Recording - October 2014 - 64

5. Motown's first record cutting room had a
Neumann AM131 lathe and a Studer C37 tape
playback machine. In the rack at the top right of
photo are two of the 7-band Type One mastering
equalizers built by Mike McLean.

6. The stereo mastering setup at Motown, with
two banks of 7-band EQs used for stereo L/R and
a single mono equalizer. The large knob on the
right (beneath the four VU meters) was the
transfer control used to switch between the two
banks of EQs during a mastering session.

7. Close up of the stereo mastering console at
Motown, which-with its Dymo Labelmaker markings-was built for performance, not looks. It
allowed switching between mono and stereo modes,
as well as monitoring different sources and tweaking
the cutter head's preview and program feeds.
frequencies for half- or normal-speed cutting. The two
Type One units provided for cutting mono album masters.
The upper unit seen here was used for setup 1, 3, 5,
7, etc. (the odd-numbered selections on the LP disc), and
64

RECORDING October 2014

the lower EQ unit was used for setup 2, 4, 6, 8, etc. (the even-numbered selections)."
The process was complex and required some quick timing. "There was also
a lot of paperwork to keep track of the various versions and changes," McLean
adds. "You went to cut the LP with six or seven cuts on each side, each with different equalization settings. Then you'd have to preset the second set of equalization for the next song and switch back and forth. It could be a nightmare."
"The Westrex cutter that everybody else was using had a resonance at the
high-end that was bad for naturalness of sound but very good because it took
the heat off the drive coil. You could push those about as loud as you wanted,
because in that sense, that resonance was working for you," McLean explains.
"The Teldec cutter was pure, sweet and resonance-free right out to 20 kHz, but
had nothing to give you help on that power requirement. The solution was a
converter for the Neumann lathe that made it run at half speed, so all you had
to do was run your master tape at half speed and fix the equalization."
The latter step required taking all the EQ settings from the mastering notes
and cutting the values of all the center frequencies in half, so for example,
a -3 dB cut at 320 Hz would become a -3 dB cut at 160 Hz; +4 at 5 kHz
would become +4 dB at 2.5 kHz, etc. Of course, later, on full-speed playback, all the frequencies are doubled, the program plays back at the correct speed, and your mastering EQ changes occur at the right frequencies.
The net effect of the half-speed mastering process yields more recording
level without overheating the cutter head and/or clipping the recording
amplifier. "We tried it out and indeed did find out that it let us increase the
maximum level by 8 dB, compared to what it was," McLean notes.
A solution for this would be an equalizer with a single switch that globally reduced all its center frequencies by 50 percent, which required a custom unit. "I began with the Langevin EQ 252a graphic equalizer design by
Arthur C. Davis. We then built something based on the same schematic-
but different packaging, better switches and all that, because we wanted
half-speed frequencies as well as the full-speed."
Several versions of the mastering equalizer were made. "The two mono
units could be switched from full-speed to half-speed; 2-channel equalizers
were later made for the stereo disk cutting room. The changeover switch
itself was a hell of a component with about eight decks on it to switch all
those LC resonant circuits on those resonant circuits. On full-speed, it would
route through one set of capacitors and chokes-which provided the correct
frequencies-and for half-speed, it would toggle to another complete set of
elements to provide the right frequencies for half-speed."
Eventually, Motown added a room with stereo disk cutting capability, and
the process of half-speed mastering to cut stereo releases became far more
complex. The new disc cutting room featured a Neumann type SX68 cutter
head and Neumann AM 32B lathe, which was equipped with preview-controlled variable pitch and depth of cut.
"The stereo room had its own set of problems, because it not only had to
switch for left and right channels of the program but also the preview feeds
for the new variable-pitch and depth Neumann lathe. The preview feeds
had to be equalized, along with the program material. So for stereo, you'd
need two EQ channels (left and right) for the program, two more equalizers
(L/R) for the preview and then four more equalizer channels for the next
band on the record. Constantly resetting each set of four EQs for the next
cut, over and over on an album [while the disk was cutting] was a hell of a
mess." Pictures 6 and 7 show the EQ racks and the console.
A mess? Perhaps. Complicated? Certainly. But the right combination of a
dedicated crew, talented producers and engineers, great artists, memorable
songs and the leadership of Berry Gordy all made an indelible stamp on
the world. And the rest-as they say-is history.
History revealed
If gear could talk, what tales they'd tell. And here was a processor that handled hundreds of mastering sessions on classic Motown releases. Of course,
you never know what treasures lie at the next garage sale, swap meet or flea
market, but the process is kind of like fishing. Even if you don't snag anything,
it's still fun to go out and drop your hook in the water... because you never
know what you might reel in. Give it a try!
George Petersen (petersen@recordingmag.com) is the former editor of Mix
Magazine and currently runs FRONT of HOUSE, a publication for the live
sound and touring industry.

Recording - October 2014

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