Hertz ADC
(Advanced D-Class)

SP 4.900 is the first Hertz amplifier featuring the renewed Hertz ADC (Advanced D-Class) output stage, reaching up to 85% efficiency and delivering an impressive power rating of 160 x 4 (4Ω) W RMS or 500 W x 2 (4Ω) W RMS when bridged, with an ultra-compact size of 211.6 (8.3) x 130 (5.1) mm (in.). Being ultra-compact with an impressive power, SP 4.900 is the ideal choice for Motorcycle application and for under-seat in sport cars and behind-seat installations in trucks.


Hertz ADC technology ensures SP 4.900 overtakes the usual ultra-compact amplifier performances, delivering an outstanding 105 dBA S/N Ratio and 0.02% THD specifications, and almost completely eliminating EMI and RFI noise, for peerless sound quality.

This versatility is perfect to drive high power (4Ω) front speakers with a bridged (4Ω) subwoofer.

SP 4.900 is fully protected against overheating and DC outputs, immediately switching in protection mode (red led on) to save your speaker system.

The IP55 certified Aluminum chassis offers maximum protection against humidity and external agents and the absence of internal cooling fan prevents internal accumulation of dirt. SP 4.900 main board has conformal coating layers to prevent harm caused by internal condensation, a condition that can happen when warm, moist air meets the amp chassis of a lower temperature.

All controls are protected by a removable aluminum panel, to make the SP 4.900 IP55 compliant, preventing humidity reaching the switches.

SP 4.900 features a built-in sealed power cord, line inputs and speaker outputs for a bulletproof motorcycle application providing safe power delivery in even the worse weather conditions. The solid power supply harness ensures ultra-stable power and ground connection, preventing any loss of contact caused by vibration. Due to his specialized design, SP 4.900 is the ultimate option for Motorcycle, Marine, and Powersports applications.

SP 4.900 features built-in USS (Universal Speakers Simulator), a dynamic load circuit on Hi-Level inputs which initially shows the OEM output channel a load low enough to neutralize OEM speaker outputs muting protection circuit. Once the circuit activates, a higher load is introduced – still low enough to damp Class D outputs, but not low enough to cause current issues or heat dissipation problems.

SP 4.900 offers both remote-in signal detection and DC offset sensing on the speaker inputs for automatic turn on, providing total integration with any vehicle.

The versatile crossover filters and control knob are all located on a single side, to allow an easy calibration when the product is installed.

The filters section includes extremely flexible high-pass and low-pass crossovers, adjustable from 50 Hz to 5 kHz with 12 dB/Oct slope. Together with a bass-boost control (45 Hz, 0÷8 dB), they allow both front channels to be configured for full-range operation, or for use with a subwoofer and related speakers.

The high-pass crossover can also be used to optimize the performance of SPL Show NEO high-efficiency coaxial speakers, the perfect partners for SP 4.900.