The Drunk Beaver XR MD-1 Metal Mind is a metal distortion pedal that reworks the dual-gain-stage architecture of the Exar MD-03 and MD-04, themselves derived from the Boss MT-2 Metal Zone. Drunk Beaver builds it with low-noise op-amps, power supply filtering, true-bypass switching, fixed filters and an active three-band EQ1. It sits in the maker's XR Series of distortion pedals1.
Where the circuit comes from
The Boss MT-2 Metal Zone, designed by what Electric Druid's Tom calls "those clever Boss engineers of the 1980's", is the origin of the gain architecture here2. Electric Druid's circuit analysis of the MT-2 found that its gain stage runs from a minimum of x2 to a maximum of x252, set by R051 and VR12. The Exar MD-03 and MD-04 that the Metal Mind reworks largely copy that Boss gain architecture but go with a more straightforward three-band active EQ1. Drunk Beaver's contribution is to rework the whole design with low-noise op-amps and power supply filtering1.
The controls
The Metal Mind carries five controls, three of them EQ1:
| Control | Type | What it does |
|---|---|---|
| Gyrator Lows | Active gyrator EQ, centered at 86Hz | Bass bandpass control1 |
| Gyrator Mids | Active gyrator EQ, centered at 533Hz | Mid bandpass control1 |
| High-Pass Filter | Active high-pass filter, centered at 7.2kHz | High control1 |
| Metal / Gain | Gain | Amount of distortion1 |
| Level | Output level | Overall volume1 |
Essentially, the Bass and Mids are gyrators, meaning peak or bandpass filters, while the High is a high-pass filter1. A gyrator is an op-amp circuit that mimics an inductor, which is how the pedal builds its bandpass EQ sections without coils.
Vintage and Modern settings
Guitar Pedal X's reviewer Stefan Karlsson published two preferred setting recipes, one leaning vintage and one modern1:
- Vintage: Low @ Max, Mid @ Min, High @ Noon, Level @ Noon, Metal @ 3 o'clock1
- Modern: Low @ Max, Mid @ 3 o'clock, High @ Noon, Level @ Noon, Metal @ 3 o'clock1
The difference between the two is the Mid control: min for the Vintage voicing, 3 o'clock for the Modern one. Karlsson adds a caution on the Modern setting: "But for the Modern setting I don't like to go above 3 o'c - as beyond that it starts to alter the texture of the pedal and add more noise"1.
What reviewers found
Karlsson's verdict on the build and behavior: "The pedal has an incredibly low noise floor, and significant range on every dial."1 The low-noise op-amps and power supply filtering Drunk Beaver added to the MT-2-derived architecture appear to be doing their job in that account1.
As of the 9 September 2026 review, only a few remaining first batch editions were available direct from the Drunk Beaver Rocks webstore1.
Videos
Pair of Pandas
Questions
What is a gyrator EQ?
A gyrator is a circuit built around an op-amp and capacitors that behaves like an inductor, letting a pedal build a bandpass or peak filter without a physical coil. On the Metal Mind, the Bass and Mids controls are gyrator filters, meaning peak or bandpass filters, while the High control is a high-pass filter centered at 7.2kHz.
Is the Metal Mind based on the Boss Metal Zone?
Indirectly, yes. Guitar Pedal X describes the MD-1 as a rework of the Exar MD-03 and MD-04 pedals, which largely copy the Boss MT-2 Metal Zone gain architecture but use a more straightforward three-band active EQ. The Metal Mind takes that same dual-gain-stage architecture and adds low-noise op-amps and power supply filtering.
How much does the Metal Mind cost?
Guitar Pedal X lists the Metal Mind at $90 / €90 / 349 PLN as of its September 2026 review.
What are the Vintage and Modern settings?
Reviewer Stefan Karlsson's preferred Vintage settings are Low at max, Mid at min, High at noon, Level at noon and Metal at 3 o'clock. For the Modern setting he keeps everything the same but raises the Mid control to 3 o'clock. He cautions against pushing the Mids beyond 3 o'clock on the Modern setting, as it alters the pedal's texture and adds noise.
Is the first batch still available?
As of the September 2026 review, a few remaining first batch editions were available direct from the Drunk Beaver Rocks webstore.
Sources (2)
- Guitar Pedal X, Guitar Pedal X, 2026-09-09
- Boss MT-2 Metal Zone pedal analysis, Electric Druid (electricdruid.net), 2016-01-22
