CAPI 553F 500-series EQ

Projects > CAPI 553F 500-series EQ

Classic Audio Products’s latest offering is a slightly updated take on API 553 EQ, a lesser-known counterpart to the legendary 550. Though originally designed as a simpler, lower-cost alternative to the 550, the 553 is inductor-based and contains crucial elements of the “classic API” sound–a 2520 discrete op-amp, and the 2503-model output transformer. CAPI’s DIY version contains a few updates, including HPF and LPF filters, a balanced input stage, and new, Ed Anderson-designed inductors.

553F Features:

  • 3-band inductor-based EQ operation
  • 100Hz low-band, 2.7kHz mid-band, 10kHz high-band
  • 2520 discrete op-amp balanced receiver and output stages
  • MPP-core inductors and 2503 output transformer from Ed Anderson
  • 30Hz / 70Hz / 110Hz HPF
  • 12kHz / 22kHz / 28kHz LPF
  • 500-series compatible (+/-16VDC power rails needed)


  • $302.99 USD for complete kit

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