They seem like an elegant solution to one of the fundamental problems of multi-way speakers, the fact that the sound is cut up and emanates from different physical points in space.
Now, I know that putting a tweeter inside a cone woofer will result in some FR issues, but that seems a fair trade off for a true point source. Plus, if the driver is done right, then the motors of the 2 drivers align and phase/time issues become much simpler.
Or, am I missing something important here? And before someone comes in and says that the problem is the difference in beaming between a 12 inch (or 15inch) woofer and a 1 inch tweeter, lets restrict the discussion to 8 or 6 inch midranges.
Now, I know that putting a tweeter inside a cone woofer will result in some FR issues, but that seems a fair trade off for a true point source. Plus, if the driver is done right, then the motors of the 2 drivers align and phase/time issues become much simpler.
Or, am I missing something important here? And before someone comes in and says that the problem is the difference in beaming between a 12 inch (or 15inch) woofer and a 1 inch tweeter, lets restrict the discussion to 8 or 6 inch midranges.
Hard to do a crossover for, expensive, and you're typically limited to the mid/tweeter combo that they chose for you.
Other than that 😉 I'm hoping to snag some classic Utah coaxials from some Soundcraftsmen speakers, we'll see if they pass muster upon inspection.
Other than that 😉 I'm hoping to snag some classic Utah coaxials from some Soundcraftsmen speakers, we'll see if they pass muster upon inspection.
Take a look at the Tannoys. I use a home made Urei 811C clone for my center channel in my HT set-up. It's a perfect fit as far as bandwidth and a close match to my mains. It rocks on dialog and 3 would make one fine set of front channels.
Rob🙂
Rob🙂
The SEAS Loki is a nice coax design, but good coaxials tend to cost more than separate drivers of similar (or even better) performance.
Yeah, cost is an issue.
I asked the Selenium rep why they stopped making coax drivers. He said everyone at the factory loved the coax drivers, but no one bought them. So they had to drop them.
Seems that a lot of builders want to see 2 drivers if they are paying for two. 😉
FWIW, I don't think they work well under 10". At least the ones I've heard don't. The P.Audio 18" coax is quite a beast! Talk about dynamic.
I asked the Selenium rep why they stopped making coax drivers. He said everyone at the factory loved the coax drivers, but no one bought them. So they had to drop them.
Seems that a lot of builders want to see 2 drivers if they are paying for two. 😉
FWIW, I don't think they work well under 10". At least the ones I've heard don't. The P.Audio 18" coax is quite a beast! Talk about dynamic.
How about car audio market? There are a lot of coax drivers there. I am curious if anything there could be modded for home stereo by engineering crossover for example.
Yeah I know what you mean. I have had a couple of Altecs a 12" 601 A 15" 604C a Jenson 15" 501?? and a Urei/Jbl 801C. Liked all of them and the 15's worked just fine. I still have the 601 and 801 both need subwoofers below 80hz or so.
Rob🙂
The biggest issue is that mounting the tweeter mid woofer usually degrades its response more than any benefit that comes from concentric mounting. Most of the 50's generation have highly directional horns with poor response. Tweeters mounted on a post will have reflection issues from the woofer behind (unless a directional waveguide is used). The KEF Uni-Q suffered from edge reflections from the woofer surround.
Still, coaxs are great for custom in-wall. I designed a model at PSB that used a waveguide on the tweeter. A little extra directivity meant virtually no reflection from the woofer behind, smooth response and a nice ability to aim the treble as desired.
PSB Speakers - CW180R In-Wall Speaker
Another model that worked was a BBC design that had a tweeter mounted on a perforated plate in front of the woofer. The plate was transparent enough for the bass to get through and solid enough to effectively baffle the tweeter.
David
Still, coaxs are great for custom in-wall. I designed a model at PSB that used a waveguide on the tweeter. A little extra directivity meant virtually no reflection from the woofer behind, smooth response and a nice ability to aim the treble as desired.
PSB Speakers - CW180R In-Wall Speaker
Another model that worked was a BBC design that had a tweeter mounted on a perforated plate in front of the woofer. The plate was transparent enough for the bass to get through and solid enough to effectively baffle the tweeter.
David
The Thiels do well; note that they are not a 1" tweeter buried deep in the depths of a 10" woofer though. http://www.thielaudio.com/THIEL_Site05/PDF_files/PDF_tech_papers/CS3_7premtech.pdf
I have a pair of old KEF uniQ's as backups to my DIYs. They definitely have their issues, but some things they do very well (imaging). These are an early generation model, and I have a feeling they've figured some things out in the past 15 years.
The format has great potential, but, unfortunately, is the age of ipods and earpods, I doubt they get the investment in R&D that they deserve. Harmon could do it ... R&D and marketing budget aimed at home theater - the coaxial's natural ally.
The format has great potential, but, unfortunately, is the age of ipods and earpods, I doubt they get the investment in R&D that they deserve. Harmon could do it ... R&D and marketing budget aimed at home theater - the coaxial's natural ally.
Those PSB speakers look interesting - why not use something like that in a regular speaker enclosure?
Tannoy had most of the problems sorted out by about 1950.
With the deeper AlNicos the treble vc was exactly 1/4 wavelength behind the bass coil which, taking into account the phase shift introduced by the xover, results in a phase coherent output (but not time coherent) and 90deg treble horn takes over where the woofer cone dispersion narrows to 90deg. It also works pretty much like a constant directivity horn despite having been released to the public in 1947.
The crossover provides a 6dB/oct 'boost' from about 5-6kHz and a notch to remove the traditional 'horn honk'.
ME Geithain do something like the old BBC monitors and mount treble on a plate in front of the woofer.
ME-Geithain | deutsch
From what I hear they are supposed to be very good. Somehow they provide a cardioid bass response. Not cheap though…
With the deeper AlNicos the treble vc was exactly 1/4 wavelength behind the bass coil which, taking into account the phase shift introduced by the xover, results in a phase coherent output (but not time coherent) and 90deg treble horn takes over where the woofer cone dispersion narrows to 90deg. It also works pretty much like a constant directivity horn despite having been released to the public in 1947.
The crossover provides a 6dB/oct 'boost' from about 5-6kHz and a notch to remove the traditional 'horn honk'.
ME Geithain do something like the old BBC monitors and mount treble on a plate in front of the woofer.
ME-Geithain | deutsch
From what I hear they are supposed to be very good. Somehow they provide a cardioid bass response. Not cheap though…
Coaxs were more popular in the 50s when you could buy a finished unit and build your own cabinet. Similarly, a lot of the impetus for the KEF Uni-Q was to have a totally assembled unit to send to Richmond VA for assembly into local cabinets. (Didn't last long.)
The market seems to be happy with vertically stacked units. In the lateral plane the performance is the same, a coax is only better if you want to move off axis vertically as well as laterally. Still, a well designed coax has some plusses and the PSB unit mounted in a proper cabinet would be a very good system. The waveguide is near CD.
David
That is not the full truth IMO. Keep in mind that off-axis response adds to the way a speaker sounds - even when you don't want to stand up while listening.
Regards
Charles
I currently own 4 vintage 12" Dukane coaxial speakersprobably mid to late 60's vintage. They originally came out of a pair of large flat black cabinets (which I still have) with the 70v transformer still inside the cabinet. They were originally used at the Kentucky (louisville) fairgrounds as part of their sound system. Previous owner tried to use them for his rockband after seperating them from their transformers: didn't like the sound and passed them on to me.
Three of the drivers literally had no foam surround left, one of the drivers which sported a cloth accordian surround, survived and was useable in it's current state.
They all have the same physical dimensions, have a patented 'phase plate' surrounding a 4" cone tweeter with a capaitor filter. One tweet water damaged but still plays. The other tweets seem to be ok. The odd driver w/ accordian surround has a very similar phase plate, but different color, more detailed in shape and states 'patent pending'. I replaced the surrounds on the other 3 with a generic surrond kit which fit nearly perfectly. I've done some hunting on the net- there is very little to go on.
I've put them a couple of them in smaller cabs, both with and without ports- not the deep bass one would think, nor the crisp highs, but not all together unpleasant sounding either. They do seem quite efficient, however. Maybe larger cabs?
The cabs are pretty big: 35"x24"x19" (HxWxD), and were sealed. ~4" of insulation (glass type) on all walls, black, and UGLY.
As only three of them matched, I had visions of placing the best of the three in a couple of retro looking cabs, but expirementing with a couple of 15x15x22 (largest unused box I had available) cabs has not been all that promising so I've backed off on that one for a while.
Anyone have any ideas (other them putting back into garage- only cabs) for a simple design that might help me fall back in love with my coaxials sound? If I could hear what they were truly capable of I know I'd be more inspired to find a better home for them.
If not a design, maybe some info, or a collector who could fill me in a little as to their value or whether they are truly worthy of anything other then the oversized, not so wife friendly cabs they came out of.
Three of the drivers literally had no foam surround left, one of the drivers which sported a cloth accordian surround, survived and was useable in it's current state.
They all have the same physical dimensions, have a patented 'phase plate' surrounding a 4" cone tweeter with a capaitor filter. One tweet water damaged but still plays. The other tweets seem to be ok. The odd driver w/ accordian surround has a very similar phase plate, but different color, more detailed in shape and states 'patent pending'. I replaced the surrounds on the other 3 with a generic surrond kit which fit nearly perfectly. I've done some hunting on the net- there is very little to go on.
I've put them a couple of them in smaller cabs, both with and without ports- not the deep bass one would think, nor the crisp highs, but not all together unpleasant sounding either. They do seem quite efficient, however. Maybe larger cabs?
The cabs are pretty big: 35"x24"x19" (HxWxD), and were sealed. ~4" of insulation (glass type) on all walls, black, and UGLY.
As only three of them matched, I had visions of placing the best of the three in a couple of retro looking cabs, but expirementing with a couple of 15x15x22 (largest unused box I had available) cabs has not been all that promising so I've backed off on that one for a while.
Anyone have any ideas (other them putting back into garage- only cabs) for a simple design that might help me fall back in love with my coaxials sound? If I could hear what they were truly capable of I know I'd be more inspired to find a better home for them.
If not a design, maybe some info, or a collector who could fill me in a little as to their value or whether they are truly worthy of anything other then the oversized, not so wife friendly cabs they came out of.
Not sure what you mean by this. They are in phase but still out of time? Wouldn't they then be 360 degrees or more out of phase?
I do not know about them not being that popular Tannoy, Mark Seaton, JTR are just a few popular companies using Coaxial designs. Mark Seaton's designs are truely high quality designs.
They are exactly 360deg out of phase. At some point Tannoy bowed to market pressures and introduced an all pass filter (SyncSource in Tannoy speak) to make them time coherent as well but the cure was worse than the problem according to Tannoys own engineers.
The measurements published by Tannoy show the DCs to produce no more than 12deg phase shift across the spectrum, except where the porting takes over in the low bass.
From where the 12deg are I suspect that this is partially due to the notch filter.
The measurements published by Tannoy show the DCs to produce no more than 12deg phase shift across the spectrum, except where the porting takes over in the low bass.
From where the 12deg are I suspect that this is partially due to the notch filter.
I browsed some magazines the other day and found some good looking pictures of the KEF new Uni-Q. Ah, maybe it's not new, it's just I haven't paid any attention to the mainstream market....
KEF International
By the picture, the short waveguide of the tweeter seems smoothen the contour from dome to cone - probably a good move. And KEF mentions another technology of sealed suspension - around the inner edge of cone - to elimiate the noise of pumping etc. However I don't really get it, though. With that tiny gap (between WG and cone), and the enclosed little space under it, I guess some pumping is still unavoidable 🙁
Anyone gave it a listen?
KEF International
By the picture, the short waveguide of the tweeter seems smoothen the contour from dome to cone - probably a good move. And KEF mentions another technology of sealed suspension - around the inner edge of cone - to elimiate the noise of pumping etc. However I don't really get it, though. With that tiny gap (between WG and cone), and the enclosed little space under it, I guess some pumping is still unavoidable 🙁
Anyone gave it a listen?
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