The Rationale For High Power Amplification; Compatibility; Summary - Cello Duet 350 Owner's Manual

The Rationale for High Power Amplification

Real music fills a room. Even a soft instrument such as flute, harpsichord, or guitar is
much larger in life than most music systems can easily reproduce. Part of the
problem, until now, has been the limitations in power amplifiers. Some amps sound
sweet but have no power. Others play loud but lack natural sonic quality. At the same
time many speaker systems are not very efficient and require fairly high voltage to
reproduce musical peaks. Other speakers have low impedance curves which require
substantial current to drive. Still other speakers have low efficiency and low
i mpedance parameters which require high current and high voltage drive capability.
For example, many kinds of live music can generate musical peaks of 115dB SPL at
the listener's ears. If a speaker is rated at 85dB SPL 1W/1M, then it will require 1024
Watts to reproduce a peak of 115dB SPL! In bridged mode, the Duet 350 will handle
even this tough demand with ease. How much power speakers actually require to
produce a given sound pressure level is difficult to calculate because the impedance
curves of different designs vary so much and because other important factors are
involved.

Compatibility

The Duet 350 is virtually compatible with all high quality preamplifiers and
loudspeakers from other manufacturers. In fact, Cello engineers designed the Duet
350 specifically to be compatible with a wide variety of available equipment. The
input impedance (audio +) is 1 megOhms, so it does not load even the most sensitive
vacuum tube preamp. Output impedance is low enough to ensure against interactions
with speaker loads. Noise is low enough so that high efficiency speakers can be used
without audible residual noise. Input sensitivity is reasonably high permitting the
Duet 350 to be easily driven by any high quality preamplifier. For balanced line
inputs, the industry standard connector is the XLR type. Cello does not use XLR
connectors because they do not meet Cello's standards for contact quality and
reliability. Instead, Cello uses the 3-pin Fischer connector series for all balanced line
applications. Cello Strings cables are available through Cello authorized accounts
with 3-pin Fischer on one end (male for Duet 350 input) and XLR or RCA on the
other end for interfacing with non-Cello equipment. Use of Cello Strings cable is
highly recommended because a number of "balanced" cables on the market do not
actually provide the correct complement of conductors and shield.

Summary

The Duet 350 has achieved affordable excellence in sonic quality, power capability
and reliability. For slightly more cost than conventional amplifiers (and less than
some others), you can now own a Cello.
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