Pultec EQP-1A clone
The sessions. A journey into the making of a historical piece of gear.
August, 2008.
During the 1950s and 1960s the sound of pop recordings was further defined by the introduction of proprietary sound processing devices such as equalizers and compressors, which were manufactured by specialist electronics companies. One of the best known of these was the famous Pultec equalizer, which was used by almost all the major commercial studios of the time.
by Val.
myspace.com/dubware
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| Fig.1- Building the buffering amp. |
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| 2-The toroidal core tapped inductor-this is by far one of the most sensitive components for the magic sound of this EQ. |
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| 3-Inductor taps are then soldered on silvered OFC wires. |
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| 4-Epoxy coating- The inductor is encased in a metal screening can, and encapsulated in epoxy glue. |
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| 5-The finished inductor in its screening can. |
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| 6-The filter - Filter components are wire wound point to point. |
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| 7-Close-up of the HF selector switch |
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| 8-LF selector - This is a close-up of the Bass freq. selector. Notice the big polypropylene capacitors. |
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| 9-Point-to-point cabling. |
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| 10-Inside the case, finished work. |
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| 11-LF Sine wave response. Showing actual response at 40Hz. Very linear and distortionless. |
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| 12-HF square wave. Response to a 20KHz square wave. Just a small ringing, but fast enough for a tube amp. |
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| 13 - Filter close-up. |
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| 14 - The retrofitted panel. It has the more practical XLR Neutrik audio silver contact connectors. |
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| 15 - Retro close-up. |
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| 16 - The front panel. |
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| 17 - Very similar to the original. |
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| 18 |
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| 19 - Front panel. |
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| 20 - Another view of the front panel. |
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| 21 - View from above. |
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| 22 - The tubes. Military grade original vintage tubes made in USA by General Electric were used. |
Sound clips
Description |
Original |
Processed |
| Acoustic guitar | flat | HF 12KHz boost=5, Q=5. |
| Piano | flat | HF 10KHz boost=5, Q=6 |
| Jazz piano | flat | LF 100Hz b4, HF12Khz b5, Q5 |
| Vocal | flat | HF 10KHz boost=5, Q= 3 |
| Drums | flat | LF 60Hz b4, HF10Khz b5, Q=3 |
| Snare | flat | LF 100Hz b3, HF 5KHz b5, Q2 |
| Double bass | flat | LF 60 Hz, boost=5 |
| Final Mix | flat | LF 100Hz b3, HF 10KHz b4, Q5 |
