MM-1 PRE / D.I.


Redefining what a preamp can do.

The Black Box Analog Design MM-1 Vacuum Tube Preamp is an entirely new approach to capturing audio. It is not based on any existing circuit but designed from the ground up, using the best parts and ignoring all of the standard ideas of how a preamp “should work”. The result is an incredibly versatile piece of gear that not only sounds amazing but shatters the idea of what a preamp can do!



Click "+" for detailed description of each control

1: Power switch

On/Standby/Off positions.  Standby mode sends power to the tube heaters and LEDs.

2 : Low end roll off selector

5 position, gentle low end roll off

3 : Input pad

10db input pad

4 : Input impedance

Impedance is switched by tapping into the transformer at different points in the winding. Default (button out) is standard higher impedance input.  Engaging the switch (button in) switches to lower input impedance for loading the microphone or for use with ribbon microphones.

5 : Phantom power

48 volt Phantom power fed by an isolated, regulated, linear supply

6 : Phase reverse

Phase switch

7 : Pentode gain control

The Pentode gain control tilts the response depending on the “response” selection.

8 : “Response” selection

In default mode (button out), the top end of the response is fixed and the response tilts around this fixed position.  The lower the Pentode setting, the more low end is rolled off in a tilt.  When response is engaged (button in), the top end is no longer fixed and the top end tilt moves the other way, rolling off more top end as the Pentode is decreased.

9 : Air

“Air” engages the air circuit from the HG-2 (10k harmonic shelf).  The MM-1 comes standard with a 3 db boost when air is engaged but the boost is internally adjustable.

10 : Triode gain control

The triode stage has a linear frequency response and should be used as the drive stage.  It can be used to cleanly amplify the response curve of the Pentode stage or driven into gentle saturation, hard saturation and eventually limiting.

11 : Instrument input

Plugging an instrument cable into the input automatically engages the DI and disconnects the microphone input.  The signal path of the DI follows the same topology and controls as the microphone input, with the exception fo the input transformer.

12 : Output attenuation

The output control is a passive output attenuation designed to allow you to drive the Triode stage as hard as you would like and still have the ability to trim the overall output back to your desired level.  In the fully clockwise position, there is no attenuation.

Click here for PDF manual.

Tonal Control Like Never Before

Until now, a preamp simply amplifed the signal; you essentially got one sound and the ability turn it up or down. The MM-1 on the other hand allows you to drastically shape the response curve of the unit without using an EQ, control the harmonic content from pristine to full on saturation and even control the dynamics without a compressor!

All of the shaping is done at the tubes and from the constantly variable interaction between stages allowing you to dial in virtually unlimited tonal possibilities. You can find the sweet spot of any microphone and instrument easily and naturally.  The response curve of the Pentode stage alone gives you a huge amount of control over the tone. Coupled with the independently controlled Triode stage you have virtually unlimited tones at your fingertips.

Harmonics for days…

There seems to be an obsession with THD when it comes to mic pre designs. Manufacturers boast about how “clean” their designs are and how low the THD is as if these harmonics are the plague yet the fastest growing trend in plug-in design is creating plug-ins that add back these harmonics! Tape, console, tube and various analog emulations that add pleasing harmonics and distortion are more in demand than ever! Why? Because the human ear LOVES harmonics! So why are manufacturers bragging about how they have managed to remove them from the design while mixers are having to add more emulations on to compensate? We have no idea but we certainly aren’t! We love harmonics and our pre has been designed to SOUND amazing! We give you the ability to add a ton of rich, beautiful and musical harmonics and give you unprecidented control over it!

All Tube, All Analog

Our entirely analog audio circuit uses only tubes for amplification and is entirely free of op amps, ICs and transistors! From precisely, hand matched resistors and capacitors to custom wound transformers, every part is selected and built for the absolute highest quality sound.

Real Power

We all know that a piece of gear is only as good as its power supply! For that reason, our preamps use a massive toroidal to supply 350v of pure, linear power to get the most out of the tubes. Real power means real sound!


  • Independently controlled Pentode and Triode tube stages
  • Custom wound input and output transformers
  • Entirely analog audio path (No ICs or Op amps)
  • Switchable input impedance at input transformer 
  • 5 position, gentle and musical roll off
  • “Air” circuit from the HG-2
  • Two response modes
  • 15 db pad
  • Linear power supply
  • Passive output attenuation control
  • 48v Phantom power 
  • Dual voltage