Nathan vs Leslie Train Horns: Which Locomotive Horn Sounds Better?

Nathan vs Leslie is the oldest argument in the locomotive horn hobby: the two companies that built nearly every chime horn on North American rails took opposite approaches to what a warning horn should sound like, and once you know why, “which sounds better” stops being a coin flip and becomes a question about your own taste.

Two companies, two philosophies

Leslie is the older name by half a century. Per Wikipedia’s Leslie Controls entry, the Leslie Company was established in 1900 in Paterson, New Jersey, bought the rights to the Tyfon whistle design in 1930, and by 1935 Leslie-Tyfon horns were standard on American railroads. For decades Leslie outsold Nathan.

Nathan’s horns come from AirChime, built on the work of Robert Swanson, a British Columbia steam-whistle maker who disliked thin single-note air horns. Per Wikipedia, the five-note H5 arrived in 1949, the M series in 1950, the P series in 1953, and the K series in 1954, and the result is routinely described as “the most melodic horn in railroading.”

That word, melodic, is the fault line. According to LocomotiveHorns.info, Leslie’s first SuperTyfon horns of 1951, the S3J and S5D, copied the chords of AirChime’s M3 and M5. In late 1952 Leslie dropped them, reportedly under pressure from AirChime and Nathan, for the S3L and S5T. Leslie then marketed the new horns on the theory that a slightly off-key, less-pleasing chord works better as a warning device. Nathan chased music. Leslie chased attention.

Both names survive. Nathan Manufacturing is a division of Micro Precision Group, and per Wikipedia, on 11/16/2021 HornBlasters acquired the Air Whistles Division of Circor Leslie Controls and now builds the Supertyfon RS line.

The chords: B major 6th vs a deliberate discord

The Nathan K5LA plays a B major 6th chord: D♯, F♯, G♯, B, and a second D♯ an octave up. Wikipedia’s Nathan entry credits the 1975 retuning to Amtrak’s Deane Ellsworth, who wanted the 1954 K5H’s somber D♯ minor voicing turned into something friendlier for passenger service. Per the same source, it became North America’s most popular locomotive horn by the late 1980s and is standard on Amtrak, CSX, and Norfolk Southern, with the bottom D♯ at about 311 Hz.

Leslie’s bell numbers tell you the pitch. LocomotiveHorns.info’s chord table shows a 440 bell playing A and a 311 bell playing D♯, so the three-digit numbers are frequencies in hertz, and the two-digit numbers on modern horns follow the same idea:

Horn	Bells	Notes heard	Chord
Leslie RS-3L / S-3L	#25, #31, #44	C, D♯, A	No conventional name
Leslie RS-5T / S-5T	#25, #31, #37, #44, #55	C, D♯, F♯, A, C♯	C diminished with a flatted 9th
Nathan K5LA	#1, #2, #3A, #4A, #5	D♯, F♯, G♯, B, D♯	B major 6th

Leslie’s bottom note sits around C, below the K5LA’s D♯ fundamental, which is why enthusiasts describe the Leslie as deeper and more bass-forward. And that #25 bell is famously not what the catalog says. Per LocomotiveHorns.info, the 25 bell plays C rather than the advertised B. SoundTraxx’s horn history explains how it happened: in the mid-1960s Leslie recast its two-piece #25 and #31 bells as one-piece castings, the #31 came out fine, and the #25 “came out as a discord and out of tune.” Leslie kept making it that way for decades, and per SoundTraxx it “has become one of the favorite horns of railfans and horn collectors, even with its discord.”

The K5LA is a consonant, resolved major chord that reads as musical. The RS-3L is a slightly sour, unresolved cluster that reads as urgent. Both are intentional. For the physics of why stacked notes carry, see our guide to why train horns make a chord.

How they are built

The two brands also make sound differently at the diaphragm. HornBlasters describes the Nathan K3 as die-cast aluminum with “stainless steel dual diaphragm technology,” and SoundTraxx notes the early K horns were sand-cast before Nathan moved to die casting.

Leslie’s SuperTyfon uses what Wikipedia’s train horn article calls a “back-pressure power chamber design” developed by Kockums of Sweden to enhance diaphragm oscillation. Per LocomotiveHorns.info, the power chambers are interchangeable among any bell on any SuperTyfon horn. The modern RS chamber, per SoundTraxx, uses a single stainless steel diaphragm with a rubber gasket in place of the old two-piece S-head part, and the RS heads “tend to chirp when the whistle valve is opened.” Railfans listen for that chirp.

For an aftermarket buyer the practical difference is the envelope:

Nathan K3 (HornBlasters)

32 lb, 18.25 x 16.25 x 9.75 in, 1/2 in NPT inlet

Nathan K5LA (HornBlasters kit)

37 lb, 19 x 29.75 x 9.25 in

Leslie RS-3L (HornBlasters)

25 lb, 26.5 x 17.5 x 9.25 in, 1/2 in NPT inlet

Leslie RS-5T (HornBlasters)

25 lb, 26.5 x 17.5 x 9.25 in, 1/2 in NPT inlet

HornBlasters bills the RS-3L as “the largest available 3-chime horn.” The Nathan is heavier; the Leslie is harder to hide.

Loudness and air appetite

On the rails, neither brand is allowed to be louder. Per 49 CFR 229.129 at Cornell’s Legal Information Institute, a lead locomotive horn must produce between 96 and 110 dB(A) measured 100 feet forward of the locomotive.

Aftermarket ratings differ. HornBlasters lists both the RS-3L and RS-5T at 144 dB at 100 PSI with a 3.5-mile audibility claim and no stated measurement distance, and its loudest-horns page puts the Nathan K5LA at 149.4 dB in third-party testing it commissioned. Those figures were not measured under identical conditions, so treat them as retailer claims. Our guide to advertised vs real-world decibels explains why the stated distance matters more than the number.

What shows up consistently in owner reports is air consumption. In a Train Horn Forums thread comparing the Nathan K3LA, P3, and K5LL with the Leslie RS-3L, one owner called Leslies “air hogs” and said a 5-gallon tank “won’t quite cut it,” while another recommended a 9-gallon tank. In a separate Nathan vs Leslie thread, a poster was blunt: “Leslies need a lot of air…10 gallons of air, minimum.” Locomotive Parts Supply lists both horns at 90 to 140 PSI, so the difference is volume, not pressure. If you are sizing a system, start with our air tank size guide.

What railfans actually say

Two camps show up in every forum thread.

• Team Nathan: “I’m not real big on the Leslies. No offense to anyone, it’s just a personal preference,” wrote one Train Horn Forums member, who preferred the K-series chord and drooled over the vintage M5.
• Team Leslie: “Leslies are MUCH more commanding and are hella louder! And who says Leslies can’t sound beautiful?” answered another in the same thread.
• The RS-3L fan club: “loudest and most unique sound is the leslie rs3l,” said a poster in the K3LA-versus-RS-3L thread.

One nuance from that thread matters before you judge a Leslie from a video clip. Because its notes sit lower, an owner observed that it “don’t sound as loud up close” even when it carries farther. That matches what our guide on how far a train horn can be heard covers: low notes lose less over distance.

Railroads voted with purchase orders. Per SoundTraxx, the S3L is “probably one of the most widely used locomotive horns in the world,” yet the Nathan K horn replaced the Leslie S5T on CSX, and Wikipedia’s Leslie entry sums it up: “At one time, most trains used Leslie horns, but now Nathan has the majority of the market.”

Price, availability, and warranty in 2026

Because HornBlasters owns the Leslie tooling, new Supertyfons are easy to buy; aftermarket Nathan K horns are reconditioned or rebuilt units.

Horn	Condition	Price	Warranty
Nathan K3 (HornBlasters)	Reconditioned, new internals	$1,949.99	5-year defect
Nathan K5LA (Locomotive Parts Supply)	Rebuilt, tested	$1,699.95	Not stated
Nathan K5LA complete kit (HornBlasters)	Reconditioned horn, new air system	$4,999.99 to $5,199.99	5-year horn, 2-year kit
Leslie RS-3L (HornBlasters)	New production	$2,849.99	1-year defect
Leslie RS-3L (Locomotive Parts Supply)	Rebuilt, tested	$1,149.95	Not stated
Leslie RS-5T (HornBlasters)	New production, made in USA	$3,999.99	1-year defect

Prices verified 09/16/2026 and subject to change. A new Leslie costs more than a reconditioned Nathan but carries a shorter warranty, while a rebuilt Leslie three-chime is the cheapest genuine locomotive horn on this list. Before buying either one used, run through our used locomotive horn checklist, because decades on a cab roof can hide worn diaphragms under fresh paint.

So which sounds better?

No measurement settles it. Here is how we would decide:

• Pick Nathan if you want the sound most Americans hear in their head when they think “train.” The K5LA’s B major 6th is the voice of Amtrak and Class I freight, and the 5-year warranty on a reconditioned K3 is hard to argue with. If you are torn between the three- and five-chime versions, read our K3LA vs K5LA comparison.
• Pick Leslie if you want the deeper, slightly sour 1950s freight-yard tone, the chirp on valve opening, and the bragging rights of the horn railfans nicknamed “The King of Train Horns.” Budget for a bigger tank and a bigger mounting envelope.
• Pick neither if your tank is under 5 gallons or you cannot frame-mount 25 to 38 lb of cast aluminum. A kit from our loudest train horns ranking sounds better on a small tank than a starved locomotive horn.

Our lean: for a daily-driven pickup, the Nathan K3 or K5LA is the safer buy on warranty and air use. For a show truck or a railfan who knows which chord they are chasing, the Leslie RS-3L is the more distinctive sound, and nothing else makes it.

Keep reading

• Buying a used locomotive horn: K5LA and RS-3L checklist
• Nathan K3LA vs K5LA: which K-series sound fits you?
• The loudest train horns you can buy
• Nathan AirChime K5LA review
• Leslie RS-3L Supertyfon review

Sources

• Wikipedia — Leslie Controls — founding in 1900 in Paterson, NJ; 1930 Tyfon rights; standard on US railroads after 1935; Leslie outsold Nathan; Nathan now holds the majority of the market; HornBlasters acquired the Air Whistles Division of Circor Leslie Controls on 11/16/2021
• Wikipedia — Nathan Manufacturing — Robert Swanson and the 1949 H5; P series 1953; K5H 1954; K5LA 1975 retuning for Amtrak’s Deane Ellsworth; B major 6th notes; Amtrak/CSX/Norfolk Southern adoption; “most melodic horn in railroading”; K bell #1 at 311 Hz; Micro Precision Group ownership
• Wikipedia — Train horn — AirChime M/P/K series dates; SuperTyfon back-pressure power chamber developed by Kockums; AirChime sold to Nathan Manufacturing
• LocomotiveHorns.info — Leslie SuperTyfon — 1951 S3J/S5D, late-1952 switch to S3L/S5T, off-key warning theory, interchangeable power chambers, chord table (S-3L C/D♯/A, S-5T C/D♯/F♯/A/C♯), 25 bell plays C not B, bell numbers as frequencies
• SoundTraxx — Locomotive Airhorn History — mid-1960s one-piece #25 bell discord, railfan popularity, S3L usage, S5T on GM&O and Frisco, RS single-diaphragm chamber and chirp, K series sand-cast then die-cast, K5LA replacing S5T on CSX
• HornBlasters — Leslie RS-3L Supertyfon Train Horn — $2,849.99, 144 dB at 100 PSI, 3.5-mile claim, 25 lb, 26.5 x 17.5 x 9.25 in, 1/2 in NPT, 1-year warranty, “largest available 3-chime horn”
• HornBlasters — Leslie RS-5T Supertyfon Train Horn — $3,999.99, 144 dB at 100 PSI, 25 lb, 26.5 x 17.5 x 9.25 in, made in USA, 1-year warranty
• HornBlasters — Nathan AirChime K3 Train Horn — $1,949.99, reconditioned with new internals, 32 lb, 18.25 x 16.25 x 9.75 in, 1/2 in NPT, 5-year warranty, die-cast aluminum with stainless dual diaphragms
• HornBlasters — Nathan AirChime K5 Train Horn Kit — kit pricing $4,999.99 and $5,199.99, 37 lb, 19 x 29.75 x 9.25 in, 5-year horn and 2-year kit warranty
• HornBlasters — The World’s Loudest Train Horns — K5LA 149.4 dB in third-party testing commissioned by HornBlasters; RS-5T 144 dB at 100 PSI, “slightly discordant,” “King of Train Horns” nickname, 1951 design date
• HornBlasters — Leslie SuperTyfon Horns History — Tyfon 1934, Chime-Tone 1950, SuperTyfon 1951 model lineup
• Locomotive Parts Supply — Leslie Supertyfon RS3L — $1,149.95 rebuilt, #25/#31/#44 bells, 90 to 140 PSI, about 30 lb
• Locomotive Parts Supply — Nathan AirChime K5LA — $1,699.95 rebuilt, 90 to 140 PSI, about 38 lb
• Train Horn Forums — Nathan vs Leslie — owner quotes on Leslie volume, harshness, personal preference, and the 10-gallon air recommendation
• Train Horn Forums — Nathan P3 vs K3LA vs K5LL vs Leslie RS3L — “air hogs,” 5-gallon tank insufficient, 9-gallon recommendation, RS-3L “loudest and most unique,” lower notes sound softer up close
• Cornell LII — 49 CFR 229.129 — federal 96 to 110 dB(A) at 100 ft requirement for lead locomotive horns