This single channel Mid Frequency EQ is the secret weapon for vocal, guitar, snare and all the other midrange instruments that are the meat of the mix.
Specially useful for midband oriented instruments such as guitars, vocals, harmonicas, and violins, the MID FREQUENCY ENHANCED PULTEC EQ (MEQ-5 type) shares the same features and specifications as our 'EQP-1A' version. The differences lie in the passive EQ section: In the MID EQ, the DIP and PEAK controls function on much sharper bell-shaped curves centered on the selected frequencies, which gives the engineer-producer more precise control over the vitally important midrange and makes this unit indispensable for mastering engineers. The MID EQ also completely fills the frequency gaps between the low frequency and high frequency sections of our Enhanced Pultec EQP-1A type EQ; thus the combination of the two provides a most flexible palette of possibilities for tracking or mastering.
The all-tube Mid Equalizer utilizes the original WESTERN ELECTRIC passive-equalization circuit found in the long-out-ofproduction and justifiably famous PULTECS. According to experts, Western Electric developed the passive EQ in the 30's to improve speech quality in a typical telephone system. This may help to explain the choice of curves and frequencies. Western Electric also seem to have brought us the balanced audio & the 600 ohm standard. Eugene Shenk of Pulse Technologies re-discovered the EQ and added his vacuum tube gain make up amplifier. While Pultec sold a healthy number of units to broadcast, when transistors came in, many jumped to the new technology and Pultec fell on hard times. It was not until the mid 70's and early 80's with the big new recording studios, that engineers and producers found that nothing had the same magic that old Pultec tube EQs could give. Twenty years later, and they are still favorites (along with old British console EQs) and today few understand why they sound so good. Its not "just" the tubes.
We can offer a few good reasons. First - the EQ is passive. That means that the components involved have no gain. A typical modern parametric EQ can use 10 to 20 op-amps, each with many, many transistors. Music generally prefers a simple path with the fewest parts to pass a signal through. This also is one of the big advantages to tube circuits - simplicity. The EQ uses a few capacitors, inductors and resistors (or pots). No headroom problems, no crossover distortions, no slew induced distortions.
Second- Transformers can add a nice fat low end. That euphonic bottom was partially due to transformer saturation. In other words the lower and louder a signal got, the more it saturated (added some extra harmonics to the ultra lows where most speakers are deficient). It helps us percieve that there was some energy down there without hearing the distortion as such. The older transformers suffered from wide band distortion and losses in the highs. This is rarely wanted. Modern high quality transformers are much better in the highs and generally much lower distortion, due to improvements in materials, but they can still saturate - the way we like. Third - Op-amp circuits have limitations. They use negative feedback to control gain. Often enough, this can cause a loss of transient accuracy and/or instability. Most op-amp EQ circuits rely on some very small signal levels that are prone to cross-over distortions in the push-pull outputs. Older op-amps have slow PNP transistors that began rolling off at a few hundred hertz causing crossover distortions. Headroom can be a hard ceiling (+20 dBu) that gets nasty when significant amounts of boost are called for. All of this worsens when driving capacitive wire or low impedances. The better solid state EQs are discrete with high voltage power supplies for headroom. Our Langevin Pultec is that style. The Manley tube version beats it.
Manley uses an all-tube gain block with a +31 dBu capability and less than 10 dB of feedback. Four triodes are used for "flat" class A gain stages and demonstrate the beauty of simplicity. We use a similar line amp in our 40 dB Mic Preamps and Electro-Optical Limiters and some of our audiophile hi-fi preamps.
Our version of this classic EQ incorporates modern audiophile grade components with our proven line-amp for absolute sonic beauty... Conductive plastic potentiometers and sealed gold-contact switches, polystyrene and rolled film and foil capacitors, and a our own transformers combine with a regulated stiff power supply and state-of-the-art tube circuitry to bring another classic PULTEC that is optimized for voice - but not only voice. They get used daily in mastering and seems to be the right tool for a huge numer of applications. Beyond the improvements in pure fidelity, we added extra frequencies and better interfacing, and it's only 1U!
