API 550
Summary
Abstract
The API 550 series EQs (550A, 550B) are 500-series proportional-Q equalizers that are staples of recording studios worldwide. Described as “tough and musical,” they excel at broad-stroke tone shaping during tracking, particularly on drums. The 550A is a 3-band design while the 550B adds a fourth band and additional frequency options. Vintage units may have lower input headroom than expected.
Key Characteristics
- 550A: 3-band proportional-Q EQ — simpler, more focused frequency choices
- 550B: 4-band proportional-Q EQ with more frequency options per band
- 5500: Dual-channel version with range scaling (2dB/1dB/0.5dB increments) and stepped controls for easy recall
- Proportional-Q design means bandwidth narrows as boost/cut amount increases — naturally musical behavior
- 500-series format makes them easy to integrate into lunchbox-based workflows
- Vintage units may distort more easily than expected due to lower input headroom
Use Cases
- Drum tracking — “always a great choice” for broad EQ moves while recording
- Guitar and bass tone shaping during recording
- Channel EQ in 500-series signal chains paired with preamps and compressors
- Mix bus EQ when the API color is desired (5500)
Settings & Sweet Spots
- Broad-stroke boosts and cuts during tracking — the proportional-Q keeps things musical
- Works exceptionally well paired with API-style preamps like the CAPI VP28
- The 550A with its limited frequency choices forces commitment and often leads to better decisions
- Be mindful of input levels from hot preamps — vintage 550B units can distort at the input stage
Comparable Alternatives
| Gear | Notes |
|---|---|
| CAPI 550 clones | Budget DIY alternative; sound is there with the right op-amps |
| Phoenix DRS-EQ | Another 500-series EQ option praised for drum tracking |
| Neve 1081 EQ | Different EQ flavor; Neve is broader, API is punchier |
| Undertone Audio MPEQ-1 | More flexible but steeper learning curve |
Common Mistakes
- Not accounting for gain staging between hot preamp outputs and vintage 550 inputs
- Assuming CAPI clones will sound identical without selecting the top-tier op-amps
- Overlooking the 550A in favor of the 550B — the simpler 3-band design is preferred by some for its focus
See Also
Source Discussions
Community Insights
“550a is always a great choice.” — hyanrarvey
“What a great sounding EQ. So tough and musical.” — NoahNeedleman
“Nice choices. I ended up with a similar chain when I got my lunchbox. I have the capi vp 28, diode bridge and 550b eq. I use the comp and eq on just about everything.” — BakerBaker
“I just bought some older used API 550b’s and feel like, do these generally distort super easy? Like they have low input headroom?” — Eric Martin