Hertz CS 250 S4 — 10" Sealed-Box Subwoofer for Tour-Pak, Trike and Custom Harley Enclosures
The Hertz CS 250 S4 is a conventional 10″ subwoofer from the Cento range, built for builds that can provide a properly designed sealed enclosure. Hertz optimises its electroacoustic design for sealed boxes starting from 16 litres, and pairs it with a mono amplifier in the 300–400 W RMS region. It is the sensible traditional-subwoofer choice for Tour-Pak, trike and custom-box installs where the airspace genuinely exists.
Who This Is For
The CS 250 S4 suits riders building a Tour-Pak subwoofer, a trike boot install, or a fabricated bass box where the enclosure can be built to specification. It is not the right driver for a standard saddlebag you still want to use for luggage: 16 litres is not a large car-audio box, but it is meaningful volume once you try to package it inside a Harley bag. If mounting depth or enclosure volume is your real constraint, the Hertz MPS 250 S4 is the ultra-shallow alternative at 82.6 mm depth. If you need serious low-frequency output from a saddlebag rather than a purpose-built box, a large-format motorcycle mid-bass driver such as the Cicada CMB8.S4 is the better tool.
What This Is Best For
- Properly designed sealed enclosures from 16 litres — Hertz states the driver's electroacoustic design is optimised for sealed boxes starting at 16 litres (0.57 cu ft). Build to that and the response arrives as designed. Starve it of volume and the low end simply will not develop. On the road: a Tour-Pak or custom box built to specification delivers smooth, controlled low end rather than the thin, peaky result an undersized enclosure produces.
- Moderate mono amplifier pairing at 300–400 W RMS — At 300 W continuous and a single 4 Ω voice coil, this driver is straightforward to wire and does not demand a high-output electrical upgrade. Matching the amplifier to the driver rather than overpowering it is what keeps it reliable. On the road: usable bass without rebuilding the charging system to support it.
- 12.5 mm Xmax for controlled excursion — Hertz publishes 12.5 mm of linear excursion, which is what allows a 300 W driver to produce genuine bottom-octave output in a correctly sized sealed box. On the road: low-frequency content stays clean at volume instead of hardening as the driver runs out of travel.
- Polypropylene cone with a durable surround — A polypropylene diaphragm is dimensionally stable across temperature and resistant to moisture, which matters for any driver living in a motorcycle enclosure through Australian summers and wet winters. On the road: consistent performance from a cold morning start through a hot afternoon run, without the compliance changes that degrade cheaper materials over time.
- 115 mm mounting depth — Shallow enough for many purpose-built motorcycle enclosures, though it still needs the enclosure volume behind it. Confirm both depth and airspace before committing to a design. On the road: fits the kind of fabricated enclosure a good installer builds, provided the box is designed around the driver rather than the other way round.
Enclosure volume is the deciding factor, not mounting depth
The most common mistake with this driver is treating it as a saddlebag subwoofer because the mounting depth looks manageable. Depth and volume are different constraints. Hertz specifies enclosures from 16 litres, and a Harley saddlebag that still carries luggage rarely offers that once the mounting ring, amplifier rack and your gear are accounted for. If you have a Tour-Pak, a trike boot or you are fabricating a dedicated box, this is the right driver and the more efficient answer than a high-power motorcycle mid-bass. If your enclosure is a working saddlebag, look at a driver designed for that volume instead. Contact MAA before ordering if you are unsure which situation you are in.
Recommended System Use
- Tour-Pak subwoofer enclosures built to 16 litres or greater
- Trike boot and rear-compartment installs
- Custom fabricated sealed bass boxes
- Balanced systems seeking smooth low-end reinforcement rather than maximum SPL
- Mono amplifier pairing at 300–400 W RMS
Fitment
- Suitable for custom Harley-Davidson Touring enclosures where the required volume can be provided
- Compatible with motorcycle-specific sealed boxes from various manufacturers
- Works with Tour-Pak, trike and custom-box layouts
The Bottom Line
The CS 250 S4 is a well-executed conventional subwoofer, and it does the job traditional subwoofers do best: smooth, controlled bottom-octave output from a sealed enclosure built to specification. Give it 16 litres and a 300–400 W mono channel and it performs exactly as intended. Ask it to work in a compromised saddlebag and it will disappoint, as any driver would outside the conditions it was designed around. Contact MAA to confirm your enclosure plan before ordering.
Technical Specifications
| Size | 254 mm (10") |
|---|---|
| Impedance | Single 4 Ω voice coil |
| RMS Power | 300 W |
| Peak Power | 600 W |
| Sensitivity | 84 dB SPL |
| Xmax | 12.5 mm |
| Voice Coil Diameter | 35 mm (1.38") |
| Mounting Depth | 115 mm (4.53") |
| Cone Material | Polypropylene |
| Recommended Enclosure | Sealed, optimised from 16 litres (0.57 cu ft) |
Specifications per Hertz published technical documentation. Frequency response is published by Hertz as a response graph rather than a stated range, so no range figure is quoted here.
Need Help Choosing a Subwoofer?
We can help you match the right enclosure, amplifier and charging setup to get clean, usable bass from your Harley without sacrificing storage or reliability. If your build cannot provide 16 litres, tell us and we will point you at a driver designed for the space you actually have.
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.