The lunchbox gives an engineer the flexibility to bring along specialized EQ effects to any situation: 550A, 550b or 560. The lunchbox utilizes an external power supply. API makes several modules for the lunchbox, including the 512c Mic Preamplifier, the 525 Compressor, the 527 Compressor, the 550A 3-band EQ, the 550b 4-band EQ and the 560 Graphic EQ. Combinations of these modules make perfect stereo recording packages (two 512cs and two 550bs) or vocalist's box (one 512c, two EQs and one 527).

Other uses for the versatile lunchbox include:

• Multi-track recording of acoustic and electronic audio sources
• Sound reinforcement systems and recording to multi-track formats
• Multiple facility projects where portability is a plus
• Broadcast and audio for video production
• Custom channel input strips

NOTE: The older 560A equalizer may use pin 15 for a "direct output" and must be disabled on the 560A circuit board edge connector by cutting a trace. This will eliminate 48 volts from damaging the 560A series equalizers.