Pultec EQM-1A Tube Mastering Equalizer

As described on the EQP-1A product page, the 3U EQP-1A was/is an enhanced version of the original (1953) Pultec product, the EQP-1. The EQM-1A (mastering version) takes the EQP-1/EQP-1A evolution a significant step farther by replacing the BOOST/ATTEN potentiometers with 21-position (and BW with 11-position) ELMA switches, loaded with precision metal film resistors to achieve custom tapers for each control. 

The current design implements our “full-range, progressive-taper” design, which provides 0.5 dB per step precision for the first 50% of rotation and then progressively larger (1 or 2 dB) steps as the control is rotated from 50% to 100% of rotation. This allows precise control for subtle equalization for mix bus or similar applications or the full 18-20 dB BOOST/ATTEN of the potted version when tracking or mixing of individual tracks. Furthermore, the stepped controls make recall a breeze and the precise tracking between units is essential for stereo image retention when using a pair on the stereo mix bus.