JL Audio 12W3v3-4

Overall summary

In this sample and under these test conditions, the 1 V baseline distortion is very elevated below 40 Hz, with THD around 30Hz reaching past 6 percent, and over 9 percent at 20 Hz. The major peak around 30 Hz is dominant H2 distortion. Below ≈25 Hz, dominant H3 distortion is the largest harmonic component, with H3 distortion above 4 percent at 20 Hz. From ≈40 Hz through ≈120 Hz, THD generally stays around about 1 to 1.8 percent, with smaller peaks around 40 Hz (≈1.8 percent) and 60 Hz (≈1.6 percent), both dominated by H2 distortion.

The high level sweep at 17 V shows a broad rise in THD across essentially the full bandwidth, with THD at 20 Hz at ≈8.7 percent, dropping to ≈6.0 percent around 30 Hz, then rising to a broad maximum around roughly 70 to 90 Hz at ≈10.5 percent. At this drive level, H2 distortion is dominant below ≈25 Hz and remains dominant from ≈30 to 120 Hz, which is a clear shift versus the 1 V sweep where H3 distortion was more prominent below ≈25 Hz. H3 distortion remains elevated at the very low end at 17 V (≈4.0 percent at 20 Hz), but it is comparatively lower through most of ≈40 to 120 Hz, where it stays near ≈0 to 1 percent while H2 distortion carries most of the total.

Large signal results show BL 70 percent at 13.81 mm one way with an inward bias that varies across stroke. At low excursion, it is about 4mm off center, but is about 1.7 mm at its limits, which can correlate with increased even order distortion and aligns with the dominant H2 distortion seen across most of the 20 to 120 Hz band. CMS 50 percent was not reached within the protection window, and CMS behavior is close to centered in this sample. Inductance is the earliest limit reached, with the 17 percent Le variance criterion crossed at only 5.38 mm one way, indicating inductance variation is the practical clean one way limit for this sample.

From a sealed enclosure perspective, the manufacturer stated 1.25 ft³ net sealed corresponds to 0.737 Qtc for this sample, while a 0.707 Qtc target requires about 1.42 ft³ net on this sample. Those volumes are moderate for a 12 inch driver and keep sealed sizing requirements reasonable for the intended use case.

Manufacturer's suggested use case

The manufacturer positions the W3v3 series as a medium-power subwoofer line intended to deliver deep, articulate bass in compact sealed or ported enclosures, and notes that the motor system is DMA optimized for linear force over excursion. The manufacturer also highlights Elevated Frame Cooling for heat dissipation and reliability, along with a mineral-filled polypropylene cone and rubber surround.

For the 12W3v3-4 specifically, the manufacturer lists 500 W continuous power handling, 87.15 dB sensitivity (1 W/1 m), 13.0 mm one way Xmax, and a nominal 4 ohm impedance. The manufacturer recommends compact sealed or ported use, and provides enclosure sizing guidance for both.

Our suggested use case

In this sample and under these test conditions, sealed enclosures around the manufacturer stated 1.25 ft³ net (0.737 Qtc on this sample) through about 1.42 ft³ net (0.707 Qtc on this sample) are the most direct fit for how the driver parameters land. The earliest standardized linearity limit is the 17 percent Le variance point of only 5.4 mm one way excursion, so inductance variation is the practical clean one way limit in this sample even though BL and CMS based excursion limits extend much farther, and is most likely a contributor to the high distortion seen on this subwoofer. If more clean headroom is required within that Le-limited region, using multiple drivers reduces the per-driver stroke demand at a given output.

Testing and linearity limits vs. what is advertised

What it took to reach our high-level sweep limit, and how that compares to the published specs.

High-level sweep rule: Set just under the BL 70 percent point from LSI

High-level sweep limit for this sample: 17 volts

Approximate electrical power at that limit at 20Hz: 75 watts. Real power varies with frequency and impedance. volts

Rated power (published): 500 W

Power used to hit the standardized limits in free air, relative to their xmax rating free air: ≈15.0 percent. Hits 13.8 mm in free air with 75 watts of power. Real power varies with frequency and impedance.

Claimed Xmax vs. measured at BL 70%: 13.8 mm, 106.2 percent of the manufacturer’s claim of 13.0 mm

Xmax @ 50% Cms: >15.11 mm one way, >116.2 percent of the manufacturer’s claim of 13.0 mm

Xmax @ 17% Le: 5.4 mm, only 41.5 percent of the manufacturer’s claim of 13.0 mm

Manufacturer suggested sealed enclosure size (and its resulting QTC): Claimed 1.25 ft³ nets a QTC of 0.737

Required sealed enclosure for 0.707 QTC: 1.42 ft³ nets a 0.707 QTC

Xmax @ 50% Cms: >15.11 mm one way, >116.2 percent of the manufacturer’s claim of 13.0 mm

Overall performance snapshot

This is our subjective interpretation of the objective data. How we derive these scores can be found on the home page of the testing section.

Distortion & frequency response - TRF measurements

Method recap: Klippel TRF was used for response and harmonics, and Klippel LSI was used for large signal parameters. Nearfield mic placement was 1/10 cone diameter plus 2 inches, on axis. Response is captured to 1 kHz and THD is captured to 500 Hz, with 1/6 octave smoothing. Two drive levels were used, a 1 V baseline and a high level sweep at 17 V set just under the BL 70 percent limit from LSI for this unit. LSI thresholds are BL 70 percent, CMS 50 percent, and a 17 percent Le variance criterion. At 17 V this sample reached 11.3 mm one way at 20 Hz in free air.

At 1 volt - baseline

In this sample and under these test conditions, the 1 V baseline is very jagged and elevated below 40 Hz, with THD at 20 Hz going beyond 8 percent. The most concerning feature is a peak around 30 Hz at about 6.5 percent with dominant H2 distortion. Below ≈25 Hz, dominant H3 distortion is the largest harmonic, with H3 distortion at about 4.3 percent at 20 Hz. From ≈40 Hz through ≈120 Hz, THD is generally around about 0.8 to 1.8 percent, with smaller H2 distortion peaks around 40 Hz (≈1.8 percent) and 60 Hz (≈1.6 percent).

At high level voltage (17 volts)

At 17 V, distortion shifts from the low level jagged behavior to a broader, higher baseline across most of 20 to 120 Hz. THD is about 8.7 percent at 20 Hz, drops to about 6.0 percent around 30 Hz, then rises to a broad maximum around roughly 70 to 90 Hz at about 10.5 percent. Below ≈25 Hz, dominant H2 distortion is the primary contributor at this drive level, and H2 distortion remains dominant from ≈30 Hz through ≈120 Hz. H3 distortion is comparatively lower through most of ≈40 to 120 Hz at about 0 to 1 percent, though it is still about 4.0 percent at 20 Hz. Above the typical subwoofer band, THD rises sharply again with large peaks in the 250 to 450 Hz region, which is notable but outside typical use.

Delta - 1 volt distortion vs. high level distortion

Compared with 1 V, the high level sweep shows substantially higher THD from about 35 Hz through 120 Hz, while the 20 to 30 Hz region stays closer to the baseline due to the already elevated low level peak near 30 Hz. Harmonic distortion balance shifts at the very low end, with dominant H3 distortion below ≈25 Hz at 1 V giving way to dominant H2 distortion below ≈25 Hz at 17 V. The slight inward bias in BL symmetry can correlate with increased even order distortion, which is consistent with the stronger H2 distortion contribution at the higher drive. The early 17 percent Le variance limit at 5.4 mm one way indicates inductance variation is the first standardized limit criterion crossed on this sample and can also be contributing to the unusually high distortion in the higher voltage test.

What this means in practice

In this sample and under these test conditions, the high level sweep shows up to 10.5 percent THD in our desired passband. The 1 V baseline is much lower through most of ≈40 to 120 Hz at about 0.8 to 1.8 percent THD, but it becomes peaky below 40 Hz and exceeds the visible THD window at 20 Hz. Overall, this is just a high distortion driver that is apparent at both low level, as well as higher power levels and is not very accurate to the input signal.

Motor & suspension linearity - LSI measurements

Method recap: Klippel LSI large-signal identification for this unit, cold and used for enclosure computations. Standard thresholds in this project are BL 70 percent, CMS 50 percent, and a 17 percent inductance variance criterion. Commentary below ties the large-signal behavior to the acoustic results.

Bl(x)

Bl(x) shows how much motor force a speaker produces as the voice coil moves, B is magnetic field strength and L is the wire length in that field. A high, wide, symmetrical BL curve means linear control and low distortion, a steep or uneven drop means earlier output limits and rising distortion, which is why BL(x) is often the most telling single Klippel LSI indicator of real performance.

Bl(x) window and shape

BL 70 percent occurs at 13.81 mm of one way excursion. The BL curve is shifted around the center, but is more centered on the extreme limits, and rolls off somewhat gradually toward the ends. The shape of the BL curve shows that there is pretty heavy inward bias. This asymmetry in the BL shape could be a cause of the very high second order distortion.

Bl(x) symmetry

The BL symmetry point at xprot (mechanical limit that we set for the test) is -1.64 mm, but lower excursion shows asymmetry by almost 5 mm, indicating an inward bias on this sample. The BL asymmetry metric is 16.64 percent, which again, is consistent with H2 distortion being the dominant harmonic through most of 20 to 120 Hz in the TRF measurements.

Cms(x)

Cms(x) is suspension compliance versus displacement, the inverse of stiffness. When the curve is broad and symmetrical, motion is linear and distortion stays low. Early roll off or offset indicates progressive stiffening or mis-centering, which adds mechanical distortion and caps clean excursion.

Cms(x) window and shape

CMS 50 percent was not reached within the protection window, so Xmax at 50 percent CMS is >15.11 mm one way, which is favorable. Cms at rest is about 0.30 mm/N, and the provided Cms(x) curve shows compliance gradually decreasing as displacement approaches the ends of the measured range.

Cms(x) symmetry

CMS behavior is close to centered in this sample, with no large offset visible in the compliance curve. Within the evaluated stroke, this suggests suspension nonlinearity nor its symmetry are not the primary limiters for this subwoofer.

Inductance - Le(x) and Le(i)

Le(x) and Le(i) measure how a subwoofer’s voice coil inductance changes with position and current. These curves show how stable the motor’s magnetic field is under real movement and drive conditions. When inductance varies heavily, it causes distortion, uneven response, and a loss of upper-band clarity, which is why Le(x) and Le(i) are critical for evaluating how clean and consistent a motor’s behavior really is.

Level and shape

Le at rest is pretty high, at 3.39 mH, and the 17 percent variance criterion is crossed at a mere 5.38 mm one way, which is the earliest standardized limit for this sample and therefore the practical clean one way limit by a notable margin. Le(x) shows strong position dependence, falling from about 4.9 mH at roughly -15 mm to about 2.1 mH at roughly +15 mm. This type of Le(x) variation can correlate with elevated distortion when it appears.

Current dependence

Le(i) rises moderately with current, increasing from about 3.0 mH at -8 A to about 3.8 mH at +8 A. This amount of change is more than nearly all of the other subwoofers we have tested.

Qts(x)

Qts(x) is the driver’s total damping versus excursion, combining electrical and mechanical losses. Stable, symmetrical Qts(x) means consistent control, while large variation or asymmetry signals uneven damping that can shift response, raise distortion, and cause compression.

Qts stability

Qts at x=0 is 0.36 cold and 0.39 warm. Qts(x), as normal, rises with displacement on both sides, but is asymmetrical and rises more on the coil-out side in this sample. This indicates damping is not constant nor symmertical with stroke, which can contribute to increasing distortion and compression behavior as drive rises.

LSI takeaway

The earliest limiting mechanism in this sample is inductance variation, with the 17 percent Le variance criterion reached at 5.38 mm one way, making it the practical clean one way limit. BL 70 percent is 13.81 mm one way with a broad BL curve, but it has an inward asymmetry and bias that can correlate with increased H2 distortion, consistent with the TRF harmonic balance. CMS 50 percent was not reached within the xprot window (>15.11 mm one way), and CMS symmetry is close to centered, so suspension compliance is not the primary limiter in this sample. Le(x) varies strongly with position and Le(i) shows moderate current dependence, which can correlate with H3 distortion when present, and it explains why the Le limit is reached early. Qts shifts from 0.36 cold to 0.39 warm and rises noticeably with stroke, which indicates changing damping with drive that can contribute to compression at higher output.

Enclosure alignment calculations

Manufacturer sealed enclosured recommendations and the resulting QTC: 1.25 ft³ nets a QTC of 0.737

Sealed volume required for 0.707 QTC on this sample: 1.42 ft³

Applicable for infinite baffle? Not recommended for IB in this sample, based on the low cold Qts (0.36) and the fact that a moderate sealed enclosure already reaches 0.707 Qtc.

T/S parameters