Dynaudio Esotar² 1200

Overall summary

In this sample and under these test conditions, the Esotar² 1200 presents as a premium sealed-box subwoofer with a clean, well-controlled limit structure and low distortion at its use-case output levels. The three conventional large-signal criteria on this unit, BL 70 percent, CMS 50 percent, and the 17 percent inductance limit, all cluster near ±14 mm one-way (xBL ≈ 14.37 mm, xC ≈ 13.87 mm, xL ≈ 14.23 mm). That cluster is comfortably above the brochure’s “linear p-p” figure of 20.5 mm, which implies 10.25 mm one-way, so the published linear claim reads conservative for this sample. These ~14mm one-way limits are its only real downside, being that it doesn’t have a lot of excursion and clean volume potential is a bit more limited than most modern 12” subwoofers.

On the microphone, the 1 V baseline shows ~10 percent THD at 20 Hz with about 6.5 percent H2 distortion, along with another H2 distortion feature around 30 Hz that hits ~5 percent. At the standardized high-level, just below 70% BL criterion sweep of 10 V for this unit, distortion performance is good: THD is below 5 percent across the 20 to 120 Hz band, peaking near ~4 percent at 20 Hz and sitting around ~3 percent elsewhere. The benign jump from a slightly noisy low-level baseline to a clean high-level sweep suggests a low-drive mechanical or airflow noise floor that becomes masked under normal operating current, not a resonance that would persist with level.

Because Dynaudio does not publish sealed alignment volumes for this driver, we modeled from large-signal cold parameters. On this sample, ~0.95 ft³ sealed returns Qtc ≈ 0.707, placing the driver squarely in the “normal box size, neutral alignment” category for car use. With a large-signal cold Qts around the high-0.2s on this sample, we do not consider it an infinite-baffle candidate. The net picture is straightforward: use a normal sealed enclosure, expect low distortion and stable response to the edge of a ~13 to 14 mm one-way practical window, and add cone area rather than relying on low-frequency boost if you need substantially more output. As mentioned before, it’s a very accurate sounding subwoofer, but it is a bit limited on its output capabilities being it is limited to 14mm one-way xmax."

Manufacturer's suggested use case

Dynaudio positions the Esotar² 1200 as a reference-grade 12 inch automotive subwoofer built around a large 75 mm aluminum voice coil, an MSP cone on a rigid die-cast basket, and a massive dual-stacked motor. The brochure emphasizes very low distortion, quick transient behavior, and easy integration into high-performance systems, with headline items of 400 W long-term IEC power handling and 58 mm peak-to-peak maximum mechanical excursion (xmech) capability. The intended use reads as refined, sealed-box bass for high-end systems where control, predictability, and integration matter more than marketing theatrics and high volume systems.

Our suggested use case

Run it sealed. Start at ~0.95 ft³ net for ~0.707 Qtc using the large-signal cold set. Treat ~13 to 14 mm one-way as the practical clean operating target in normal sealed use on this unit; the 10 V sweep supports that headroom without in-band spikes, and BL, CMS, and Le all converge near that stroke. If more output is required, add cone area rather than leaning on heavy low-frequency boost due to its relatively limited xmax. We do not recommend IB with this model given the low Qts on this sample. We do not use or recommend high-pass filters on subwoofers in this project, since the goal is to show true low-frequency behavior.

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: 10 volts

Approximate electrical power at that limit at 20Hz: ~30 W into ~3.33 Ω Re in free air (real power varies with frequency and impedance) volts

Rated power (published): 400 W RMS (long-term IEC)

Power used to hit the standardized limits in free air, relative to their xmax rating free air: ~8 percent

Claimed Xmax vs. measured at BL 70%: 10.25 mm claim (from 20.5 mm p-p) vs 14.37 mm measured, ~140 percent of the claimed 10.25 mm

Xmax @ 50% Cms: 13.87 mm, ~135 percent of the claimed 10.25 mm

Xmax @ 17% Le: 14.23 mm from Le(x)/Le(i) variation on this sample, ~139 percent of the claimed 10.25 mm xmax

Manufacturer suggested sealed enclosure size (and its resulting QTC): No manufacturer recommendations.

Required sealed enclosure for 0.707 QTC: 0.95ft³ nets a 0.707 QTC.

Xmax @ 50% Cms: 13.87 mm, ~135 percent of the claimed 10.25 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-oct smoothing. Two drive levels, 1 V baseline and a high level set at 10 V per the under BL-70 rule derived from LSI for this unit, reaching 8.3mm at 20Hz for this sample. Distortion reported both as percent and by harmonic.

At 1 volt - baseline

Baseline distortion at 20 Hz is about 10 percent with H2 distortion ≈ 6.5 percent, and there is another H2 distortion feature near 30 Hz that reaches ~5 percent. Above roughly 40 Hz, the curve drops toward lower values in a normal, orderly way for a modern 12 working lightly. The character of the low-level artifacts does not indicate a sharp in-band resonance, and they do not persist in relative terms when level is raised. My personal theory, there is some low level mechanical noise that is measurable when the input signal is low, but is masked as volume is raised.

At high level voltage (10 volts)

At the standardized near-limit drive for this sample (10 volts, free air), THD remains below 5 percent across the 20 to 120 Hz band, peaking near ~4 percent at 20 Hz and running ~3 percent through most of the rest of the passband. The harmonic structure remains orderly with no new narrow in-band features. This matches the large-signal picture where BL, CMS, and Le limits arrive together near ±14 mm and none of them pinches clean headroom prematurely on this unit.

Delta - 1 volt distortion vs. high level distortion

The move from 1 V to 10 V is benign: a slightly noisy low-level baseline becomes clean and predictable at realistic drive. Nothing in the 10 V sweep suggests a hidden in-band problem, and the shape change tracks well with the measured LSI limit cluster.

What this means in practice

At real listening levels, this sample stays clean and predictable. The 10 volt sweep holds THD under 5 percent from 20 to 120 Hz, about 4 percent at 20 Hz and about 3 percent elsewhere, with no narrow in band spikes as level rises. The 1 volt baseline shows ~6.5 percent H2 at 20 Hz and a ~5 percent H2 feature near 30 Hz, but those low level artifacts are masked once current and excursion increase. This aligns with the LSI picture where BL, CMS, and Le limits arrive together near ±14 mm one way, and with the 10 volt free air result of ~8.5 mm at 20 Hz there is usable headroom before a mechanism becomes dominant.

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

The BL 70 percent point occurs at ~14.37 mm one-way on this sample. The central shelf is broad and the roll-off toward the boundary is smooth in both directions. In practical terms this gives the motor contribution room to operate cleanly to the vicinity of the other two limits.

Bl(x) symmetry

Behavior reads well controlled in the usable window for this sample, which fits the absence of strong even-order distortion growth at the high-level sweep.

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

We are using CMS for suspension commentary here. CMS 50 percent occurs at ~13.87 mm one-way on this sample, very close to the BL boundary. Compliance falls progressively with stroke as expected, with no hard knee appearing inside the standardized window.

Cms(x) symmetry

The CMS curve shows the expected coil-in versus coil-out difference in stiffness, but not to a degree that creates visible in-band distortion surprises in the 10V acoustic sweep on this sample.

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

The 17 percent inductance criterion occurs at ~14.23 mm one-way, effectively co-located with BL and CMS on this sample. The overall inductance curve shape is relatively linear and par for the course.

Current dependence

Within the levels used here, inductance behavior tracks the clean acoustic result, staying out of the way as a practical limit at our 10V TRF measurement.

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

Warm-state Qts at rest on this run sits in the high-0.2s. Over the near-limit operating window, the damping picture does not introduce in-band response drift in the 10V distortion measurement, which supports the sealed-box recommendation and the “no IB” guidance for this unit.

LSI takeaway

In this sample and under these test conditions, BL 70 percent, CMS 50 percent, and the 17 percent inductance limit all arrive close to ±14 mm one-way. That clustering, combined with the clean 10 V TRF sweep, points to predictable sealed-box behavior with practical clean headroom around ~13 to 14 mm one-way and no sharp in-band artifacts at the standardized near-limit drive. Its only main downside is that xmax is a bit on the low side for what most people need these days, and power handling is also a bit low.

Enclosure alignment calculations

Manufacturer sealed enclosured recommendations and the resulting QTC: There is no manufacturer recommended enclosure size.

Sealed volume required for 0.707 QTC on this sample: 0.95ft³ nets a 0.707 QTC.

Applicable for infinite baffle? No. QTC and xmax are too low.

T/S parameters