Primare
A34.2
Power Amplifier

Overview 

The A34.2 is a 2 x 150 watt stereo power amplifier utilising proprietary UFPD technology. It is
designed to provide high power output with very low distortion for Primare’s PRE32 audiophile
preamplifier and all other preamps, as well as multi-channel audio processors. UFPD’s instantaneous
rise time results in a naturally fast, clean and agile sound over a much wider frequency range and with
exceptional headroom. Ecologically the A34.2 is far superior to conventional Class A/B designs being
extremely efficient without generating excessive heat.

Audiophile Topology

• The A34.2 houses two discrete UFPD amplifiers housed in a heavy gauge alloy steel chassis, which
  provides strength, rigidity, and screening, while being effective at damping vibrations from external
  sources. Each channel incorporates unbalanced (RCA) and balanced (XLR) inputs, as well as high
  quality gold plated speaker terminals, trigger and RS232 control inputs.
• The A34.2 can easily be switched to bridged mode and will then provide one fully balanced mono
  channel capable of delivering up to 550W into 8ohms.
• 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 and is present in equal amounts 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.
• All audio signal switching between bridged or stereo mode, unbalanced (RCA) or balanced (XLR)
  inputs is carried out using high performance signal relays.
• The A34.2 incorporates a preamp stage comprising Burr-Brown OPA2134 and Analogue Devices
  AD8512 OP-amps that automatically maintains a constant gain of 30dB (unbalanced) and 24dB
  (balanced), while stabilising input impedance at 15kohm in stereo or bridged configuration.

Ultra Fast Power Device (UFPD) Class-D Amplifier

• The use of switch mode power electronics is gaining in popularity as the result of its lower energy
  consumption and as a way to squeeze more amplifier channels into smaller spaces. Unfortunately
  Class D amplifiers and their switch mode power supplies have traditionally deserved a reputation for
  poor audio quality because it is very difficult to produce a full range ‘hi-fi’ signal through them. A major
  source of distortion is the demodulation filter on the output which becomes unstable with variations in
  loudspeaker impedance, unless it’s controlled by sufficient feedback. The failure to provide enough
  feedback to cope with dynamic changes in loudspeaker impedance across the audio band results in
  the ‘classic’ Class D sound of rising THD with frequency. While very dynamic and vivid initially, it can
  sound tiring and uncontrolled in the long term, especially when driving complex loads like multi-driver
  speakers.
• Primare’s UFPD (Ultra Fast Power Device) provides for the possibilities of an ‘audiophile’ Class D
  design. It is a Class D technology which has a consistent 26dB feedback loop gain across the entire
  audio range and is stable way beyond the audio band. This is quite easy to achieve in conventional
  linear ‘continuous signal’ amplifiers, but much more difficult in ‘non-continuous’ high speed switching
  amplifiers.

Features

UFPD notes:

• UFPD switching frequency is above 300kHz.
• The output filter cut-off is higher than the audio band but is well below 300kHz.

UFPD displays:

• Wide bandwidth
• Flat frequency response
• Load independant frequency response
• Low output impedance in the entire audio band
• Low THD in the entire audio band
• Low noise

Most Class D technologies display:

• Limited bandwidth
• Peaking frequency response
• Load dependant frequency response
• High output impedance at high frequencies
• High THD at high frequencies
• High noise