- +Real-world 147.7 dB figure from the brand's own testing — honest specs
- +Fast ~39-second recovery from 110 to 150 PSI (Viair 400C, 2.62 CFM)
- +Premium hardware: 1/2" Black Widow stainless valve, liquid-filled gauge, 40A relay
- +Lifetime manufacturer-defect warranty on the US-made Shocker XL horns
- +Four individually mounted bells simplify tight-space installs
- −Discontinued — new units no longer sold by HornBlasters
- −Short 33% compressor duty cycle at 100 PSI
- −Only 3-5 seconds of continuous honk from the 2-gallon tank
- −Premium $983.99 base price while it was sold
- −No dB rating or test distance printed on the kit page itself
Methodology
This review aggregates publicly available information from manufacturer specifications, retailer listings, and verified user reviews. We do not perform hands-on testing. Last reviewed: August 9, 2026. Primary sources for this article are HornBlasters’ official product page for the Conductor’s Special 240 (P/N HK-S4-240), the standalone Shocker XL horn listing, and HornBlasters’ own published decibel-testing article. One important note up front: as of this review date, HornBlasters lists the Conductor’s Special 240 as discontinued, with all three variants showing sold out. We’re keeping this review live as a reference for used-market buyers and for anyone comparing it against the kits that replaced it.
Quick verdict
The Conductor’s Special 240 was the “impatient person’s” Conductor’s Special: the same insanely loud Shocker XL 4-trumpet horns as the rest of the line, paired with the Viair 400C — one of the fastest-filling compressors HornBlasters ever offered in a 2-gallon kit, recovering from 110 to 150 PSI in about 39 seconds. The trade-off was a short 33% duty cycle, and the kit commanded a near-$1,000 price before bracket bundles. We rate it 4.1/5: an excellent, honestly specced kit whose only real strike today is that you can’t buy it new anymore.
What it is
The Conductor’s Special 240 is a complete onboard-air train horn kit built around HornBlasters’ flagship Shocker XL horns — four individually mounted, hand-tuned trumpets that the brand tunes to the US Train Horn Chord so they mimic the tone of a real locomotive’s Nathan AirChime. Per HornBlasters’ own comparative testing, the Shocker XL reaches 147.7 decibels versus 149.4 for a genuine Nathan — a “tiny 1.7 dB difference,” as the brand puts it. Notably, that decibel figure is published on HornBlasters’ blog rather than printed on the kit page itself, and no test distance is disclosed.
The “240” in the name follows HornBlasters’ naming convention: a Viair 400-series compressor feeding a 2-gallon tank. Within the Conductor’s Special family it sat between the entry kits and the big 5-gallon rigs — see our HornBlasters hub for the full line. Its pitch was speed: where the sibling 232 kit leaned on a higher-duty-cycle compressor, the 240’s Viair 400C moved 2.62 CFM at free flow and refilled the tank fast enough that you could honk, wait well under a minute, and honk again at full pressure. It was aimed at pickup and SUV owners who wanted maximum volume with minimum downtime between blasts.
HornBlasters sold the kit in three configurations: the base package at $983.99, a single-tank spare tire delete bracket bundle at $1,337.98, and a dual-tank bracket bundle at $1,469.98 — the bracket versions mounted the whole air system in place of the truck’s spare tire instead of eating bed or frame space. Like the rest of the line, the system doubled as general onboard air, and HornBlasters explicitly notes it can fill vehicle tires in emergency situations.
Specifications
| Spec | Value |
|---|---|
| Part number | HK-S4-240 |
| Horns | Shocker XL, 4 individually mounted trumpets |
| Sound output | 147.7 dB per HornBlasters’ own testing (test distance not disclosed) |
| Bell lengths | 19.50″, 16.25″, 14.75″, 12.75″ |
| Flare diameter | 5″ |
| Horn material | Fiberglass-reinforced ABS with stainless-steel diaphragms |
| Compressor | Viair 400C, 12V DC |
| Free-flow output | 2.62 CFM |
| Duty cycle | 33% at 100 PSI |
| Max amp draw | 28 amps (40-amp relay included) |
| Tank | 2-gallon, 6-port, 17″L × 6″D × 8″H, 10 lb |
| Operating pressure | 150 PSI (compressor restarts at 110 PSI) |
| Fill time, 0–150 PSI | ~1 min 52 sec (±5 sec) |
| Recovery, 110–150 PSI | ~39 sec (±3 sec) |
| Honk duration | 3–5 seconds continuous per tank |
| Valve | 1/2″ NPT Black Widow stainless-steel electric air valve |
| Price (while sold) | $983.99 base; $1,337.98 single-tank bracket; $1,469.98 dual-tank bracket |
| Warranty | Lifetime (horns) / 1 year (Viair compressor) / 2 years (other components) |
| Status | Discontinued (all variants sold out) |
What’s in the box
- Shocker XL train horns — 4-piece set with mounting hardware
- 2-gallon, 6-port air tank
- Viair 400C 12-volt compressor with remote-mountable intake filter
- Spare air filter elements (5-pack)
- 110/150 PSI pressure switch with 40-amp relay
- 1/2″ NPT Black Widow stainless-steel electric air valve
- 200 PSI stainless liquid-filled air gauge
- Air line: 10 ft of 5/16″, 17 ft of 1/2″, 6 ft of 3/8″
- Wiring: 22 ft red 10-gauge power lead plus 22 ft blue and 22 ft grey 18-gauge leads, fuse holder and fuses
- Brass NPT fittings kit with safety valve and blow-off
- Air line cutter and earplugs
That’s a genuinely all-inclusive load-out — the 1/2″ main line and full-bore Black Widow valve matter, because valve and line diameter are two of the biggest real-world factors in how hard a horn hits (see our guide on air line sizing).
Pros
- Shocker XL horns carry a real-world 147.7 dB figure from the brand’s own comparative testing — refreshingly honest next to competitors’ inflated “150+ dB” claims
- Fastest practical recovery in the 2-gallon Conductor’s Special family: roughly 39 seconds from 110 back to 150 PSI
- Premium supporting hardware — 1/2″ Black Widow stainless valve, liquid-filled gauge, 40-amp relay and full wiring kit included
- Lifetime manufacturer-defect warranty on the US-made horns
- Four individually mounted bells make it far easier to package under a pickup than one-piece quad castings
- Doubles as emergency onboard air for topping off tires
Cons
- Discontinued — no longer available new from HornBlasters; used or new-old-stock only
- Viair 400C’s 33% duty cycle at 100 PSI is short; sustained repeated honking will hit thermal limits sooner than higher-duty compressors
- 2-gallon tank supports only 3–5 seconds of continuous honk before pressure sags
- At $983.99 base (and up to $1,469.98 with the dual-tank bracket bundle), it sat firmly in premium territory
- No decibel rating or test distance printed on the kit page itself — the number lives on a separate brand blog post
Alternatives
- HornBlasters Conductor’s Special 232 — the closest living relative: the same Shocker XL horns on a 2-gallon system with a longer-duty compressor, still available new.
- HornBlasters Conductor’s Special 540 — same horns with a 5-gallon tank for dramatically longer honk time, if you have the mounting space — though HornBlasters has since discontinued it too.
- HornBlasters Conductor’s Special 544 Nightmare — the max-effort option, stepping up to a 5-gallon air system for people who found the 240’s 2-gallon air supply limiting.
Install / compatibility notes
This is a full onboard-air install, not a bolt-on: you’re mounting four horn bells, a 17-inch tank, and a compressor, then running air line and a switched 12V circuit. Plan on a full day for a first-time DIY job — our step-by-step install guide walks the whole sequence. Electrically, the Viair 400C draws up to 28 amps, and the kit ships with the correct 40-amp relay and 10-gauge power lead; follow our amp draw, fuse and wire gauge guide if you extend any runs.
The tank needs about 17″ × 6″ of flat real estate — frame rail or under-bed mounting on pickups is typical. The single- and dual-tank spare tire delete bracket variants existed precisely to solve this on trucks, relocating the system into the spare tire’s spot under the truck. Mind the compressor’s 33% duty cycle: after long fills, give it a rest, and consider our duty cycle explainer before planning any marathon honk sessions. Because performance peaks at 150 PSI, also check whether your state restricts horn use on public roads — our state legality index covers the map.
Sources
- HornBlasters — Conductor’s Special 240 Train Horn Kit (HK-S4-240) product page — all kit specs (compressor, tank, PSI, fill times, honk duration, dimensions, weights, included items, warranty, pricing, discontinued status)
- HornBlasters — Shocker XL Train Horn product page — bell lengths, materials, horn weight, made-in-USA and warranty statements, standalone horn pricing
- HornBlasters — “Fire Up Your Train Horns!” blog article — the 147.7 dB Shocker XL figure and 149.4 dB Nathan AirChime comparison
- HornBlasters — Conductor’s Special 232 product page (HK-S4-232) — 232 current availability and pricing, HornBlasters 3Q compressor duty cycle (100% at 100 PSI) backing the compressor comparison
- HornBlasters — Conductor’s Special 540 product page (HK-S4-540) — 540 discontinued status
- HornBlasters — Spare Tire Delete Kit product page — spare tire delete bracket mounting (replaces the spare tire in its location under the truck)
Train Horn Hub aggregates publicly available data. We do not test products in-house. All trademarks belong to their respective owners.
A fast-recovering, honestly specced flagship-horn kit that earned its near-$1,000 price — but it's discontinued, so today it's a used-market pick; buyers wanting it new should look at the Conductor's Special 232 instead.
Frequently asked questions
Quick answers to the questions people ask most about this topic.
- How loud is the Conductor's Special 240 really?
- The kit uses HornBlasters' Shocker XL horns, which the brand's own comparative testing puts at 147.7 dB — about 1.7 dB below a genuine Nathan AirChime. No test distance is disclosed, and the figure appears on HornBlasters' blog rather than on the kit page.
- Is the Conductor's Special 240 still available?
- No. HornBlasters lists the HK-S4-240 as discontinued, with all three variants sold out. The closest current equivalent is the Conductor's Special 232 (same horns, 2-gallon system); the 5-gallon Conductor's Special 540 has also been discontinued.
- How long can you honk before the tank runs out?
- Per HornBlasters, the 2-gallon tank at 150 PSI supports about 3-5 seconds of continuous honking. The Viair 400C then refills from 110 back to 150 PSI in roughly 39 seconds.
- What made the 240 different from other Conductor's Special kits?
- The Viair 400C compressor. At 2.62 CFM free flow it was one of the fastest-filling compressors HornBlasters offered, trading a shorter 33% duty cycle for much quicker recovery between honks.
- What warranty did the kit carry?
- Lifetime manufacturer-defect coverage on the Shocker XL horns, 1 year on the Viair 400C compressor, and 2 years on the remaining components, plus a 30-day satisfaction guarantee (a 15% restocking fee could apply).
