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The Signal Transfer Company is the only source for PCBs guaranteed to comply with the power amplifier design philosophy pioneered by Douglas Self. Due to current conditions the decision has been made that in future only bare PCBs will be offered.

The crosstalk performance of preamplifiers, and the linearity of power amplifiers is often defined by the fine details of PCB layout. An apparently minor error can have dreadful effects on performance.

Our PCBs have been designed with meticulous care at every point. The board layouts are precisely the same as those approved by Douglas Self when his famous series of articles appeared. You can therefore be confident that in some respects at least, proper operation is "built-in".

We supply the finest quality fibreglass PCBs, double-sided with gold-plated pads. All boards have full solder mask and a silk-screen component layout.

Each PCB is supplied with extensive constructional notes, previously unpublished information about the design, and a detailed parts list to make ordering components simple.

Douglas Self is available to answer any questions relating directly to Signal Transfer products.
He can be contacted at the NEW email address:

The Douglas Self Site

If you like to keep an eye on Douglas Self's website, click the box above. Be aware that the old site at aqpl43.dsl.pipex.com is no longer being updated. The Douglas Self Site is at: douglas-self.com

The Devinyliser PCB
The Devinyliser is an innovative solution to the problem of subsonic disturbances from vinyl. Subsonic disturbances essentially cause vertical stylus movements, causing anti-phase signals in the Left and Right channels. L-R crossfeed at low frequencies cancels the anti-phase signals, converting bass information to mono.

The basic idea is not new but it has never caught on, because in all previous attempts the anti-phase filtering slope always comes out as -6dB/octave, no matter what order of lowpass filter is used to control crossfeeding. We have used sophisticated allpass filtering to time-correct the lowpass filter group delay, giving a much steeper slope of -18dB/octave from a 2nd-order Butterworth filter. The intrusion of crossfeed into the audio band is thus minimised.

Douglas Self presented papers on the Devinyliser at the 140th AES Convention at Paris in June 2016, and at the October 2016 meeting of the London AES at Kings College, London.

The Devinyliser PCB is available as PCB** 20:00 each

Compact Blameless Power Amplifier
The Signal Transfer amplifier power supply provides a high-current power supply for feeding two of our power amplifiers, combined with closely regulated +/-17V supplies at 500 mA for powering op-amp circuitry, including the Low-Noise Balanced Input Card, and the Amplifier and Loudspeaker Protection Card.

Available as PCB0014 27:50 each

Compact Blameless Power Amplifier
The Compact Blameless Power Amplifier. A small-format Class-B power amplifier card that will fit into minimal space when the full low-impedance load driving capabilities of the Load-Invariant Amplifier are not required. in every other respect this design has all the features of the of the other amplifiers we offer, and it gives the full Blameless performance into 8 Ohm loads.

Available as PCB009: 23:00 each

Protection card
A comprehensive amplifier & speaker protection card that provides relay muting and guards against DC offset errors that can destroy expensive speakers almost instantly. It also gives a slow turn-on and fast turn-off to mute power-up and power-down transients, two channels of over-temperature protection, and a shutdown input.

Available as PCB008: 23:00 each