Martin Logan Depth Subwoofer

Description

The MartinLogan Depth is a compact, sealed powered subwoofer built around three 8-inch aluminum-cone drivers. Its “BalancedForce” arrangement places the drivers in opposing pairs, with a third driver completing the system. The design aims to reduce cabinet vibration while providing substantial bass from a relatively small enclosure. A built-in 300-watt RMS amplifier powers the drivers, and servo control monitors their movement.

The Depth offers several ways to integrate with a system: stereo RCA line inputs, an LFE input, and high-level speaker inputs. Its selectable low-pass crossover ranges from 30 to 80 Hz, and a high-pass output can route filtered signal to the main speakers. Phase can be adjusted in four steps—0°, 90°, 180°, or 270°—and a 25 Hz control provides up to ±12 dB of adjustment. These controls are useful for tailoring the subwoofer to the room and speakers, but careful placement and listening tests remain important.

The sealed design and specified 20–150 Hz response make the Depth a flexible partner for both music and home theater. Its 16-inch-square footprint is manageable compared with many subwoofers, although the 65-pound cabinet is not lightweight. The 300-watt amplifier is rated for 500 watts peak. It also includes an automatic signal-sensing standby function and outputs that can support integration with additional subwoofer equipment.

A Stereophile review of the Depth listed a frequency response of 20–150 Hz, ±3 dB, and described it as a servo-controlled, sealed subwoofer using BalancedForce Technology. An owner reviewing the later Depth i—a related model, not the exact original Depth—reported that the subwoofer “dramatically increased” the depth and width of the soundstage in his system, and praised its low-frequency extension and dynamics. That is an individual listening impression of the Depth i, so it should not be taken as a controlled finding or assumed to apply identically to every Depth.

The Depth may particularly suit systems where a conventional subwoofer’s cabinet vibration or size is a concern, and its high-level connections can make it convenient to use with two-channel systems. Its performance will depend on room acoustics, placement, crossover settings, and the capabilities of the main speakers. As with any used subwoofer, a proper in-room audition are more informative than specifications alone.

• Type: Powered, servo-controlled subwoofer; sealed enclosure
• Driver array: Three 8-inch high-excursion aluminum-cone woofers with 1.5-inch push-pull voice coils
• Technology: BalancedForce
• Frequency response: 20–150 Hz (±3 dB)
• Amplifier: 300 W RMS, 500 W peak, Class D
• Low-pass crossover: 30, 35, 45, 55, 65, or 80 Hz; 18 dB/octave; defeatable
• High-pass filter: 40 or 70 Hz; defeatable
• Phase settings: 0°, 90°, 180°, 270°
• 25 Hz adjustment: ±12 dB
• Inputs: Two RCA line-level, one RCA LFE, high-level speaker inputs
• Outputs: RCA high-pass output and RCA output without high-pass filtering
• Dimensions (W × H × D): 16.6 × 16.25 × 16.15 inches
• Weight: 65 pounds (29.5 kg)