SB Acoustics SB23NACS45-8 8″ Woofer

Up for test is SB Acoustics’ SB23NACS45-8, 8″ Woofer.

After looking at Revel’s new(ish) Performa3 Lineup, I realized that they are, at least in part, using SB acoustics drivers.  The Revel F208 uses (2) 8 inch woofers, which bear a striking resemblance to the SB’s under review here.Though, most certainly tweaked to fit their needs. did a review on the Revel F206 which contains pictures of the SB labeled drivers, pulled from their cabinets. In these pictures you can see the driver model number, containing the same naming scheme SB has for their drivers.  For example: 6moons’  picture of the tweeter in the f206 (here) carries the model number “SB26ADC-C000-4-RVL”.  You’ll notice SB’s site has a tweeter model #SB26ADC-C000-4.

Further, if you view the pictures of the raw woofer drivers, you’ll notice a lot of similarities such as the inverse-ribbed cone, and basket design.  While it seems apparent Revel used SB as an ally in the production of this speaker, odds are high Revel didn’t just use these SB drivers ‘off the shelf’.  One obvious difference is the black cone used in the Revel lineup rather than the aluminum colored cone presented here.  That said, the connection me curious about the ‘raw’ driver performance.  I went to SB’s site and located the 8″ driver.  I contacted Madisound to inquire about the product and was informed it wasn’t on their site just yet as they had recently taken shipment of them.  So, I placed an order for a set and got some testing done recently.


First, some photos:

IMG_8495 IMG_8501 IMG_8497 IMG_8498 IMG_8502

Testing the small signal parameters:

I tested both drivers back to back to compare their consistency.  Below are the values obtained for each.

Sample 1 Sample 2 Units Description
Re 5.47 5.48 Ohm electrical voice coil resistance at DC
Le 0.364 0.358 mH frequency independent part of voice coil inductance
L2 0.401 0.379 mH para-inductance of voice coil
R2 2.18 2.17 Ohm electrical resistance due to eddy current losses
Cmes 455 465 µF electrical capacitance representing moving mass
Lces 61.9 64.17 mH electrical inductance representing driver compliance
Res 50.6 48.9 Ohm resistance due to mechanical losses
fs 30 29.1 Hz driver resonance frequency
Mms 30.81 31.177 g mechanical mass of driver diaphragm assembly including air load and voice coil
Mmd (Sd) 27.223 27.589 g mechanical mass of voice coil and diaphragm without air load
Rms 1.338 1.371 kg/s mechanical resistance of  total-driver losses
Cms 0.914 0.957 mm/N mechanical compliance of driver suspension
Kms 1.09 1.05 N/mm mechanical stiffness of driver suspension
Bl 8.23 8.189 N/A force factor (Bl product)
Qtp 0.423 0.42 total Q-factor considering all losses
Qms 4.338 4.162 mechanical Q-factor of driver in free air considering Rms only
Qes 0.469 0.466 electrical Q-factor of driver in free air considering Re only
Qts 0.423 0.419 total Q-factor considering Re and Rms only
Vas 60.3473 63.1788 l equivalent air volume of suspension
n0 0.334 0.322 % reference efficiency (2 pi-radiation using Re)
Lm 87.44 87.28 dB characteristic sound pressure level (SPL at 1m for 1W @ Re)
Lnom 89.09 88.93 dB nominal sensitivity (SPL at 1m for 1W @ Zn)
Madd 9.75 9.75 g additional mass
Sd 216 216 cm² diaphragm area


Overall, the comparison between the two units is pretty much on par.



Large Signal LSI Klippel Testing:

I didn’t have the time to test both samples so the following is all “Sample 1” driver.

Displacement Limits thresholds can be changed in Processing property page
X Bl @ Bl min=82% 5.6 mm Displacement limit due to force factor variation
X C @ C min=75% 3.7 mm Displacement limit due to compliance variation
X L @ Z max=10 % >6.2 mm Displacement limit due to inductance variation
X d @ d2=10% 38 mm Displacement limit due to IM distortion (Doppler)
Asymmetry (IEC 62458)
Ak 25.39 % Stiffness asymmetry Ak(Xpeak)
Xsym -0.61 mm Symmetry point of Bl(x) at maximal excursion

SB Acoustics SB23NACS45-8 bl SB Acoustics SB23NACS45-8 bl sym SB Acoustics SB23NACS45-8 cms SB Acoustics SB23NACS45-8 kms SB Acoustics SB23NACS45-8 kms sym SB Acoustics SB23NACS45-8 lx SB Acoustics SB23NACS45-8 LI

2 thoughts on “SB Acoustics SB23NACS45-8 8″ Woofer

  1. Hi Erin,
    Many thanks for posting the measurements on SB Acoustcs SB23NACS45.
    Excellent data!
    I’m wondering why you didn’t publish the Harmonic Distortion so far.
    Are the data too disappointing to being published?
    Best regards

    • Frank,
      To be honest, I simply didn’t get around to it. I posted these up for sale on a forum shortly after performing the large-signal analysis and they sold quickly; more quickly than I had planned. I had to package them up and ship them off the next day and didn’t have the opportunity to test them further.

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