Manley Enhanced Pultec EQP-1A is a single channel passive equaliser in a 1U chassis, built on the topology of the classic EQP-1A and extended with frequencies the original never had. Gain after the passive section is recovered by a single ended valve stage.
A curve no parametric equaliser will build
The low section carries separate boost and cut controls working at offset frequencies. Set together they produce a lift at the very bottom and a dip just above it, which is how you get a bass foundation that does not crowd the mids. Manley added a 20 Hz boost on top of that, giving access to the range felt more in the body than heard by the ear, along with a 25 kHz shelf that opens the top without reaching into presence.
Passive equalisation, valve make-up
All the equalisation happens on passive components, and the valves do not shape the response, they restore the level after it. That is where this circuit gets its character: a boost sounds gentle even at large settings, because there is no feedback loop sharpening the curve. The equaliser can be set flat or taken out of the path altogether. Gain is factory set to unity, with extra available on a trimpot at the rear panel.
KEY FEATURES
- Single channel passive equaliser in a 1U chassis
- Classic EQP-1A topology with valve make-up gain
- Simultaneous boost and cut on the low band
- An extra 20 Hz boost not found in the original
- An extra 25 kHz shelf in the high section
- Bandwidth control in the high section
- Continuous conductive plastic potentiometers
- Can be set flat or bypassed entirely
- Transformer balanced and capacitor coupled unbalanced outputs
- Gain trimpot on the rear panel
- Valves: 12AX7WA plus 6414 or 5965
TECHNICAL SPECIFICATIONS
- Channels: 1
- Frequency response: 10 Hz to 70 kHz
- THD: below 0.01%
- Signal to noise ratio: 116 dB
- Maximum output: +30 dBv
- Valves: 1 x 12AX7WA, 1 x 6414 or 5965
- Outputs: transformer balanced and unbalanced
- Dimensions: 19 x 1.75 x 10 inches, 1U
