Urei LA-4 Silverface Compressor Single #4310A (Vintage)

The Universal Audio / Urei LA-4 Compressor/Limiter was the successor to the popular LA-3. Unlike its predecessor, the LA-4 is not class A, using IC chips instead. It also marks a change to an LED-based optical element, instead of the T4 opto cell found in the LA-3.

The LA-4 has selectable ratios of 2:1, 4:1, 8:1, 12:1, and 20:1. The primary controls both have a stacked-pot design: Threshold/Ratio on the left and Output Level/Meter on the right. Compared to the LA-3A, these controls are reversed, making them more similar to an 1176. The unit is stereo switchable via the faceplate toggle switch. In the silverface iteration, there is an LED Power indicator above the toggle switch, now residing on the side of the faceplate. The Input Overload LED is moved to below the rotary control, where the power switch is on the blackface version.