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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.

DEVICE TYPE Optical Compressor Yes, T4Bx or T4B photocell BASIC FEATURES All stepped manipulators 24 step Elma switches Stereo Link Yes, RCA-RCA cable INPUT & OUTPUT Input Impedance (balanced) 600 Ohm Output Impedance (balanced) 600 Ohm Audio transformers Input: Sowter, Output: Edcor LEVELS 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 TIME CONSTANTS Attack: 1ms Release: 0.5 – 5s (50% @ 60ms) DISTORTION (@ 20 HZ - 20 KHZ) THD+N 85 dB (A) POWER Voltage 115/230V AC, 50 - 60Hz Power consumption 40W Power supply Internal PACKING BOX Dimensions 70 x 50 x 30cm Shipping weight 7kg OTHERS Tube set 2x6N1P-EW, 6N2P-EW, 6AQ5