SP 4.500 features Hertz ADC (Advanced D-Class) output stage, reaching up to 87% efficiency and delivering an impressive power rating of 90 x 4 (4Ω) W RMS or 300 W x 2 (4Ω) W RMS when bridged, with an ultra-compact size of 192.7 (7.58) x 130 (5.1) mm (in.) x 49 (1.9).
Buyer confidence
88%Highlights
- Up to 87% efficiency thanks to ADC (Advanced D-Class) output stage.
- USS (Universal Speakers Simulators) allows SP 4.500 to work with head units featuring the “speaker load detection” circuit.
- 90 W RMS x 4 (4Ω) with ultra-compact size: 192.7 x 130 x 49 / 7.59 x 5.12 x 1.93 (mm/inch)
- IP55 aluminum chassis for maximum protection against humidity and external agents.
Key specs
Full specs- Channels
- 4 - 3 - 2
- Nominal power supply voltage
- 11 ÷ 15 VDC
- Pulse Operating voltage
- 6 ÷ 16 VDC
- Idling current
- 0.9 A
- Idling current when off
- 0.03 mA
- Consumption @ 14.4 VDC, MIN load impedance (Max Musical Power)
- 27 A
- Remote IN
- 6 ÷ 15 VDC (9 mA)
- DC-REM - Remote Turn on by SPK DC from OUTPUT BTL speakers
- 3.5 ÷ 7 VDC
Key specs
Full specs- Channels
- 4 - 3 - 2
- Nominal power supply voltage
- 11 ÷ 15 VDC
- Pulse Operating voltage
- 6 ÷ 16 VDC
- Idling current
- 0.9 A
Highlights
Overview- Up to 87% efficiency thanks to ADC (Advanced D-Class) output stage.
- USS (Universal Speakers Simulators) allows SP 4.500 to work with head units featuring the “speaker load detection” circuit.
- 90 W RMS x 4 (4Ω) with ultra-compact size: 192.7 x 130 x 49 / 7.59 x 5.12 x 1.93 (mm/inch)
Overview
SP 4.500 features Hertz ADC (Advanced D-Class) output stage, reaching up to 87% efficiency and delivering an impressive power rating of 90 x 4 (4Ω) W RMS or 300 W x 2 (4Ω) W RMS when bridged, with an ultra-compact size of 192.7 (7.58) x 130 (5.1) mm (in.) x 49 (1.9). Being ultra-compact with impressive power, SP 4.500 is the ideal choice for Motorcycle applications and for under-seat in sports cars and behind-seat installations in trucks.
Key features
- Up to 87% efficiency thanks to ADC (Advanced D-Class) output stage.
- USS (Universal Speakers Simulators) allows SP 4.500 to work with head units featuring the “speaker load detection” circuit.
- 90 W RMS x 4 (4Ω) with ultra-compact size: 192.7 x 130 x 49 / 7.59 x 5.12 x 1.93 (mm/inch)
- IP55 aluminum chassis for maximum protection against humidity and external agents.
- No cooling fan to prevent internal accumulation of dirt.
- Sealed power cord, line inputs and speaker outputs to prevent oxidation.
- Crossover filters and controls on a single side to facilitate calibration when the product is installed.
- Balanced fully-differential high-noise rejection inputs.
- ART (Automatic Remote Turn-On/Off) automatically turns on/off the amplifier when the OEM head-unit turns on/off (can be enabled/disabled).
- Technology
More info
Hertz ADC
(Advanced D-Class)
The Herz SP compact amplifier range consists of three high-performance models. There are two four-channel models, the flagship SP4.900 with 160 x 4 W RMS at 4Ω and the SP4.500 with 90 x 4 W RMS at 4Ω, and a mono model SP1.900 boasting 1000 W RMS at 1Ω.
Hertz SP amplifier are the first Hertz amplifier featuring the renewed Hertz ADC (Advanced D-Class) output stage, reaching up to 87% efficiency and delivering an impressive power rating, with an ultra-compact size.
Being ultra-compact with an impressive power, SP amplifiers are the ideal choice for Motorcycle application and for under-seat in sport cars and behind-seat installations in trucks.
Hertz ADC technology ensures SP amplifiers overtake the usual ultra-compact amplifier performances, delivering an outstanding S/N Ratio and THD specifications, and almost completely eliminating EMI and RFI noise, for peerless sound quality.
This versatility of the four-channel models is perfect to drive high-power (4Ω) front speakers with a bridged (4Ω) subwoofer.
SP amplifiers are 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 an internal cooling fan prevents the accumulation of dirt. SP amplifier’s 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.
SP amplifiers feature a built-in sealed power cord, line inputs, and speaker outputs for a bulletproof motorcycle application providing safe power delivery in even the worst weather conditions. The solid power supply harness ensures ultra-stable power and ground connection, preventing any loss of contact caused by vibration. Due to its specific design, SP amplifiers are 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 amplifiers.
Technologies

Technology
Up to 87% efficiency thanks to ADC (Advanced D-Class) output stage

Technology
USS (Universal Speakers Simulators) allows SP 4.500 to work with head units featuring the “speaker load detection”

Technology
90 x 4 RMS (4Ω) with ultra-compact size (192.7 x 130 x 49 mm)

Technology
IP55 aluminum chassis for maximum protection against humidity and external agents
Specs
General Specs
| Channels | 4 - 3 - 2 |
| Nominal power supply voltage | 11 ÷ 15 VDC |
| Pulse Operating voltage | 6 ÷ 16 VDC |
| Idling current | 0.9 A |
| Idling current when off | 0.03 mA |
| Consumption @ 14.4 VDC, MIN load impedance (Max Musical Power) | 27 A |
| Remote IN | 6 ÷ 15 VDC (9 mA) |
| DC-REM - Remote Turn on by SPK DC from OUTPUT BTL speakers | 3.5 ÷ 7 VDC |
| Distortion - THD @ 1 kHz, 4Ω, 70% Rated Power | <0.02% |
| Damping factor @ 1 kHz, 4Ω, 2 VRMS | >150 |
| Bandwidth @ -3 dB | 10 Hz ÷ 35 kHz |
| S/N ratio (A weighted @ 1 V Input) | 100 dBA |
| Pre-In sensitivity | 0.6 ÷ 6 VRMS |
| Speaker-In sensitivity | 2.2 ÷ 22 VRMS |
| @ 4Ch | 2Ω |
| @ 3Ch | 2Ω + 2Ω + 4Ω |
| @ 2Ch | 4Ω |
| IP Rating | IP55 |
| Operating Temperature Range | 0°C (32°F) to 55°C (131°F) |
| Max size (mm/inch) | 192.7 x 130 x 49 / 7.58 x 4.18 x 1.9 |
| Weight (kg/lbs) | 2.15 / 4.74 |
| Adjustable Crossovers | yes |
Output Power
| 4 Ch: | 90 W x 4 (4Ω) |
| 4 Ch: | 150 W x 4 (2Ω) |
| 3 Ch: | 80 W x 2 (4Ω) + 330 W x 1 (4Ω) |
| 3 Ch: | 145 W x 2 (2Ω) + 300 W x 1 (4Ω) |
| 2 Ch: | 300 W x 2 (4Ω) |
| Total Power | 600 W |
INPUTS / FILTERS
| INPUTS: | Pre IN / Speaker IN |
| Full | Yes |
| Hi-pass | 50 ÷ 5k Hz @ 12 dB/Oct. |
| Lo-pass: | 50 ÷ 5k Hz @ 12 dB/Oct. |
| Full | Yes |
| Hi-pass | 50 ÷ 5k Hz @ 12 dB/Oct. |
| Lo-pass | 50 ÷ 5k Hz @ 12 dB/Oct. |
| Bass Boost 45Hz (adjustable) | OUT 3 - 4 (0 ÷ 8) dB [LP = ON only] |
Physical Specs

| mm | in |
| A | 185.7 | 7.31 |
| B | 192.7 | 7.58 |
| C | 107 | 4.21 |
| D | 130 | 5.12 |
| E | 49 | 1.93 |
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