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IGS ONE Leveling Amplifier

  • Description
  • Specifications
Classic LA2A style opto tube compressor!


The IGS 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.

It is known that in the case of ONE LA the nature of the device depends on the T4B photo-cell.


T4Bx optocell

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.


Stereo pair

Matched pairs are also available. The link socket is located on the rear panel. The RCA-RCA cable is all you need to link two units. Perfect stereo matching is achieved by hand selected tubes and Elma switches.

Optical Compressor Yes, T4Bx or T4B photocell
All stepped manipulators 24 step Elma switches
Stereo Link Yes, RCA-RCA cable
Input Impedance (balanced) 600 Ohm
Output Impedance (balanced) 600 Ohm
Audio transformers Input: Sowter, Output: Edcor
Operating Level +4dBu
Max input level +16dBu
Max output level +18dBu
Dynamic Range >110 dBA (@ 1kHz, +24 dBu)
Max. gain 30dB
Max Gain Reduction 36 dB
Attack: 1ms
Release: 0.5 – 5s (50% @ 60ms)
THD+N 85 dB (A)
Voltage 115/230V AC, 50 - 60Hz
Power consumption 40W
Power supply Internal
Dimensions 70 x 50 x 30cm
Shipping weight 7kg
Tube set 2x6N1P-EW, 6N2P-EW, 6AQ5
More in this category: « IGS ONE LA 500 IGS Tubecore 500 »


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