SLAPS-M8v2 Passive Radiator

Key Features

• Increases output without added amplifier power or enclosure volume
• Suitable for high output needs where space is limited
• User-tunable adjustments can be set to match a range of vehicle requirements and musical preferences
• Installs just like a subwoofer
• Slim-mount design is only 3-inches deep
• No increase over existing sealed subwoofer enclosure sizes
• No annoying port noise
• Easy tuning for quick adjustments
• Preinstalled 160g mass with hardware included

The SLAPS-M8v2 passive radiator boasts impressive performance with extended excursion capability. It also features a very rational price due to the annular stamped steel chassis. Earthquake SLAPS are tunable passive radiators that provide additional bass without additional amplifier power or enclosure volume. Designed to perfectly complement all good-quality long-throw woofers on the market, SLAPS add up to +6dB of bass compared to regular sealed and ported enclosures. The benefit of being user-tunable is that they can be integrated into virtually any subwoofer and cabinet combination.

The SLAPS-M8v2 passive radiator is a patented passive device that significantly increases subwoofer efficiency and the ability for ultra-low frequency reproduction. SLAPS is short for Symmetrically Loaded Audio Passive System. As the name indicates, SLAPS is built symmetrically, distinguishing it from traditional passive devices. SLAPS technology integrates identical components in its suspension design, resulting in identical stoke regardless of forward or backward motion. The pneumatic coupling between SLAPS and an active driver results in high efficiency and performance.

SLAPS overcomes the limitations known from the conventional sealed and ported enclosures that tend to limit excursion. The unique design allows the active driver compression-free excursion, resulting in deep, dynamic, and powerful bass response.

The patented design of the SLAPS-M8v2 passive radiator and all of Earthquake’s SLAPS passive bass radiators differ from other passive devices today by incorporating a double edge suspension and no center spider. SLAPS is designed from the ground up to be operated and controlled pneumatically. Traditional passive devices are often just regular active drivers where the primary motor system (voice coil and magnet) has been removed. Conventional devices are designed to be powered electrically, in which the force emanates from the driver’s conical center. A passive device is operated pneumatically by air pressure from the active driver. A traditional unit does not perform identically in positive and negative pressure environments for pneumatic operation. (imploding edge suspension and positive over ring).

Earthquake SLAPS are far superior to the competition because they have a dual structure of identical opposites, i.e., there is an introvert, an extrovert edge suspension, and no spider. This gives identical properties in both the negative and positive pressure domains. Thus, SLAPS behave pistonically and accurately; they do not have the “hesitation” traditional passive devices seem to have when you observe them in operation.

SLAPS opens up new subwoofer design possibilities where even smaller enclosures can be tuned to low frequencies. The Earthquake MiniMe series of powered subwoofers is a prime example of this. The low weight allows great flexibility in terms of weight attachment. SLAPS can be custom-tuned for optimum performance in various enclosure sizes and active device configurations.

Damping is critical in a passive device because it does not have a magnet motor system to control it. It is essential that the passive device is constantly “leaning” up against the pneumatic environment in the cabinet. If the device’s compliance is too weak, the result is over-shoot and over-ring. For example, a transient in the music causes a rapid pressure ratio change in the cabinet, and control over the device can be lost – making it move more than it should. The same thing can happen to a standard woofer unit if the suspension + motor system is not built correctly. The design of the edge suspension itself is crucial. If not precisely designed, it may implode, i.e., be sucked backward if the pressure in the enclosure is too intense. A full implosion is rare, but in most typical slave/passive/drone designs, some “dimples” in edge suspension can be visible already at medium load. The average passive device only has a one-way edge suspension, so the dimples will only occur when negative pressure is present. Asymmetrical artifacts = distortion.

SLAPS’ dual structure is based on the principle of identical opposites, which eliminates the circumstances that would allow asymmetric nonlinearities because the device is subjected to identical loads. You could argue that it does not fundamentally resolve dimples at high loads, as they will still occur, but offsets them as they now occur similarly under both positive and negative pressure.

SLAPS enables the transfer of high amplifier power into low frequency output. Since the device does not have to fight against increasing pneumatic pressure in a closed cabinet or over-excurt close to a port tuning frequency. SLAPS has no annoying port noise and enables deep bass from a compact volume. It promotes the dynamics of a small system in which a closed enclosure design has difficulties. In a closed cabinet design, the pneumatic loading of the woofer increases as a function of its travel, which causes compression. SLAPS technology possesses none of these limitations. It allows tuning below 10Hz, making any worries about tuning frequency superfluous.

The SLAPS-M8v2 passive radiator is featured in the MiniMe DSP P8B and MiniMe DSP P8W home audio subwoofers.