Grimm Audio SB1 Motion Feedback Subwoofer

The Grimm Audio SB1 does what no conventional subwoofer can: it measures the cone's movement 96,000 times per second and corrects it in real time. Digital Motional Feedback reduces distortion by up to 30 dB, delivering bass that is linear to 20 Hz without the bloat, resonance, or delayed decay that plagues every other sub in this price range. Designed in the Netherlands to transform any Grimm LS1 speaker into a full three-way system, the SB1 sits beneath the loudspeaker between its support legs, connected by short cables that carry both signal and power.

Key Features of the Grimm Audio SB1

• Digital Motional Feedback (DMF): A piezoelectric acceleration sensor mounted directly on the cone feeds a 96 kHz correction loop, reducing distortion by up to 30 dB compared to conventional subwoofers.
• Linear to 20 Hz: Flat frequency response from 20 Hz to 250 Hz (+/-2 dB) in half-space placement, with driver resonance tuned to 15 Hz (Q of 0.5).
• 700W nCore Hypex Amplification: Class D power module delivers clean, controlled output with a maximum SPL of 96 dB per unit (102 dB per pair) across 30-250 Hz.
• Phase-Corrected Crossover: When paired with any LS1 speaker, the system's DSP implements a phase-corrected crossover at 70 Hz without phase discontinuity.
• Upward-Firing 10" Aluminum Woofer: Modified driver with acceleration sensor fires upward, transferring minimal energy into the LS1's support legs.
• Sealed Enclosure: No port, no passive radiator. Multi-layered CNC-machined MDF construction eliminates cabinet resonance.
• IEC Pass-Through: Built-in mains outlet powers the LS1 speaker directly, reducing cable clutter to a single power cord from the wall.
• Third-Party Compatibility: A rear-panel switch enables standalone operation with non-Grimm speakers via XLR input.
• Ultra-Low DSP Latency: 38 microsecond processing delay ensures perfect time alignment with the main speakers.

Digital Motional Feedback: Engineering That Hears the Driver

Below 100 Hz, loudspeaker drivers must move enormous volumes of air. High excursion levels and the fundamental driver resonance produce rising distortion and a characteristic "thickening" of bass that colors everything. Motional feedback, the concept of monitoring a driver's actual movement and correcting it electronically, has existed since the 1970s. Grimm Audio's implementation is different in both precision and execution.

An analog piezoelectric acceleration sensor is bonded to the SB1's aluminum cone, providing 16-bit resolution at 96 dB signal-to-noise ratio with bandwidth exceeding 3 kHz. This sensor feeds a digital correction loop that combines smart DSP processing with current-drive amplification. The result: up to 30 dB of distortion reduction across the effective feedback range (up to 250 Hz). The low-distortion aluminum woofer, already a high-performance driver, becomes something closer to a laboratory instrument. Bass notes start and stop with precision that sealed and ported designs simply cannot match. The technology is licensed from RMS Acoustics and refined by Grimm's own engineering team, building on a lineage that began with the LS1s-DMF in 2016.

Built for the Grimm LS1 System

The SB1 was designed as the bass extension for Grimm's LS1 loudspeaker series, converting any two-way LS1 into a full three-way active system. Physically, the sub fits beneath the LS1 between its support legs, keeping the main speaker at the correct listening height while adding genuine deep bass capability. Short cables pass both digital data and power between the units, and the IEC pass-through means only one power cord runs to the wall per channel.

The LS1's internal DSP handles crossover duties, implementing a phase-corrected filter at 70 Hz that maintains the system's legendary time-domain accuracy. There is no external processor to configure, no crossover knob to adjust. The system simply works as an integrated whole. Reviewers consistently note that the SB1 "disappears" into the sound, filling out the bottom octaves without ever calling attention to itself.

The SB1 is compatible with all current LS1 models: the LS1c, LS1v2, and LS1a.

Third-Party Speaker Compatibility

A rear-panel switch sets the SB1 to standalone mode for use with non-Grimm speakers. In this configuration, the sub accepts a mono XLR signal (RCA adapter compatible) and operates as a conventional powered subwoofer. Note that standalone mode does not include built-in volume control, adjustable crossover, or low-pass filtering. An external active crossover or AV receiver/processor is required for proper integration with third-party systems. The Mono variant is sold as a single unit for this purpose.

Explore the Full Grimm Audio Loudspeaker Series

The SB1 pairs with every speaker in the Grimm LS1 range. The Grimm Audio LS1c is the flagship two-way, featuring beryllium dome tweeter and the most refined cabinet construction. The LS1v2 delivers the core LS1 experience at a lower price point, while the LS1a makes the LS1 philosophy accessible to a wider audience. For source components, the MU1 Music Streamer and MU2 Digital Music Streamer were designed as the ideal digital front end for the LS1 system.

The Listening Room Difference

We're a third-generation family business with a brick-and-mortar showroom in Chestertown, Maryland, and a reputation built on exceptional service and relentless passion for hifi. Whether you're visiting in person or ordering online, we bring decades of experience, personalized service, and honest guidance to every interaction. We don't just ship boxes. We help build systems, answer your questions like real humans, and make sure every detail of your setup is right, from the cables to the final connection. Our passion is helping you get the most out of your gear, with support that lasts well beyond the sale.

Grimm Audio SB1 Specifications