The Icon Audio Stereo 20 SE

A delightfully simple 20 watt Single Ended pure valve amplifier

Designed by David Shaw, founder of Icon Audio.

Many people yearn for the idea of a very simple amplifier using only one output valve (or Single Ended), believing that the absence of a phase splitter and “push-pull” output stage will bring them closer to the elusive “inner detail” of music reproduction.
It is certainly true the SE amplifiers have a magical sound of their own. Our new Stereo 20 SE is no exception. Two years in design and another year the for the listening and “tweaking”, as technically SE amplifiers do not measure as well as their Push-Pull cousins, so many adjustments are made by “ear”.

We believe that our new ST20SE has a truly “Golden Sound”!

How did we do it? Well first by addressing the common problems that SE amplifiers tend to suffer from. Such as:

• Low power output (usually 9 watts max)
• Poor bass (due to transformer saturation)
• Hum and noise (no push-pull noise cancelling)

There are various solutions to these problems: For more power we could use one of the “transmitter” triodes like the 845, but these are very power hungry and difficult to drive, demanding big, high voltage power supplies and powerful driver stages (e.g. the expensive 300B)

The logical choice is the superb GEC KT88. It is very efficient, working well with simple power supplies. The KT88s easy driving qualities make it easy to design a simple high quality low noise driver. And because the transformers are not saturated the bass response is excellent.
All these things add up to keep the purchase cost and running costs down, not the quality.

Designed by David Shaw, founder of Icon Audio. The driver stage is the venerable 6SN7. Probably the best sounding Hi Fi driver valve. Quiet, silky smooth and dynamic. The large custom wound transformers are able to deliver very deep bass notes and smooth clean treble.

SE amplifiers are very sensitive to the power supply, and sound better with a valve rectifier. We use the Western Electric designed 275 valve rectifier (centre) a large “choke” in a traditional “Pi” configuration. This gives very low source impedance with a huge reserve of power available for large transients without clipping.

This combination gives a very smooth and detailed sound stage which works well to bring out the colour and texture of older recordings and whilst not overemphasizing the harshness of many modern digital recordings. This makes for a very easy to live with amplifier that still has plenty of power to control modern speakers. A new feature of the Stereo 20 SE is the ability to reduce the sensitivity to work with pre amplifiers if required. This is not done by the usual attenuation which increases noise and reduces quality, but genuinely changes the sensitivity of the input.

The brand new gold and black design features solid alloy legs and knobs. And our famous stainless steel and Plexiglas valve cover to create a stunning visual impression.

On the scales at 20Kg this amplifier is no lightweight in quality or performance and should give many years of excellent service.

Specifications and Features

• Comprehensive manual supplied
• Full instructions for valve change included
• All hand wired point to point
• No printed circuit board to ‘colour’ sound
• Japanese Blue ALPS volume pot.
• Class A, all Triode front end
• 2x KT88/6550 precisely matched for best performance
• 2x 6SN7 driver valves
• 2x 20w RMS continuous per channel
• Signal to noise level -90db
• Freq response better than 20hz-20kHz +0 – 0.5db
• Total harmonic distortion typically less than 0.1% 1khz
• Suitable for 4 to 16ohm loudspeakers
• Japanese steel EI transformers with low oxygen copper
• Attractive valve cover included in the price
• High quality 2W metal film, & wire-wound resistors
• Blue LED mains indicator
• Polypropylene audio capacitors (Jensen option)
• Silver TEFLON audio cable
• Custom hand wound output transformers
• Ceramic valve holders for minimum leakage
• Centre tapped heater circuit for minimum hum
• ‘Soft start’ device incorporated
• Gold plated Input & speaker terminals
• Three line inputs with Gold plated terminals
• 350mv input sensitivity (integrated mode)
• 1000mv (1v) sensitivity (Power amplifier mode)
• 230/240volts 150watts typicly, 250w max. 2A AS fuse
• C E, ROHS, WEEE compliant
• 400W, 400D, 250H, 20kg (remember to allow space for connections and ventilation)

Specifications subject to change, errors & omissions excepted. General 13/08/08)

Downloads

For full details of this product (including pricing, options and delivery details) pls download the PDF.

The updated Stereo 20 SE

PDF