TH-18 Flat to 35hz! (Xoc1's design) - Page 146 - diyAudio
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Old 6th October 2013, 01:09 AM   #1451
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FS-audio, sorry saw the JB1800 and assumed jbl and for some reason wouldn't let me edit
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Old 6th October 2013, 03:03 AM   #1452
djk is offline djk
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http://www.paudiothailand.com/pdf/products/E-18ELF.pdf

This driver is available in OZ, and is suited for use in a tapped horn.

By the coil overhang plus 1/4 of the gap height method the x-max is 9.5mm

Cannon Sound carries P-Audio, there may be others. P-Audio also makes other suitable drivers that could probably be ordered for you as well.

http://www.paudiothailand.com/pdf/pr...IMF-HP18B2.pdf
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Last edited by djk; 6th October 2013 at 03:31 AM.
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Old 6th October 2013, 04:55 AM   #1453
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Th P-Audio certainly is an option. The JB doesnt look as good but I have used the 15" in some ss15's and have yet to have any issues.

I love deep low frequency subs but the install is probably going to need to be cheap so realistically going down close to 40hz is ok for my needs, so the BOB dual 18 seams like its still a contender but not ideal.
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Old 6th October 2013, 11:44 PM   #1454
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Got em back. Got some nice sub power now woohoo!
Gotta make grills, brace the mouth, put on heavy duty casters and coat with duratex as well as add neutrik connectors.
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Old 18th October 2013, 07:03 AM   #1455
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Hey guys, I'm a bit late to get onto this thread, so much to read!

I recently picked up some Beyma G550's to replace some cheap Dayton 18's in a simple 186 litre reflex cab, and I'm considering building some tapped horns for them (or possibly new drivers again).

I'm inexperienced with horns, are the G550's a potential candidate?

Cheers
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Old 18th October 2013, 02:56 PM   #1456
xrk971 is offline xrk971  United States
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Quote:
Originally Posted by rossgiblin View Post
Hey guys, I'm a bit late to get onto this thread, so much to read!

I recently picked up some Beyma G550's to replace some cheap Dayton 18's in a simple 186 litre reflex cab, and I'm considering building some tapped horns for them (or possibly new drivers again).

I'm inexperienced with horns, are the G550's a potential candidate?

Cheers
Using TundraLTD's Akabak model, the Beyma G550 looks pretty good in a sim with a 30Hz -12dB/oct high pass filter and 120Hz -48dB/oct low pass filter applied.

Here is the SPL vs freq at 2.83V for reference

Click the image to open in full size.

Here is the SPL at xmax which requires 57 volts or 406 watts rms

Click the image to open in full size.

Here is the cone excursion at 57 volts

Click the image to open in full size.
Here is the impedance

Click the image to open in full size.

Looks like a good performer with good efficiency.


Cheers,
X
Attached Images
File Type: png TH18-BeymaG550-Freq-1m.png (12.5 KB, 598 views)
File Type: png TH18-BeymaG550-Freq-1m-at-xmax.png (20.7 KB, 609 views)
File Type: png TH18-BeymaG550-Displ-406watts.png (20.6 KB, 606 views)
File Type: png TH18-BeymaG550-Impedance.png (20.9 KB, 608 views)
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Old 19th October 2013, 03:17 AM   #1457
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Wow, thanks so much X! Bit more information than I was expecting and then some

Is the ~126dB output at 100Hz far off what the quoted drivers achieve? As the beyma is rated to 900w (I think) with close to 9mm xMax), 406 watts is a little conservative...?

I'm not sure how distorted the sound will get in this setup running the driver closer to it's xMech.

More compression inside the horn to limit excursion, or will peak output be vastly greater than the sim?
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Old 19th October 2013, 01:17 PM   #1458
xrk971 is offline xrk971  United States
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126 dB at 406 watts is close to the efficiency that the Beymas are capable of - that is why I show the response at 1 watt, it is about 98 dB. You cannot put more power into it as the TH design doesn't control excursion enough - this is common for TH's. 126 dB is no slouch though and will get cops called to your party in a blink if they were used at home. You could high pass at a higher cutoff and limit bass to say 55 to 60 Hz and that will boost max SPL. You could play with tweaking the channel gaps to change compression ratio but that will go off plan and the nice box design provided in this thread will no longer be valid. I will leave tweaking the design up to the OP.

Last edited by xrk971; 19th October 2013 at 01:20 PM.
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Old 19th October 2013, 07:22 PM   #1459
Xoc1 is offline Xoc1  United Kingdom
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The 406 watts is a theoretical figure it does not include any power compression losses. The Beyma spec sheet for the G550 has a graph for power compression.
http://profesional.beyma.com/pdf/18G550E.pdf
At 406W the power compression is already 2.2dB
At 900W the power compression is 4dB. A 4dB reduction from 900W calculates to a theoretical 358W.
This indicates that the driver will actually require 900W plus to reach X-max.
Regards Xoc1
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Old 29th October 2013, 03:26 AM   #1460
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Finally got a chance to remove the drivers, fit new Heavy Duty casters, neutrik terminals, and some duratex.
I couldn't decide on white or black, so I mixed the two and love the result! I have to do another coat or two and do my PAL12's to match.
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