microZOTL MZ2 Headphone Amp / Preamp / 1-watt Speaker Amp
The successor to David Berning's original micro-ZOTL, the MZ2 continues to offer what Berning intended it to: an introduction to ZOTL TEC.
Equally a headphone amplifier, integrated amplifier, and preamp, the MZ2 is considered reference-grade for powering almost any headphone, as a 1 wpc amp for extremely efficient speakers, and as a preamp performing well above its price.
Hand-built by our small team just outside of Washington, DC, each MZ2 involves 12 hours of delicate work, including precise hand-winding of several proprietary components, and several days of burn-in and testing.
While technically an OTL amplifier, not having traditional output transformers, the MZ2 is an entirely different kind of circuit that is able to achieve low output impedance and low-current tube operation, which translates to easy matching to almost any headphone or speaker and a very long tube life. ZOTL technology results in amps with the transparency of OTL without the many limitations of OTL designs: purely tube amplification that achieves a theoretically ideal turns ratio and happily interacts with speakers from 2 to 16 ohms, or above. Headphones from 16 to 600 ohms are powered without any hum.
The MZ2 an on-board jumper that allows the user to switch between using 6SN7 and 12SN7 tubes.
The MZ2 has more gain than most preamps, so it can drive headphones. 12AU7 tubes also work in the MZ2, and lower the gain.
LPS Linear Power Supply - the original microZOTL has a switching power supply, which comes with a basic unit. It's low cost allows the MZ2 to be available at a very low price. But the linear supply (LPS) is a much better supply utilizing super low ESR caps and a super low noise Belleson regulator. You get better sonics with more dynamics.
Distinguished visually from the MicroZOTL2 by its silver screws and white power LED, the MZ2-S was designed in response to customer feedback and discussions about the amp. We wanted a “pre-rolled” tube amplifier that arrived with NOS tubes selected to match well with the circuit, so that the many people interested in tube rolling and old-stock tubes could get that experience without having to go through the uncertain and involved process of choosing and sourcing their own.
We’ve altered the circuit of the amp to take 12SN7 output tubes instead of the more common, and more sought after, 6SN7. Doing this made it feasible to provide a full NOS complement at minimal price increase, and every MZ2-S comes with a pair of RCA 12SN7 and a pair of 6201 tubes, a military-spec version of the 12AT7 that owners of the MicroZOTL2 have favored. Developing the MZ2-S also led us to look at our linear power supply again, and we’ve significantly upgraded the regulator. The MZ2-S is our offering for a end-game headphone amp, preamp, or low-power stereo amp that doesn’t ask for any upgrades.
Designed by David Berning - one of the world’s premier amplifier designers
Hand-made just outside Washington, DC
External power supply - extremely low noise floor
Drive high efficiency speakers (95db efficiency or higher) to adequate volume.
Universal voltage power supply or high quality linear power supply
2 selectable inputs
Class A preamplifier output
Transformer-less design eliminates intermodulation distortion inherent in all transformer designs
Simulates the correct transformer turns ratio using impedance converter
Low impedance output easily matches wide range of headphones and speakers
No heavy power or audio transformers
Optimized tube life expectancy of 10 - 20 years based on use
Amplifier class: Push-pull Class A, no feedback
Sensitivity: 0.6V RMS [full output]
Output impedance: (measured @ 0.5A, 60 Hz) 2 ohms
Input impedance: 50k
Power Supply Input: Manually switchable 120V(+/- 10%) / 220V(+/- 10%) 50-60hz operation
Power Supply Output: 12VDC 2.5 amps
Hum and noise: minimum 60mV RMS or 90dB below full output (20Hz-20kHz)
Power consumption from ac power source: 33W
Power output: with 4-ohm load: 1W, 1% THD, with 14-ohm load: 0.5W, 1% THD
Channel separation: (4-ohm loads) 46dB, 100Hz-10kHz, (14-ohm loads): 54 dB, 100Hz-10kHz
Frequency response full power: (4-ohm load) +0, -1dB 10Hz-20kHz, (14-ohm load): +0, -1dB 5Hz-50kHz,
Voltage gain: (4-ohm load): 10.3dB, (14-ohm load): 12.4dB
Size: Amplifier: 9 1/2 inches (24.1 cm)wide, 4 3/4 inches (12.0 cm) tall, 7 7/8 inches (19.7 cm) deep (including connectors); External PSU: 12" (30.48 cm) x 3.25" (8.26 cm) x 4.25" (10.8 cm)
Net weight: 8.94 lbs (4.1 kg) - amplifier and external power supply)
Finish: black Aluminum case and faceplate w/ lexan top
Tube complement per channel: NOS 6201/12AT7 input, NOS 12SN7 output