Primare AB • Limstensgatan 7 • SE-21616 Limhamn • Sweden • Tel +46 40 6548800 •
www.primare.net
September 2014
Design Brief - PRE32 pre-amplifier
7 pages
The PRE32 is an upgradable audiophile pre-amplifier designed to match the Primare A34.2 and
all Primare power amplifiers. It features the comprehensive OLED display and control
parameters established by the EISA award-winning I32 integrated amplifier. The PRE32 is
housed in a heavy gauge alloy steel chassis, and incorporates two pairs (L/R) of low-noise
balanced XLR inputs and 4 pairs of RCA inputs. In addition there are two pairs of RCA outputs
and a single pair of balanced XLR outputs, as well as a record output, RS232, trigger, IR and
RF inputs. MEDIA/streaming connections such as USB, iPod, LAN etc are available through the
modular MM30 media board, which may be enhanced with a high quality aptX Bluetooth
upgrade.
Audiophile Topology
All signal paths are fully balanced and as short as possible. All signal treatments (source selection,
volume and channel balance trims) are performed purely in the analogue domain. Unbalanced inputs
are converted to balanced signals by a conversion stage buffered by the excellent sounding Burr
Brown OPA2134 op-amps and fed to volume and balance controls employing closely matched
NJW1195 attenuators in a balanced configuration. Source selection is via high performance signal
relays.
Balanced signal transmission means that two identical signal lines are used to carry the same signal
with opposite phase. Any noise is common to both lines, is present in equal amounts and with identical
phase. At the receiving end a (differential) receiver retains the opposite phase signals (music) and
rejects the common phase ones (noise) leaving only the pure original signal. Balanced circuits
therefore keep the signal as free as possible from interference.
The four (L/R balanced) single-ended 16dB gain stage modules are fully separated. Each has its own
proprietary PCB, incorporating a custom designed copper heat sink, which also acts as a shield. The
gain module layout incorporates ultra-short signal paths and only the finest discrete components such
as MOSFET transistors, MELF resistors and polypropylene capacitors. Active, well-balanced current
sources are used instead of passive resistor networks.
The PRE32 is DC coupled from input to output. There are no capacitors in the signal path. Instead
active DC servos are used to compensate for any DC present, ensuring that the outputs are always
free from DC components.
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