IGS Audio One Leveling Amplifier Optical Compressor

The IGS Audio ONE LA is an optical compressor, inspired by the legendary solution well known from the '60s. This is a very easy to use and great sounding tool.

The IGS ONE LA is an input and output transformer balanced, full tube device. The input of the system includes a Sowter 4383 transformer, the output an Edcor 15k/600. Two 6N1P-EW dual-triodes are installed on the audio circuit, while the compression circuit is equipped with the 6N2P-EW triode and the 6AQ5 pentode, which control the work of the T4Bx photocell.

The One LA 19" has simple controls: a Peak-Reduction knob controls the gain of the side-chain circuit, and therefore, the gain reduction threshold; Gain Control for the make-up gain; and a Limit/Compress switch to alter the compression ratio. The VU meter may also be switched to show gain reduction or output level.

The original solution used the TELETRONIX electroluminescent panel, that was illuminating the photo resistor. The idea of opto-compression originated in the past is still being cultivated today. IGS Audio has developed its own photocell equivalent to T4B called T4BX. The use of carefully selected components in the production of the T4BX photocell, and their individual measurement and matching, result in completely repetitive sound qualities of each device.

Specifications:

• Optical Compressor T4B photocell
• All stepped manipulators: 24 step Elma switches
• Stereo Link: RCA-RCA cable
• Input Impedance (balanced): 600 ohm
• Output Impedance (balanced): 600 ohm
• Audio transformers: input - Sowter, output - Edcor
• Operating level: +4 dBu
• Max input level: +16dBu
• Max output level: +18 dBu
• Max gain: 30 dB
• Max gain reduction: 36 dB
• Attack: 1ms
• Release: 0.5 – 5s (50% @ 60ms)
• Frequency response: 20Hz - 20kHz; +/- 0.3dB
• THD+N: 85 dB (A)
• Voltage: 115/230V AC, 50 - 60Hz
• Tube set: 2x6N1P-EW, 6N2P-EW, 6AQ5