SB Acoustics SB17NAC35-8

JasonP

I just nabbed a pair of these from Meniscus, and I have to say they are quite attractive looking drivers. Well, depending on how you feel about bright metallic cones. Assuredly by now you know all things metallic are good in my book. These drivers have been around a few years and an OEM version of them ended up in the Revel Performa3 line of speakers (though black coned for the easily annoyed masses). Given Jeff B.'s penchant for building designs with SB Acoustics drivers I was waiting patiently for him to do a build with them and just listening to the. However that seems to be something that isn't going to happen, so I'm going to make a small two-way with them. Based on what data I was able to see at audioexcite.com: http://www.audioexcite.com/?page_id=5833, they look to have world class distortion performance in the midrange. Couple that with a reinforced cone that acts as a piston below 3k and this sure looks great to me. The HD graphs on that site even look better than several of the SS Revelators that were tested, which shocked me. Those tests are on the 4 ohm version, and these are the 8 I picked up so it'll be interesting to see any differences between the two.

Pics:

squamishdroc

Nice! I'm a bit of a SB fan boy

ScottS

I've had my eye on these for a while.  My recent positive experience with the SB12PAC only raises the interest level further.  I am really curious how high these can cross.

JasonP

No T/S params quite yet, but free air impedance sweeps done after minimal break-in.



Fs is 32 hz on one, 34 hz on another. Published spec. is 31.5 hz. Not too shabby, and within what I'd call acceptable tolerance.



Zoomed in look between 100 and 5000 hz. Glitch shown in the published graph at just over 600 hz is real. We'll see how audible it is in listening.



1k to 20k. Mild breakup induced blip at about 7.5k. Seemed barely noticeable in the stepped sine sweep.

More to come.

JasonP

LIMP determined T/S Params, added mass method:

Loudspeaker parameters:

• Fs  = 33.76 Hz
• Re  = 5.70 ohms[dc]
• Le  = 68.92 uH
• L2  = 374.22 uH
• R2  = 2.76 ohms
• Qt  = 0.47
• Qes = 0.50
• Qms = 7.89
• Mms = 13.98 grams
• Rms = 0.378948 kg/s
• Cms = 0.001590 m/N
• Vas = 31.02 liters
• Sd= 117.86 cm^2
• Bl  = 5.818487 Tm
• ETA = 0.23 %
• Lp(2.83V/1m) = 87.19 dB

Added Mass Method
Added mass = 10.00 grams
Diameter= 12.25 cm

Loudspeaker parameters:

• Fs  = 32.09 Hz
• Re  = 5.70 ohms[dc]
• Le  = 67.51 uH
• L2  = 363.33 uH
• R2  = 2.65 ohms
• Qt  = 0.43
• Qes = 0.46
• Qms = 6.21
• Mms = 14.71 grams
• Rms = 0.484199 kg/s
• Cms = 0.001672 m/N
• Vas = 32.61 liters
• Sd= 117.86 cm^2
• Bl  = 6.057836 Tm
• ETA = 0.22 %
• Lp(2.83V/1m) = 87.10 dB

Added Mass Method:
Added mass = 10.00 grams
Diameter= 12.25 cm

Looks pretty good to me.Perhaps there is a minor consistency issue in weight between cone and voice coil assembly of units, that would explain the slightly higher Fs and Qts of the first unit above. /speculation.

jr@mac

Judging by the calculated sensitivity, I would wager those differences are inconsequential. Anymore, that is what I look at, anyways. Should offer a pretty solid foundation to build a great imaging speaker.