The GA-8000 microphone is a tube microphone equipped with a semiconductor active cooling system that results in a higher signal-to-noise ratio compared to most other tube microphones. It delivers very high-quality performance and a modern sound character.

The GA-8000 uses a ROGERS ceramic circuit board that has superior insulation properties and offers more stable performance. The coupling and bypass capacitors are of very high quality, resulting in deep and precise low-frequency performance and delicate, transparent high-frequency reproduction.

The semiconductor active cooling and external cooling system used in the GA-8000 ensures the highest possible signal-to-noise ratio. The tube (a 6AU6) is mounted in an aluminum casing, with the semiconductor cooling chip attached to the bottom of the case.

The temperature of the tube in the GA-8000 is effectively kept low during operation, as the heat generated by the tube is actively dissipated. The heat produced by the tube is transferred to the back of the semiconductor and then to the efficient outer aluminum alloy heat sink at the rear of the microphone. This heat sink dissipates the heat from the semiconductor cooling chip into the air surrounding the GA-8000.

PCB Board

A ROGERS ceramic gold-plated circuit board is used. This type of circuit board is typically used in high-end aerospace communication products and costs about twenty (20!) times more than a standard PCB board.

Capsule

A manufacturer with over twenty years of microphone capsule production experience produces a capsule with a modern sound character. The capsule used in the GA-8000 can handle high sound pressure levels.

Tube

To ensure a long tube life, we use a NOS CIFTE 6AU6 tube from France, which has a maximum anode voltage rating of about 300V. The tube in this circuit operates at an anode voltage of 90V and generates more heat than tubes in many other tube microphones that typically use voltages between 35-50V. The higher voltage used in the GA-8000 increases heat dissipation, making the semiconductor active cooling system an important design element.

Power Supply

The GA-8000 uses a modern power supply with solid-state rectifiers and a FET-based stabilizer for the high voltage rail.

After extensive listening tests comparing a tube rectifying circuit with a solid-state one, we preferred the sound of the latter, so this is what we decided to use. An additional advantage is that there is no need to worry about replacing tubes in the power supply.

Capacitors, Resistors and Solder

The metal resistors and electrolytic capacitors from Japan are special audiophile types. The coupling capacitors are Siemens EPCOS from Germany.
The connecting wires inside the GA-8000 are oxygen-free copper wires from Japan. The solder is FELDER silver/copper-containing solder from Germany.

Shockmount

Rycote USM-VB

Features:

• Designed for the highest possible sound reproduction quality.
• Suitable for vocal recording in studios and film post-production houses.
• High sensitivity of -33dB/Pa.
• Low noise and low distortion due to built-in cooling system.
• Large diaphragm capsule.
• Electronically selectable directivity: Omni and Cardioid.

Specifications

• Microphone Type: Tube Condenser
• Polar Pattern: Cardioid, Omni
• Frequency Response: 20Hz-20kHz
• Max SPL: 137dB (Cardioid), 140dB (Omni)
• Output Impedance: 100 ohms
• Signal to Noise Ratio: 76dB
• Self Noise: 18dB (A-weighted)
• Tube: 6AU6
• Color: Black