 Verticals:


your call!
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post #22 of 66 Old 10-30-2011, 12:57 PM
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Great measurements!
Thank you thank you thank you!

Are these available in a GB or generally?

I'd be crossing this at 1.6k. Exactly what I was looking for.
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post #23 of 66 Old 10-30-2011, 01:08 PM - Thread Starter
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Originally Posted by Skywave-Rider View Post

Great measurements!
Thank you thank you thank you!

Are these available in a GB or generally?

I'd be crossing this at 1.6k. Exactly what I was looking for.

ErichH is heading up the GB on these.
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post #24 of 66 Old 10-30-2011, 01:17 PM
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It would seem that the only significant reason for favoring the 18" or 15" SEOS is the lower crossover point.
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post #25 of 66 Old 10-30-2011, 01:46 PM
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Quote:
Originally Posted by Skywave-Rider View Post

I'd be crossing this at 1.6k. Exactly what I was looking for.

Why so high? You could use one of the smaller ones for that XO freq.

Though the 10 doesn't look nearly as nice as the 12 http://www.avsforum.com/avs-vb/showp...postcount=1087

Quote:
Originally Posted by rajacat View Post

It would seem that the only significant reason for favoring the 18" or 15" SEOS is the lower crossover point.

What other reason would there be?

Noah
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post #26 of 66 Old 10-30-2011, 02:11 PM
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Quote:
Originally Posted by noah katz View Post

What other reason would there be?

I was thinking that their might be some differences in the relative dimensions of the 10, 12, 15 and 18 thereby influencing the pattern and control of the sound wave. If there isn't then it follows that the measurements should be exactly the same above 2k or so.
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post #27 of 66 Old 10-30-2011, 02:20 PM - Thread Starter
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I think If I was doing cost-no-object, I'd be going with SEOS12/DE250 and a 12inch B&C or TD12M.

For cost-and-SIZE-no-object, SEOS18/DE250 and a TD15M or similar.

I still don't like the idea of using a larger dia CD driver, bigger horn, and an additional tweeter, but I can see why some people might. I like the effect of not hearing that a speaker is there.
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post #28 of 66 Old 10-30-2011, 05:36 PM
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Quote:
Originally Posted by noah katz View Post

Why so high? You could use one of the smaller ones for that XO freq.

Though the 10 doesn't look nearly as nice as the 12 http://www.avsforum.com/avs-vb/showp...postcount=1087



What other reason would there be?

There are advantages to using the larger waveguides. The most obvious is the superior vertical pattern control. I'd estimate that the SEOS-12 is holding pattern vertically down to about 2-2.2khz. This isn't a glaring deficiency. Vertical pattern control is not nearly as important as horizontal, but it does affect the power response.
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post #29 of 66 Old 10-30-2011, 10:45 PM
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Quote:
Originally Posted by noah katz View Post

Why so high? You could use one of the smaller ones for that XO freq.

Though the 10 doesn't look nearly as nice as the 12 http://www.avsforum.com/avs-vb/showp...postcount=1087



What other reason would there be?

From looking at bwaslo's polar graphs, I think both the vertical and horizontal will line up pretty well at -6dB off-axis points with a 12" woofer's directivity, which is what I will use.
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post #30 of 66 Old 10-30-2011, 11:56 PM
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Quote:
Originally Posted by Skywave-Rider View Post

From looking at bwaslo's polar graphs, I think both the vertical and horizontal will line up pretty well at -6dB off-axis points with a 12" woofer's directivity

At what freq will you put the XO?

Noah
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