AudioScape introduces the ASA-6A, a mono tube vari-gain compressor inspired by the legendary RCA BA-6A broadcast limiter from 1951. Renowned for its thick, weighty tone, this nine-tube design offers smooth, musical compression, making it perfect for vocals, bass, or acoustic guitars—just as guitar icon Jimmy Page famously used the original BA6A.
The AudioScape ASA-6A adds a modern twist with a front-panel NFB switch, boosting input gain by 5 dB to drive the transformers and gain-stage tubes into rich saturation, ideal for fattening up guitars and snares. With creamy, incandescent tone, Hammond transformers, and superb box tone, the ASA-6A brings vintage tube compression to a whole new level.
When RCA introduced the BA-6A in 1951, they touted its nine-tube design as “economical” yet “high-quality.” Ironically, it’s those nine tubes and hefty transformers that made it sound phenomenal when saturated—not ideal for radio broadcasts but legendary for the acoustic guitars on “Tangerine” from Led Zeppelin III.
The AudioScape ASA-6A is a faithful recreation of this all-tube vari-gain heavyweight from the early 1950s. Its rich, thick tone stems from its massive gain potential, yet its variable-gain design ensures the compression stays smooth and musical. The ratio gently increases with input gain, delivering a soft-knee slope that thickens beautifully when pushed. A modern addition is the OFF setting on the BAL-LIM rotary switch, which bypasses the compressor entirely, allowing users to run audio through the tube amplifier for lush, woolly saturation without compression.
For added gain, the front-panel NFB switch reduces negative feedback, driving the front end with an extra +5 dB of gain. This saturates the transformers and lights up the gain-stage tubes, further enhancing the AudioScape ASA-6A’s sonic weight. Dynamic control has also been improved with adjustable Attack and Release parameters, offering flexibility for everything from warming up vocals or bass to fattening up snare drums or acoustic guitars.
While modern enhancements make the AudioScape ASA-6A versatile for today’s studios, its vintage tone remains intact. Setting the Attack, Release, and Threshold controls to their stock positions delivers the original BA6A sound, combining authentic tube warmth with modern usability.
Transformer & Tube Complement (9 Tubes Total)
- 6SK7 (x2)
- 6J7 (x2)
- 6H6
- OD3
- 6V6 (x2) matched pair
- 5R4
- Hammond choke
- Hammond filament transformer
- Hammond dual-primary power transformer
- Proprietary custom-wound input, output, and interstage transformers, true to the originals
AudioScape ASA-6A Features
- NFB toggle switch offers “Stock” mode or “Drive” mode with +5 dB input gain
- BAL-LIM rotary switch with Single, Dual, and OFF settings, allowing bypass of the compressor for tube saturation
- 20-position stepped Input and Output controls for precise saturation options
- Adjustable Attack, Release, and Threshold controls with stock BA6A designations
- 120 Hz sidechain HPF for nuanced triggering
- PIO AUDIO capacitors
- Allen-Bradley carbon comp resistors in key signal path areas
- Authentic vintage replica knobs
- Umber grey front panel with vintage-style scale plates
- Electronically balanced +4 dBu circuitry
- Custom stepped switches, Allen Bradley, and Alpha potentiometers
- Custom vintage-style lighted VU gain-reduction meter
- Neutrik® XLR input and output connectors
- Dual-primary 120 V/240 V power supply (prewired for the region of purchase)
