Release Friday Oct 2nd 8:30am CDT/ 13:30 UTC
First 20 Units come with a free Schiit IMP!
THE DESIGN
A refined Output Transformerless amplifier built around ZMF’s Airmid circuit topology — featuring an Aegis tube-rectified power supply, gyrator-loaded input stage, and actively loaded power pentode output. A clean, directly coupled signal path with a single film output capacitor.
TUBE COMPATIBILITY
An optional tube set featuring "select" Vintage 5U4G, Vintage 6SN7 and TAD KT-88 Black Plate bundle is available for $200 as an add on. The stock set is included as well when purchased.
Roll your own sound - full list here: https://docs.google.com/spreadsheets/d/1aMW8v7Nq9WAfBGaWFw-lE0Zoaz4dW2RlWbl5OngDPb0/edit?usp=sharing
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RECTIFIER |
INPUT |
OUTPUT |
|
GZ34 · 5R4 · 5U4 GZ32 · GZ37 · 274B Many others compatible (not low-current types, e.g. 5Y3) |
6SN7 12AU7 (with adapter) 6J5 (with adapter) Additional input options to be confirmed |
EL34 · EL37 · KT66 KT77 · KT88 · 6550 · 6L6 High-current power pentodes, bias current fixed at 60mA |
THREE-POSITION FEEDBACK SWITCH
Shape your sound from dynamic to smooth
|
OFF |
MODERATE |
HIGH |
|
No feedback 73Ω Output Impedance Maximum dynamics and punch |
Medium feedback 38Ω Output Impedance Balanced dynamics and refinement |
High feedback 21Ω Output Impedance Smoothest, lowest distortion |
Three feedback settings let you shape Airmid from dynamic to smooth, and match it to more headphones. Off gives you the most punch and life. High lowers output impedance from 73Ω to 21Ω for the smoothest, lowest-distortion sound and a firmer grip on lower-impedance headphones. For demanding planars, add the Schiit Imp for $99. It makes a 20Ω planar look like a 160Ω load to Airmid, so the amp drives it easily and its tube sound stays intact.
THE SOUND
Spacious. Dynamic. Detailed.
Spacious and diffuse sense of space · Impact and definition
Low distortion with active loading · Highly detailed and resolving
THE CIRCUIT
Aegis tube-rectified power supply — proven ZMF power supply design with wide rectifier compatibility
Gyrator-loaded 6SN7 input stage — active loading for low distortion and high detail without cathode bypass
Directly coupled input to output — no coupling capacitor between stages for purest signal transfer
Actively loaded power pentode output — current sink loaded cathode follower for low impedance drive
Single 4.7μF film output capacitor — minimal signal path, maximum transparency
Regulated DC heater supply — ultra-low noise floor for the input stage
Time-delayed startup protection — safe power-on sequencing for tube longevity
Optional global negative feedback — three settings to match your headphones and preferences
Preamp outputs — use the Airmid as a tube preamp for your speaker system or other amplifiers
THE DESIGNER
The Airmid was created by Keenan McKnight-Gwyn, known as L0rdGwyn on Head-Fi, a prolific DIY tube amplifier designer whose legendary thread has become a cornerstone of the Head-Fi DIY community. His builds — spanning SET amplifiers, OTLs, DACs, and phono stages — are renowned for their engineering rigor and sonic excellence.
Named after the Gaelic goddess of healing, the original Airmid was a hand-built OTL of which only five were ever made — praised for its outstanding detail retrieval, clarity, and spacious presentation. Community members described it as “beautiful and fast,” with a sound that “left me speechless.”
The ZMF Airmid is a collaboration between L0rdGwyn and ZMF Headphones to bring a refined, production version of this celebrated circuit to a wider audience for the first time. The production design adapts the original topology with a simplified input stage, power pentode outputs, and a three-position feedback switch — making L0rdGwyn’s acclaimed OTL sound accessible beyond the five originals.