ASA-6A Tube Vari-Mu Compressor

History of the BA6A Limiting Amplifier

When RCA introduced its BA6A compressor in 1951, they actually cited the nine-tube design as economical, yet “high-quality”, “employing only 9 tubes…”. But it’s all those tubes and all the iron in the transformers that made it sound so great when saturated. Not so good for radio broadcasts, but incredible for the acoustic guitars on “Tangerine” from Led Zep III!

AudioScape’s ASA-6A is a faithful recreation of that all-tube variable-gain heavyweight from the early 1950’s. The thickness and weight it imparts is due partly to the monstrous amount of gain it adds. But, owing to its variable-gain design, the compression never suffocates the track, even with all that gain. The ratio increases only as the input gain increases, giving it a gentle, soft-knee slope. But the harder you hit it, the thicker it gets.

ASA-6A: New Modern Features

The core circuit of the ASA-6A is faithful to the RCA original down to the NOS tubes and Hammond transformers throughout. AudioScape has added some new modifications to expand the versatility of this amazing circuit even further, such as:

• Individual attack, release, and threshold controls for better control of dynamics - each with “stock” settings marked to match the original if desired
• “NFB” front panel switch to drive the entire circuit with an additional +5dB of gain by reducing negative feedback
• “OFF” position on BAL-LIM rotary switch to bypass limiting and drive the the all-tube line amplifier by itself

This compressor is truly one of the finest examples of vintage vari-mu tube circuitry ever built. AudioScape thinks you’ll love it as much as they do!

FEATURES & SPECS:

• Handcrafted in the USA
• NFB toggle switches between the original "Stock" mode and the new "Drive" mode, which boosts input gain by 5dв
• 3 Time-Constant options via the BAL-Limit rotary switch: Single or Dual, or Off, which bypasses the compressor entirely, but still passes a fat signal through all those tubes
• Custom 20 position stepped Input and Output Controls, tweaked for maximum usable range; allowing for countless saturation options
• Attack, Release and Threshold controls added with stock BA-6A designations on each scale plate
• 120 Hz Sidechain HPF for more nuanced triggering
• PIO AUDIO Capacitors
• Allen-Bradley carbon comp resistors in key areas of the signal path
• Period correct knobs
• Umber Gray front panel with vintage style scale plates
• Electronically Balanced +4dBu circuitry
• Custom stepped switches, Allen Bradley and Alpha pots
• Custom Vintage-Styled Lighted VU Gain-Reduction Meter
• Neutrik® XLR Input and Output Connectors
• Dual Primary 120V/240V Power Supply (prewired for region of purchase)

**specifications, parts & pricing subject to change because sht happens ;-)*

DOCUMENTATION:

ASA-6A QUICK-START

ASA-6A MANUAL