The PEQ-1A is a 2U-high mono tube unit based on the Pultec EQP-1A. This is however not a faithful copy of the original, but rather an improved version which, besides increased abilities, preserves the sonic quality of incoming signal.
Simple at first sight the equalization section is in fact very flexible giving you the tool to powerfully shape tonality without side effects. With the low frequency section you can boost bass without muddying the low mids, and the high frequency section can add sheen and "air" in an almost exciter-like fashion, but with much more natural results. Introduced warmth in the bottom end and sparkle in the treble give individual tracks and entire mixes more depth, punch, presence and clarity.
The PEQ-1a consists of a passive equalizer that is coupled to a tube amplifier restoring the gain. The passive circuit uses inductors and capacitors to achieve equalization giving the most musical results and the least distortion possible. The gain recovery amplifier is unique in several respects. It uses commonly available tubes in a high-voltage, feedbackless push-pull circuit coupled to specially wound output transformer which provides balanced and floating output.
Another improvement is increased input impedance. A lot of contemporary equipment cannot drive the traditional 600 ohms load sufficiently. The PEQ-1a has input impedance more than 3 times higher, thus it doesn't load down the output of the preceding device.
Very gentle equalization curves make Pultec-type EQs sound very musical. This device is not an exception.
The equalizer has a low frequency shelving boost and attenuation, which can be used simultaneously for special effects, as well as a peaking high frequency boost with variable bandwidth and a high frequency shelving attenuation.
As for the make-up amplifier, it uses a configuration that has intrinsic high bandwidth and linearity, and does not need feedback to improve them. As a result you end up with minimum transient distortion. It also gives more open and effortless sound. The bypass switch omits equalization section leaving tube amplifier in the signal path. The power supply has full regulation of the +B and heater voltages. Each unit is hand-build with great attention to details.
Despite having old-style features, the PEQ-1a is very versatile and is perfectly adequate to modern recording techniques. With new frequencies it became yet more flexible than the original. This is the ultimate equalizer to make silky smooth enhancements to vocals, bass, drums and complete mixes, but all of the other sources would benefit as well.
LOW FREQUENCY SECTION:
Shelving Boost: 0 to +16dB
Shelving Attenuation: 0 to -20dB
@ 20, 30, 60, 100 Hz
HIGH FREQUENCY SECTION:
Peaking Boost: 0 to +18dB (Sharp Bandwidth)
0 to +8dB (Broad Bandwidth)
@ 1, 1.5, 2, 3, 4, 6, 8, 10, 12, 16 kHz
Shelving Attenuation: 0 to -18dB
@ 5, 10, 20, 40 kHz
Gain: 0dB +/-0.5dB
Input Impedance: >1.8 kOhms, balanced
Output Impedance: 50 Ohms, balanced and floating
Maximum Output Level: >+20dBu (1% THD) [600 ohms]
Frequency Response: better than 2Hz..40kHz -3dB [600 ohms]
Tubes: (1) ECC82/12AU7, (1) ECC83/12AX7
Power Requirements: 115V or 230V (factory option), 12VA