Universal Audio DCS-RP Manual - Manual (Page 13)

8
Application Notes
The DCS Transimpedance Preamp
For applications requiring transparent amplification of microphones and Instruments, the preamps' transimpedance
circuitry ensures the highest possible quality of signal transfer from input to output. The Remote Preamp is designed
for use with hi-definition digital recording systems operating at 24-bits and 44.1K, 48K, 96K or 192K sample rates,
or sound reinforcement systems requiring extremely high audio fidelity and dynamic range.
The term 'transimpedance' refers to transistor configurations employing current-feedback to provide gain and
distortion immunity without the loss of sonic detail or musicality.
The Remote Preamp's wide-bandwidth design allows audio from 4Hz to 150kHz to pass through the preamp
without altering the phase relationships between fundamental frequencies and overtones. Noise and distortion are
kept to near-theoretical minimums so critical signals may be generously amplified without degrading the quality or
character of the sound source. Zero-Coloration Preamps are especially useful for capturing the sound source with its
original qualities and character so that later processing may occur with maximum flexibility. There are no
transformers, tubes, compressors, or limiters in the preamp signal path - all technologies that provide useful
benefits, but may of course add permanent audio coloration. For may users, the useful characteristics of these
devices are preferred at the mix stage—and are commonly implemented using DSP processors and plug-ins with
excellent (and reverse-able) results, such as those found on Universal Audio’s UAD plug-in platform.
Amplification of Voice and Acoustic Instruments
Amplification of voice and acoustic Instruments often requires precise signal handling with meticulous attention to
detail, definition and accuracy. Applications such as classical or jazz recording and reinforcement demand faithful
transfer of performances exactly as they happen - without coloration, processing, noise or distortion. The DCS
transimpedance preamps are ideal for use in these applications.
Direct Instrument (DI)
Pickups and acoustic transducers require connection to high-impedance (high-Z) inputs to maximize transfer of
signal and high frequencies from the Instrument. The DCS DIs provide extremely high impedance (4 Meg-ohms
balanced, 2 Meg-ohms unbalanced) and transformer-less coupling of signals to the preamps through high-voltage,
Class-A, discrete-transistor electronics.
In general, the higher the DI input impedance, the better the device is for passing high frequencies, harmonics and
overtones. In some situations, sound quality may be improved by inserting a high quality instrument (DI) preamp
between the instrument and processing device or stage amp. Conveniently, the Remote Preamp provides a
secondary low-level (-10dBV) output from the A/B Stereo jack for such uses.
Connecting balanced line levels to DI inputs
Many professional keyboard instruments or instrument processors provide balanced line-level outputs and should be
connected accordingly for best performance. The Remote Preamp DI input connectors accept balanced TRS cables
for this purpose. When the DI switch is turned on, the preamp automatically changes gain ranging to accommodate
signals sent from these devices. In cases where users wish to feed professional line levels to recorders or mixers with
low-level RCA inputs (or even guitar amps), the Remote Preamp provides the flexibility to reduce signal levels when
necessary. Dial down the GAIN and set GAIN Trim
to a low level.
Devices like keyboards, guitar processors, and stomp boxes with unbalanced outputs may be adapted for use with
balanced recorder and mixer microphone inputs, and long cable runs, using the Remote Preamp. The preamp allows
gain, phase, filtering to be set for optimum results; and provides balanced outputs for long-haul connection to
recorder or mixer microphone inputs with a "TRS to XLR" cable or snake.