Well, I'm certainly not up to THAT task! I was more thinking that one of the major OEMs might give this a try. Many OEMs already have sandwich cones of various types which do tend to be better behaved in terms of damping, etc. All else being equal; a sandwich cone makes a lot of sense. I have doped paper cones before to treat ringing and such but that is an easy thing to do and not a big risk with an in-expensive driver. Doping DOES help; it dampens unwanted peaks but doesn't add significant mass so it is a worthwhile endeavor.
Fair enough 
I'd be worried about destroying the driver too.
I did a little reading here and it sounds like the small capacitor in parallel with the inductor results in the creation of a "Parallel Resonant Band-Stop Filter" which seems to result in a steeper roll-off. Since the capacitor is so small a value, at a 6 ohm load it has a -3db point of 80kHz, making the trough of the band-stop/notch above the range of hearing, so we effectively see extra attenuation in the high end for the woofer. Not sure if there are any downsides to sending 80kHz+ frequencies through to the woofer really aince it's so far out of hearing range, but within the hearing range it certainly seems helpful.
I'd be worried about destroying the driver too.I did a little reading here and it sounds like the small capacitor in parallel with the inductor results in the creation of a "Parallel Resonant Band-Stop Filter" which seems to result in a steeper roll-off. Since the capacitor is so small a value, at a 6 ohm load it has a -3db point of 80kHz, making the trough of the band-stop/notch above the range of hearing, so we effectively see extra attenuation in the high end for the woofer. Not sure if there are any downsides to sending 80kHz+ frequencies through to the woofer really aince it's so far out of hearing range, but within the hearing range it certainly seems helpful.
The implementation is the difficult part. Making a sandwich of course increases the stiffness, but increasing the mass also brings down the breakup frequencies which is directly counter-productive.
The current state of the art in purely pistonic metallic diaphragms appears to be ribbed/corrugated metal such as what SB Acoustics does. The effect would be similar (and probably give a better result) in either magnesium or beryllium, but I question whether the ductility of those latter metals is enough to allow the additional drawing stresses.
Why not try stiffening ribs instead of a sandwich over the entire cone? Pick an arbitrary number of ribs (spokes), and make some plastic foam strips that you can epoxy on to the back of the cone, from e.g. Airex, Divinycell, etc. You can then stiffen the ribs by adding Al foil (thicker than kitchen foil, of course) on the back face of the foam strips.
Yes, I was also thinking along these same lines. The SS Revelator sliced cones do a similar thing but with a paper composite cone; the glue over the slices is said to dramatically reduce break up modes. The crimping in the SB metal cones has a very similar effect as I understand it.
The ribs in the SB cones don't "reduce" breakup modes. They push them further out of the passband, which is even better. There's basically no damping to speak of. With the SS sliced cones, there's likely more of a damping effect with just a slight increase in stiffness.
SB15NBAC30 (with ribs) - peak is ~10 dB over average
ZA14W08 (no ribs) - peak is ~10.5 dB over average
SB17NBAC30 (with ribs) - peak is ~10.5 dB over average
RS180 (no ribs) - peak is... hard to tell due to falling response before the peak
The other thing to consider is the shape of the cone as well. http://resources.prismsound.com/tm/LOUDSOFT_Cones_stiffness_ALMA_2003.pdf
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Thanks for the info!,
I will read this last paper later; just received parts for my current project so time to play around. I have always been interested in these things. The new Satori Textreme cones have my interest as well. I did read up on this material and technology. More later...
Interesting comparison. You can add that at least from the SB provided datasheets, the behavior of the NAC/NBAC drivers and the CAC drivers is basically identical. If the 'ceramic' layer is anything other than cosmetic, it isn't showing up in the datasheet measurements. Unfortunately, hificompass hasn't tested a CAC, and I'm not aware of any other apples-apples comparisons with more detail than the datasheets.
Curt has measured both the SB15CAC and SB17CAC. We used the SB15CAC as a mid in our Travelers design.
SB15CAC first...
Basically identical distortion measurements. The SB15CAC can cross higher.
HTH
Jim
Attachments
That looks very good. Usually I never see so flat a FR or distortion curves... it's almost not a curve
Perhaps i don't know how to grasp your curves, but is the THD an astonishing 60dB below the speaker output in the mid-range? .1%?
B.
Yes, that is correct. Curt is the "brains" of our collaboration and the resident crossover genus. So, any in depth questions will be deferred to him.
The quick answer beyond yes is the CAC drivers are extremely low distortion and well behaved with exceptional detail and accuracy. Yes, I'm a big fan of the CAC's.
HTH
Jim
I also agree they are very low distortion. I do still like the Satori "sound" better though when used in a 2-way (I have the MR16 and MW16 Satoris both and also the 17CAC). Again, it just may be personal taste as to why I prefer the Satoris. Also again, I'm interested in an all CAC 3-way. Anyone do a 3-way yet with the new SB26CDC?
Have a read up on the Jeff Bagby / Javad Shadzi Ceramicos below -
DIY Loudspeaker Project Pad Public Group | Facebook
Floorstanding closed/sealed box - 2x23CAC, 1x15CAC, 1x26CDC. All on 2nd order crossovers.
The Revel F228Be uses the same bass/mid but in a vented box but with a Be tweeter.
F228Be | 3-way Dual 8" Floorstanding Loudspeaker
No, the Revel BE series drivers are not from SB - they're OEM with a similar cone but don't have the characteristic ribs. The Performa 3 (F206 and F208) do seem to use the SB drivers, though.
I have an active 3 way I finished about 5 weeks ago. Each side has a SB34NRX75-6 12 inch woofer in a 70 liter sealed box with EQ to extend the response down to 27 Hz. This crosses at 200 Hz LR4 to an SB17CAC35-4, which crosses at 2 kHz LR4 to an SB26CDC-C000-4. Here is my thread: New active 3-Way, Hypex and SB
OK, thanks; I'll check it out! My newest project is the 3 1/2 way; I started a new thread on it under the multi-way forum. I am using the SB29NRX75-6 in closed 33 liter no EQ. I have a separate sub for below 40 Hz. I haven't gotten the 29's in their new box yet though; still doing break-in. I have a smallish room so I'm going to have to put the sub box in the corner behind the TV. The TV is on a small cabinet at 45 degrees in the corner. This is to make room for the stereo pair 29's. that will be on either side of the TV cabinet. The mids. and tweeter will go above the 29's boxes. I will keep the sub plate amp. out (separate) so I can access all the controls from in front with the rest of the electronics.
I have some SB17CAC35-4; same as you. I tried them in a small 2-way but preferred my Satoris over the CAC's. I was thinking of a small 3-way with the 17CAC, 12CAC and the 26CDC tweet. My youngest nephew will be heading to college soon and will need a small speaker pair but with high quality drivers. I put my 17CAC in a 16 liter vented box. Great bass but I didn't care for the mids regardless of which tweeters I tried. That's why I'm leaning toward a small 3-way. He will "major" in Trombone so he already has a keen ear for "accuracy" in recording reproduction.
Thanks again!
I am doing a quick 2-way for someone using the SB17CAC35-4. I am using the PE 0.25 cu ft closed box; it sounds pretty good so far. This is a quick project; not much time or thought required. I have some Vifa Horn tweeters with Titanium driver; cheap but they sound pretty good together here.
I had also tried the same SB17CAC in the PE 0.56 cu ft box vented; it worked well here too.
The point is; if you want a quick and cheap 2-way closed; the PE 0.25 cu ft box is a good match; vented, the 0.56 cu ft box is also a good match. It couldn't get much easier than this as I already have all the parts I need.
I still prefer the Satori MW16 as it is more articulate and refined than the CAC. Neither of these drivers can take a ton of power and they also seem to reach their excursion limits sooner than I hoped regardless of box style.
I am REALLY looking forward to the TexTreme Satori line. They will be expensive (at least at first offering) but I'm hoping for really great performance; I will most likely get the MW19 TexTreme for my 3 1/2 way project...EVENTUALLY!
I had also tried the same SB17CAC in the PE 0.56 cu ft box vented; it worked well here too.
The point is; if you want a quick and cheap 2-way closed; the PE 0.25 cu ft box is a good match; vented, the 0.56 cu ft box is also a good match. It couldn't get much easier than this as I already have all the parts I need.
I still prefer the Satori MW16 as it is more articulate and refined than the CAC. Neither of these drivers can take a ton of power and they also seem to reach their excursion limits sooner than I hoped regardless of box style.
I am REALLY looking forward to the TexTreme Satori line. They will be expensive (at least at first offering) but I'm hoping for really great performance; I will most likely get the MW19 TexTreme for my 3 1/2 way project...EVENTUALLY!
Hello oldspkrguy!
Regarding your question, I have just returned from my local speakerstore here in Stockholm!
My aim is a 3-way full sbceramic driven by dsp (hypex FA123)
Tweeter : SB26CDC-C00-4
Mid: SB15CAC30-4
Woofer: SB23CACS45-4
I will let you know when all is said and done, maybe even post some measurements if interesting?
The thing is they had everything in stock except the 8" so it might b a couple of weeks of wait.