The Essentials to Know About the API 2500+ Stereo Bus Compressor
- Legendary stereo bus compression with Blend function for integrated parallel compression.
- API dynamic signature thanks to 2520 amps and the THRUST circuit for punchy lows.
- Two detection philosophies, " Old " (feedback) and " New " (feed-forward), to shape punch and color.
- Variable L/R linking, auto make-up gain, and Sidechain input for full mix bus control.
A Modernized API Classic
The 2500+ continues the sonic aesthetic of API consoles and outboard gear while adding refinements expected in modern studios. The "+" version modernizes the famous 2500 by notably integrating a blend control for parallel compression, while preserving the musicality and robustness that have made the brand renowned.
Who Is It For and What Are Its Uses?
Ideal on the mix bus to "glue" a mix without squashing it, the 2500+ also excels on drum buses, instrument groupings, and summed mixing configurations. Its ability to shift from transparent compression to more energetic action makes it a relevant choice for mixing and pre-mastering.
Key Features to Sculpt Punch and Tone
THRUST: Solid and Controlled Lows
The patented high-pass filter, placed before the RMS detector, protects detection from low frequencies to preserve the impact of the low end while controlling the entire mix.
Two Detection Behaviors
The "Old" mode (feedback type, legacy of the API 525) offers more musical and organic compression. The "New" mode (feed-forward type) provides faster and more precise action, ideal for modern punch.
Variable Stereo Linking
Finely adjust the degree of correlation between left and right channels: from dual-mono compression to perfectly linked stereo, preserving width and image stability.
Blend and Make-up Gain
The Blend control facilitates parallel compression without external routing. The automatic make-up gain maintains a constant output level during threshold or ratio changes.
Technical Specifications
Processing and Modes
- Stereo bus compressor with blend function (integrated parallel compression).
- Dual-channel design: linked stereo or use as two separate units.
- Selectable envelopes: "Old" (feedback, API 525 type) and "New" (feed-forward).
- Typical behavior reminiscent of classic API 525, 1176, and Fairchild compressors.
Controls and Parameters
- Threshold adjustable from -20 dB to +10 dB.
- Selectable ratio, attack time, and release.
- Automatic or manual make-up gain.
- Variable linking between left and right channels.
Sidechain and Filtering
- Patented high-pass filter in the path before the RMS detector (THRUST circuit).
- Sidechain input for external detection control.
Electronics and Format
- API 2520 operational amplifiers for the brand's sonic signature.
- 19" rack-mountable unit.
Applications
- Ideal summing compressor for stereo buses, drum buses, and instrument groupings.