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My new VOTs


TBrennan

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almost beautiful, certainly literally very nice,

what are the specs on the drivers? any idea of the combined specs, like efficiency? how does the sound compare to the Cornwalls? what crossovers did you use? what is the benefit of the wood horn? who made the cabinets? how much did everything set you back? what comes next?

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Colin's Music System Cornwall 1s & Klipsch subs; lights out & tubes glowing!

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Colin---The cabinets were made by a friend from Altec plans, they are made of 3/4 baltic birch. The woofers are interesting, Altec 515Bs, in the opinion of many the finest woofer ever made. It has a 3" edgewound voicecoil and a 4.4lb Alnico magnet with a flux density of 14,750 gauss, that's compression driver territory. The 515B has an efficiency of 103db, horn loaded I figure it's at least 106-108, somewhere up there. The upper bass and midrange from this driver-cabinet is absolutely the finest I've ever heard; vocals have a presence and sense of reality that's uncanny and startling, that is where the thing really shines. Bass below 100hz is weak, that's a compromise of the cabinet design. The JBL compression driver comes in at 700 (I use a DOD active crossover, 3rd order slopes) and extends on axis up to around 15-16khz. The wooden horn is a pure tractrix, Bruce Edgar claims the tractrix works best as a round horn and that rectangular ones introduce some minor problems. The massive wood construction makes questions of horn damping moot. The compression driver has an efficiency of about 110db, system efficiency is that of the bassbin as the JBLs are padded down by the controls on the DOD. Compared to a Cornwall IMO these things have weaker lower bass, much better midrange (smoother and more palpable) and less zing in the highs though I think the highs sound smoother and more realistic. There is not a hint of horn coloration and of course they have all the dynamics, clarity and lack of strain associated with all good horn systems. This comparison would pretty much hold true for Khorns too. Sometimes instead of the Edgar-JBL top end I use a standard Altec VOT one; 806 drivers on 511B horns, then I crossover at 500hz. I'm not sure which I prefer and there's no consensus among my friends, some prefer the Altec top-end and some the JBL-Edgar. As soon as I get adaptors I'll replace the JBL drivers with new JBL 2427 drivers I recently purchased from the JBL Pro online tent sale. The 2 4846 bassbins I also purchased there will take care of the weakness of the bass below 100hz when they arrive. Total cost, lets see. The cabinets were $350 (I only paid the cost of materials), the 515Bs I picked up in a secondhand store for $200 (a steal, check them on ebay), I bought the JBL drivers for $250 and paid $225 for the saladbowls, bought them used too. And the DOD crossover was about $200. That's $1225 for the whole schmear, not bad. And the 2427s were only $70 each (JBL is practically GIVING stuff away on that tent-sale, these drivers are $300 each at Parts Express) which will lower the cost of the system. The 4846s are $220 each (each contains 2 15" 2226 woofers, 1 of these woofers is $300 at Parts Express), JBL ships them for free! I figure with the 4846s in the rig I'm about done though I'll still mess around, you know how it goes.

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TBrennan,

I was wondering, where do you get the JBL 4846 Cabinets for $220 each from? Any contact info you can give me? What do these cabinets look like? Any info you could give me on them would be greatly appreciated, I'm looking to supplement the bottom end on my Cornwall system, and think this might be a great way to do it.

Thanks alot

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markvi82@hotmail.com

1981 Cornwall I's

Yamaha DSP-A1000 integrated amp

Acoustic Research AR3A's for Pro-Logic rears

(Music only setup)

Marantz CD Player

Yamaha Turntable with Stanton EE Cartridge

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"I was wondering, where do you get the JBL 4846 Cabinets for $220 each from? Any contact info you can give me? What do these cabinets look like? Any info you could give me on them would be greatly appreciated, I'm looking to supplement the bottom end on my Cornwall system, and think this might be a great way to do it." If you have Cornwall IIs they are rated at 101dB and -3dB at 38hz. The JBL4648A-8 is only 100dB and is -3dB at 45hz. http://www.jblpro.com/pub/cinema/4648a.pdf they are only about an inch or so bigger than a Cornwall in each dimension. They are not a subwoofer. Buy them here http://www.jblpro.com/Tent_Sale/sale_items.htm If you re-port the box to 31hz and use 6dB of boost at 31hz the response will be -3dB at 31hz.The efficency at 31hz will be 91dB/W/1M and an 8 ohm load.A bridged Adcom GFA555 will do 650W into this, or +28dB.At the 300W per driver level the JBL2226 has about 3dB of power compression so a bridged Adcom GFA555 + JBL4648A-8 at 31hz will play about 116dB.Without re-porting the 4508 box is tuned to 40hz and is -10dB at 35hz.A 16 cu ft bandpass box could be built for the drivers and would be 98.5dB/W/1M and -3dB at 28hz and 100hz with no eq.

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Quest ce se Le "VOT"? -- (had been away from the hobby/obsession for a while -- which may help explain why I finally own my house!)cwm32.gif

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It is meet to recall that the Great Green Heron rarely flies upside down in the moonlight - (Foo Ling ca. 1304 BCE)

This message has been edited by lynnm on 12-27-2001 at 11:46 PM

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mdeneen---Oh My! VERY nice, gorgeous, I dig it the most The cabinets are so cool, remind of the old cormIs that a PhaseLinear 400? Is the crossover a Rane? Yeah man, Altecs are just so smooth. I too find that the benefits of using a high performence compression driver to cover both mids and highs outweigh the slight loss of extension. I have a set of JBL 076 "catseye" horn tweeters sitting around unused (they're very pretty though) though I occasionally tinker with the idea of bringing them in around 12khz. But highs with Altec or JBL drivers sound so natural and pleasing the idea never goes anywhere. Congratulations on a very nice job.

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