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L CAO in OB W/ Eminence Woofer
L CAO in OB W/ Eminence Woofer
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Old 24th July 2012, 09:08 PM   #131
soundaatma is offline soundaatma  United States
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Hello Nuuk,
Nice build with 2 GR drivers in a compact dipole. Did you use a simulation program for this kind of a woofer configuration. Martin's MathCAD sheets can do only H and U frames. What are benefits and tradeoffs of your folding scheme. Did you try a W-frame...though I have no idea how to simulate that either.

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Old 24th July 2012, 10:17 PM   #132
Nuuk is offline Nuuk  United Kingdom
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Originally Posted by soundaatma View Post
Hello Nuuk,
Nice build with 2 GR drivers in a compact dipole. Did you use a simulation program for this kind of a woofer configuration. Martin's MathCAD sheets can do only H and U frames. What are benefits and tradeoffs of your folding scheme. Did you try a W-frame...though I have no idea how to simulate that either.

I made those speakers some years ago, and shamefully pulled them to pieces when I ran out of room in my hi-fi over-run home. It was before I was aware of Martin's MathCad so I just built the woofer enclosure to be as compact as I could so that it fitted in between the 'legs' (side panels) of the main baffle.

I haven't tried a W-baffle. I only use the woofers up to around 90 hz and I wonder if one design will have that much audible difference to another. Not saying that it won't but these days I don't have the energy or money to try them all. Currently I am very satisfied with 15 inch Hawthorne Augies on a flat baffle under my Goodmans 201's. Anyway, I don't want to take Gary's thread on the L Cao's too far off track.
The truth need not be veiled, for it veils itself from the eyes of the ignorant.
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Old 24th July 2012, 11:47 PM   #133
Garytr is offline Garytr  Canada
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Nuuk nice cabinets.

Awkwardbydesign this is a subjective question, but will try to respond with some objective reasoning:
The Alnico has a different spider, phenolic, than the ceramic and claims better transient response and better FR at both extremes due to the Alnico magnet and resulting parameters. Nelson Pass already noted the ceramic had quite a bit of treble output, and his response graph looks decent, a liitle shy above 18khz.

My previous speakers were a mini line array of 4 Fostex FF85K's per channel (=94db efficiency, same as L.Cao)which had a peak of 6db at 19k and response to 32khz I don't notice anything missing on the L.Cao, but have no balance control on my pre to A/B the two.

Just my two coppers.
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Old 25th July 2012, 08:03 PM   #134
Nelson Pass is offline Nelson Pass  United States
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L CAO in OB W/ Eminence Woofer
Recently I got around to trying the L Cao with the Alnico magnets. I was
surprised to find that the response curve was quite a bit different, and the
drivers were accompanied by an LRC designed to notch the midrange
response. Listening to them without the network gave a rather dull
presentation, and with the network I still found the top end pretty soft.

It's a mystery as to why they should be so different, but at this point if you
are considering them you might want to think about a tweeter above 5 KHz.

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Old 26th July 2012, 08:53 AM   #135
awkwardbydesign is offline awkwardbydesign  England
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Garytr and Nelson; thanks for the replies.
At the moment I use Jordan JX125s for midrange, 150Hz up to about 4kHz, active xover to the bass, but temporarily passive to the Jordan JX6RHD treble. My active xover is 4 way, if I wish, so the idea is to set the MF/HF xover point to suit whichever drivers I settle on.
The Jordan 125s have a big resonant peak at about 6kHz, so I want to move away from them, and saw the original thread about the L.Cao 8" drivers.
I could use the JX6s down to 150Hz, or even lower, but power handling would be compromised. In fact, I did that with two JX6s per side, but then bought the 125s hoping for more power without compromising the sound. Unfortunately they don't sound as good as I had hoped.
I would like to stay with wide range drivers, as that moves xover points away from the midrange region, but the 125's peak makes that difficult. If the L.Cao 8" drivers are transparent enough from 150Hz to say, 6kHz, then they might suit.
I still have a pair of Shackman electrostatic panels from the 70s, so I could try them for HF, and if the MF drivers are used in OB, that might suit the Shackmans. Or stick with the Jordan JX6s, as I already have them. If that doesn't work, then a leaf or ribbon, whatever seems to match without great expense.
I have 4 KEF B139 (racetrack style) drivers to play with for isobaric bass, and a Parasound HCA-1205A 5 channel power amp, so I can use 4 channels, one for each driver. The rest is valve.
Unfortunately, I have to sell before I buy new stuff, so it's hard to just try things!
Recently I have been acoustically tailoring my living room, as it was echoey and boomy; much better now, so I'm ready to start playing with speakers again.
BTW Gary, looking at your pics reminded me, I used to run Jordan JX92s above my bass cabs, with a square metal cage fixed to the bass cabs to support a "sock" of grill fabric. The Jordan's cabs were sat on top of the bass cabs with spikes between. When I tried hanging the MF cabs with cotton shoelaces (I don't know if it has to be cotton!) from the grill frame, so they could swing back and forth, the way the bass cleaned up was astonishing. I hadn't expected the bass to improve. I thought it would be the midrange! My MF cabs had enough mass, I think, to make them stable. The new speakers will definitely start out that way, and I will then spike them to the bass cabs for comparison. At the moment my current speakers rest on Max Townshend style inner tube stands, as that seems to minimise interaction with the room. That didn't work so well with the electronics, though, maybe I didn't do it well enough.

Last edited by awkwardbydesign; 26th July 2012 at 09:18 AM.
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