Mercury EQ-P1 MKIV is a mono passive tube program equalizer based on the Pultec EQP-1A — a design that has stood in mastering rooms since the fifties and still has no convincing replacement. The make-up gain stage here runs in a balanced push-pull configuration.
An equalizer that adds something even when you boost nothing
A Pultec works differently from an EQ in a DAW: the filters are passive, so they only subtract, and the lost level is made up by a tube gain stage. It is that stage, not the curve, that adds the characteristic density — which is why the unit changes the sound even with the controls set flat.
The trick people buy a Pultec for
You can boost and cut the same low band at once. The filters have different curves, so instead of cancelling they leave the very bottom lifted and the mud just above it removed. On kick and bass that gives depth without thickness — an effect a parametric EQ cannot simply reproduce.
KEY FEATURES
- Mono tube program equalizer
- Passive circuit in Pultec EQP-1A topology
- Balanced push-pull make-up gain stage
- Simultaneous boost and cut on the same low band
- Audible character even at flat settings
- Designed and built by Mercury Recording Equipment
TECHNICAL SPECIFICATIONS
- Type: tube program equalizer, passive filters
- Channels: 1 (mono)
- Reference circuit: Pultec EQP-1A
- Gain stage: tube, balanced push-pull
- Revision: MKIV
