Loudest Aftermarket Train Horns Tested: Six Kits vs Their Decibel Claims

Introduction

Aftermarket car and truck horns are a lawless corner of online shopping. Listings throw around decibel numbers ranging from 118 all the way to 600, often on products costing less than a nice dinner. To put that in perspective: 600 decibels is not a loud horn, it is an extinction-level pressure event far beyond anything sound can physically do in our atmosphere. For reference, the loudest sound in recorded history, the 1883 Krakatoa eruption, is estimated at around 310 decibels, and a jet aircraft sits near 140.

We bought six horns, wired each one up with a sound meter placed at two meters, and measured what they actually produce compared to what the listings claim. The results range from honest to billions of times off target.

How We Tested

Every horn was measured at two meters, the most common rating standard for this category. We first ran each horn from a standalone 12V battery, then with the vehicle running so the alternator pushed closer to 14 volts. Since the car-on setup produced a small but real gain, all final numbers below reflect that condition.

One reminder that makes these results easier to read: decibels are logarithmic. Six decibels is not six percent louder, it is roughly twice the sound pressure. Small number differences mean big real-world differences, which is exactly why exaggerated listings are so effective at fooling buyers.

Baseline: Hella Supertone Puck Style Horn

We started with a name brand as a sanity check. The Hella Supertone puck horn is rated by Hella at 118 decibels at two meters, and it costs around $27. In testing it peaked at 110.5 dB on battery and 111 dB with the car running. That is meaningfully short of the rating, roughly a two-fold difference in sound pressure, but it is by far the most honest claim on this list, and it still produces a sharp, attention-grabbing blast. As a baseline and a known-quantity upgrade, it remains a sensible pick.

Zbrand 300dB Super Loud Train Horn Kit

The Zbrand kit pairs a high-pitch and low-pitch horn that fill gaps in each other’s wavelength for a fuller blast. It costs about $17 and advertises 300 decibels, which would put it in Krakatoa territory. Individually the horns peaked around 106 dB, and together they reached 112.2 dB. That pairing does genuinely add punch beyond what two single horns suggest, making it about 15 percent louder than the Hella in measured terms. But it was 187.8 decibels short of its claim, which works out to billions of times quieter than advertised. Good little horn, absurd marketing.

Viking Horns V621K Dual Trumpet Horn Kit

The Viking V621K is a proper dual trumpet kit at around $80, complete with dedicated air pumps and a separate relay. Its marketing materials claim 129 decibels, though interestingly the spec sheet on its own listing states 118. Measured with the car running, it produced roughly 119 dB, about 72 percent louder than our Hella baseline in sound pressure terms, and in person the difference was obvious. Against the 129 claim it misses by 13.3 dB, but against that 118 spec sheet number it is essentially on target. This is the first horn here that sounds and feels like serious equipment.

E-Tech 150dB Train Style Horn

At just $18, the E-Tech single trumpet horn weighs what feels like a couple of ounces and looks suspiciously identical to countless no-name clones sold across every major marketplace. Its unusually good reviews made it worth a shot. It measured 118.2 dB, louder than the Hella and nearly matching the $80 Viking, and it sounds convincingly like a full-size truck horn. It is not remotely 150 decibels, missing by 31.8 dB, but for the money it is the standout value of the entire test.

Mega Blast Dual Trumpet Horn Kit

The Mega Blast is the outlier here: a dual trumpet kit made in Italy at roughly ten times the price of the budget horns, north of $160, and the largest horn on the day. It uses two separate relays and feels substantially more substantial in build quality. Measured output was 119.2 dB, the loudest single horn we tested, about 250 percent of the Hella baseline in sound pressure. We hoped for something in the 120s given the price, but it still delivered the strongest honest performance, and it is the obvious step up if budget horns feel flimsy to you.

Vovly 600dB 12V Dual Trumpet Horn

The Vovly claims 600 decibels for $22, a number that would threaten global extinction if real. In its favor, it ships with the pump and relay pre-mounted on the base, making it the simplest here to hook up. Measured output came in around 113 to 114 dB, roughly 146 percent of our Hella baseline and noticeably grating on the ears. That puts it 485.7 decibels short of advertised, which by logarithmic math is on the order of a trillion-billion times quieter than the claim. It works. It is just not a weapon.

All Six Horns Together

For science, we wired every horn up at once. The meter initially maxed out and glitched past its 130 dB range, so we applied the inverse square law, moved the meter to eight meters, and calculated the combined output at two meters back to roughly 130 dB. Louder than any single horn, as expected, and genuinely startling.

Buying Advice

If you want the best value, the E-Tech delivers near-Viking output for $18 and sounds like a real 18-wheeler. If you want the loudest measured blast, the Italian Mega Blast wins at a much higher price. If you want a brand-name baseline, the Hella is the most honest rating here. Ignore the triple-digit decibel claims entirely; every single one was wildly off, and a horn in the 110 to 119 dB range is already far louder than a stock car horn.

Conclusion

Every horn we tested produced usable output between roughly 106 and 119 decibels, regardless of what the listings promised. The gap between marketing and physics is the real story, but the good news is that the affordable winners genuinely perform. Match the horn to your budget and mounting space, and any of the top picks will make your vehicle far more audible.