Sugden Audio A21 Signature Pure Class ‘A’ Integrated Amplifier

Sugden A21 Signature Remote Volume Pure Class ‘A’ Integrated Amplifier – 23 watts

The Sugden A21 Pure Class ‘A’ Integrated Amplifier has a lineage stretching back almost 50 years.

In 1967 James Edward Sugden designed and produced the worlds first commercially available solid state pure Class ‘A’ amplifier the A21. The initial A21 was sold under the Richard Allan brand name, which had an established quality line of loudspeakers.

However, in 1967 the A21 was also marketed under the Sugden brand name – JES (short for James Edward Sugden). The A21 was for the audiophile the first experience of high fidelity music reproduction in the home.

The latest version, the A21 Signature was released in 2015.

Its origins are the A21 (1967) followed by the A21a series which started production in 1989.  The original A21a model was in production between 1989 to 2000, a facelift version between 2000 to 2007, and the A21a Series 2 between 2007 and 2015.  The A21a Series 2 featured the following upgrades: heavier chassis and strengthened case, 10mm thick aluminium front panel, remote volume control and beefier power supply. At the same time the mono and tape loop switching and the balance control were deleted enabling improvements to the pre-amplifier circuit by shortening signal paths.

While the A21 has a legendary heritage it also maintains hand made craftsmanship rare in the current automated and mass-produced manufacturing settings.  The A21 Signature continues to be hand made and individually tested. Sugden manufacture in-house the metal cases, assemblies, knobs and parts and carry out the finishing processes, including screen-printing.

The A21 Signature’s pure class ‘A’ design provides affordable high-end performance from a beautifully engineered single box integrated amplifier.  Compact in size with a simple but stylish design, the A21 Signature is possibly the only amplifier you will ever need. With many of the original A21’s still in daily use after fifty years, it could also last a life time.

The A21 Signature provides a large soundstage and depth to all types of music, importantly you can listen to it for hours without fatigue.  The single ended circuit provides impressive dynamics and incredible bass.


Inputs – Five line level or four line level with optional MM/MC phono board.

Outputs – Pre-Amplifier Out (Variable), tape out (fixed) and one pair stereo multi-way binding posts.

Remote Control – Volume up/down.

Earth terminal.


Line Level Sensitivity – 170mV for maximum output.

Phono Input Sensitivity – 3mV/Moving Magnet, 0.2V/Moving Coil for maximum output.

Phono Loading – Moving Magnet 47K, Moving Coil 100 ohm.

Power Output – 23 watts per channel into 8 ohms both channels working.

Frequency Response – 10Hz to 20kHz +/- 0.5dB.

Bandwidth – 6Hz to 200kHz +/- 3db.

Signal to Noise – >83db.

Nett Weight – 11kg.

Dimensions – 92mm x 430mm x 350mm (HWD).

Recommended Retail Prices:

AUD$4,995.00 – A21L Integrated Amplifier (Line Only).

AUD$5,295.00 – A21I Integrated Amplifier with MM/MC phono board.

E. & O. E.

The A21 Signature like all Sugden integrated amplifiers is dual mono construction with separate right channel, left channel and pre-amplifier stage. The three separate circuit boards are connected with silver aviation grade cable.


Sugden Signature Plug-in MM/MC Phono Board. The board is very easily retrofitted to a line only integrated amplifier.

Sugden A21a Signature Pure Class ‘A’ Integrated Amplifier – Graphite finish.

Sugden A21 Signature Pure Class ‘A’ Integrated Amplifier -input selection switch on left side with volume control centred.

Sugden A21 Signature Rear Panel layout.






Sugden A21 Signature Pure Class ‘A’ Integrated Amplifier.