Service Manual
UP4
M
IC
P
REAMPLIFIER
October 23, 2009
Fairlight UP-4 Mic Preamp
Page 5
5
UP4 Mic Preamplifier
The UP4 is a four channel, one rack unit remote controlled universal preamplifier designed by
Smart Research.
If used in conjunction with the DREAM family both gain and phantom power functions are
accessible directly from the surface controls or via the Softmix GUI. The remote connection to
the DREAM family is accomplished via a simple Ethernet connection. The design whilst
allowing for remote control maintains the best achievable performance for any form of
available audio circuitry. Input and output levels of up-to +28dBu are accepted and with an
EIN figure of -133dBu the system defines the "state of the art" for a universal input stage.
Providing the ability to locate the preamplifier at the nearest available point to the signal
source, the UP4 can reduce many forms of signal degradation that may appear when driving
cables direcly with un-buffered low level signals These may manifest themselves as, radiated
noise pickup, microphone cable noise, capacitive ringing effects, slew rate degradation, loss
of high frequencies and increased distortion.
UP4 key Specifications
•
EIN50Ohm source, +64dB gain, referenced to +4dBu133dBu
•
Frequency Response - Between 10 and /- 0.1dB
•
THD100-20Khz, 1Khz/0dBu signal @12dB gain setting0.0003%
•
THD100-20Khz, 1Khz/-64dBu signal @64dB gain setting0.02%
•
CMRR At 0dB gain setting, 1kHz-70dBu
•
CMRR At +64dB gain setting, 1kHz-80dBu
•
Input Headroom All gain se28dBu
•
Output Headroom All gain s28dBu
•
Crosstalk Measured at +64 Gain, clip second channel>-100dBu
•
Input Impedance Optimised at low/high gains. Ohms. 6K8/1K6
•
Power consumption Selectable 100-230 volts40 Watts
Remote Control:
Two options have been provided. Ethernet allows for control from devices such as Fairlight's
Dream; or Apple and IBM computers (software is provided). Also, various PUP units can
interface using an audio XLR data cable. This long range signal can be patched through
normal audio tie lines, such as a multicore between a stage and mixing position.
Technical discussion
PUP represents many years of development by Alan Smart. Noise, CMRR, Distortion,
Headroom, Crosstalk, Dynamic Range are exemplary, and outperform all other tested units
evaluated so far (Focusrite Blue, Massenburg); and also beating all published specs so far
examined (Amek 9098, DACS, APHEX - though one DACS unit however has a better published
CMRR spec at 1KHz).
The circuit is a unique variant of instrumentation amplifier topology, starting with the good
CMRR performance typical of this format. All internal audio circuitry is fully balanced,
maintaining symmetry from input to output, which helps further reject noise, crosstalk, and
distortion products.
