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I've been kind of rolling this around in the back of my mind for a while now...
I know the Cona was/is a well loved piece of kit that's long discontinued. I'm wondering if it's possible to clone one?
I have found a fair number (about 6 or 7) DVC 8 inch woofers available from standard speaker sellers (PartsExprese, Madisound, etc.). And back in the day I designed a line of Sonotube cylindrical subwoofers for a startup audio company (that sadly never made it out of startup) that, while not as good looking as a Cona weren't far off.
So, what I need to see how feasible this is are specs and details of the Cona. I have almost bought one to take it apart, but thought I'd ask here. What I need to know are:
Details of the crossover, preferably values and topology (2nd order, 1st order, component values and/or freq of xover)
Thiele/Small parameters on the woofer, along with volume and tuning on the cabinet
I can sort of back some of this out from the specs, efficiency and F3 and such, but it'd be better if I had a driver to measure or the actual specs.
So, can anyone help with this info? If I can get enough info to actually clone one, seems it would make a nice writeup/project for the forum.
Thanks.
Jeff
I'm afraid I'm recovering from the BeoVirus.
Certainly you can build something similar, but to really clone it you will need a dual voice coil driver. I haven't really looked, but I suspect the available choices are quite limited.
--mika
Hi,
hey do turn up on ebay regularly. Maybe It's easier to just buy one ?
I do have one that I will sell soon, the plastic case was broken when the movers dropped it.Everything inside still works well..... just needs to have a new case made.
As I said, I've already found at least 7 DVC 8 inch drivers without much of a look. One or two seem prime candidates just eyeballing the TS parameters. Of course I'd have to run some simulations to predict performance more accurately. Even if not a complete match, I expect I could get close at a slightly different volume or box tuning. The main issue IMO is matching the efficiency, a few HZ up or down from low end cutoff won't matter as much as an efficiency mismatch with the sats (usually Beovox 50/100).
Wish I'd picked up one earlier, I can take TS measurements pretty easily with my Woofer Tester.
Jeff:As I said, I've already found at least 7 DVC 8 inch drivers without much of a look.
Oh yes, sorry, I thought of that abbreviation as a brand name
In my humble view using a subwoofer is succumbing to non-natural sound anyway, so I wouldn't worry too much of the parameters. Seeing the Cona crossover would of course be helpful - I don't think there are any schematics around? Coming to think of it, I don't think I've ever even seen one open!
I've never seen one open either, and have seen darned few in the flesh. I'm pretty sure equivalent crossover parts can be found easily if I only knew what they were. Lots of sources for stock coils and also places that will custom wind them for not too much money more than stock. Usually take a stock and pull off enough windings to trim them.
I still think the most important thing is to match efficiency with the original, but I think that can be done. It'd be a fun project I think. Of course, knowing the volume and such you could also modify the form factor. For example, I have a pair of CX50s up in my kitchen, on a shelf that runs around the vault ceiling, it's kind of a step back from the wall rather than a free standing shelf. It'd be easy to hide, say, a Cona Clone made in a longer, shallow box up there out of sight and would improve the sound. You could also probably make one thin enough to sit behind a couch or under a stereo cabinet. Say under the space below the cabinet and the floor.
I will have to keep my eyes open for another opportunity to get one unless I can get the parameters elsewhere. I kick myself for missing the two that were on sale here recently. Ah well, I've got other irons in the fire so it'd be a couple of months before I can focus exclusively on this, like fixing the issue with my remote mains switches.
I built a couple subwoofers back in the late 80s using Madisound's 8 ohm, 12" DVC driver. One was for a buddy who had a pair of very small Infinity bookshelfs (bookshelves?).
The Madisound at the time was meant for a sealed cabinet on the small side (box wasn't much different than about a 14" cube). We rolled that one off with an 18 dB/octave high pass filter with no low pass on the Infinitys (Infinities?).
The second was for my uncle's Bose 901's - Series II I think. We never did get a good blend with passive filters. He ended up just buying different speakers altogether before we tried an active approach.
Did I have a point? Oh, yes. Madisound driver was a great value and not finicky about its box.
inside cona
Interesting, looks like a 2nd order lowpass and a first order high pass, if I am reading it right (can't recall which are the in and out connectors on the bottom. Interesting ports too, typical of the wall mount Beovoxes as well. Any idea what the values of the caps are?
I also remember that Madisound driver, they also had a little 8 inch one that worked really well in a 1 cu ft cabinet. Good drivers at a decent price. I used quite a few Audio Concepts DV12 drivers back in the day too, incredible things, very very long Xmax and longer non-linear throw, could get incredible bass extension out of them.
cooldude: Hi, hey do turn up on ebay regularly. Maybe It's easier to just buy one ? I do have one that I will sell soon, the plastic case was broken when the movers dropped it.Everything inside still works well..... just needs to have a new case made.
Interesting, I'll be interested in what you ask for it when you sell it. I might be interested, sounds like the perfect already sacrificed donor unit. I wouldn't need the cabinet, just the bottom where the driver attaches with the ports and such.
Jeff: Interesting, I'll be interested in what you ask for it when you sell it. I might be interested, sounds like the perfect already sacrificed donor unit. I wouldn't need the cabinet, just the bottom where the driver attaches with the ports and such.
make me an offer.
cooldude: Jeff: Interesting, I'll be interested in what you ask for it when you sell it. I might be interested, sounds like the perfect already sacrificed donor unit. I wouldn't need the cabinet, just the bottom where the driver attaches with the ports and such. make me an offer.
Well, it's worth about 20-30 bucks to me, US. Probably low but that's what I'd spend on such a thing.
As for cloning, I've found the following two drivers that seem to be good candidates:
http://www.mcmelectronics.com/product/MCM-AUDIO-SELECT-55-1455-/55-1455
and
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=296-414
with this one as a not as good but probably useable:
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=295-132
Crossover is at 195 hz for the Cona according to documentation, and the CX's were 6 ohm loads, and the Cona an 8 ohm unit. I can calculate a good enough approximation to the crossover from this, from the pic it's 2nd order low pass, 1st order high pass. For the high pass I'd go with a large electrolytic bypassed with a smaller film cap, I think that'd sound better than just one large lytic.
I hope to get time to run some sims this weekend on these drivers, see if I can get close to the volume and such. From the specs the Cona goes down to around 40 hz, but it's +4/-8 dB, so it's likely a higher than 40 hz F3.
Oddly enough, in looking at the service manuals online here, the CX's used series crossovers, not that usual, most speakers are parallel crossovers.
Beo4 'til I die!
Why not buy a proper one off of leslie?
http://archivedforum2.beoworld.org/forums/t/1116.aspx
Free advertisement, thanks Ronnie, you're my pal Must have the same set in white somewhere
Brengen & Ophalen
ronnie1995:Why not buy a proper one
No problem Leslie
True evan, but get it while you can as they are getting rare now.
Two good reasons, they are getting rare and it's fun.
I thought it'd be an interesting project to see how close you could get, and if it works well it would provide an option for those who want one but can't find one. After all there were a lot more CXs sold than Conas. Plus being DIY its possible to tailor the cabinet to something other than a cylinder. Say you want to put it in a corner, use a triangular cabinet, or such.
Thanks for the info on the caps, that helps a lot! I'm swamped with work and family issues for a few weeks, but hope to get time to run some driver/cabinet simulations on the PC. Depending on how those turn out will tell if this is worth going forward with.
No matter what cabinet used one aspect needs to be the same and that's the down firing woofer, that helps increase the effective slope of the low pass crossover and cut out any higher freq sounds from making the woofer too easy to locate.
ronnie1995:True evan, but get it while you can as they are getting rare now.