STC003 Precision Preamplifier - CML Audio

STC003 Precision Preamplifier

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STC003 Precision Preamplifier II

After an extended period of development, improvement and extensive sourcing of the best possible components the STC003 Precision Preamplifier is not only back it is now probably the best preamplifier in the world…

The STC003 Precision Preamplifier is available in a variety of options from bare PCB to fully assembled and tested unit. All kit options are supplied with build notes. See options »

A case kit is now available which includes a ready-machined and printed case, mains transformer, wiring assemblies, knobs and mechanical fixings.

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.

► Full specification details for the STC003 Precision Preamplifier can be found on the Signal Transfer Company website »



  • 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.



  • Moving-coil Input sensitivity: 0.1 or 0.5 mV rms (switchable).
  • Moving-coil Input impedance: 100 Ohms.
  • Moving-magnet Input sensitivity: 5 mV rms.
  • Moving-magnet Input impedance: 47K.
  • Line Input sensitivity: 150mV rms.
  • Line Input impedance: Greater than 200K.
  • CD Input sensitivity: 1V rms.
  • CD Input impedance: Greater than 10K.
  • Maximum signal level: greater than 8V rms.
  • 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 2.2V rms 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 150mV rms.
  • Distortion (line-level stages): Less than 0.001% THD 10Hz – 20kHz. At 8V rms output; level in actual use is 50mV – 500mV rms.
  • Freq response -1dB at 10Hz – 50kHz.
  • Noise out (volume at zero) Less than -114dBu (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 244mm overall.

Case Kit

The Case and Transformer Kit comprises:

  • Machined, painted & printed front and rear panels.
  • Machined and painted base and top panels.
  • High-quality collet knobs with caps.
  • High-quality toroidal mains transformer pre-fitted to case.
  • Mains IEC inlet and rocker power switch.
  • Built and tested mains wiring assembly with double-insulated mains wiring and insulating boot for IEC connector.
  • PCB standoffs pre-fitted to case.
  • Chassis ground connections pre-fitted to case.
  • All nuts, screws and washers, etc.
  • Four self-adhesive feet (not shown). Some additional parts are supplied pre-fitted.




01 » STC003 – FRONT VIEW


02 » STC003 – REAR VIEW


03 » STC003 – Case Kit, PCB and INTERNAL VIEW


Product Order Details

STC003 Precision Preamplifier Options and Price List
Reference Quantity Price (£) Description Order
STC003PCB 1+ £129.00 PCB and build notes only. Contact CML Audio »
STC003PCB4 1+ £150.00 PCB, build notes, switches and buttons. Contact CML Audio »
STC003CASE 1+ £225.00 Painted and printed case. Contact CML Audio »
STC003KIT 1+ £355.00 Kit of parts, PCB and build notes (NB. Excludes case). Contact CML Audio »
STC003BLD 1+ £650.00 Fully assembled and tested unit (NB. Excludes case). Contact CML Audio »
STC003UNIT 1+ £925.00 Fully assembled and tested unit (including case). Contact CML Audio »

E&OE: While every effort has been made to ensure all information supplied is accurate, no liability is accepted for the consequences of any errors or omissions. All products are subject to availability. All prices are quoted in (£) Sterling and unless otherwise stated, are exclusive of VAT. CML Audio reserves the right to change the product range and prices without prior notice.



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