Groove Tubes GT67
Multi-Pattern Tube Condenser Microphone
The GT-67 is a multipattern tube condenser — essentially, a multipattern version of the GT-66 Cardioid tube condenser. It was for several years the flagship microphone in the Groove Tubes line.
The GT-67 uses components familiar to the GT product line: a 32mm, center-terminated true condenser capsule with Aspen Pittman’s disk resonator system, a custom-wound nickel-core output transformer, and a GT6205M vacuum tube-based impedance conversion circuit.
The mic has very high sensitivity, 35 mV/Pa, making it useful for quiet sources at the possible expense of clipping on very loud sources. The mic has a switchable -10dB pad to provide extra headroom in such cases, giving it a max SPL (padded) of 140dB.
A switchable high-pass filter provides a -12dB rolloff below 75Hz.
The mic provided four polar patterns: Cardioid, Omni, Hypercardioid, and Figure-8. From what we can discern, the polar pattern is selectable via a pair of mini toggle switches on the rear of the microphone body (confirmation forthcoming), rather than from the power supply.
The GT67 included an elastic shockmount (p/n SM4), a power supply, a 25-foot cable, and a hard mount (p/n HM1).
Sound On Sound
The supercardioid and cardioid polar patterns on the GT67 were interesting to play with. Both seemed to have a significant rear tail at high frequencies, and the cardioid setting was very much wider than the supercardioid option at middle and low frequencies. The provision of this extra [supercardioid] switch increased the flexibility of the mic, and I found I tended to use the supercardioid mode when close miking, to maximise separation. More distant sources — and especially those that tended to move — benefited from the cardioid setting.
The Groove Tubes GT67 is also known as: GT-67.
|Pickup Patterns||Pads & Filters|
(35 mV/Pa; 20 - 20,000 Hz)
Cardioid (35 mV/Pa; 20 - 20,000 Hz)
Hypercardioid (35 mV/Pa; 20 - 20,000 Hz)
Bidirectional (35 mV/Pa; 20 - 20,000 Hz)
| Diaphragm diameter: 26mm
Capsule diameter: 32mm
Diaphragm gauge: 3 microns
|200 Ohms (Low)||Max SPL: 140 dB
Self-noise: 23.0 dB(A)
|680g (23.99oz)||190mm (7.48'')||n/a||
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