SEAS CA12RCY vs. W12CY003
I'm designing a HT center speaker to go with my pair of SEAS A26 fronts. The sofa is only about 3 m (10 ft) from the TV, so power isn't really an issue, but off-axis response is. My goal is to have a response 30 degrees off-axis that is +/- 3 dB as flat as on-axis.
With the height in my TV cabinet restricted to 14 cm (5,5"), I am looking at 27TBCD/GB-DXT as tweeter (great off-axis response!) and either CA12RCY or W12CY003 as woofer. Both woofers have paper cones, great off-axis response and a smooth frequency response.
And that's the thing: I can't explain the €99 ($109) difference between them. The fact that the Excel woofer has a phase plug doesn't significantly benefit its specs or frequency response. On the contrary: its recommended range is smaller than that of its little Prestige brother.
What am I missing?
I did find these measurements by AudioExcite, but am unsure what to think of them. First, they indicate that the drivers should not be used above 2 kHz while SEAS recommends 5 kHz for the CA12RCY and 3.5 kHz for the W12CY003. The frequency response of the latter in particular is not at all what SEAS specified, and that's not SEAS style. I'm suspecting more issues than just baffle step, perhaps some resonance.
I'm designing a HT center speaker to go with my pair of SEAS A26 fronts. The sofa is only about 3 m (10 ft) from the TV, so power isn't really an issue, but off-axis response is. My goal is to have a response 30 degrees off-axis that is +/- 3 dB as flat as on-axis.
With the height in my TV cabinet restricted to 14 cm (5,5"), I am looking at 27TBCD/GB-DXT as tweeter (great off-axis response!) and either CA12RCY or W12CY003 as woofer. Both woofers have paper cones, great off-axis response and a smooth frequency response.
And that's the thing: I can't explain the €99 ($109) difference between them. The fact that the Excel woofer has a phase plug doesn't significantly benefit its specs or frequency response. On the contrary: its recommended range is smaller than that of its little Prestige brother.
What am I missing?
I did find these measurements by AudioExcite, but am unsure what to think of them. First, they indicate that the drivers should not be used above 2 kHz while SEAS recommends 5 kHz for the CA12RCY and 3.5 kHz for the W12CY003. The frequency response of the latter in particular is not at all what SEAS specified, and that's not SEAS style. I'm suspecting more issues than just baffle step, perhaps some resonance.
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Troels uses MCA12R up to 3.6khz on his 3 way classic.Nice cheap wonderfull mid
H1304-08 MCA12RC
Thanx for posting other seas mids measurements!!
H1304-08 MCA12RC
Thanx for posting other seas mids measurements!!
Thanks for the suggestion. I prefer the center to be a 2 way to save space. Question is: will the MCA12RC fit the bill, with a crossover to a L26ROY subwoofer? SEAS only recommends the MCA12RC as low as 400 Hz.
I found waterfall and distortion graphs of the W12CY003 and MCA12RC here and here by Robsan-DIY. The W12CY003 seems to have less distortion overall, but with a nasty peak around 1 kHz. Both seem usable from 150 Hz up.
Still can't figure out the difference between the CA12RCY and W12CY003. Robsan-DIY's measurements match those by AudioExcite, including the resonance around 1 kHz. They prove to be the cheaper CA12RCY to be better overall than the W12CY003.
The first problem is that a large tweeter like the DXT placed next a midwoofer and crossed at 2kHz or so will not have an even 30 degree beamwidth horizontally (though it may have a nice one vertically!) because the difference in path length in the crossover region will be a large fraction of the wavelength. A good centre speakers will have the tweeter above a midrange and crossover sideways at low frequency where the wavelengths are long. If costs force a 2 way then the tweeter is usually small and placed as close as possible to the midwoofers and possibly a bit above.
The AudioExcite measurements use a large box compared to the SEAS measurements. It is very difficult to distinguish what is baffle step bump and what might be bumps on a flat baffle.
A typical midrange driver will have only a small deflection of a mm or so whereas a midwoofer will have more and a lower sensitivity. A midrange will have a lower limit around 300-400 Hz. The lower limit for a small midwoofer will depend on how close you sit and whether you listen at less than standard volumes (i.e. cinema sound levels). Trying to reach down to a sub would be stretching things.
Cones come in various flavours such as metal, hardish "paper" and strongly damped "paper" and they sound and behave differently. A midrange has the option of a stiff surround which can better control the resonance you are concerned about but a midwoofer with some sort of bass extension does not have this option.
The Excel driver has a significantly better motor and some deflection to work at lower frequencies. The Prestige is a dedicated midrange and unsuitable for your purposes.
The main difference between the two drivers is the extensive use of copper within the excel driver. This increases linearity and pushes down distortion, it also linearises the Le x curve.
Andy is right though in that if you place the dxt and mid woofer horizontally that you will need to cross as low as the dxt can manage to maintain good horizontal dispersion. Luckily the dxt can handle low xover points. With steep xovers 1.2-1.4kHz is fine.
Andy is right though in that if you place the dxt and mid woofer horizontally that you will need to cross as low as the dxt can manage to maintain good horizontal dispersion. Luckily the dxt can handle low xover points. With steep xovers 1.2-1.4kHz is fine.
The CA12 is a simple doped paper cone whereas the W12 is nextel coated and has a better motor assembly.
I'd expect the W12 to have the more refined sound and the CA12 to be more dynamic but possibly coloured.
I'd expect the W12 to have the more refined sound and the CA12 to be more dynamic but possibly coloured.
At high excursions and SPL I'd expect the W12 to actually be more dynamic. It will have lower distortion and the smooth Le vs displacement, due to the better motor, will keep it's performance more linear, especially when paired with a passive xover.
Centre channels are often run pretty hard, I wouldn't want to skimp on any driver used in one. Of course one doesn't need to pay a large amount of money for a driver with nice amounts of copper in the gap and the W12 wouldn't be my first choice if cost were a concern but then neither would the CA12 either.
Centre channels are often run pretty hard, I wouldn't want to skimp on any driver used in one. Of course one doesn't need to pay a large amount of money for a driver with nice amounts of copper in the gap and the W12 wouldn't be my first choice if cost were a concern but then neither would the CA12 either.
Thank you all for triggering me to read up on acoustic lobing. I now understand the specific driver placement of Troels' CENTER 641. Unfortunately, I just don't have that height to spare within WAF constraints.
Back to the drawing board, perhaps a 12 cm coaxial.
Back to the drawing board, perhaps a 12 cm coaxial.
The H1152-08 CA12RCY is a poor choice of bassmid beacause of the steep dip after the edge resonance at 1.5kHz. You'd need to either cross it very low around 2kHz or add a parallel LCR trap to equalise it.
The E0044-08S W12CY003 is much better behaved hence it's use in Eekel's Mini.
Too expensive IMO. Why not do this? Vifa PL14WJ-. Even MTM.
The E0044-08S W12CY003 is much better behaved hence it's use in Eekel's Mini.
Too expensive IMO. Why not do this? Vifa PL14WJ-. Even MTM.
Another suggestion: https://www.madisoundspeakerstore.c...mw13p-8-5-egyptian-papyrus-cone-woofer-8-ohm/
I don't believe that driver as been offered as a Vifa for quite some time now and is also too large for his application. The closest thing: https://www.madisoundspeakerstore.c...y-12w/4524g-4.5-fiberglass-cone-woofer-4-ohm/
I was going to recommend the 5" Satori too. It would make for a killer small centre imo when crossed over low. The DXT would make a perfect tweeter in that combination, but you would need to cross it down at its limits for the best off axis performance. We're talking 1.2-1.4k with a 4th order acoustic.
The SEAS coax is obviously a no brainer if you want the best off axis response, but it wont be for everyone.
If you want less expensive the RS125 from Dayton would be pretty good too. You can get it in the truncated frame that would make it easier to use.
The SEAS coax is obviously a no brainer if you want the best off axis response, but it wont be for everyone.
If you want less expensive the RS125 from Dayton would be pretty good too. You can get it in the truncated frame that would make it easier to use.
That would address the beam width but on its own in a room you would almost certainly have inadequate SPL from 80 Hz to a few hundred Hz. You would need two other 12 cm drivers crossed over reasonably low at 400-500 Hz. Possibly four given the small cone area.
Unless the user doesn't listen loud. Lots don't listen at reference levels. Still I agree with you one 4.5" driver won't go particularly loud.
It is a 4.5" driver with the middle missing. Something more like the cone area of a 3.5" driver or so. For reasonable SPLs it should be fine above 400-500 Hz and, given it is a coaxial, reducing the displacement will reduce the modulation of the tweeter output.
Well the middle contributes a surprisingly small amount to the overall SD, but yes it does reduce it a little.
You can actually get 105dB out of the thing half space (which being in the TV rack will be close to) with a 4th order acoustic xover at 150Hz. This is remaining within xmax.
If you don't mind using xmech, for a little added distortion for peaks, then it will go down as low as 110Hz. I think I'd pick 125Hz just to be on the safe side.
The above is in a 3 litre 100% stuffed sealed box.
It's more capable than I thought it was going to be. But if you're really space constrained eating into xmech a little isn't a bad thing.
Now if you were really going all out for a small centre I'd go with the L12 Coax in say 1 litre of volume at one end of the cabinet + 2
Dayton Audio RS125-4 5" Reference Woofer 4 Ohm - Reference Series - Loudspeaker Drivers By Series - Loudspeaker Components
wired in series.
Or use a suitable driver from Peerless/Tymphany with their truncated frames.
Transducer Detail | Tymphany
Indeed I don't listen loud, typically only around -50 dB and certainly never louder than -30 dB.
However, these 4,5" drivers have a nominal impedance of 4Ω and my amp doesn't handle loads lower than 6Ω. Adding a 3.3Ω resistor in series with the woofer "fixes" the impedance but drops the characteristic sensitivity to a measly 76 dB SPL. A new amp doesn't fit the budget, and I can't go active since my amp doesn't have a pre-out for the center.
As for going "all out" with the center, well, I certainly want to have a frequency response that's appropriate for a center. If that means two more drivers then sure. But won't adding more woofers next to a coaxial still cause lobing with the tweeter?
Though this may be going off topic judging by the title, I very much appreciate your input in this quest for a small but fine center speaker.
Not if crossed low at 300-500Hz to woofers rather than 2-3kHz to a midrange/midwoofer. The wavelength of the sound is a lot longer at these frequencies and so the difference in path length from the driver centres to the ear is a lot smaller fraction of the wavelength causing only a small amount of cancellation off axis.
The low height is a quite severe design constraint. Two, perhaps four, 4.5" drivers side by side is straightforward. What goes in the middle is the question. Some options:
1) 3 way with coaxial tweeter/midrange.
2) 3 way with small diameter neo tweeter between and above a pair of small diameter 3" midrange drivers.
3) 2 way with large tweeter crossed as low as practical with steep slopes placed to the side of the midwoofers.
4) 2 way with smallish tweeter squeezed as close as possible above and between the midwoofers.
If you are using the A26 kit with the 1.5" T35 tweeter as the main speakers then option 3) with this large tweeter might be the natural way to go. I would examine possibly machining the faceplates to get closer. If you opt for four 4.5" drivers to help keep up with the main speakers then the outer pair will probably need to be brought in at a lower frequency. Given the location I am not sure how much baffle step will be needed which can often be helpful with 2.5 way designs.
Thanks for laying down the options. XDir simulations show that I need a MTM crossed no higher than 1.1 kHz to obtain -3 dB off-axis 30 degrees both ways. I'm following the "Tweeter crossed at 1 kHz?" thread with interest. The preliminary answer seems to be "not with sufficient power".
So I'm thinking: if I'm trying to run a tweeter full range, well, then why not use a full range driver? Probably in a FAST design with a supporting woofer crossed around 300-400 Hz. This seems a viable 2 way option.
For a 3 way with a small tweeter above the woofers, I found this thread with 3" woofers and full ranges inspiring. I'd have to look for a matching tweeter.
For reference, I asked SEAS about the CA12RCY vs. W12CY003. They answered:
A 3"-4" driver will have both severe breakup and severe beaming at high frequencies. FAST is an option for enthusiasts that are able to set aside these sorts of issues. Here is an example of the typical directivity.
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