TH-18 Flat to 35hz! (Xoc1's design) - Page 50 - diyAudio
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Old 14th February 2012, 10:58 AM   #491
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so with Xco1's T18 here, should the baffle have this shape?
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Old 14th February 2012, 03:27 PM   #492
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Quote:
Originally Posted by scameron78 View Post
so with Xco1's T18 here, should the baffle have this shape?
Without performing an A/B test, hard to say.
PASC did mention the Keystone TH design had better cone control than the TH18 design using the same speaker, perhaps you could ask him to try the shaped plate and see if it helps.

Or DIY .

Art
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Old 27th February 2012, 12:27 AM   #493
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Quote:
Originally Posted by weltersys View Post
Without performing an A/B test, hard to say.
PASC did mention the Keystone TH design had better cone control than the TH18 design using the same speaker, perhaps you could ask him to try the shaped plate and see if it helps.

Or DIY .

Art
@Scameron: or at least build the plate and ship it to him to test
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Old 29th February 2012, 07:04 AM   #494
grec13 is offline grec13  United States
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Default Keystone TH compatability

Aloha everybody.

I got a question for Art.
First of all.
Thank you for sharing your knowledge and experience with us.
I'm looking for home bass solution in 35-90hz range.
Will the JBL LE14A or JBL 2235H work in the Keystone TH?
I tried Martinson TH15, it didn't work with them. Seems like a sound is choking inside the cabinet.

thank you.

Quote:
Originally Posted by weltersys View Post
Without performing an A/B test, hard to say.
PASC did mention the Keystone TH design had better cone control than the TH18 design using the same speaker, perhaps you could ask him to try the shaped plate and see if it helps.

Or DIY .

Art
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Old 29th February 2012, 03:45 PM   #495
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Quote:
Originally Posted by grec13 View Post
Aloha everybody.

I got a question for Art.
First of all.
Thank you for sharing your knowledge and experience with us.
I'm looking for home bass solution in 35-90hz range.
Will the JBL LE14A or JBL 2235H work in the Keystone TH?
I tried Martinson TH15, it didn't work with them. Seems like a sound is choking inside the cabinet.

thank you.
Sergey,

Although every speaker put in the Keystone "worked", work is a relative term. The Eminence 4015LF had decent frequency response, but the relatively lightweight cone, fine in a ported cabinet, distorted badly when pushed to Xmax in the tapped horn. Sims don't show distortion.
The JBL cones you ask about would probably fare little better (and possibly worse) than the 4015LF.

The LE14A only has an Xmax of 5.08mm, the 2235H is only 8.38mm.
The B&C18SW115 has an Xmax of around 15, three times the former, and almost double the latter.
Doubling Xmax allows for about 6 dB more output.

B&C now has a new cheaper (heavier slab magnet) driver, the 18TBW100 (4 or 8 ohm) with similar specs to the 18SW115.
It models well in both XOC1's TH-18 or the Keystone, though in the Keystone it can take more power before exceeding Xmax, and put out a bit more level.

Art

Last edited by weltersys; 29th February 2012 at 03:47 PM.
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Old 29th February 2012, 03:59 PM   #496
fhperez is offline fhperez  United States
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Quote:
Originally Posted by weltersys View Post
Sergey,


B&C now has a new cheaper (heavier slab magnet) driver, the 18TBW100 (4 or 8 ohm) with similar specs to the 18SW115.
It models well in both XOC1's TH-18 or the Keystone, though in the Keystone it can take more power before exceeding Xmax, and put out a bit more level.

Art
Have you guys posted those numbers anywhere?
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Old 29th February 2012, 06:57 PM   #497
grec13 is offline grec13  United States
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Default Keystone TH compatability

thank you Art.
Quote:
Originally Posted by weltersys View Post
Sergey,

Although every speaker put in the Keystone "worked", work is a relative term. The Eminence 4015LF had decent frequency response, but the relatively lightweight cone, fine in a ported cabinet, distorted badly when pushed to Xmax in the tapped horn. Sims don't show distortion.
The JBL cones you ask about would probably fare little better (and possibly worse) than the 4015LF.

The LE14A only has an Xmax of 5.08mm, the 2235H is only 8.38mm.
The B&C18SW115 has an Xmax of around 15, three times the former, and almost double the latter.
Doubling Xmax allows for about 6 dB more output.

B&C now has a new cheaper (heavier slab magnet) driver, the 18TBW100 (4 or 8 ohm) with similar specs to the 18SW115.
It models well in both XOC1's TH-18 or the Keystone, though in the Keystone it can take more power before exceeding Xmax, and put out a bit more level.

Art
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Old 29th February 2012, 07:48 PM   #498
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Quote:
Originally Posted by fhperez View Post
Have you guys posted those numbers anywhere?
tundraLTD in post #3 of this wrote:
New Lower Cost B&C 18"

ďJust plugged it into my Akabak script of the TH-18 Flat to 35hz! (Xoc1's design)
It sims great hitting Xmax at just over 900w. I may have to order a few! Thanks for the find.Ē


The Xoc1 TH-18 as built rolls off below 50 Hz, the Keystone (like the Danley TH-118) rolls off below 40 Hz, closer to "Flat to 35Hz!" .

The higher LF knee of the Xoc1 TH-18 allows it to play louder higher, but excursion goes up below Fb, so it canít take as much power without sounding, a bit distressed.

The simís below show very little difference in output at Xmax for the new BC18TBW100 and the BC18SW115.

The BC18TBW100 has an Xmech (where mechanical damage will occur) of 28.5mm, Hornresp says it would take 138 volts (5874 watts in the Keystone sim) to reach that, and it would hit over 135 dB.

In real life with music, thermal compression and the stiff compliance would probably not allow hitting Xmech and long term power of around 6000 watts would probably smoke the driver, but the BC18SW115-4 has no problem with 120 volt peaks, I expect the BC18TBW100-4 would not either.

Art
Attached Images
File Type: png BCneo,Fe.png (81.0 KB, 474 views)
File Type: png Xoc1Sim.png (108.2 KB, 471 views)
File Type: png DSL,Key, Xoc1.png (154.6 KB, 457 views)
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Old 1st March 2012, 03:59 AM   #499
Djim is offline Djim  Netherlands
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Quote:
Originally Posted by weltersys View Post
The higher LF knee of the Xoc1 TH-18 allows it to play louder higher, but excursion goes up below Fb, so it canít take as much power without sounding, a bit distressed.
Hi Art,
If cut with >24dB/oct at 37Hz, drivers in the Xoc1 can handle their AES power ratings.
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Old 1st March 2012, 04:54 AM   #500
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The 18TBW100 with a 12dB Butterworth highpass @ 32Hz will do 900+watts. With a L/R 12dB highpass 1600+watts. Akabak sims show nearly NO difference in SPL output so why would you push it that much harder?

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