Undertone Audio MPDI-4 Four Channel Mic Pre  From Undertone

This four-channel mic pre brings an incredible variety of tone shaping functions. It can go from "wire with gain" to thick, creamy transformer tone!

Undertone Audio


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What We Think

Some of the greatest and most fulfilling moments in the studio occur only through experimentation and discovery. The Undertone Audio MPDI-4 is perfect for those like me who love versatility and seek complete creative control in order to explore all tonal options available before committing to a sound. It's like having a palette of vintage pres to pick and choose from, but expanded to take that to the next level with the ability to blend amongst 4 individual transformer-based options. Housed in a single rackmount unit, the MPDI-4 is a “swiss army knife” of vintage sounds combined with modern flexibility.

You’ll be hard pressed to find a 4-channel preamp in this price range that tops the tonal control features of this preamp. I really love experimenting with both the individual input transformer options and the impedance choices; dialing in just the right balance of all the available options to really get the most out of my mic on the front end. It's been incredibly fun custom tailoring my signal for best results at the source and I've fallen in love with new sounds created with settings out of my typical comfort zone found through the pure and freeing process of “flipping all the switches until it sounds right”. 

The beauty of the preamp is that with all of the different transformer and impedance options comes the ability to bypass them ALL. That means you can have a couple of channels dialed for warm tone and character, almost grit, and at the same time have another channel set to bypass all transformers for a clean, detailed and transparent preamp.  Additionally, all four front panel DI’s run through this circuitry, giving your synths, basses, and DI guitars access to this wide spectrum of color if you so desire.

Taking time to go between both spectrums with this preamp or just flipping that extra switch and stepping that rotary gain one more click can lead to an “ah-ha” moment of sound you will love. While a godsend for the tweaker engineer after a variety of color options, the MPDI-4 would be a fantastic centerpiece multi-channel preamp for those after both clean and warmer tones.


Undertone Audio MPDI-4 Four Channel Mic Pre Quick n' Dirty

In this video, Sound Pure pro audio expert David Barrett runs us through the many awesome features of the Undertone Audio MPDI-4 Four Channel Mic Pre.

  • Signal Chain
    • Undertone Audio MPDI-4 Four Channel Mic Pre

Manufacturer's Description from Undertone

The MPDI-4 is as musical as it is powerful and flexible. It features 4 individual Mic Preamp/DI circuits housed in a single 1RU chassis.  With bypassable transformers, switchable output headroom, and adjustable THD characteristics, the sound of the MPDI-4 can range from astonishingly pristine to warm, thick, and harmonically colorful. It may well be the only preamp that is truly perfect for every situation!

Undertone Audio

About Manufacturer

Undertone Audio is inspired by the idea of making professional audio products with the classic sound and musicality of Class A, single ended circuitry, packaged with some exciting new features and functionality. Our flagship product is a fully featured mixing console that truly embodies this inspiration.


  • -10 to -60 dB boost range (in stepped 5 dB increments)
  • Switchable -20 dB input pad and -10 dB output pad
  • Instrument DI
  • Switchable 600-ohm output load
  • Switchable Low impedance mode ideal for passive ribbon microphones
  • Front panel XLR–1/4" (DI) combo input
  • Phase reverse switch
  • + 48 V phantom power
  • Bypass-able input and output transformers
  • Inputs/Outputs (all XLR):
    • Mic-pre Input
    • Mic-pre direct Line Output