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Single & Dual-Channel Tube Mic Preamp


Single msrp $749
Dual msrp $1,399

Disclaimer: WA-MPX and WA-2MPX products are not sponsored, affiliated, associated, authorized, endorsed by or in any way officially connected with AMPEX products or the Ampex Corporation.
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Some History Is Worth Repeating

The WA-MPX is an authentic reproduction of the vintage tape machine tube preamp that started the birth of rock ‘n’ roll known for pure analog warmth, delivering an impressive 300v of raw power & 90dB of tube gain. During the golden era of tape recording, the original 351-style tube preamp became the kings of studio tech and signature sound in the signal chain of hit recordings for artists including Elvis Presley, Bing Crosby, Les Paul, Nat King Cole, and Roy Orbison and producers like Steve Albini- a timeless sound that continues to be pursued by elite audio engineers today. With premium components, true-to-original circuit design, and selectable tape saturation, the WA-MPX authentically reproduces all the analog tone of the original to bring vintage warmth & color to your sound.


An Authentic Vintage Experience

The WA-MPX preamps are hand-wired with 100% discrete electronics. Each channel boasts three tubes that, with the high-gain switch engaged, bring the WA-MPX up to an incredible 90dB of gain. Each channel has custom-wound, large-core CineMag transformers on the inputs and outputs - bringing each preamp circuit to 300v. WA-MPX pres are housed in steel chassis with a brushed aluminum faceplate, vintage-style bakelite knobs, and amber-tinted VU meters. All of these key components paired with traditional build technique deliver not only a legendary “tape-era” tube pre but one of the best values in an all-tube microphone preamp on the market today. Following the Warm Formula of true-to-original tone driven by premium components, all WA-MPX are carefully hand-inspected & tested at Warm Audio Headquarters in Austin, Texas.

A Tube-Based Tone-Shaping Workstation

As a premium tube mic pre, WA-MPX delivers a wide range of analog tone; from clean volume with preserved clarity for quieter sources to richer distortion that can be driven harder as the tubes are pushed to saturation. The WA-MPX sports a set of critical controls that meet the demands of everyday professional audio use including input impedance switching, +48v, polarity inversion, and input/output gain. In addition to the 80Hz hi-pass filter that can help tame unwanted bass frequencies, the WA-MPX also houses a 2kHz low-pass filter to shave off excess highs for a more vintage tone profile. The classic Warm Audio “tone” control alters the input transformer impedance for extra analog color. A “high gain” control engages an extra 20dB of tube gain to take the WA-MPX all the way to 90dB - very useful on lower output dynamic and ribbon mics. Finally, the Tape Saturation control on the WA-MPX engages a discrete circuit in the signal path adding natural compression, harmonic distortion, and focused tone filtering to emulate the sound of tape machines running at 15IPS, adding just enough imperfection to the signal, especially when used on program material for mixing and mastering.
The WA-MPX is far more than just a pre with the vibe of analog tape, it's a perfectly adaptable and extremely powerful tube mic preamp.

Premium Components - Elite Build Quality - Superior Sound

Premium 12AX7 & 12AU7 Vacuum Tubes

Using three premium vacuum tubes, two 12AX7s & one 12AU7 per channel, the WA-MPX delivers both high headroom and harmonically-rich vintage analog tone only found in the most unattainable tube microphone preamps on the market.

American-Made Transformers From CineMag

The history of CineMag transformers goes all the way back to the 1940s with connections to some of the most sought-after audio equipment of the last century. The particular CineMag output transformers inside with WA-MPX pres are custom-wound with a very large core. Like all CineMags, the input & output transformers on WA-MPX are American-made and built to exacting standards. The huge headroom and added analog color of the transformers pair beautifully with the premium tubes inside WA-MPX.

Technical Specifications (Per Channel)

  • Authentic Reproduction Of The Most Revered Tape-Era Tube Preamp

  • Fully Discrete, Hand-Built Construction With 3 Tubes Per Channel For Ultimate Analog Tone

  • Selectable Tape Saturation Adds Harmonic Distortion & Natural Compression

  • 90dB Of Analog Tube Gain Per Channel

  • Custom-Wound, Large-Core CineMag USA Transformers

  • Mic Input: 600Ω Transformer (6000Ω Rated)

  • Mic Input With “Tone” Engaged: 150Ω Transformer (1500Ω Rated)

  • Premium (2X) 12AX7 & (1X) 12AU7 Vacuum Tubes

  • 600Ω Output Attenuator

  • Engage High Gain Control For An Added 20db (From 70db To 90db) Of Clean Gain For Low-Output Mics And Low-Volume Sources

  • 48v Phantom Power & Polarity Switch

  • Classic Warm Audio Tone Control That Alters The Input Transformer Impedance Adding Extra Analog Color

  • 80Hz High-Pass Filter To Control Unruly Bass Frequencies

  • 2kHz Low-Pass Filter To Focus Preamp Power & Warmth On Mids For Added Punch

  • Inputs: XLR Mic, TS Instrument & TRS Line.

  • Outputs: XLR / TRS Line Level

  • VU Meter Level Indication

  • Frequency Response: 20Hz-20kHz

  • Aluminum Faceplate, Steel Chassis, & Vintage Bakelite-Style Knobs

  • Internal IEC 115v/230v Power Inlet

WA-MPX Standard Gain (70dB) Frequency Sweeps

No Filtering


80Hz HPF Engaged


2kHz LPF Engaged


WA-MPX High Gain (90dB) Frequency Sweeps

No Filtering


80Hz HPF Engaged


2kHz LPF Engaged


Sound Samples