Hertz S 300 S4 Review: Uno's 12-Inch Sub, Its Box Size and Budget Pairings
Updated: Oct 7
The Hertz S 300 S4 is a 12-inch (300 mm) subwoofer driver from Hertz's entry-level Uno range, and when we checked it was the only subwoofer on Hertz's Uno page. It presents a 4 Ω load, handles 250 W continuous and 1000 W peak, and has 89.5 dB sensitivity, which Hertz credits to its light pressed-paper cone and foam surround. Its Indian MRP is ₹9,990, the same as the Dieci DS 30.3, but the two want very different boxes: Hertz's designs for the S 300 S4 are 42 litres sealed or 50 litres ported. It suits buyers with room for a full-size box who want a 12-inch on a budget. See today's price on our Hertz S 300 S4 product page.
Quick summary
A 12-inch Uno driver rated at 250 W continuous into 4 Ω, with 89.5 dB sensitivity.
Hertz's recommended boxes are large: 42 litres sealed or 50 litres reflex tuned to 38 Hz.
A 200 to 300 W amplifier suits it, or a five-channel amplifier for a complete budget system.
We found no owner reviews or independent tests of this model.
Hertz S 300 S4 specifications
Specification | Hertz S 300 S4 |
|---|---|
Type | 12-inch (300 mm) subwoofer driver |
Impedance | 4 Ω (DC resistance 3.6 Ω) |
Power handling | 250 W continuous / 1000 W peak |
Sensitivity | 89.5 dB |
Cone and surround | Painted pressed-paper V-cone; high-excursion foam |
Voice coil | 38 mm (1.5 in) pure copper on an aluminium former |
Magnet | Ferrite, 115 x 47.5 x 25 mm |
Fs / Qts / Vas | 33 Hz / 0.6 / 82.2 l |
Xmax / Xmech | 9.1 mm / 15.1 mm |
Mounting depth | 121 mm |
Mounting hole (Hertz box designs) | 279 mm |
Weight | 3 kg |
Recommended sealed box | 42 l, Fb 56 Hz, Qtc 0.89 |
Recommended reflex box | 50 l, Fb 38 Hz, 264 mm port length |
India MRP | ₹9,990 |
Figures come from Hertz's official S 300 S4 page and tech sheet, and they match our store listing. Hertz doesn't publish a frequency response for this model, so we haven't quoted one.
A light cone built for efficiency
Hertz's approach with the S 300 S4 is to keep the moving parts light. The cone is painted pressed paper in Hertz's V-cone profile, which the company says stops it deforming as it moves, and it hangs on a high-excursion foam surround. The motor uses low-carbon steel with a high-density ferrite magnet, refined with FEM simulation, and the 38 mm pure copper voice coil is wound on an aluminium former for thermal and mechanical capacity.
Foam surrounds are light and compliant, which helps efficiency, but they generally tolerate years of heat and sunlight less well than rubber. In an Indian summer, keep the sub out of direct sun through the rear glass. Hertz also supplies an ABS gasket for a neat finish where the driver meets the baffle.
The box question: 42 litres is not small
Hertz's feature list says the S 300 S4 is designed for small sealed or reflex boxes, but the recommended designs on the same page, which Hertz itself labels compact, tell a different story. The sealed box is 42 litres, about 460 x 370 x 320 mm built from 12 mm wood, with a Qtc of 0.89. The reflex box is 50 litres, about 650 x 338 x 338 mm in 19 mm wood, tuned to 38 Hz with a 264 mm-long port. Both use a 279 mm mounting hole, and Hertz suggests a 90 Hz, 12 dB/oct low-pass for each.
Plan for those volumes, not the small-box wording. A 42-litre box takes a real share of a hatchback's boot, and the 50-litre ported box suits sedans and SUVs with space to spare.
Amplifier pairing and a budget Uno system
As a passive driver, the S 300 S4 needs an amplifier. Its 4 Ω load and 250 W continuous rating suit an amplifier giving 200 to 300 W into 4 Ω. The mono Zapco ST-1B (₹15,990 MRP) is rated at 200 W into 4 Ω, though it lists RCA inputs only; Hertz's own DP 1.500 is rated at 280 W into 4 Ω and adds a speaker-level input for factory head units.
For a complete Uno system on one amplifier, the five-channel Zapco ST-5B (₹22,990 MRP) is rated at 4 x 70 W plus 1 x 250 W into 4 Ω and lists an OEM speaker-level input. Its sub channel matches this driver's continuous rating, and its four main channels can run a front pair of Hertz K 165 components, which Hertz rates at 75 W continuous, plus rear speakers. Set the gains with a test tone, and start from Hertz's suggested 90 Hz low-pass.
What owners and reviewers say about the Hertz S 300 S4
When we checked in October 2026, we found no owner reviews or independent tests of the S 300 S4 in the places we looked. Hertz's product page and its Uno subwoofer page carry no reviews, and UK retailer Four Car Audio, whose Hertz Uno range includes speakers, doesn't list this sub.
What remains is Hertz's own material, which is promotional: the company describes Uno as the first step into the Hertz Sound Experience and calls its subwoofers the best factory replacements in their price range. If you've installed an S 300 S4, we'd like to hear how it has worked in your car.
S 300 S4 vs DS 30.3, CS 300 and JL 12W0v3-4
The Dieci DS 30.3 shares the ₹9,990 MRP, the 12-inch size, the 4 Ω load and the 250 W continuous rating. It differs in its polypropylene cone with a butyl rubber surround, 91 dB sensitivity, and a recommended sealed box half the size at 21 litres. For most small cars, that box size settles it in the DS 30.3's favour; the S 300 S4 makes sense when you have room for its bigger enclosures.
The Cento CS 300 (₹19,990 MRP) handles 350 W continuous in a 32-litre sealed box but is less sensitive at 86.5 dB. Across brands, the JL Audio 12W0v3-4 (₹18,490 MRP) handles 300 W, quotes 85.64 dB at 1 W/1 m, and wants a similar 38.94-litre sealed or 49.55-litre ported box. On paper the S 300 S4 is more sensitive at roughly half the MRP, though Hertz doesn't state its measurement conditions, so treat the gap as indicative.
Who should buy it, and who shouldn't
Buy the S 300 S4 if you have the boot space for a 42-litre sealed or 50-litre ported box and want a budget 12-inch system built around one amplifier.
Look elsewhere if your boot is small (the DS 30.3 or the 10-inch DS 25.3 need far less space), or you'd rather buy on the strength of owner reviews, which we couldn't find for this model.
Installation notes for Indian cars
Build the box from MDF to Hertz's volumes and seal every joint; with a 121 mm mounting depth and 279 mm mounting hole, the published designs give you the dimensions to work from. A box this size is heavy, so bolt or strap it down to stay put over speed breakers and broken roads.
Mount the amplifier where air can reach it, not under the boot carpet, and fuse its power cable close to the battery, to the rating in the amplifier's instructions. A 12-inch also wakes up boot-lid and number-plate rattles; our sound damping guide shows where to start. VA3 Car Studio in Ghaziabad offers professional installation.
Price and where to buy
The Hertz S 300 S4 carries an MRP of ₹9,990. VA3 Car Studio often sells below MRP, so check the current offer on our S 300 S4 product page. The box contains the subwoofer, and Hertz lists no grille as included.
The bottom line
The S 300 S4 is an efficient, sensibly specified 12-inch at an entry-level MRP. Its catch is the box: Hertz's designs are 42 and 50 litres, so it needs space that many small cars can't spare, and we found no owner feedback. If you have the room, it's a straightforward budget 12-inch; if you don't, look at the DS 30.3.
Hertz S 300 S4 FAQ
What box does the Hertz S 300 S4 need?
Hertz recommends a 42-litre sealed box with a Qtc of 0.89, or a 50-litre reflex box tuned to 38 Hz with a 264 mm-long port. Both use a 279 mm mounting hole and a suggested 90 Hz low-pass.
What amplifier should I use with the S 300 S4?
One giving 200 to 300 W into 4 Ω. For a full budget system, the Zapco ST-5B's 250 W sub channel suits the S 300 S4 while its four 70 W channels drive front speakers such as the Hertz K 165.
Is the S 300 S4 or the DS 30.3 better for a small boot?
The DS 30.3. Both cost the same and handle 250 W, but Hertz designs the DS 30.3 for a 21-litre sealed box against 42 litres for the S 300 S4, and it is 1.5 dB more sensitive.
Buy the Hertz S 300 S4 Uno in India
Check the Hertz S 300 S4 Uno price in India, browse more Hertz subwoofers or compare all car subwoofers in India. Want it fitted properly? Book subwoofer installation at our Ghaziabad studio.
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