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Old 25th November 2009, 10:28 PM   #21
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The 29cm baffle is acoustically narrow to the Seas L21 midbass and is well below the 2.2 rule of thumb. I have to take it out for proper measurements later but from experience it would likely be very smooth to 1.6khz, which is usable.

I did only indoor measurements so far to find out the dipole peak, which is 460Hz. Close to Orion (400hz) and is consistent since Orion have slightly wider baffle and is folded.

What's more worrying was the L21 do not have flat response from 300-1kHz region. Hence the dipole SLP started further above to compensate this, which is around 680hz.

One day I will try the no-baffle approach and see. At the moment the physical construction complexity is a bit too much
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Old 26th November 2009, 12:29 AM   #22
CLS is offline CLS  Taiwan
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Hi gainphile,

Do you really run out of Xmax of the woofers?
Or the system can not take any more EQ boost?
Or, did you still EQ it flat to 20Hz? Oh, no!
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Old 26th November 2009, 01:00 AM   #23
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I still equalise it down to 20Hz. The depth of the sound is still there, but since I need to equalize more they run out of excursion much quicker. That extra 24cm the H-frame provided really makes a big difference in terms of maximum output.

I listen at "concert level" about once a week only when the wife/kids are away so I'm not missing much.
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Old 26th November 2009, 01:22 AM   #24
CLS is offline CLS  Taiwan
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Those big woofers are calling....
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Old 26th November 2009, 01:40 AM   #25
ttan98 is offline ttan98  Australia
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Quote:
Originally Posted by CLS View Post
Those big woofers are calling....
To reproduce Bass from an OB speakers each side needs at least twin 15" woofer to give you the impact ie down to 35-40Hz and sound stage, in a small room/enclosure they look daunting to horrible and the sound reproduction can be overwhelming.

Possibly a good compromise is a twin 12" woofer mounted in W-frame hence reducing the width and the sight is not so daunting. Refer to a commercial speakers by GR research, model: V2 system.
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Old 26th November 2009, 02:00 PM   #26
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You can always make a vertical 18" ripole bulit under the cabinet with flower on it

This way it could be a little bit camouflaged...
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Old 26th November 2009, 02:07 PM   #27
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Or 18" Ripole subwoofer built under the cabinet with flower on it. If you'd run it up to 80hz maybe 100hz one should be enough.
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Old 26th November 2009, 02:31 PM   #28
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Thanks. The slopes are 1.5khz and 120hz. All LR4. Some usual SLP and notches for OB.

Yes, Pluto (clone) is a love-hate relationship. They have the best holographic and realistic imaging, yet the sound is coloured by the "box". One immediately notice this when swapping over. I've done numerous swaps before.

So this S12 imaging is close to Pluto, but not there yet. For that I have to use narrower baffle like my "S9". But tonality and "purity" of sound they're miles ahead.
I've done over a thousand loudspeaker measurements in the past year, and the thing that always stands out is that a loudspeakers polar response is dramatically affected by diffraction off the cabinet edge.

It's a bit of a mystery to me why Linkwitz dismisses this effect on his site, since the evidence in a polar plot is as clear as day.

Anyways, if you want to improve the sound, you might consider using a roundover on the edges, instead of a sharp transition from one angle to the other.

The measurements show an improvement, and subjectively, the cabinet seems to "disappear."

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Old 26th November 2009, 02:48 PM   #29
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I am now more towards lying the bass-baffle down and introduce some angle between units. Here is a simulation with a 50 x 80 cm baffle with 2 Eminence Alpha15s, LP at 200 Hz 12 dB/oct LR:

Click the image to open in full size.

Click the image to open in full size.

Combining this with Stig-Erik's way of hanging units, not really in one chain but more flexible so that you can adjust for time alignment between units. With or without baffles.

This I think would be a great way to go.

/Erling

Last edited by skorpion; 26th November 2009 at 02:50 PM.
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Old 5th December 2009, 07:10 AM   #30
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Default Measurements ... at last !

Patrick Bateman's comment interested me. One reason being the diffraction effect must be avoided as much as possible and JohnK in his website argues about the importance of plain baffle, i.e. no wings.

The problem is, while I do like wingless baffle, it does not provide sufficient physical support. The OB would sway and vibrate visibly with organ passages .

So for structural support I added strips of 4cm wing. Let's see now how it measures.

Click the image to open in full size.

My typical outdoor measurement. Plenty of bush around for "attenuation" and I prefer ungated measurements. It is very difficult with weather and birds! Smallest wind blow and birds chirping shows in the measurements. The neighbour mowing the lawn did not help either
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