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| Re: Design flaw of a Dual 18" Cabinet? [message #321418 is a reply to message #321411 ] |
Sat, 10 May 2008 09:07   |
 Charlie Zureki
Messages: 266
Registered: April 2008
Location: Detroit Area |
Has No Life |
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Marjan has it right .... way too much power for those speakers,
over excursion should have been the clue.
And, I believe his High pass should have been set to 40hz or higher.
Cheers,
Hammer
Be prepared, you'll need it!
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| Re: Design flaw of a Dual 18" Cabinet? [message #321427 is a reply to message #321406 ] |
Sat, 10 May 2008 09:46 |
Charlie Zureki
Messages: 266
Registered: April 2008
Location: Detroit Area |
Has No Life |
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Don,
You'd gain additional power "handling" from the box with the same dimensions if it were a Sealed Enclosure. (Yes, the tuning would change)
But, that is a moot point considering he has too much amplifier for these speakers.
Cheers,
Hammer
Be prepared, you'll need it!
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| Re: Design flaw of a Dual 18" Cabinet? [message #321444 is a reply to message #321342 ] |
Sat, 10 May 2008 11:06 |
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| Josh Billings wrote on Fri, 09 May 2008 21:33 |
I believe these are 40x30x24 and they are slot loaded (one long slot along the bottom of the cabinet).
Also I'm using a Pl6 with the clip limiters on and don't even remember clipping them.
It was the double version of this
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=26021 1370398
Bought it from the same guy.
-Josh Billings
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For my money when you say these are "Slot loaded" you are incorrect.
I presume the ‘slot” you are talking about is the “vent” or “Port” for the box?
A true “Slot load” would be cover part of the cone on the front of the driver.
The Tom Danley Unity design has a great portion of the 5” drivers and 12” drivers covered and that “loads” the front of the driver. If done correctly closing off some of the front of the driver will stop the drivers phase response from dropping similar to attaching a horn to the front of the driver, which loads it.
Too Tall
Curtis H. List
Bridgeport, Mich.
I.A.T.S.E. Local # 274 (Gold Card)
Lansing, Mich
Independent Live Sound Engineer (and I'm Tall Too!)
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| Re: Design flaw of a Dual 18" Cabinet? [message #321446 is a reply to message #321342 ] |
Sat, 10 May 2008 11:20 |
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| Josh Billings wrote on Fri, 09 May 2008 21:33 |
I believe these are 40x30x24 and they are slot loaded (one long slot along the bottom of the cabinet).
Also I'm using a Pl6 with the clip limiters on and don't even remember clipping them.
It was the double version of this
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=26021 1370398
Bought it from the same guy.
-Josh Billings
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So, How many do you have?
Just one or two boxes?
Are you married to this driver?
With the correct interior measurements for volume, the port area, depth (number of ports also) and TS parameters I can model Xmax along with frequency response at any voltage input.
Also you can measure the current TS of the drivers are used or suspect.
You can download the free demo of Praxis and measure the TS for any driver.
If you have Smaart and you measure near field (1/4" from driver and ports) of all drivers I can also model defraction and effects from the size of front baffle, sides and where the driver and ports are positioned.
Too Tall
Curtis H. List
Bridgeport, Mich.
I.A.T.S.E. Local # 274 (Gold Card)
Lansing, Mich
Independent Live Sound Engineer (and I'm Tall Too!)
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| Re: Design flaw of a Dual 18" Cabinet? [message #321811 is a reply to message #321068 ] |
Sun, 11 May 2008 18:26 |
SteveKirby
Messages: 1104
Registered: October 2007
Location: Santa Cruz |
Has No Life |
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Josh, it shouldn't take that much time to measure the dimensions of the box, and put that into something like WinISD which you can download for free. The Beyma TS parameters are probably already in that program. That will tell you for sure what the cabinet is doing. What the expected cone excursion (xmax) and where it might unload the driver (telling you what high pass you should use)
edit to add, that any bracing or anything that improves the stiffness of the box (QL) will actually lower the F3 (3 dB down point).
[Updated on: Sun, 11 May 2008 18:35]
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| Re: Design flaw of a Dual 18" Cabinet?Here we go again [message #321899 is a reply to message #321412 ] |
Sun, 11 May 2008 23:09 |
Tim Duffin
Messages: 442
Registered: September 2004 |
Has No Life |
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Bob has the right answer.
That driver is not really a subwoofer driver. Get better drivers and all your problems will be solved. Try something that actually moves (has excursion capability). I had the same problem with an older RCF 18" driver that was not designed to have any type of excursion and kept asking "what did I do wrong?" when the answer is that the "woofer" was not designed to be loud at low freqs.
I bet if you threw a couple B & C or JBL woofers in there it would sound nice.
T
www.spl-sound.com
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| As A Beyma User............. [message #321946 is a reply to message #321917 ] |
Mon, 12 May 2008 08:36 |
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Elliot Thompson
Messages: 1076
Registered: April 2004
Location: New York |
Has No Life |
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Hopefully this will clear up a few things for it seems many are passing judgment on speakers they do not own.
Beyma 18 inch drivers are very good transducers. The G Series offer a 4.5” voice coil, double spider, and a 9 mm xmax. Now, you won’t find many 18 inch drivers offering a double spider let alone a 4.5” voice coil.
If a woofer miraculously dies there are two things to take into factor:
1. Thermal. Where the voice coil heats up to the point in burns
2. Mechanical. Where the spider or surround rips due to excessive mechanical movement.
More woofers die based on thermal than mechanical. Amplifier clipping or a sustained note at high sound pressure levels will cause a woofer to fail. Having a woofer to cover too large of a venue will also create thermal burnout.
The Beyma 18 G 50 withstands 1500 watts of program power. And it is evident by the mechanics for it has the tools to do so.
A Proprietary designed sub stems from a builder’s quest to perfect a certain tone in which he/she is having difficulty finding or cannot afford in the commercial off the shelf pre-made subwoofer market. In other words, the builder created such a design in order to work in conjunction with the mid-hi cabinets he/she is using within the chain.
When one purchases a proprietary design box, and do not use the same mid-hi cabinets as the person, who designed the box, they may encounter the type of problems you are having Josh. Trying to achieve frequencies beyond the cabinet’s efficiency bandwidth will lead to unexpected failures.
This is really getting dragged out for reasons I cannot comprehend. And as Steve mentioned, downloading a free speaker design program, reverse engineering the cabinet, going to Beyma’s site and getting the correct TS Parameters will give you the answers you are looking for.
Best Regards,
[Updated on: Mon, 12 May 2008 08:40]
Elliot
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| Re: Design flaw of a Dual 18" Cabinet?Here we go again [message #322085 is a reply to message #322060 ] |
Mon, 12 May 2008 17:06 |
Al Limberg
Messages: 1199
Registered: April 2004
Location: Saginaw, MI |
Has No Life |
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Hmmm, 6 years, 16 Labs, 2 defective drivers from first batch out of Eminence replaced under warranty. Doesn't feel like 'all the time" to me.
Al
Some people are like a Slinky.....not really good for anything, but you still can't help but smile when you see one tumble down the stairs.
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| Re: Design flaw of a Dual 18" Cabinet?Here we go again [message #322110 is a reply to message #322085 ] |
Mon, 12 May 2008 18:28 |
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Andy Peters
Messages: 5800
Registered: April 2004
Location: Tucson, AZ |
Has No Life
Contrarian |
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| Al Limberg wrote on Mon, 12 May 2008 15:06 |
Hmmm, 6 years, 16 Labs, 2 defective drivers from first batch out of Eminence replaced under warranty. Doesn't feel like 'all the time" to me.
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Hey, Al,
Don't feed the troll!
-a
"Any sufficiently advanced incompetence is indistinguishable from malice."
"Your band isn't good enough for my PA."
"On the Internet, nobody can hear you mix a band."
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