It had to happen sooner or later. Leave it to the innovators at Warm Audio to build a microphone preamp based on the tube electronics of the iconic American professional tape machine that recorded countless radio-ready hits during the golden age of analog. From the rock pioneers of the ’50s and ‘60s to today’s sound-savvy artists, the legendary “351” has been the secret sauce in the signal chain that delivers the vintage-flavored warmth and color we all seek in our own recordings. The Warm Audio WA-MPX 1-channel tube mic/line/instrument preamp incorporates an original-spec circuit design, authentically reproducing the coveted analog sonics of the original. Handwired and hand assembled using only premium, all-discrete components, including custom-wound, original-spec large-core CineMag USA transformers, the WA-MPX serves up instant “sounds-like-a-record” punch for tracks that blast right out of the speakers. But there’s so much more to this amazing preamp that makes it indispensable to modern hybrid studio workflows.

Original circuit design, full feature set

While staying true to the original circuit design, Warm Audio added all the modern amenities that make the WA-MPX impressively versatile in the studio. Used in conjunction with the preamp gain and output level controls, the tape saturation switch makes it easy to tweak your gain structure from wide-open and crystalline to sizzling hot. The addition of Warm Audio’s classic tone switch lets you modify microphone input transformer impedance for mic optimization or extra analog color. Also onboard are a great-sounding instrument DI input, handy highpass and lowpass filters, polarity reverse, and of course, 48V phantom power. The WA-MPX employs three premium vacuum tubes: two 12AX7s and one 12AU7. In a stroke of engineering genius, Warm Audio included a high-gain switch that engages the third tube, boosting the available gain from 70dB to a staggering 90dB. Now you can finally deploy your favorite, notoriously low-gain passive ribbon mic on whisper-quiet sources!

Smooth and confident in operation

The WA-MPX graces any control room rack with its alluring visuals hearkening back to the vintage tape machine that inspired it. A model of simplicity, the WA-MPX’s thick brushed aluminum front panel presents a logical and businesslike control layout with large, grippy knobs and a warmly lit VU meter. On the left, you have a rotary input select switch with mic, line, and instrument settings. To its right are the instrument jack and seven switches that engage the previously mentioned functions. And finally, there’s that gorgeous VU meter flanked by preamp gain and output level knobs. In operation, the pots and switches feel silky smooth and inspire confidence. The WA-MPX is a very professional package, but we would expect nothing less from Warm Audio. And for pros with higher channel-count requirements, note that Warm Audio also makes a 2-channel version, the Smooth and confident in operation
The WA-MPX graces any control room rack with its alluring visuals hearkening back to the vintage tape machine that inspired it. A model of simplicity, the WA-MPX’s thick brushed aluminum front panel presents a logical and businesslike control layout with large, grippy knobs and a warmly lit VU meter. On the left, you have a rotary input select switch with mic, line, and instrument settings. To its right are the instrument jack and seven switches that engage the previously mentioned functions. And finally, there’s that gorgeous VU meter flanked by preamp gain and output level knobs. In operation, the pots and switches feel silky smooth and inspire confidence. The WA-MPX is a very professional package, but we would expect nothing less from Warm Audio. And for pros with higher channel-count requirements, note that Warm Audio also makes a 2-channel version, the WA-2MPX.

An incredible value you don’t want to pass up

Warm Audio never ceases to delight the audio pros here at Sweetwater. With the WA-MPX, they’ve done it again by delivering a feature-rich, hand-assembled, boutique-grade tube preamp at an amazingly affordable price. The flexible gain structure gives you broad latitude to push the tubes, dialing in natural harmonic distortion and compression that imbues sources with authentic 15IPS reel-to-reel sound. The WA-MPX offers mic/line inputs and balanced outputs on XLR and TRS for easy integration into your studio or mobile rig. And its robust metal chassis, stout rackmount faceplate, and discrete handwired internals make it an ideal preamp for front-of-house and location recording. Equipped with a rugged internal power supply and switchable 115/230 voltage, the WA-MPX is ready for action on any continent your productions take you to. Factor in its surprisingly low price tag, and it all adds up to an incredible value. Supercharge your recordings with the sound of a legend: the Warm Audio WA-MPX tube preamp.

Features:

• Authentic reproduction of the coveted “351” tape machine tube preamp
• Fully discrete, handwired and handbuilt construction with 90dB of clean analog tube gain
• Selectable Tape saturation adds harmonic distortion and natural compression for authentic analog grit
• Custom-wound, large-core CineMag USA transformers
• Tone switch modifies mic input transformer impedance for mic optimization or extra analog color
• 600Ω output attenuator
• Vacuum tube complement: premium 12AX7 (x 2), 12AU7 (x 1)
• Preamp Gain: 70dB, 90dB with High Gain engaged
• High Gain control engages third tube in the circuit, adding 20dB of clean gain for low-output mics and quiet sources
• 48V phantom power; polarity switch
• 80Hz highpass filter controls unruly low frequencies
• 2kHz lowpass filter focuses power and warmth on mids for added punch
• Inputs: XLR Mic, TRS Line, TS Instrument
• Outputs: line-level XLR and TRS
• VU Meter Level Indication
• Frequency response: 20Hz–20kHz
• Each unit hand inspected and tested at Warm Audio HQ in Austin, Texas
• Available as a 2-channel unit, the WA-2MPX

Specs

• Preamp Type:Tube
• Number of Channels:1
• Phantom Power:Yes
• Polarity Switch:Yes
• EQ:80Hz highpass filter, 2kHz lowpass filter
• Tubes:2 x 12AX7, 1 x 12AU7
• Analog Inputs:1 x XLR, 1 x 1/4″ TRS, 1 x 1/4″ Hi-Z (front)
• Analog Outputs:1 x XLR, 1 x 1/4″ TRS
• Frequency Response:20Hz-20kHz
• Rack Spaces:2U
• Power Source:Standard IEC AC cable