The GT44 is a small-diaphragm tube condenser in a pencil form factor — an unusual combination that gives it a distinctive character in the studio. Designed by Aspen Pittman, the circuit runs a hybrid impedance conversion topology: a FET on the front end feeding a subminiature GT6205M pentode tube, with an output transformer isolating the balanced XLR output. The capsule is a 3/4-inch assembly with a 19mm, 6-micron gold-vapor-coated Mylar diaphragm — ultrathin and highly sensitive, with the smooth top-end detail you'd expect from a well-made small-diaphragm condenser, colored by the warmth and harmonic character of the tube stage behind it. Switchable -15dB pad and 75Hz high-pass filter handle loud sources and low-end rumble independently. The capsule system is interchangeable — optional omni and hypercardioid capsules are available separately. Requires the included PSM1 external power supply. A thoughtfully engineered instrument mic that occupies a genuinely unique spot in the small-diaphragm tube world.
This unit is in good condition and fully functional throughout. Cosmetic wear consistent with normal use. Photos show the condition accurately.
- Make: Groove Tubes
- Model: GT44
- Type: small-diaphragm tube condenser microphone, end-address
- Diaphragm: 19mm, 6-micron gold-vapor-coated Mylar
- Preamp topology: hybrid — FET front end, GT6205M subminiature pentode tube
- Output transformer: yes
- Polar pattern: cardioid
- Frequency response: 20Hz - 20kHz
- Sensitivity: 28mV/Pa
- Equivalent noise: 20dB SPL (A-weighted)
- Maximum SPL: 130dB (145dB with pad)
- High-pass filter: switchable, 75Hz, 12dB/octave
- Pad: switchable -15dB
- Output impedance: 200 ohms, transformer isolated
- Body: nickel-plated brass
- Dimensions: 7.5" L x 0.85" dia
- Weight: 12 oz
- Power: PSM1 external power supply (included), 7-pin cable
- Modifications: none
- Includes: PSM1 power supply, mic clip, cables, case
Ships carefully packed and insured for full value.
International buyers are welcome — please contact us for a shipping quote before purchasing.
About Mill River Music
Mill River Music is an independent, human-powered music shop located in downtown Northampton, MA, run by a team of players, enthusiasts, and certified repair technicians. Every piece of used gear we sell is personally inspected, tested, and set up before it ships — we don't list it until we'd be happy to play it ourselves.
As Martin and Taylor certified techs, we hold our guitar work to a high standard, and we're committed to full transparency about the condition of everything we sell. No surprises.
When you buy from Mill River, you're supporting an independent local business that genuinely cares — about gear, about players, and about doing things right. We're here every step of the way. Reach out anytime.
