Hertz HMP1D – Compact 1-Channel Class-D Motorcycle Subwoofer Amplifier (250W RMS @ 2Ω)
$595.00 AUD
SKU: HMP1D
Skip to product information
Hertz HMP1D – Compact 1-Channel Class-D Motorcycle Subwoofer Amplifier (250W RMS @ 2Ω)
$595.00 AUD
SKU: HMP1D
| Channels | 1 Channel |
| Power | 250W RMS |
| Year Range | 1998-2013, 2014-2023, 2024+, Trike 2009-2013, Trike 2014-2025, Trike 2026+ |
The compact, weather-resistant mono amplifier for a shallow Harley sub without a charging upgrade
The Hertz HMP 1D is a compact IP64-rated mono amplifier that delivers 150W RMS at 4 ohm and 250W RMS at 2 ohm (@ 14.4 VDC, 1% THD), sized at just 223 x 100.5 x 43.6mm. It is built to power an 8 to 10 inch motorcycle subwoofer in a fairing, Tour-Pak or custom bag enclosure, with a remote bass level control, selectable low-pass and subsonic filters and a bass boost included. Its low current draw suits a stock Harley charging system.
This is the sensible-bass mono amp: clean, controlled low end without the heavy electrical demand of a high-output sub amplifier. For a full-range front and rear build, pair it with the four-channel Hertz HMP 4D to run speakers and sub from a matched Hertz pair.
Who This Is For
You want clean daily-ride bass from a compact subwoofer without upgrading the charging system. The HMP 1D suits a shallow 8 to 10 inch sub such as a Hertz MPS 250 S4 in a Tour-Pak, side-cover or saddlebag enclosure. If you are chasing maximum SPL from dual subs, a higher-output mono amp like the SounDigital EVO PS 1200.1 is the bigger option.
What This Is Best For
- A compact single sub. 150W RMS at 4 ohm or 250W RMS at 2 ohm (@ 14.4 VDC, 1% THD) is the right power band for a shallow 8 to 10 inch motorcycle sub, which is what most riders actually fit.
- Low draw on a stock charging system. The HMP 1D asks far less of the alternator than a big mono amp, so you can add bass without an immediate stator or battery upgrade.
- Real weather resistance. The IP64-rated chassis shrugs off rain, washdowns and dust, so it can live in a fairing or side cover on a bike that rides in all conditions.
- On-the-fly control. The included remote bass level control lets you trim low end from the bars, and the selectable low-pass, subsonic and bass boost settings tune it to the enclosure.
Match the sub and the enclosure
The HMP 1D is tuned for compact bass, so pair it with a shallow 8 to 10 inch sub in a sealed enclosure sized to the driver. At 2 ohm it makes 250W RMS (@ 14.4 VDC, 1% THD), with a 300W maximum power figure quoted at 10% THD, so wire a 2 ohm sub or a parallel pair to get the most from it. Tell us your enclosure and we will help match the right sub.
Fitment
| Model | Mounting | Application |
|---|---|---|
| Harley-Davidson® Touring | Inner fairing, under-radio, side cover | 8 to 10 in subwoofer |
Inside the HMP 1D
The amplifier is a compact Class-D mono design with an IP64-rated chassis. IP64 means sealed against dust and protected from splashing water, which is exactly the exposure a fairing or side-cover amp sees. On the road: rain and a washdown do not reach the electronics, so the amp keeps working through weather that would kill an unsealed unit.
The filter set and remote level make it flexible. This is a bass-only monoblock, so the filters are built for subwoofer duty rather than full-range work: a selectable low-pass at 65, 85 or 115 Hz at 12 dB/oct, a subsonic filter set to off, 22, 32 or 45 Hz at 12 dB/oct, and a 50 Hz bass boost switchable between off, +6 dB and +9 dB. There is no high-pass filter and no full-range setting. In practice: you set the low-pass to suit the sub, use the subsonic filter to protect it from enclosure-unloading frequencies, then trim bass from the bars for a highway run or back for town without touching the amp.
Technical Specifications
| Channels | 1 (mono) |
| Power at 4 ohm (RMS) | 150W x 1 (@ 14.4 VDC, 1% THD) |
| Power at 2 ohm (RMS) | 250W x 1 (@ 14.4 VDC, 1% THD) |
| Maximum power at 2 ohm | 300W x 1 (@ 14.4 VDC, 10% THD) |
| Minimum stable impedance | 2 ohm |
| Frequency response | 10Hz to 500Hz |
| Low-pass filter | 65 / 85 / 115Hz selectable, 12dB/oct |
| Subsonic filter | Off / 22 / 32 / 45Hz, 12dB/oct |
| Bass boost | 50Hz, Off / +6dB / +9dB |
| Input sensitivity | Low level 0.2 to 5V, high level 0.8 to 20V |
| Signal-to-noise ratio | 105dB (A-weighted @ 1V) |
| THD | 0.1% (100Hz @ 4 ohm) |
| Damping factor | 300 (100Hz @ 4 ohm) |
| Supply voltage | 11 to 15 VDC |
| Fuse | 1 x 15A |
| IP rating | IP64 |
| Remote level control | Included |
| Dimensions | 223 x 100.5 x 43.6mm |
| Weight | 1.35kg |
Specifications per Hertz published technical documentation.
Australia Shipping:
- Under $500 → $19.95
- $500–$2,500 → $14.95
- Over $2,500 → FREE
- Bulky items → +$24.95 surcharge (waived over $2,500)
Fast dispatch from Brisbane. Same-day shipping on in-stock orders before 1pm AEST.
Change-of-mind returns: We accept returns within 7 days of delivery on unused, unopened products in original sealed packaging. Restocking fees apply (20–30%). Return shipping is the customer's responsibility.
No returns on opened audio gear, installed items, custom orders, or special-order products. Please check fitment carefully before installing.
Faulty or incorrect items: If you experience an issue, contact us with photos/video and your order number. We'll assess the claim and arrange repair, replacement, or refund for verified faults under the Australian Consumer Law.
Fitment assistance: If you're unsure about compatibility, reach out before ordering—we're happy to help.