Warm Audio WA-2MPX Stereo Microphone Tube Preamplifier

Before multitrack recording, before the electric guitar solo, before rock 'n' roll itself — there was the AMPEX 351. The tube preamp at the heart of that legendary tape machine shaped the sound of Les Paul, Elvis Presley, Nat King Cole, and Bing Crosby. The Warm Audio WA-2MPX faithfully recreates that circuit in a modern 2-channel stereo unit, bringing the warmth, depth, and harmonic richness of the original to your studio.

Three premium vacuum tubes per channel — two 12AX7s and one 12AU7 — deliver up to 90 dB of exceptionally clean gain, with an additional 20 dB high-gain boost for ribbon mics and low-output dynamics. Custom-wound large-core CineMag USA transformers provide the transformer coloration and low-end authority that define the vintage sound. Selectable tape saturation adds nonlinear harmonic distortion reminiscent of a tape machine running at 15 ips, while the tone switch alters input impedance to inject further color into your signal. With XLR mic, TS instrument, and TRS line inputs per channel, the WA-2MPX handles any source with authority.

Warm Audio WA-2MPX Features

• 2-channel authentic recreation of the AMPEX 351 tube preamp circuit
• 3 tubes per channel: 2 x 12AX7, 1 x 12AU7
• Up to 90 dB of gain per channel + 20 dB high-gain boost
• Custom-wound large-core CineMag USA transformers
• Selectable tape saturation — harmonic distortion at 15 ips character
• 80 Hz high-pass filter and 2 kHz low-pass filter per channel
• Tone switch for input impedance and color control
• Per-channel +48V phantom power and polarity reverse
• XLR mic, TS instrument, and TRS line inputs
• Brushed aluminum faceplate with Bakelite-style knobs
• Hand-tested and inspected in Austin, TX

Artists Who Defined the Sound

Original AMPEX 351 artists: Les Paul, Elvis Presley, Bing Crosby, Nat King Cole, Roy Orbison

Modern artists chasing this tone: Jack White, The Black Keys, Amy Winehouse, Mark Ronson, John Mayer, St. Vincent, Arctic Monkeys, The 1975

Tech Specs