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Old 26th January 2014, 12:00 PM   #1
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Talking wbin 2x15

Hello,

I would like to try and get some HR numbers for the following cabinet

W-Bin 2x15

Basically it looks like i have two of these in my garage (in Austria) and would like to get some specs on them.
They are a little large, so i was thinking of getting them cut down to half size so tht they run as 4x single driver cabinets.
They are currently loaded with DAP AB-15's which are good enough i guess, ive read that they are a good budget driver for this sort of design.

My other question would be, that I am running some RCF L18 p200n tapped horns under them (well maybe 2x per side). I want to know whether it is a good Idea to seal up the port on the front of the w-bins to give the driver more control with a sealed rear cahmber.
I get the Idea that the ports are for low frequency extension, but with the TH's I dont think Im gonna need it, and Id rather get a little more out of the w-bins in the 80-250 region. Any ideas would be great.

Like I say i need the HR data if poss to be able to do this sim myself, but I dont have access to the cabinets at the moment, and well I cant quite get my head around which exact areas to take the s1,s2 values from.

Thanks
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Old 27th January 2014, 07:33 PM   #2
rigtec is offline rigtec  United States
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[QUOTE=sketchyphish;3793488]
Quote:
"...I want to know whether it is a good Idea to seal up the port on the front of the w-bins to give the driver more control with a sealed rear cahmber."W-Bin 2x15
Hi sketchyphish,

I am unable to address your question(s) regarding the particular 15" driver that's being used in the "W-bin" cabs. However, before you seal it up, I'd definitely inquire just how these drivers will perform in a sealed environment. Some drivers are designed to be "interchangeable", so may be used in either a sealed, or a ported alignment. Now I too, have two 18 inch w-bins that were once sealed. I had removed the original "Cerwin Vega" (L-87) 18's, and upgraded to the "18Sound", 18LW1400, which were designed to perform well in a bass reflex, sealed encl., or a short-horn (horn variant). I did some research to find out just how to tune this w-bin's rear chamber "box frequency" (55hz Fb), using two 3" x 5" duct tubes. My point is to make sure that your newly "transplanted" driver will continue to work properly in this new environment.

Quote:
"...I get the Idea that the ports are for low frequency extension, but with the TH's I dont think Im gonna need it, and Id rather get a little more out of the w-bins in the 80-250 region. Any ideas would be great."
Now, making sure that I'm understanding your set-up. Are you using two different subs in the same frequency range, in the same room (tapped horns and w-bins)?? If so, they will likely "couple" destructively, introducing "phase cancellation" and other room mode phenomena. It would be much better (imho), to separate the W-bin and TH by using a line level x-over.

PS: Unless you separate them, you will likely end up with an anemic sounding low-end and squander an audible ton of your amp's power. Sorry if I missed either of your point(s)

rigtec, cheers
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Old 27th January 2014, 08:08 PM   #3
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Just to say that the sytem will be run with an active crossover. I have previously used this combination, with a 24db crossover at about 67-75hz. What im looking to do is take out the uneeded extension of the w-bin by filling in the ports, allowing for less cone movement and hopefully higher efficiency using a sealed rear chamber. But without the horn specs (HR) at the moment i cant work out if i will be cutting too much off the bottom with the ports closed.
Any smaller a port and i feel they will chuff.
Any Ideas on cutting the cabs in half ? , I guess they will work ok (needed for ease of setup and transport).
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Old 27th January 2014, 09:49 PM   #4
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Originally Posted by sketchyphish View Post
I have previously used this combination, with a 24db crossover at about 67-75hz.
Any Ideas on cutting the cabs in half ? , I guess they will work ok (needed for ease of setup and transport).
The cabinet design will work fine cut in half as singles, but then you have to move two cabinet that weigh more than the single.

The chamber is so small that port output is not that great compared to the horn output.
They will make 67 Hz no problem without, and not having the additional phase inversion going on in their lower octave will make integration with the TH simpler.

Last edited by weltersys; 27th January 2014 at 09:51 PM.
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Old 27th January 2014, 10:04 PM   #5
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Right'o Then to the chop shop we go. I need ease of moving and well to be honest the whole system will finally Run

4x TH
4x W-bin (when chopped)
and
4x MT122

So would be nice to be able to take a rig out at half that size as well as the full rig.
Mabe it would be a good idea to re-port the cabinets, so that when they run as a single a side they can still cover the needed lower end that will be missing from not having such a large horn Mouth (removeable plugs lets say).
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Old 27th January 2014, 10:24 PM   #6
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Originally Posted by sketchyphish View Post
Mabe it would be a good idea to re-port the cabinets, so that when they run as a single a side they can still cover the needed lower end that will be missing from not having such a large horn Mouth (removeable plugs lets say).
Makes sense to be able to split for two systems.

I made removable port covers from hard foam and duct tape for a 2x8" guitar/bass rig, could go low tune (one port per side open), medium(two ports open) or sealed. They have tape handles for removal.
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File Type: jpg Variable Tuning.jpg (137.8 KB, 106 views)
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Old 27th January 2014, 10:36 PM   #7
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Excellent replies people.

I think what I was trying to say with closing the port holes was that I would have more control over the driver as it would then be a sealed enclosure, also adding to the puch is perfect as its a kick bin essentially.
To be honest Id think that the output volume of the port compared to a 1000w TH would be nominal, so the efficiency I would loose by not using the rear of the driver is fine. I will just crossover at 67-75hz which ever sounds better.
An well hopefully I can do the surgery with help from a friend, but I wonder what effect the lowered Mouth area will have on the ouput of a single horn/driver, considering the length will be the same ???
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Old 27th January 2014, 10:45 PM   #8
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Quote:
Originally Posted by weltersys View Post
Makes sense to be able to split for two systems.

I made removable port covers from hard foam and duct tape for a 2x8" guitar/bass rig, could go low tune (one port per side open), medium(two ports open) or sealed. They have tape handles for removal.
Hi weltersys'

Are you a bassplayer too!!!???
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Old 27th January 2014, 11:50 PM   #9
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Originally Posted by sketchyphish View Post
An well hopefully I can do the surgery with help from a friend, but I wonder what effect the lowered Mouth area will have on the ouput of a single horn/driver, considering the length will be the same ???
Very little difference.
Most people mistake the +3 dB from doubling radiated surface area and + 3dB from doubling amp power for extended LF response.

Below are the results of measuring one and two FLH, the two have been reduced by 6 dB to make it easy to compare the frequency response.
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Old 27th January 2014, 11:53 PM   #10
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Quote:
Originally Posted by sketchyphish View Post
"electronic x-over...with a 24db crossover at about 67-75hz.
The electronic x-over part works out about right seeing that the w-bin's Fh (horn freq) cut-off is apprx 62.5hz; based on the 4' length of the horn.

Quote:
What im looking to do is take out the uneeded extension of the w-bin by filling in the ports, allowing for less cone movement and hopefully higher efficiency using a sealed rear chamber.
Sealing a low frequency enclosure will not increase the efficiency of the driver but rather hinders it's ability to turn electrical energy into motion/air movement... Remember, you're losing the benefit of the driver's resonant backwave, so all of that "pushing & pulling" behind the driver/baffle is wasted; and so is the power (in watts) it took to produce that work. But there are a few other benefits of a sealed alignment e.g., somewhat more control over the cone, transient (punch) effect more focused, power handling (mech) may be increased, "Boominess" generally more subdued, and a much smoother frequency roll-off below Fb...etc.

Quote:
"...But without the horn specs (HR) at the moment i cant work out if i will be cutting too much off the bottom with the ports closed."
Sure you can, just use the formula/rule. Take the length of the horn, in your case it's 4.5' in length; typical w-bin. You measure the horn from center triangle (or center speaker cone), in the throat, straight up along the back wall of the horn, all the way to the outer mouth edge. That's your horn length. Okay, fyi... Sound travels at the rate of 1125 feet/sec (give or take).

Divide 1125 by 4.5 feet (horn length) and it gives you your actual wavelength "in hertz", which is 250(hz). But we're not interested in finding out how many times a soundwave cycles when it travels a distance of 4.5'. We're only interested in how many times that wave will cycle when it travels one quarter of it's own length (18'), which is "62.5"cps (1125/4.5 = 250/4 = 62.5). So your w-bin has a average horn frequency of 62.5 hz; that's the frequency where the horn is most efficient; after that it'll begin to"fall-off" at a slope rate of 24db/oct.

PS: as far as bifurcating the horn, I've seen it done very successfully but I'm no carpenter and would need to seek the assistance of a trained professional! Happy building,

rigtec (Greg) regards!
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