API 225L Discrete Channel Compressor / Limiter – 200 Series Legacy Module API

The API 225L Compressor is ideal for all studio, live sound and broadcast applications. Regardless of the threshold or ratio settings, the output level always remains at unity. This unique feature allows real-time adjustments without changing the output level. Both feed forward (new) and feed back (old) gain reduction methods are selectable on the front panel. There also is a SOFT or HARD selector for either an over easy compression resulting in a very natural, uncompressed sound or a typical sharp knee type that has a much more severe limiting effect. The 225L is designed for individual channel use or two units can be combined for Stereo applications via a rear access pin. The 225L also has a side chain input for the detector amplifier.

Features:

• Threshold control from -20 to +10 dBu
• Variable compression ratio from 0 to infinity
• Adjustable release time from 50m/sec to 3 sec
• Old or New sound
• HARD or SOFT compression knee
• Always at unity gain, regardless of settings
• LED Gain Reduction meter
• API 2510 and API 2520 op-amps
• Transformer output to +28 dBu

Both “feed forward” (NEW) and “feed back” (OLD) gain reduction methods are selectable on the front panel, providing a choice of “that old way”, or “the new way” of compression. In addition, there is a “SOFT” or “HARD” selector for an “over-easy” type compression resulting in a very natural, uncompressed sound or a typical sharp knee type that lends itself to a much more severe limiting effect. The “old way” or Feed-Back method is what most of the classic compressors used for the gain control circuit. The “new way” gain reduction is more typical of the newer VCA type compressorsthat rely on RMS detectors for the gain control voltage.

The Threshold control sets the initial operating parameter. Full range of operation is achieved with signal input levels from -20 dBu to +10 dBu and output capability is +28 dBu through an integral output transformer. The output level remains constant regardless of the threshold or ratio control, much like the “more/less” Ceiling control on the API 525 compressor. This allows for live adjustments without any noticable gain changes in the program level.Release time can be adjusted by rotating the REL knob. Release time constants: 50m/sec to 3/sec.

Attack time is switch selectable at 2m/sec (F),18m/sec (M) or 75m/sec (S). Fast-Medium-Slow. (Slow in the Normal setting.)The Model 225L is designed for individual channel use or, through the use of the external LINK function, two units can be combined for Stereo applications via a rear access pin. The 225L also has a side-chain input for the detector amplifier. The Link function is available in the Legacy consoles and the 200H rack, but is not yet in the L200 Rack. Contact the factory about how to implement Link in the L200.The 225L Compressor/Limiter makes use of the 2510 and 2520 Op-amps and therefore exhibits the reliability, long life, and uniformity which are characteristic of API products.