18 Sound 10MB400 – LF Drivers

18 Sound 10MB400 – High-Sensitivity 10-Inch Ferrite Mid-Bass with Copper ISV Voice Coil and 6100 Hz Bandwidth

The 18 Sound 10MB400 is a high-sensitivity 10-inch ferrite mid-bass driver that achieves 100.5 dB sensitivity and a 6100 Hz bandwidth from a 21 g moving mass — the lightest of any 10-inch driver in 18 Sound’s ferrite mid-bass range. With a 50 mm copper ISV voice coil, a copper shorting ring on the pole piece for linearised impedance and improved transient response, and a dampened linen double half-roll surround that controls vibrational modes while providing clean excursion, the 18 Sound 10MB400 is built for applications where mid-band output, bandwidth, and clarity define the system’s quality.

The 100.5 dB sensitivity from a 10-inch driver is exceptional — 2.5 dB above the 10MB600/10MB777 platform’s 98 dB despite using a smaller 50 mm coil rather than their 75 mm. The 21 g moving mass is less than a third of the 10MB600’s 38 g, and the copper winding’s higher conductivity extracts more sensitivity from the lighter assembly. Most professional 10-inch woofers operate in the 94–98 dB sensitivity range. The 18 Sound 10MB400 sits 2.5–6.5 dB above that field.

The 6100 Hz upper bandwidth is the widest of any 10-inch driver in 18 Sound’s range — exceeding the 10MB600/10MB777’s 4500 Hz, the 10NW750’s 5000 Hz, and the 10NTLW2500’s 4500 Hz. It means the 18 Sound 10MB400 produces usable output well into the upper mid-range where vocal presence and consonant clarity define intelligibility. In compact two-way systems, the driver can be crossed over at 2500–3000 Hz with extensive overlap into the compression driver’s range.

18 Sound designed the 18 Sound 10MB400 as an extremely versatile 10-inch driver that functions in three distinct roles: mid-bass component with a 1-inch compression driver, dedicated bass driver in compact 15–25 litre reflex enclosures, or direct-radiating midrange unit. 18 Sound now lists the 10MB600 as the current alternative model.

Design and Construction of the 18 Sound 10MB400

The 18 Sound 10MB400 uses a 50 mm (2-inch) copper wire ISV (Interleaved Sandwich Voice Coil) wound on a high-strength glass fibre former. The copper winding is a notable material choice — the 10MB600/10MB777 platform uses aluminium wire on a 75 mm coil, while the 18 Sound 10MB400 uses pure copper on a smaller 50 mm coil. Copper is denser and more electrically conductive than aluminium, providing lower DC resistance per unit of conductor length. The trade-off is weight per turn, but the smaller coil diameter and ISV’s mass-balanced construction keep total moving mass to 21 g.

A copper shorting ring on the pole piece reduces voice coil inductance, linearises the impedance curve through the upper operating range, and improves transient response and phase control in the mid frequencies. For a driver operating to 6100 Hz — well into the upper mid-range — impedance control through the copper ring is critical. The 10MB600/10MB777 platform carries no such ring, which is why its 1.6 mH Le is nearly six times higher than the 18 Sound 10MB400’s 1.05 mH despite the larger coil.

The curvilinear paper cone uses 18 Sound’s high-quality wood pulp composition. The cone is carried by a dampened linen double half-roll front suspension — a unique surround choice that controls vibrational modes while providing good excursion capability. The dampened linen material absorbs resonant energy that untreated fabric or rubber surrounds would transmit back into the cone.

The 2.5 mm Xmax is deliberately short — far shorter than the 10MB600/10MB777’s 6.5 mm. The 18 Sound 10MB400 operates in the mid-bass and mid-range frequency bands where minimal cone displacement generates high SPL, sacrificing excursion for sensitivity and bandwidth.

The ferrite magnet assembly uses FEA-optimised pole pieces to maximise flux density and Bl factor in the air gap. At 4.7 kg, 260 mm overall diameter, and 121 mm depth, the 18 Sound 10MB400 is 2.5 kg lighter and 6 mm shallower than the 10MB600/10MB777’s 7.2 kg / 127 mm.

Performance and Applications for the 18 Sound 10MB400

The 18 Sound 10MB400 delivers 100.5 dB sensitivity across a 65 Hz – 6100 Hz bandwidth — the highest sensitivity and widest bandwidth of any ferrite 10-inch mid-bass in 18 Sound’s range. The Thiele–Small parameters show a versatile alignment profile: Qts of 0.33 and EBP of 189 Hz place the driver in the sealed/vented transitional zone.

18 Sound recommends a 20-litre (0.71 ft³) vented enclosure tuned to 75 Hz. The 250 W AES / 320 W continuous program power handling is far lower than the 10MB600/10MB777’s 450 W — the trade-off for the lighter coil and higher sensitivity. For the 18 Sound 10MB400’s intended role in mid-bass and mid-range reproduction, 250 W AES provides adequate headroom, especially since the 100.5 dB sensitivity means less amplifier power is needed to reach any given SPL.

The three-role versatility that 18 Sound highlights — mid-bass, bass, or midrange depending on system architecture — is genuine. At 100.5 dB sensitivity with 6100 Hz bandwidth, few 10-inch drivers from any manufacturer span all three roles as convincingly.

The comparison across the ferrite 10-inch mid-bass tier gives builders clear decision criteria. The 18 Sound 10MB400 delivers the highest sensitivity (100.5 dB), widest bandwidth (6100 Hz), lightest weight (4.7 kg), and lowest inductance (1.05 mH via copper ring) — the efficiency and bandwidth specialist. The 10MB600/10MB777 platform delivers nearly double the power handling (450 vs 250 W AES) and more than double the Xmax (6.5 vs 2.5 mm) from a heavier 75 mm coil — the displacement and power specialist.

Conclusion – 18 Sound 10MB400 Mid-Bass Driver

The 18 Sound 10MB400 is the highest-sensitivity, widest-bandwidth ferrite 10-inch driver in 18 Sound’s range — achieved through a 50 mm copper ISV coil with copper shorting ring rather than the larger 75 mm aluminium coil found on the 10MB600/10MB777 platform. The trade-off is displacement: 2.5 mm Xmax limits low-frequency output below 100 Hz, positioning this as a mid-band sensitivity driver rather than a bass-extension driver.

The copper shorting ring, copper ISV coil, and dampened linen surround together provide the impedance linearisation and transient response that mid-band-focused drivers need. For compact two-way systems, stage monitors, vocal reinforcement, and direct-radiating midrange applications where a 10-inch driver needs to deliver 100.5 dB sensitivity across the widest possible bandwidth from a lighter, proven ferrite platform, the 18 Sound 10MB400 is the efficiency benchmark of 18 Sound’s 10-inch ferrite range.