CAPI BT50 550-Style 500 Series Equalizer Built by MW Analog


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BLUE LED VERSION. The BT50 brings the meaty, euphoric tone of the very first, highly-prized 550 500 Series equalizer to your lunchbox. 

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Special Order. Typically Ships in 2–3 Weeks.

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We've partnered with MW Analog to offer their custom assembled products. The BT50 is CAPI’s take on the venerable vintage API® 550 EQ module. The goal was to have the vintage sweetness of the original (pre A) 550 EQ, but with the extra frequencies of the original 550A. Perfect for kick, guitars, bass (the old cranked 800Hz trick works perfectly), vocals, or anything else. Bring the vintage 550 type EQ to your lunchbox® without decades of dust inside! 


  • Fully Ready BT50 EQ Module
  • Custom Blue EQ In LED
  • 2 x GAR 2520 Opamps
  • 1 Year Warranty (90 days on opamps)

The Overview
The BT50 was designed with the goal of capturing the meaty, euphoric tone of the very first, highly-prized 550 500 Series equalizers. 

The module features the familar three EQ bands with Proportional Q, where the Q narrows with higher boosts or cuts, but has improved upon the original by splitting the origninal bandpass filtering into separate low-pass and high-pass filters at 50Hz and 15kHz repectively, instead of both being linked to a single switch. 

The original 550 also only had three frequencies on each of the the high and low bands. The BT50 has expanded those to the five frequency selection of the later 550A modules.

While the BT50 maintains the traditional unbalanced input, which can lead to a 6dB signal drop when driven by certain devices’ outputs, it also adds a user switchable shunt jumper to make up the 6dB at the output stage. 

As a happy side effect of the rotary switches used in the BT50, the concentric labeling and concentric knobs correspond to either other. Note: this is the opposite of the vintage and current 550s. 

The BT50 will definitely impress and is perfect for sculpting vocals, drums, guitars, or even the main buss.

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