Arc Audio A10

Overall summary

In this sample and under these test conditions, the 1 volt baseline distortion run shows extremely high low frequency distortion that features very obvious peaks. Distortion exceeds 30 percent around 20 Hz and includes a spike near 30 Hz that reaches approximately 25%; H2 distortion and H3 distortion are both present across the lowest octave. Above roughly 50 Hz, the 1 V sweep calms down to a somewhat normal level of distortion.

At the near limit sweep, distortion presents as a broad rise toward the lowest octave with dominant H2 distortion from roughly 25 to 60 Hz with a peak of approximately 16% distortion at 20hz, plus a distinctive notch centered near 30 Hz where THD drops to around 3 percent before rising again. This notch is complete opposite of what we see in the 1v baseline distortion sweep, which indicates that there is most likely a lot of flexing from the cone/dustcap structure over stroke, which can create peaks and dips in distortion as stroke changes. This is one exact reason why we test at 1v, and at a higher power level just below xmax. H3 distortion remains visible at the very bottom, but H2 still dominates.

Large signal data on this sample show a BL 70 percent one way limit of 10.23 mm, a CMS 50 percent point not reached within the ±12.76 mm evaluation window, and a 17% inductance variance limit at only 4.32 mm one way. BL symmetry is good across the entire stroke, while the suspension exhibits measurable asymmetry at low excursion. Inductance is high at rest and varies strongly with position; Le(i) also shows some current dependence. These LSI findings align with the measured mix of even order and odd order content: the asymmetry tracks with H2 distortion, and the strong Le(x) swing aligns with elevated H3 distortion at the bottom, though I am wondering if the cone structure is responsible for most of the measurable distortion.

For sealed use, the manufacturers 0.60 ft³ sealed enclosure recommendation computes on this sample to a Qtc of 0.851, while approximately 1.17 ft³ is required to reach 0.707 Qtc. Within that context and given the early inductance based limit, usable headroom in the lowest octave is very modest for a single unit. Multiple drivers raise clean headroom when Le is the earliest limit.

Manufacturer's suggested use case

Arc Audio positions the A Series as low profile subwoofers intended for limited depth applications, with progressive heat pressed poly injected pulp cones, UV grade polyether surrounds, progressive Nomex blend spiders, and stamped steel baskets. The A10 is published at 250 W RMS, 500 W musical power, 8 mm one way xmax, and 85.4 dB sensitivity at 1 W/1 m; sealed guidance lists 0.40 to 0.90 ft³ with 0.60 ft³ labeled optimal.

Our suggested use case

Based on this sample and these measurements, sealed alignments in the 0.50 to 1.20 ft³ range are the straightforward path. Its best use case is being used as a front subwoofer between a more capable rear subwoofer, and front midbass drivers. Having a high pass filter will help reduce the very high low frequency distortion that we see in the TRF measurements.

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: 14 volts

Approximate electrical power at that limit at 20Hz: ~50 watts. Real power varies with frequency and impedance. volts

Rated power (published): 250 watts.

Power used to hit the standardized limits in free air, relative to their xmax rating free air: ~22 percent. Hits the 10.2 mm BL 70 percent xmax in free air with 55 watts of power.

Claimed Xmax vs. measured at BL 70%: 10.23 mm, 127.9 percent of the manufacturer’s claim of 8 mm.

Xmax @ 50% CMS: > 12.76 mm, >159.5 percent of the manufacturer’s claim of 8 mm.

Xmax @ 17% Le: 4.32 mm, only 54.0 percent of the manufacturer’s claim of 8 mm.

Manufacturer suggested sealed enclosure size (and its resulting QTC): Manufacturer suggested 0.6 ft³ enclosure nets a QTC of 0.851.

Required sealed enclosure for 0.707 QTC: 1.17 ft³

Xmax @ 50% CMS: > 12.76 mm, >159.5 percent of the manufacturer’s claim of 8 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: Nearfield mic positioned at 1/10th the cone diameter plus 2 inches, on axis. Response measured to 1 kHz and THD to 500 Hz. 1/6‑octave smoothing. Two drive levels, 1 V baseline and a high level set at 14 V per the under BL‑70 rule derived from LSI for this unit.

At 1 volt - baseline

The distortion curve is jagged with multiple peaks below 40 Hz. THD rises steeply toward the bottom, exceeding 30 percent around 20 Hz with a narrow spike near 30 Hz that reaches about 25 percent. Both H2 distortion and H3 distortion are visible across the lowest octave. Above about 50 Hz, THD falls to relatively normal levels.

At high level voltage (14 volts)

As level increases, distortion forms a broad rise to the lowest frequencies rather than isolated spikes. H2 distortion is the dominant component through much of 25 to 60 Hz, with H3 distortion most visible in the very low band. A striking feature is a deep reduction in THD centered near 30 Hz that drops to about 3 percent before climbing again below and above that point. This dip is most likely due to the design of the cone/dustcap structure and its flex over stroke. Above roughly 50 Hz, THD trends downward into the high‑single‑digits by 100 Hz.

Delta - 1 volt distortion vs. high level distortion

Operation for the high‑level sweep was set just under the BL 70 percent limit and remained below the CMS 50 percent point on this unit. Compared with the 1 V baseline, the high‑level sweep shows a broader, level‑dependent rise in the bottom octave with H2 distortion dominant over much of the band and H3 distortion most evident at the very bottom. The increased odd‑order component at low frequency is consistent with the strong Le(x) variation seen in LSI, while the even‑order content aligns with the observed suspension asymmetry at low excursion. The real worry here, as mentioned previously is the massive distortion peak at 30hz with low levels of drive changing into a massive dip at higher drive. This is most likely due to varying cone/dustcap flex as the cone moves at different levels of stroke.

What this means in practice

In this sample and under these test conditions, the Arc Audio A10 shows unusually high low‑frequency distortion that changes dramatically with drive level. At 1 volt, THD is jagged below 40 Hz with a large 32 percent peak near 20 Hz and another around 30 Hz near 25 percent. Both H2 distortion and H3 distortion are visible across the lowest octave and drop sharply above 50 Hz. At 14 volts, the distortion pattern smooths into a broad rise toward the bottom, dominated by H2 distortion between 25 and 60 Hz and H3 distortion below 25 Hz. The deep 30 Hz distortion dip on the 14v measurement vs the large 30hz peak in the 1v measurement is likely from cone or dust‑cap flex that changes behavior at varying levels of excursion. The contrast between the low‑level spike and high‑level dip suggests flexing cone behavior over stroke that shapes the driver’s unique distortion profile.

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 is 10.23 mm one way. The BL curve is reasonably linear, but not exactly flat and rolls off with excursion which indicates a moderate shelf that focuses motor force near center. When asymmetry is present at small stroke, this can elevate even‑order content.

Bl(x) symmetry

Near‑limit symmetry is good; the symmetry point reported at stroke limits is about −0.26 mm, which tracks with the testing engineer note of “Good BL symmetry.” This behavior is consistent with the lack of pronounced even‑order BL‑driven artifacts at high excursion.

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 ±12.76 mm window, which is favorable for mechanical headroom and lack of distortion added from suspension components. The curve shape shows progressive stiffening only at higher excursions.

Cms(x) symmetry

The suspension having an asymmetry of roughly 3 mm is observed on this sample per the graphs, which may be contributing to the even‑order H2 distortion visible in the TRF results.

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

In this test with this sample, Le at rest is high, at 2.47 mH. The 17 percent Le variance threshold is reached at a very low 4.32 mm one way excursion, occurring earlier than BL or CMS and setting the practical clean one‑way limit on this unit. Le(x) varies strongly with position, which is consistent with and may be a contributor of the observed H3 distortion at the lowest frequencies.

Current dependence

Le(i) shows a moderate upward drift with current, indicating slight additional inductance modulation under drive.

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 near center is about 0.48 cold and rises with stroke, especially outward, reaching much higher values toward the extremes. This indicates diminishing electrical‑mechanical damping as excursion increases, which matches the trend toward higher distortion at lower frequencies and higher drive.

LSI takeaway

The earliest limiting mechanism on this sample is inductance, with the 17 percent variance threshold at 4.32 mm one way. The BL shelf is moderate with good near‑limit symmetry; BL behavior is not the constraint here and does not add strong even‑order content by itself. CMS 50 percent is beyond the tested window, and low‑excursion asymmetry of roughly a few millimeters aligns with the H2 distortion observed in the lowest band. Inductance swing is strong and Le(i) shows moderate current dependence, which aligns with the H3 distortion seen at the very bottom. Qts rises slightly asymmetrically with stroke, implying reduced control and a tendency toward compression at higher excursion.

Enclosure alignment calculations

Manufacturer sealed enclosured recommendations and the resulting QTC: 0.60 ft³ sealed nets a Qtc of 0.851 on this sample.

Sealed volume required for 0.707 QTC on this sample: 1.17 ft³

Applicable for infinite baffle? Not a good choice for infinite baffle due to its very low xmax, high levels of low frequency distortion, and a QTS spec that is not ideal for infinite baffle use.

T/S parameters