AndrewJ - I have no experience with HP coaxs and to what extent it limits the cone motion. It does appear to me to be a tradeoff of complexity of HPing as high as 250 Hz -- that's pretty high for subs and using a 150-200 Hz 1st order HP which would easily blend in with the subs. If the excursion were "sufficiently" control with the lower HP then that would be my preference. If there was still "notable" excursion then, of course, you would have to go steeper and or higher to alleviate this. Seems to me that if the excursion were a serious problem then these drivers would not be very well rated without some excursion limiting, but that does not seem to be the case.
I think if you follow what AndrewJ and I are discussing you will get the answer to your question. There are trade-offs both ways.
I think it depends on the the specific concentric.
If we're talking about a 5" or 6" coax like the KEF Blade mid or the TAD R1 mid, I'd personally cross it high enough that the baffle step loss can be woven right into the high pass, rather than putting more power into the driver in a power hungry region.
Now, if we're talking about the 8" KEF Q900 coax, you have more leeway.
Sure.
Also I just realized that AndrewJ is Andrew Jones.
So two big big experts, that too especially in waveguides and coaxs, talking on this subject would mean stop typing anymore and just follow what get written further
I think that context was what was missing from your earlier post because it had raised my eyebrow too. Yes, that particular mid-bass driver might be a good candidate to HP 1st order around there. In a selaed box, that probably gives you a 3rd order rolloff below ~80hz where it'd probably be ~8-10 db down.
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Which is a lot of excursion reduction. Remember that the excursion problem is linear, but SPL reduction is log. A small reduction of SPL can be a big reduction of excursion. The reverse is also true, which is the Achilles' heal of LF EQ.
The data you reference is actually from my site, which was linked earlier in this thread. I didn't perform this with the other Kef drivers I tested, though. I do agree it shows the potential for serious issues when the woofer/mid isn't high-passed.
Agreed. I have the R-series midrange (my test data here) in my DIY build and have them high passed around 450hz. I did this because this is approximately where baffle step is, in conjunction with the spacing of the woofer below it being larger than 1/2 wave. These are the main L/R in my HT, and I'm using a Kef R200c for center.
I also use them in my car (yea, yea, I know, car audio is stupid) and high pass them around 350hz. I do my best to limit the cone motion while obtaining some semblance of a good match at the crossover. This is a picture of my finished towers using a 10" Scanspeak woofer:
I'll throw this out there: if you (not anyone else) are interested in testing the r-series driver linked above, I'll send you one of my spares to play around with. If you're interested, PM me and we can work out the details.
- Erin
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heck, if it really would be useful, I could pluck the driver from the Q100's I have as well (used as surrounds in my HT). The data you see on the Q100 is actually from one of those speakers.
Also, FWIW, I did testing on the raw LS50 drive unit as well:
http://medleysmusings.com/kef-ls50-drive-unit/
Also, FWIW, I did testing on the raw LS50 drive unit as well:
http://medleysmusings.com/kef-ls50-drive-unit/
COAX-18
Measured pretty well. Having heard it, it would be money well spent with woofers to deal with the bottom end aka tad reference clone. The only thing that it doesn't do as well as big woofer + waveguide is the dynamics. It's not quite as 'big' sounding.
You guys may have seen this but if not:
http://www.madisoundspeakerstore.com/pdf/KingRO4Y Kit.pdf
It's linked on the c18 product page. Very interesting.
http://www.madisoundspeakerstore.com/pdf/KingRO4Y Kit.pdf
It's linked on the c18 product page. Very interesting.
That driver in general does look nice. Price seems fair for two Seas Excel drivers, and the design reminds me of the shallow Pioneer/TAD stuff (and it probably has the same inherent on-axis suckout)
For once, we've got a good concentric that isn't proprietary. I just wish it was an 8-inch, so I could get the pattern control a bit lower for my purposes.
The mouth termination (tweeter-to-WG/cone) doesn't look as clean as KEF/TAD-Pioneer/Tannoy. Doesn't look like any improvement from previous Seas drivers. Though a very good speaker can be made from the Seas parts (see, eg Gradient Revolution).
Also, I found out yesterday that Pioneer raised their spares prices a bit* but the magnesium-ceramic concentric is still close in price to the Seas driver at 515 plus shipping and apparently sales tax. Now, I don't know if Pioneer requires a serial number to sell them now, but if not that's the way to go for an expensive small concentric IMO.
*installer's sub took the scrims I had peeled off the grilles for the S-IW891 in walls I'm using for side-surround,and coated them with paint when they painted the grills; cost them $120 to get me new grills so I could get new scrims! Kind of outlandish pricing for a strip of cloth, but fortunately not my mistake.
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Yeah, except for the measurements/sound and looks, they really suck.
Even the old ones are quite good. For example, here are measurements of the next step up from the Q15 Earl measured, the RDM Two. IIRC both the Q15 and RDM Two come from the tail end of the Andrew Jones era at KEF.
Given that the concentrics themselves are maybe 88-89 dB/2.83V/1m sensitive, no real point to using them with higher efficiency woofers. Also, I'm not sure why they had to be thin (the S-3EX/S-4EX/S-8EX have fairly deep cabs) but it's worth noting that at least once (S-IW891L Mr. Jones paired that concentric with a sweet-looking 8" large-coil neo-magnet TAD woofer:
It's a little shallower than the biggest ScanSpeak Illuminator (admittedly, a smaller-diameter driver) but not by a lot.
As for a good concentric, the Omnes Audio CX 3.0 frankly looks like the nicest part available to hobbyists. And it's pretty cheap, too. Now, it's smaller and obviously has wider coverage than the others mentioned in this thread, but it's a well-refined little design. From outward appearances it looks like some of the Sonance in wall/in ceiling speakers use a variant of this driver.
Yeah, except for the measurements/sound and looks, they really suck.
That was my take on it as well. Without data you can say anything that you want. Once there is data then you just look foolish making dumb statements. Data doesn't level the plating field, it takes it away.
A quality driver with a well-equalized active crossover, though i am not sure anyone has documented any success yet with it passively. It was popularized when early versions of the well-received upscale Seaton Catalyst used it with a pair of 12-inch woofers.
Although I'm sure they're excellent, the Tannoy stuff just miss my interest radar. I want to do something with more "readily available" drivers rather than a one-off with replacement parts (likewise, CST or KEF or Genelec, even though it's all creme de la creme). Right now there is a specific unit i have had my eye on, but it would be an almost blind purchase.
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