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History of the Model 4-710d
Like the microphone, preamplifiers come in all shapes, sizes and colors. And, like a microphone, the
preamp is one of many devices that may impart a sound to a recording... or may conversely attempt to
avoid coloration. In this way, mics and preamps can be compared to the various paints, brushes and
surfaces a visual artist may choose from, or to the various films, lenses and filters the photographer
uses in his process. In the same way that a photographer might choose a certain filter to reject a
certain type of light, a recording engineer may do the same with a mic to tailor out a certain frequency
range. The photographer may choose a particular film to convey a certain atmosphere, and a recordist
might choose a particular preamp for the very same reason. The critical decision is whether or not the
given device imparts the
correct
character (or lack thereof) for a given recording. The best thing about
choosing the right mic and preamp for the job is that when the session is going great and the music is
truly happening, the quality, character and nuanced detail of the engineer’s tools really begin to shine.
Because it is the component which transforms the very low-level signal from a microphone into a
useable signal—a critical transition of energy—the quality of the preamplifier plays a huge role in
shaping the final signal. And ultimately, a great mic preamp is all about great design.
Throughout the half-century or so of modern recording technology, a number of preamp designs have
been introduced, all with their own strengths and weaknesses. Early preamplifiers relied on vacuum
tubes to boost signal. One of the most popular preamps of the era was the one inside the 610 console
built by Bill Putnam Sr. in 1960 for his United Recording facility in Hollywood. As was the case with
most of Putnam’s innovations, the 610 was the pragmatic solution for a recurring problem in the
studios of the era: how to fix a console without interrupting a session. The traditional console of the
time was a one-piece control surface with all components connected via patch cords. If a problem
occurred, the session came to a halt while the console was dismantled. Putnam’s answer was to build
a mic-pre with gain control, echo send and adjustable EQ on a single modular chassis, using a printed
circuit board. Though modular consoles are commonplace today, the 610 was quite a breakthrough at
the time.
While the 610 was designed for practical reasons, it was its sound that made it popular with the
recording artists who frequented Putnam’s studios in the 1960s. The unique character of its micro-
phone preamplifier in particular made it a favorite of legendary engineers like Bruce Botnick, Bones
Howe, Lee Hershberg, and Bruce Swedien, who has described the character of the preamp as “clear
and open” and “very musical.” The 610 console was used in hundreds of studio sessions for interna-
tionally renowned artists such as Frank Sinatra, Ray Charles, Sarah Vaughan, the Mamas and Papas,
the Fifth Dimension, Herb Alpert, and Sergio Mendes. The Beach Boys’ milestone
Pet Sounds
album
was also recorded using a 610.
But by the mid 1960’s, tiny solid-state components called transistors, followed by advanced techno-
logical innovations such as FETs (Field Effect Transistors), op amps (operational amplifiers), and ICs
(Integrated Circuits), had become ubiquitous and inexpensive to manufacture. These all did the job of
vacuum tubes, but with greater efficiency and reliability, less heat, much smaller size, and much
longer lifetimes. For these reasons, audio circuit designers such as Bill Putnam began creating pre-
amplifiers using transistors instead of tubes. One of the first of these was the Universal Audio 1108.
This was an exquisitely designed, widely used single-stage modular preamp made for modular re-
cording consoles. It featured input and output transformers, with connections for modular equalizers
such as the UA 508 EQ. This amp design became the basis for the enormously popular 1176 limiter,
which utilized the same output transformer. Interestingly, the 1108 has probably been used on many
more classic recordings than the 610, due to its broad popularity.
