Groove Tubes GT-33

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Pricing & Availability

MSRP: $299
Discontinued

Reviews & News

GT-33 Documentation

GT-33 Cutsheet

Detachable-Capsule Pencil Condenser Microphone

The GT-33 is a pencil condenser with interchangeable capsules and a transformer-coupled output. It was designed by Aspen Pittman, and introduced in 2001 at an MSRP of $599.

The mic has high sensitivity (26mV/Pa) and moderate self-noise (20dBA). Onboard switches enable a pad (-15dB, raising the max SPL to 150-155 depending on which version of the literature can be believed) and high-pass filter (-12dB/octave cutoff below 75Hz).

The mic shipped with a removable Cardioid capsule; Groove Tubes sold both Omni and Hypercardioid capsules separately. These capsules were also compatible with the GT-44 tube pencil mic.

The FET-based impedance-conversion circuitry is made with through-hole components. The output transformer is clearly visible on the board.

The Groove Tubes line was distributed by Midiman (later renamed M-Audio) beginning in 2001; in 2003, the GT33 FET had an MSRP of $399 for a single or $798 for “Certified Matched Pairs.”

Recording
I recently tried the M-Audio GT33 ($280), made by Groove Tubes, which is a medium-diaphragm solid-state mic. In my review I found the sound very close to that of a Shure SM81, but the GT33 has an omni capsule available as an accessory, [whereas] the SM81 doesn’t.

The Groove Tubes GT-33 is also known as: GT33 FET, GT33.

Specifications

Compatible Capsules

	Groove Tubes C1 Cardioid 19mm Cardioid capsule Sensitivity: 28 mV/Pa Freq. Resp.: 20 - 20,000 Hz MSRP: $99 \| discontinued
	Groove Tubes C2 Hyper 19mm Hypercardioid capsule Sensitivity: 28 mV/Pa Freq. Resp.: 20 - 20,000 Hz MSRP: $99 \| discontinued
	Groove Tubes C3 Omni 19mm Omnidirectional capsule Sensitivity: 28 mV/Pa Freq. Resp.: 20 - 20,000 Hz MSRP: $99 \| discontinued