Reviewing Manley's Massive Passive Stereo Tube Equalizer
The following is reprinted with permission from the January 1999 issue of EQ magazine.
Manley introduces an EQ that hearkens back to the ones found on old British consoles, but with a modern twist
Located some 40 miles east of Los Angeles in Chino, CA, Manley Labs has garnered a solid reputation for its work with vacuum-tube electronics under the steady leadership of EveAnna Manley. For the professional side of the market, the company’s products range from hand-crafted microphones, mic preamps, equalizers, and limiters to studio monitors. The other half of the company’s product line focuses on high-end audiophile equipment.
At the recent Audio Engineering Society (AES) show in San Francisco, the company introduced its new Massive Passive Stereo EQ — and with a name (and look) like this, it’s the kind of piece that inspires gear lust! This 3U rackmountable processor has a light bluish/purple brushed faceplate outfitted with a collection of rotary pots and switches that are easy to understand without having to ever open an operation manual. The look of the unit is quite "classic," while the feel is very "Germanic" or solid — almost to the point of saying, "Get in my way and I’ll flatten you!"
The Massive Passive Stereo EQ is a 2-channel, 4-band equalizer with high-pass and low-pass filters, gain control, and an all-tube signal path. "Passive" refers to the tone shaping circuit not using any active circuitry such as ICs (Integrated Circuits), transistors, FETs (Field Effect Transistors), or tubes. The tube circuitry serves to make up gain lost in the tone circuit. Only metal film resistors, film capacitors, and hand-wound inductors sculpt the sound.
The look of the unit is quite logical, and there is no doubt upon first glance that this is a stereo device. There is an identical set of controls on both the left and right sides of the faceplate with a series of smaller buttons and switches that run down the center. The center controls include a Power switch positioned between the Left and Right In (or bypass) switches. Beneath these three switches are the Left and Right Low-Pass plus Left and Right High-Pass controls.
The High-Pass and Low-Pass Filters
The unit’s very steep passive filters are designed to remove garbage above or below the spectrum of the music that you want to keep. The 18 kHz HF filter is 60 dB/octave, the 12 kHz filter is 30 dB/octave, and lower frequencies are 18 dB/octave and optimized for natural sound. These filter shapes have a deliberate bump so that the typical side effect of "dullness" is minimized. The frequencies for these filters are as follows:
High Pass: 22 Hz, 39, 68, 120, 220
Low Pass: 18 K, 12 K, 9 K, 7 K5, 6 K
A "Massive" EQ
The four per-channel EQ bands have a very wide range of 11 frequencies each — all overlapping and interleaving (22 Hz–1 kHz, 82 Hz–4 kHz, 220 Hz–10 kHz, 560 Hz–27 kHz). With the interleaving, approximately 1/4-octave resolution is given through most of the frequency spectrum, and 1/2-octave at the extremes. Every band can be separately bypassed. Manley Labs engineer Craig Hutchison tells us, "Modular thinking to accommodate the massive quantity of high-quality and physically large components inspired how the individual equalizer bands are physically built and mounted. The EQ frequencies are strongly reminiscent of old British console modules." Their frequencies are positioned as follows:
Low: 22 Hz, 33, 47, 68, 100, 150, 220, 330, 470, 680, 1 K
Low Mid: 82 Hz, 120, 180, 270, 390, 560, 820, 1 K2, 1 K8, 2 K7, 3 K9
High Mid: 220 Hz, 330, 470, 680, 1 K, 1 K5, 2 K2, 3 K3, 4 K7, 6 K8, 10 K
High: 560 Hz, 820, 1 K2, 1 K8, 2 K7, 3 K9, 5 K6, 8 K2, 12 K, 18 K, 27 K
The boost/cut range for each of the four per-channel EQ bands is variable from 0 to 20 dB. This constant bandwidth design widens the "Q" as you get closer to flat.
One very unique character trait of the Massive Passive Stereo EQ lies in its ability to provide multiband EQ with every band individually switchable between Shelf and Bell. Above each EQ band are the Boost/Out/Cut toggle switches and the Bell and Shelf mode toggle switches. LEDs illuminating the nomenclature indicate the current status mode of each band. The Boost/Out/Cut switch makes it easy to return to flat for signal comparisons. With the unit’s high shelves, you can simultaneously control air and sibilance for vocal work with just a single band of EQ — eliminating the need to add a de-esser into the signal path.
So What About Them Tubes?
Three tubes form the makeup gain amplifiers for each channel, bringing the total to six dual triodes: two 5751’s and four 6414’s. The "In" pushbutton switches send the entire unit into hard-wire bypass mode, as does the warm-up delay circuit.
A Few Incidentals
For feeding and returning signals, the unit has both floating transformer-balanced XLR connectors and transformerless unbalanced 1/4-inch phone connectors. Additionally, the 1/4-inch jacks can be set for +4 dBm or –10 dBm levels. The Massive Passive Stereo EQ is a unique cross between the famous old Pultecs, Neve, and API modules that all use rotary switches to select frequencies with individual capacitors and inductors and the best fully discrete parametric EQs because of their wide control possibilities and minimal electronic coloration. Slated to ship in January of ’99 at $4800, it’s not cheap, but with a stellar reputation such as this company’s, you can’t go wrong!