CAPI VP28 Two-Stage Preamp

Projects > CAPI VP28 Two-Stage Preamp

The VP28 is a two-stage preamp based around vintage API circuitry with a three-frequency high-pass filter and output booster. It could be considered a combination of the VP25 preamp circuit and the VC528 console channel. Each channel requires two discreet opamps and three transformers!


  • Switchable 40Hz, 80Hz, and 160Hz HPF
  • -6dB and -12dB per octave settings for the HPF
  • Optional stepped input gain
  • Balanced t-pad output attenuator
  • Post-fader output boost
  • Employs 2520-style discreet opamps
  • API-replica input and output transformers by Ed Anderson
  • Two stages of amplification for up to 70dB of gain
  • Compatible with the API 500-series format
  • Requires +/-16vdc and +48vdc power rails


  • $287.99 for partial kit (opamps not included)

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One thought on “CAPI VP28 Two-Stage Preamp

  1. Updating to reflect changed website & company name for Classic Audio Products, Inc. Their website mentions that they should not be referred to as “Classic API,” as it sounds like the API people might have had something to say about that.

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