Hertz SP4.500 – Advanced 4-Channel Class-D Motorcycle Amplifier (600W RMS / 150W x4 @ 2Ω)
$800.00 AUD
SKU: SP4500
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Hertz SP4.500 – Advanced 4-Channel Class-D Motorcycle Amplifier (600W RMS / 150W x4 @ 2Ω)
$800.00 AUD
SKU: SP4500
| Channels | 4 Channel |
| Power | 4x90W RMS |
| Year Range | 1998-2013, 2014-2023, 2024+, Trike 2009-2013, Trike 2014-2025, Trike 2026+ |
Hertz SP 4.500 – Compact 4-Channel Amplifier for High-Efficiency Harley Audio Builds
The Hertz SP 4.500 is a compact, efficient 4-channel Class-D amplifier tailored for motorcycle audio systems that run high-sensitivity speakers and need clean power without the complexity of oversized amps. With an IP55 weather-resistant rating and a low-profile chassis, it fits easily into Harley Touring fairings while delivering reliable performance at volume.
Who This Is For
- Riders running high-sensitivity speakers, such as the Hertz SX and SV series, who want clean power without an oversized amp.
- Street Glide and Road Glide builds where fairing space is tight and the amplifier has to sit low-profile.
- Riders who want a front stage and a subwoofer from one amplifier, using 3-channel mode instead of adding a second amp.
- Bikes on stock or mildly upgraded charging systems, provided fused power and ground wiring are correctly sized.
Key Features
- 90 W × 4 RMS @ 4 Ω (@ 14.4 VDC, 1% THD) – ideal for powering high-efficiency SPL speakers.
- 150 W × 4 RMS @ 2 Ω (@ 14.4 VDC, 1% THD) – additional headroom for demanding systems.
- Bridged Mode: 300 W × 2 RMS @ 4 Ω (@ 14.4 VDC, 1% THD) when running 2-channel configurations.
- 3-Channel Mode: 80 W × 2 @ 4 Ω + 330 W × 1 @ 4 Ω, or 145 W × 2 @ 2 Ω + 300 W × 1 @ 4 Ω (@ 14.4 VDC, 1% THD) – run a front stage and a subwoofer from a single amplifier.
- Up to 87% efficient ADC (Advanced D-Class) output stage with a 27 A maximum musical current draw.
- IP55 weather resistance protects against water, dust, and road grime.
- Ultra-compact chassis (192.7 × 130 × 49 mm) fits tight Harley fairings.
- Pre-level and speaker-level inputs (0.6–6 V and 2.2–22 V) for flexible system integration.
- Selectable crossovers for high-pass, low-pass, or full-range operation, adjustable 50 Hz to 5 kHz @ 12 dB/octave on both channel pairs.
Why It Works on Harleys
- Perfect match for high-efficiency speakers like Hertz SX and SV series.
- Compact size allows clean installation in Street Glide and Road Glide fairings.
- Weather-ready design handles open-air motorcycle environments.
- Efficient power draw suits bikes running stock or mildly upgraded charging systems, once fused power and ground wiring are correctly sized.
Recommended System Use
- Front Stage: Powers 6.5″ coaxials or SPL midranges with ease.
- Full Bike System: Run front + rear speakers on one amplifier.
- Front Stage + Subwoofer: 3-channel mode drives a pair of speakers plus a subwoofer from the one amplifier – the simplest way to add low-end without a second amp.
- Active Setups: Use two channels for mids and two for tweeters when DSP-controlled.
Fitment
- Designed for Harley-Davidson® Touring motorcycles
- Suitable for Street Glide, Road Glide, Ultra Limited and CVO models
- Fits factory fairings, amp trays, or aftermarket amp plates
Specifications
| Channels | 4 |
| RMS Power @ 4 Ω | 90 W × 4 @ 14.4 VDC, 1% THD |
| RMS Power @ 2 Ω | 150 W × 4 @ 14.4 VDC, 1% THD |
| RMS Power (Bridged @ 4 Ω) | 300 W × 2 @ 14.4 VDC, 1% THD |
| RMS Power (3-Channel Mode) | 80 W × 2 @ 4 Ω + 330 W × 1 @ 4 Ω, or 145 W × 2 @ 2 Ω + 300 W × 1 @ 4 Ω (@ 14.4 VDC, 1% THD) |
| Total RMS Power | 600 W @ 14.4 VDC, 1% THD |
| CEA-2006 Power | 75 W × 4 @ 4 Ω |
| Minimum Load Impedance | 2 Ω (4-channel), 2 + 2 + 4 Ω (3-channel), 4 Ω (bridged) |
| THD | < 0.02% @ 1 kHz, 4 Ω, 70% rated power |
| Efficiency | Up to 87% |
| Max Musical Current Draw | 27 A |
| Bandwidth (−3 dB) | 10–35,000 Hz |
| Signal-to-Noise Ratio | 100 dBA |
| Damping Factor | > 150 |
| Pre-In Sensitivity | 0.6–6 V |
| Speaker-In Sensitivity | 2.2–22 V |
| Crossovers | HPF / LPF / Full-Range – 50 Hz to 5 kHz @ 12 dB/octave, high-pass and low-pass, on both channel pairs |
| Dimensions | 192.7 × 130 × 49 mm |
| Weight | 2.15 kg |
| IP Rating | IP55 |
Specifications per Hertz published technical documentation.
Need System Design Help?
The SP 4.500 is ideal for efficient SPL setups. We can help you match speakers, crossovers, and DSP settings to create a clean, balanced system for your Harley.
Related collections
This part is listed in: All 2014–2023 Touring Audio · Amplifiers · Hertz – Amplifiers
Australia Shipping:
- Under $500 → $19.95
- $500–$2,500 → $14.95
- $2,500 and above → FREE
- Bulky items → +$25 surcharge (waived once your order reaches $2,500)
Fast dispatch from Brisbane. In-stock orders placed before 1pm AEST usually ship the same business day.
Change of mind: Request a return within 30 days of delivery. The product must be unused, unopened and in its original sealed packaging, valued at $50 or more, and you'll need an RMA number from us before sending anything. Return freight is yours, and a restocking fee of up to 15% may apply – we'll confirm any fee before the return is accepted.
Not returnable for change of mind: opened, installed or test-fitted items, special-order and custom products, custom harnesses, completed tuning, gift cards and items under $50.
Fitment: If we confirmed fitment in writing based on accurate bike details and it doesn't fit, we'll put it right and cover reasonable freight. Not sure? Ask us before you order – we're happy to help.
Faulty, damaged or wrong item: Contact us first with your order number. Faults follow our RMA and warranty process, and none of this affects your rights under the Australian Consumer Law.