Converting 3 Pi to 4 Pi [message #53487] |
Sat, 02 May 2009 06:02 ![Go to next message Go to next message](/forum/theme/AudioRoundTable/images/down.png) |
Champion
Messages: 40 Registered: May 2009
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Baron |
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Hi Wayne, I have asked about using the JBL2226 on the 3Pi awhile ago, and you mentioned that the box size is suitable but the trouble is to rework the cabinet to fit the driver and the port. I wonder if I can cut a big hole (basically remove almost the whole front panel) and replace it with a new one that can fit the 2226 and a new port? Would that work? I built the 3 pi with the horn placed outside the box so have plenty of space of the mid/woofer. BTW, have you try out the AE 12" driver?
Thanks.
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Re: Converting 3 Pi to 4 Pi [message #53488 is a reply to message #53487] |
Sat, 02 May 2009 11:40 ![Go to previous message Go to previous message](/forum/theme/AudioRoundTable/images/up.png) ![Go to next message Go to next message](/forum/theme/AudioRoundTable/images/down.png) |
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Wayne Parham
Messages: 18756 Registered: January 2001
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Illuminati (33rd Degree) |
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Replacing the front baffle would probably be the best way to do it, actually. Use a port with the same area (6.25" x 3.5") as the four π, but make it a 1.5" shorter to tune the Helmholtz frequency to 38Hz (8.5" long). The JBL 2226 will sound very nice in this cabinet, virtually identical with the stock four π design.Note - If you mount the tweeter outboard, move the woofer all the way up to the top of the box. The woofer and tweeter should be as close together vertically as possible. Are you using a wood horn? About the TD12S, I ordered a pair a week or two ago, so I expect them to arrive any day now. I'll evaluate it in the three π cabinet and make any crossover changes necessary to optimize. if it works out, I'll add it as an upgrade option for that model and for the six π cornerhorn. I am hopeful the TD12S works out, giving the three π and six π models an upgrade path similar to the JBL 2226 in the four π and seven π models.
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Re: Converting 3 Pi to 4 Pi [message #53489 is a reply to message #53488] |
Sun, 03 May 2009 09:04 ![Go to previous message Go to previous message](/forum/theme/AudioRoundTable/images/up.png) ![Go to next message Go to next message](/forum/theme/AudioRoundTable/images/down.png) |
Champion
Messages: 40 Registered: May 2009
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Baron |
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Thanks Wayne, that sounds good, at least it is possible to use the 2226. No I have not upgrade to the wood horn. At $700 each it is a bit out of my reach at this stage, and the mid woofer upgrade is probably my next step when I can afford, then the wood horn.Thanks again for your help.
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Re: Converting 3 Pi to 4 Pi [message #53494 is a reply to message #53490] |
Mon, 04 May 2009 11:55 ![Go to previous message Go to previous message](/forum/theme/AudioRoundTable/images/up.png) ![Go to next message Go to next message](/forum/theme/AudioRoundTable/images/down.png) |
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Wayne Parham
Messages: 18756 Registered: January 2001
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Illuminati (33rd Degree) |
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Injection molding is an expensive process, feasable only for fairly large production runs. I'd really need to expect about 1000 units to be sold to make it worthwhile, so I'd have inventory for a few years. That's something I would consider, but I'm not at all displeased with the H290.The H290 is a pretty good part. I'm not sure how much attention was paid during its design, if it was on purpose or accident, but whatever the case it does a surprisingly good job in terms of directionality and smoothness of response. It's perfect for this application. From what I've seen, it's better than most of the so called waveguides out there. The wood horn is only slightly better acoustically, mostly in the vertical. Its larger size helps a great deal reducing mouth reflection when used as a stand-alone horn, not mounted on a baffle. That's its intended use, so it was important to make sure it worked well when sitting on top of a cabinet instead of mounted flush on a baffle. It was designed to be a beautiful piece of art that also worked well acoustically. We make it from wood with interesting grains and cut graceful lines on a CNC machine. It really is a work of art as much as anything else. You lose the aesthetic appeal when doing an injection mold. I suppose it could work if the whole cabinet was painted. A highly polished paint job, something like a piano finish, perhaps. That could be a good look. But the whole point is that for baffle mounting - where I see an injection molded horn being used - the baffle helps horn loading and it doesn't need the larger mouth for this frequency range. The H290 is a fine horn for baffle mounting.
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