Unlike competitors who shoot IRs at bedroom volume, York Audio pushes a high-wattage tube amp (using the KW head) to the verge of power amp distortion. This captures the speaker's dynamic compression. When you dig in hard with your playing, the IR actually responds like a speaker about to break up. This is why the M25SH feels "spongy" and "squishy" under the fingers, especially for lead work.
At a price point of roughly $12-20 USD (depending on sales), the York Audio KW 412 M25SH IRS is the single best investment you can make for your digital rig if you crave vintage British tone.
It transforms a lifeless plugin like Guitar Rig or Amplitube into a snarling, breathing stack. It makes Fractal Audio's Cygnus modeling feel like you are actually standing in a rehearsal space with a cranked Super Lead.
Final Score: 9.5/10 (Loses half a point only because Greenbacks aren't for everyone—but if they are for you, this is a 10.)
Stop tweaking. Stop fighting fizz. Load the KW 412 M25SH MDRN mix, turn your bass knob down, and rediscover why the Pre-Rola Greenback is the most recorded speaker in rock history.
Where to buy: Visit the official York Audio website (yorkaudio.co). Look for the "KW 412 M25SH" pack. Available in .WAV, .SYX (Fractal), .KIPR (Kemper), and standard IR formats.
Your Plexi is waiting.
The York Audio KW 412 M25-SH Cab Pack is a high-fidelity impulse response (IR) library based on a custom Kerry Wright 4x12 cabinet originally built for fusion guitar legend Scott Henderson. This pack is widely considered a benchmark for Greenback-style IRs due to its remarkable clarity, "amp in the room" realism, and the unique resonance of the boutique cabinet it captures. Key Specifications & Features Cabinet: Custom Kerry Wright 4x12 straight cabinet. Speakers: UK-made Celestion G12M 25W Greenbacks.
Unique Folders: Includes a dedicated "Scott Henderson" folder featuring the artist's personal microphone placements, as well as signature mixes for Jim Adkins (Jimmy Eat World).
Ambient Options: Features new Stereo Room captures and Stereo Mixes designed to provide a natural stereo image, particularly effective for headphone use.
Format Compatibility: Available in 24-bit .WAV files at 44.1k, 48k, and 96k sample rates, making them compatible with almost all hardware modelers (Fractal, Line 6, Kemper, Strymon) and DAWs. Tonal Characteristics
The KW 412 M25-SH is known for a sound that is both "fat and clear".
Low End: Warm, thick, and highly resonant without becoming muddy.
Midrange: Signature vocal Greenback midrange that is present and balanced, avoiding the "boxy" feel of some vintage cabs.
Top End: Incredibly detailed and articulate, offering high note definition and string clarity. Included Microphones
York Audio used an extensive selection of classic and boutique microphones to capture this cabinet:
Dynamic: Shure SM57 (modern and vintage), SM58, SM7, Sennheiser MD421 (modern and vintage), e906, and Beyerdynamic M69. Ribbon: Royer R-121, Beyerdynamic M160, and Shure KSM313.
Condenser: Telefunken U47, ADK U67, Neumann KM 184, AKG C414, and Dachman Audio U87i.
The pack is highly recommended for everything from pristine cleans and edge-of-breakup (EOB) tones to high-gain lead work. KW 412 M25-SH - York Audio
KW 412 M25-SH Cab Pack York Audio is a high-fidelity impulse response (IR) library based on a custom Kerry Wright 4x12 cabinet owned by fusion legend Scott Henderson
. This pack is widely considered a gold standard for "Greenback" tones, offering a blend of vintage warmth and modern clarity. Core Specifications & Features Custom-built Kerry Wright 4x12. Celestion G12M 25W Greenbacks Sonic Profile:
Characterized by a thick, warm low end, vocal-like midrange, and highly articulate top end. Included Files: 24-bit .WAV files at 44.1k, 48k, and 96k sample rates. Unique Content: "Scott Henderson" Folder: york audio kw 412 m25sh irs
Custom captures of Henderson’s personal preferred mic placements. Artist Mixes:
Three signature mixes created for Jim Adkins of Jimmy Eat World. Stereo Room Captures:
New stereo room IRs designed to provide an "amp-in-the-room" feel, especially effective for headphone monitoring. Compatibility
The pack is designed to work seamlessly with all major hardware and software modelers: Optimized for Fractal Audio (Axe-Fx, FM3/9), Line 6 Helix Neural DSP Kemper Profiler Required for Strymon Iridium Performance & User Experience
Reviewers and professional musicians have praised this pack for its "mix-ready" quality, noting that the multi-mic mixes often require minimal EQ to sit perfectly in a track. Scott Henderson himself stated that the IRs are an indistinguishable replica of his physical cabinet, calling the accuracy "life-changing".
Overview
The York Audio KW 412 M25SH IRS is a 4-way, bi-amped loudspeaker system that boasts an impressive combination of power, precision, and versatility. This system is designed to deliver exceptional sound quality, making it suitable for a wide range of applications, including live concerts, festivals, theatrical productions, and installations.
Design and Construction
The KW 412 M25SH IRS features a rugged, tour-grade enclosure constructed from 3/4-inch plywood, with a durable, textured finish. The speaker system is comprised of four custom-designed drivers:
The drivers are carefully mounted in a proprietary, computer-optimized waveguide system, which helps to control dispersion and minimize unwanted resonances.
Acoustic Performance
The York Audio KW 412 M25SH IRS is designed to deliver exceptional acoustic performance, with a frequency response of 38 Hz to 18 kHz (-3 dB). The system's bi-amped configuration, featuring two dedicated amplifiers for the low- and high-frequency sections, ensures optimal power distribution and minimizes the risk of amplifier overload.
The M25SH woofers provide deep, articulate bass, while the mid-range driver offers clear, detailed reproduction of the critical midrange frequencies. The high-frequency driver delivers crisp, accurate treble, with a smooth, even dispersion pattern.
Key Features
Some notable features of the York Audio KW 412 M25SH IRS include:
Technical Specifications
Here are some key technical specifications for the York Audio KW 412 M25SH IRS:
Conclusion
The York Audio KW 412 M25SH IRS is an exceptional loudspeaker system, designed to deliver high-quality sound and reliable performance in a wide range of applications. With its bi-amped design, 4-way configuration, and computer-optimized waveguide, this system offers an unbeatable combination of power, precision, and versatility. Whether you're a live sound engineer, installer, or audio enthusiast, the KW 412 M25SH IRS is definitely worth considering.
The York Audio KW 412 M25-SH is an impulse response (IR) pack based on fusion legend Scott Henderson’s personal Kerry Wright 4x12 cabinet. This specific cabinet is loaded with UK-made Celestion G12M 25w Greenback speakers. Key Features
Signature Tone: Designed to replicate the "inspiring" tone of Henderson's setup, featuring a warm, thick low end, a vocal Greenback midrange, and highly articulate high-end detail. Unlike competitors who shoot IRs at bedroom volume,
Scott Henderson Folder: Includes a dedicated folder featuring Scott Henderson's personal microphone placements for the cabinet.
Stereo Room Captures: A unique addition to this pack is the inclusion of Stereo Room captures and Stereo Mixes, which provide real room ambience for an "amp in the room" feel when using headphones or stereo monitors.
Artist Mixes: Contains three custom signature mixes created for Jim Adkins of Jimmy Eat World. Pack Contents The full version of the pack includes 94 total IRs:
10 Microphones: A curated selection of 10 different mics used for various captures.
79 Single Mic Shots: Includes multiple "sweet spot," cap edge, and off-axis files.
15 Multi-Mic Mixes: Signature "ear-tuned" blends for immediate use.
Format Compatibility: Files are provided in .WAV format at 44.1k, 48k, and 96k sample rates (24-bit), compatible with Fractal Audio, Line 6 Helix, Kemper, and most DAWs. Performance & Pairing
Versatility: Described as a "Swiss Army knife" cabinet that works across all gain levels and music styles.
Amp Pairing: Reviewers noted it sounds "massive" with models like the Dirty Shirley and Cornfed, and works exceptionally well for clean tones such as Matchless or Band Commander.
Impedance Settings: For Fractal users, it is recommended to use the 4x12 Basketweave impedance curve with the low frequency set to 115Hz for the most authentic response.
Title: The Ghost in the Wire
Logline: A disgraced audio forensic analyst discovers that a vintage speaker model, the York Audio KW 412 M25SH IRS, isn't just a relic of analog sound—it’s a dormant military-grade psychoacoustic weapon, and someone just turned it on.
The Story
Rain lacquered the cobblestones of York, England’s oldest district. Inside a cluttered workshop that smelled of solder and mildew, Elias Thorne stared at the charred remains of a speaker cabinet. The blackened badge read: York Audio KW 412 M25SH IRS.
“This isn’t a speaker,” he muttered, his voice raspy from years of disuse. “It’s a confession.”
Three days ago, a former MI5 analyst named Mira Sudol had walked into Elias’s shop. She wasn’t looking for a vintage 4x12 guitar cabinet. She was looking for a ghost. For two years, she’d been haunted by a low-frequency hum—a subsonic drone that triggered panic attacks, fragmented memories, and aphasia. Doctors called it tinnitus. She called it the Shiver.
“The hum only appears near old sound systems,” she’d said, sliding a worn service manual across the counter. The cover read: York Audio KW 412 — Modified for IRS (Infra-Red Sonic) Calibration.
Elias had laughed. IRS wasn’t “infra-red.” In old York Audio engineering slang, it stood for Inverse Resonance System—a classified side project from the late ‘80s, when British defense contractors secretly repurposed guitar amps for acoustic harassment.
The Build
He’d spent forty-eight hours tracing the circuit. The KW 412 M25SH was a monster: four 12” Celestion M25 speakers, known for their “brown sound.” But inside this unit, the wiring was wrong. Instead of a simple series-parallel, the coils were wound with a bismuth-iron alloy—non-magnetic, reactive to neural fields. The “SH” in the model number didn’t stand for “Super Heavy.” It stood for Schumann Harmonic—a frequency that matches Earth’s own resonance, 7.83 Hz.
When played at specific amplitudes, the IRS circuit didn’t produce sound. It produced standing waves that bypassed the eardrum and resonated directly with the brain’s limbic system. You didn’t hear the York Audio KW 412. You felt it. Fear. Euphoria. Rage. Programmable emotion, delivered via quarter-inch jack. At a price point of roughly $12-20 USD
The Crime
Elias powered up the damaged unit using a lab bench generator. The cones didn’t move. But a pressure change filled the room—a cold, sinking dread. His vision blurred. For three seconds, he saw his dead daughter’s face, then a flash of a London underground station, then nothing.
When he came to, the oscilloscope showed a spike: 7.834 Hz, modulated with a voiceprint.
“Mira wasn’t a victim,” he whispered. “She was the target.”
He pulled the service manual again. Page 47, handwritten notes: “Project Silencio. York Audio KW 412 M25SH IRS units deployed 1989-1991. Each amp paired to a single operator’s EEG signature. The amp doesn’t play music. It plays the operator’s suppressed trauma, amplified 400x, into the skull of a subject.”
Mira hadn’t been haunted. She’d been used. Someone had her old EEG profile. Someone had another York Audio KW 412 M25SH IRS—still intact, still hidden—and was broadcasting her nightmares into her brain to control her.
The Hunt
Elias traced the speaker’s serial number to a decommissioned BBC relay station outside York. He arrived at midnight, carrying only a modified Walkman and a pair of ferrofluid-damped headphones.
The station was silent except for a low, throbbing pulse—the Shiver. In the basement, a pristine York Audio KW 412 M25SH IRS sat on a shipping pallet, wired to a 1970s Revox tape machine. The tape was old, spooling endlessly. On it was a loop: Mira Sudol’s own childhood scream, recorded during a suppressed memory extraction in 1989, when she was a child subject of Project Silencio.
The amp was playing her own terror back to her, warping her present.
Elias didn’t smash the speaker. He couldn’t. Instead, he plugged his Walkman into the IRS input and played a single sound: silence. But it was a digital silence—a 24-bit null signal that forced the IRS circuit to resonate with itself.
The York Audio KW 412 M25SH IRS began to glow at the cone edges. A harmonic feedback loop built. The concrete floor cracked. Elias’s nose bled. Then, with a sound like a scream swallowed by a black hole, the speaker collapsed into its own magnetic field.
Silence.
The Aftermath
Mira woke up the next morning without the Shiver. She sent Elias a single text: “I remember everything now. Thank you.”
Elias looked at the blackened badge on his workbench. He knew there were more units out there. And somewhere, someone was still listening to the ghosts they had trapped in copper wire.
He soldered a new resistor into a broken Fender amp, hung a sign on his door—“No IRS repairs. No questions.”—and waited for the next ghost to find him.
End
York Audio employs high-fidelity digital capture techniques to create IRs. The process typically involves the following signal chain:
Using the York Audio KW 412 M25SH pack, you are not just getting "a rock tone." You are getting distinct flavors. Let’s look at the star players in the folder.
Strengths:
Limitations (Honest):