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Out of stock - Accepts Pre-Orders
Out of Stock - Allows Pre-Orders
Message us in discord or our website chat to find out pre-order time.
- 230V (CE Certified)
ZMF Airmid
Output Transformerless Tube Headphone Amplifier
- Production version of L0rdGwyn's acclaimed hand-built Airmid OTL
- Aegis tube-rectified power supply and gyrator-loaded 6SN7 input stage
- Actively loaded power pentode output, directly coupled with no coupling capacitor
- Three-position feedback switch: 73Ω, 38Ω or 21Ω output impedance
- Preamp outputs and wide tube-rolling compatibility
VAT and Duties Included for UK and Eligible EU Customers.
If you are outside the UK or EU, the price does not include any taxes. Local taxes and import duties will be extra. They will be raised by the local authorities and billed directly to the customer.
VAT and Import Taxes FAQ
ZMF Airmid
THE STORY
Introducing Airmid
Airmid started life as a hand-built output transformerless (OTL) amplifier designed by Keenan McKnight-Gwyn. Named after the Gaelic goddess of healing, only a handful were ever made, yet they became known for outstanding detail, clarity and a remarkably open, spacious presentation.
ZMF's Airmid is the second collaboration between Zach and Keenan, following the Aegis. It brings a refined production version of that celebrated circuit to more listeners for the first time, with a simplified input stage, power pentode outputs and a three-position feedback switch.
behind the Airmid amplifier
Who is L0rdGwyn?
Known on Head-Fi as L0rdGwyn, Keenan McKnight-Gwyn is a prolific DIY tube amplifier designer whose build thread has become a cornerstone of the community. His work spans SET amplifiers, OTLs, DACs and phono stages, all known for careful engineering and outstanding sound. After designing the circuit behind the Aegis, he partnered with ZMF again to turn his original Airmid into a production amplifier.
The Circuit
Direct-coupled, actively loaded, tube-rectified.
An Aegis tube-rectified power supply feeds a gyrator-loaded 6SN7 input stage. Active loading keeps distortion low and detail high without a cathode bypass capacitor, and the input is directly coupled to the output with no coupling capacitor in the signal path.
The output stage is an actively loaded power pentode, a cathode follower with a current-sink load, for low-impedance drive. A DC heater supply keeps the input stage quiet, and time-delayed startup protects the tubes at every power-on.
Tube Rolling Paradise
Airmid sounds great with its stock tubes and invites rolling. Rectifier: GZ34, 5R4, 5U4, GZ37, 274B and many more (not low-current types such as 5Y3). Input: 6SN7, or 12AU7 and 6J5 with an adapter. Output: EL34, EL37, KT66, KT77, KT88, 6550 and 6L6, with bias fixed at 60mA.
Shape Your Sound
A three-position feedback switch takes Airmid from dynamic to smooth. Off gives the most punch at 73Ω output impedance, Moderate balances drive and refinement at 38Ω, and High gives the lowest distortion at 21Ω with a firmer grip on lower-impedance headphones.
Spacious, Dynamic, Detailed
Airmid opens the music up around you. Voices and instruments spread out naturally, so you hear the room as well as the performance, while notes still land with weight and definition. Fine textures and decays come through cleanly without ever sounding forward or fatiguing. Preamp outputs also let it serve as a tube preamp for speakers or another amplifier.
Aegis-derived tube-rectified power supply
Three-position global feedback switch
Directly coupled 6SN7 input stage
Actively loaded power pentode output
Technical Specifications
Electrical Specifications
-
Output transformerless (OTL), direct coupled
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Feedback off: 73Ω · Moderate: 38Ω · High: 21Ω
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Headphone, preamp
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230V (CE certified)
Tube Complement
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GZ34, 5R4, 5U4, GZ37, 274B and others (not low-current types such as 5Y3)
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6SN7 (12AU7 or 6J5 with adapter)
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EL34, EL37, KT66, KT77, KT88, 6550, 6L6 (bias fixed at 60mA)
Physical Specifications
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14.25" x 12.25" x 8" (36.2 x 31.1 x 20.3 cm)
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29.5 pounds (13.4kg)
Customer reviews
Shipping, returns & warranty
- Dispatch
- 1–3 business days In-stock items, Monday to Friday except bank holidays, subject to stock and security checks.
- Delivery
- Tracked or signed Delivery options and costs are shown at checkout. We don't profit from shipping charges.
- Returns
- 14 days For electronics such as DACs, amps and players, in like-new condition with all original packaging and accessories.
Good to know
- Return shipping is paid by the customer.
- Open box, B-stock, refurbished and clearance items can't be returned.
- Please add a valid phone number at checkout in case we need to verify your identity.
- New products
- 1-year manufacturer warranty Most products. The exact warranty is set by the manufacturer.
- Pre-owned & open box
- 3 months B-grade, open box, refurbished, ex-demo and second-hand items.
- Covered
- Defects in materials, parts and workmanship
- Not covered
- Accidents, misuse and unauthorised repairs Including abnormal conditions, deliberate abuse and operator error.
- Making a claim
- Send it to us, we ship it back free You cover shipping to Elise Audio; we pay to send the repaired or replacement product back.