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 has a very high-quality performance and modern sound character.

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

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

The temperature of the tube in the GA-8000 is the effectively kept down when the GA-8000 is in it´s working state, the heat generated by the tube is actively dissipated. The heat that the tube generates is transferred to the reverse side of the semiconductor and transferred to the effective outer aluminum alloy heat sink at the rear of the microphone. This heat sink will then dissipate the heat from semiconductor cooling chip to the air surrounding the GA-8000.

PCB Board

A ROGERS ceramic gold-plated circuit board is used. This type of circuit board is usually used in high-end aerospace communication products, the cost is about twenty (20!) times higher than an ordinary PCB board.

Capsule

A manufacturer with more than twenty years of microphone capsule production experience are producing a capsule that have a modern sound character. The capsule used in the GA-8000 can handle a high sound pressure level.

Tube

In order to ensure the tube will have a long life, we are using a NOS CIFTE 6AU6 tube from France, it has a maximum anode voltage rating of about 300V. The tube in this circuit has an anode voltage of 90V and will generate more heat than tubes in many other tube microphones that typically uses voltages between 35-50V. The higher voltage used in the GA-8000 increases the heat dissipation so the semiconductor active cooling system is an important element in the design.

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 a lot of listening tests comparing a tube rectifying circuit with a solid state one, we found that we did prefer the sound of the latter so this is what we decided to use. The 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 capacitor from Japan are of special audiophile audio 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.
• A 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