The A-Type 525 is a discrete VCR compressor/limiter in 500-series format, modelled on a classic American design from the 1970s. The entire signal path uses discrete through-hole components – no integrated circuits in the compression stage. Input balancing is handled by an SSM2141 op-amp; the output runs through an IGS Custom transformer. A second audio transformer sits in the feedback path: it conditions the detection signal before returning it to the VCR (Voltage Controlled Resistor), which directly controls the resistance of the first gain stage. This is a true feedback topology – the compressor responds to what has already passed through the first amplification stage rather than anticipating the input, which produces the characteristically musical gain reduction behaviour associated with classic American hardware from that era.
Compress switch – one control instead of two
The control layout is where the A-Type 525 separates itself from standard clones. The Compress switch simultaneously adjusts Gain and Threshold together, allowing the engineer to dial in compression depth while keeping peak output level constant. This removes one of the most common errors in evaluating compressor behaviour in-session: mistaking loudness for effectiveness. Separate Threshold and Output controls remain available for independent fine-tuning of the activation point and output level. Attack time is fixed at 15 µs – fast enough for transient control on drums, picked bass, and acoustic guitar. Release time is user-selectable across four discrete steps: 0.1 s, 0.5 s, 1.5 s, and 2.0 s.
Limiter and de-esser without additional modules
Beyond Compressor (2:1) and Limiter (20:1) modes, the A-Type 525 includes a built-in de-esser – a function that typically requires a separate module or a DAW insert. The de-esser attenuates sibilance in vocal recordings without touching the surrounding frequency content, making it possible to handle sibilance control at the tracking stage directly in the 500-series chain. Hardwire bypass and multi-unit linking capability complete the feature set for stereo or multi-channel setups. Maximum gain reduction is 25 dB; maximum input level +27 dBu, maximum output level +28 dBu.
KEY FEATURES
- Discrete VCR feedback topology – no integrated circuits in the compression path
- Compress switch – simultaneous Gain and Threshold adjustment without peak level change
- Fixed attack time: 15 µs
- Four release times: 0.1 / 0.5 / 1.5 / 2.0 s
- Operating modes: Compressor (2:1), Limiter (20:1), De-Esser
- Balanced input: SSM2141 op-amp
- Transformer output: IGS Custom
- Second transformer in the feedback detection path
- Hardwire bypass
- Multi-unit linking for stereo and multi-channel use
- 3-year manufacturer warranty
TECHNICAL SPECIFICATIONS
- Type: discrete VCR compressor/limiter, 500-series, mono
- Operating modes: Compressor 2:1, Limiter 20:1, De-Esser
- Attack time: 15 µs (fixed)
- Release time: 0.1 / 0.5 / 1.5 / 2.0 s
- Maximum gain reduction: 25 dB
- Maximum gain: 25 dB
- Input impedance (balanced): 10 kΩ, SSM2141
- Output impedance (balanced): 75 Ω, IGS Custom transformer
- Operating level: +4 dBu
- Maximum input level: +27 dBu
- Maximum output level: +28 dBu
- Bypass: hardwire
- Linking: yes
- Format: 500-series, single slot
