The Precision Preamplifier is back. After an extended period of development and improvement, we present The Precision Preamplifier 2.0 What's new: High-quality onboard headphone amplifier added Extra line input added LED illuminated button facility for all font-panel switches Pots can be either ALPS 16mm or Ohmeg Green Eco-pots PCB now has gold-flashed pads Now fully RoHS compliant There are four ways to buy the preamplifier PCB003: 1: Bare PCB & build notes: £129.00 2: Bare PCB, build notes, switches & buttons: £150.00 3: Bare PCB, all PCB components, & build notes: £355:00 4: Assembled & tested PCB. Includes build notes: £650.00 A case kit is now available which includes a ready-machined and printed case, mains transformer, wiring assemblies, knobs & mechanical fixings. See the cases page.

The Precision Preamplifier fully assembled in the case Close-ups of the front and rear panels of the preamplifier can be seen just below

The Precision Preamplifier is probably the best preamplifier in the world. If you examine the list of features below you will see why we feel justified in saying that.

F E A T U R E S.

• Separate moving magnet and moving coil inputs. Moving coil has two gain options to match a wide range of cartridges.
• Five line level inputs, including one specialised for CD input.
• Tape in/out with monitor switch.
• Extremely flexible tone controls, continuously variable over a wide range in turnover frequency as well as the usual boost and cut. May be switched out completely for before/after comparisons without introducing any glitch or momentary loss of signal.
• Output muting relays for positive control of turn-on and turn-off transients.
• Exceptional RIAA accuracy of +/-0.05 dB. Surprisingly, this does not require specialised and expensive components. All done by design.
• Very low noise; this is probably the quietest preamplifier ever made. When the paper describing the design was first published, Douglas Self issued a challenge to anyone who thought they had a quieter preamplifier. It is our information that no-one has attempted to take this up.
• Extremely low interchannel crosstalk. Better than -100 dB 20 Hz - 20 kHz. You will have no difficulty in achieving this performance, as it is built into the PCB layout.
• Very low crosstalk between inputs: 95 dB at 10 kHz.
• Very low distortion. THD better than 0.001%, 20 Hz - 20 kHz at 8 Vrms. This is about ten times the normal operating level, so in real use the distortion introduced is vanishingly small. It is certainly too low to measure.
• Absolute phase is preserved on all inputs and outputs.
• Easily obtainable parts. The only op-amps used are the 5532 and the TL072, both of which are easy to find world-wide. Their performance is exceptional here because of the way they are used.
• All parts except the mains transformer and mains power wiring fit on the PCB.
• Mounting positions for standard gold-plated phono sockets provided.
• High-quality double-sided plated-through-hole PCB with gold-flashed pads, solder mask both sides and full screen print.

S P E C I F I C A T I O N S.

• Moving-coil Input sensitivity: 0.1 or 0.5 mVrms (switchable)
• Moving-coil Input impedance: 100 Ohms
• Moving-magnet Input sensitivity: 5 mVrms
• Moving-magnet Input impedance: 47K
• Line Input sensitivity: 150 mVrms
• Line Input impedance: Greater than 200K
• CD Input sensitivity: 1 Vrms
• CD Input impedance: Greater than 10K
• Maximum signal level: greater than 8 Vrms.
• Minimum load on output: 600 Ohms.
• Distortion (moving-coil stage alone): Less than 0.001% THD 20Hz - 2kHz. Less than 0.003% THD 10Hz - 20kHz. At 2.2 Vrms output, level in actual use is about 5mV rms.
• Distortion (moving-magnet RIAA stage alone): Less than 0.001% THD 200Hz - 10kHz. Less than 0.003% THD 40Hz - 20kHz. At 8 Vrms output, level in actual use is about 150 mVrms.
• Distortion (line-level stages): Less than 0.001% THD 10Hz - 20kHz. At 8V rms output; level in actual use is 50mV - 500mVrms.
• Freq response -1dB at 10Hz - 50kHz
• Noise out (volume at zero) Less than -114 dBu (20-22kHz bandwidth, rms)
• Noise out (volume at unity gain, line in) Less than -105 dBu (20-22kHz bandwidth, rms)
• Transformer requirements: 18v-0-18V (200mA or greater)
• Board size 412 by 244 mm overall.