Manley Mid Frequency EQ Owner's Manual

MANLEY

LABORATORIES, INC.

OWNER'S MANUAL

ENHANCED

MID FREQUENCY

PULTEC EQUALIZER

MANLEY LABORATORIES, INC.

13880 MAGNOLIA AVE.

CHINO, CA. 91710 USA

TEL: [phone]
FAX: [phone]

email: [e-mail]

http://www.manleylabs.com

CONTENTS

SECTION PAGE

INTRODUCTION 3

EQ HINTS 4

FRONT PANEL 5

REAR PANEL 6

MAINS CONNECTIONS 7

TECH NOTES 8

TROUBLESHOOTING 9, 10

CURVES 11

WARRANTY 13

WARRANTY REGISTRATION 14

APPENDIX:
WIRING YOUR OWN CABLES ?
TEMPLATE FOR STORING SETTINGS



INTRODUCTION

THANK YOU!...

for purchasing the Manley Laboratories Enhanced Pultec Mid Frequency Equalizer. 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 !

Please take a few moments to read through this manual carefully as it contains information essential to proper
operation of this unit. Thank you again, and please enjoy!

3

EQ HINTS

We usually give a few hints about tricks commonly used with our products. With an

EQ of this type it is not so likely you need much help.

The most common question we get asked about our Pultecs is "Why not a boost/cut
knob in each band?". We don't know why it was designed that way for sure. It was designed
in the 1930's by Western Electric to improve voice through telephone lines. We believe it was
done this way because it was the most practical in a simple passive design. This was before
op-amps and Baxandall type cut / boost circuits were common. We do know how to design
& build that style but it wouldn't be a Pultec, it would need twice as many parts or not be
passive. Standard EQs are easy - Our customers requested Pultecs when they could have
anything except a new well built Pultec. David and EveAnna flew to New Jersey to request
permission from Eugene Shenk of Pulse Technologies to use the circuits and name. Mr Shenk
was gracious enough to give it to them. Permission was also obtained from Western Electric
because they originated this passive EQ. We just improved it for a different era.

The obvious application is voice. Many acoustic and electric instruments benefit
from the choice of frequencies and bandwidths. We know it has been the magic touch on
harmonicas, acoustic guitars, and violins. Because almost all instruments have a reasonable
amount of mids, it can be handy very often. We suggest it in combination with another EQ
like the Manley Pultec EQP1-A which focuses on lows and highs. The frequencies
complement each other. This combination has proved powerful and flexible for mastering.

Many of the most recognised engineers suggest cutting rather than boosting.
According to them, it sounds like less phase shift and resonance. They would start by dipping

a little in the 150 to 1.5K area and not by boosting lows, then highs, then.... One obvious

advantage to this is maximised headroom. The Mid Dip section is great for this approach.

Another advanced technique of EQ is to approach it "in the mix" rather than "soloed'
and more as an arrangement tool than making every single sound huge. It is based on finding
optimum areas in the spectrum of the mix to emphasize each sound. The denser the
arrangement, the more this may be needed. It is most difficult when the band participates in
the mix. Each player wants to hear thier instrument oversized, up-front and dramatic.
Producers and engineers who can hear, in their head, what the mix should be with one or two
passes of the tape have the method. The Mid Eq has proven to be a great tool for that approach.
The opposite approach is every sound is big, and most of the tracks are muted. However when
one gets great arrangements & great musicians playing together these "tricks" are not really
needed much. A hit song will probably be a hit regardless of your efforts or the mix but the
best memories is when it all clicked.

The Mid Pultec has pretty narrow bandwidths, appropriate for fine-tuning or creating
some unusual character. Approach it like a fine tip paint brush. If what you need is a roller
brush, save the Mid EQ for something else like the final touch-ups. Try it on percussion, snare
or sax. These instruments often challenge the transient accuracy of solid state Eqs. They
might take on a smeared, edgy or pink noise quality. The better the monitor system the more
obvious this can be heard. Manley's circuits may sound quicker, cleaner & warmer.

4

BYPASS

IN

200 300 500 700 1000

PEAK .7 1 1.5 2 3

5 6

4

7

8

3
2

1

.4 4

9

10

.3 .2 kHz 7 5

1.5 2 3 4 5

5 6

4

7

8

3
2

9

1

10

HIGH FREQUENCY kHz Hz LOW FREQUENCY

PEAKDIP

5 6

4

7

8

3

2

9

1

10

MID - FREQUENCY EQUALIZER

HANDCRAFTED IN CHINO, CALIFORNIA

A IN / BYPASS - Bypass, of course, disables the EQ function. The signal

always passes through the tubes.

B Hz LOW FREQUENCY - Determines frequency at which maximum low

frequency PEAK occurs. Choices are 200, 300, 500, 800 and 1 kHz.

C PEAK (LOW FREQUENCY) - Provides continuously variable BOOST from

0 to 11-12 dB to the selected low frequency. See the curves on page 11.

D MID FREQUENCY SELECT - Dermines frequency at which maximum DIP

in the mids occurs. 11 frequencies from 200 Hz to 7K. The 200 to 800
frequencies are great for clearing up some of the mud in sounds, 1 kHz to 4
khz to tame the nasal tones and painful hard sounds while the 5 or 7 kHz are
often used to compensate for microphone diaphragm resonances.

E MID FREQUENCY DIP - (peak) Provides continuously variable CUT from

0 to -10 or -12 dB to the selected mids. As with most LC passive EQs, as one
selects higher frequencies, the bandwidth narrows slightly and a little more
range of cut (or boost) is possible.

F HIGH FREQUENCY SELECT - Determines frequency at which maximum

high frequency PEAK occurs. Choices are: 1.5 kHz, 2, 3, 4, & 5 kHz.

G HIGH FREQUENCY PEAK - Provides continuously variable BOOST from

0 to 10 dB of the selected high frequency.

H LED POWER INDICATOR - When power is first turned on, the LED

should turn on RED. About 20 seconds later it will change to GREEN
indicating the signal can pass through. This is a power-on, power-off mute
circuit to prevent thumps and noises as the tubes are warming up (or cooling).
It is smart enough to ignore quick black-outs.

I POWER SWITCH - Powers the unit ON when switched UP. We suggest

turning the unit off when the session is over. The tubes will last longer.