Stereo 40 MkIV (6L6)

Not just another “budget” amplifier! We took a long hard look at our award winning Stereo 40 MKIV to see where cost savings could be made without sacrificing any quality.

Firstly, we removed all non-essential features like “standby” and “headphone” etc which have no impact on audio quality.

Secondly the excellent 6L6/KT66 group of valves are more than 50% cheaper than the KT88/EL34 types with only a relatively small loss in power (30+30W UL).

Thirdly the lower power requirements of the 6L6/KT66 means a saving in the amount of transformer copper and iron used and power consumption.

In summary the ST40 6L6 has all the performance and quality of the ST40 MKIV using exactly the same circuit and chassis at a considerable cost saving.

At the time of writing the ST40 6L6 may be re-valved for only £120.

In line with our other amplifiers there are many valve and capacitor upgrade options like the Genalex KT66 and Tung Sol 6L6.

 

Circuit Design.

In common with the ST40, ST60 and ST300 the David Shaw designed Cascode circuit uses the 6SN7 driver valve, probably the best sounding valve ever made! This means that there are only two types of valves used with the obvious benefits for the owner.

 

Output Transformers

Key to astonishing performance of the ST40 6L6 are the handmade output transformers which have helped win us so many awards.

The ST40 6L6 transformers stay faithful to the original formula with the low distortion tertiary winding almost unique in modern amplifiers.

Designed and manufactured in house Tertiary Wound means they have an extra (third) winding which reduces distortion, allowing the use of using less global feedback.

Choke Regulated Power Supply

Working in conjunction with the smoothing capacitors the large choke gives super-smooth power regulation for a silent background.

Low Feedback design. Too much feedback can spoil the sound of an amplifier. We only use a moderate amount in the Stereo 40 6L6.

GEC KT66 and U.S. 6L6 valves

The lower cost forerunners of the KT88 and still considered by many to be amongst the finest Beam Pentode valves ever created, efficient, easy to drive with low distortion the Stereo 40 6L6 is designed to get the best out of this valve in big dynamics and micro detail.

30+30 Watts per channel.

In tests 30 watts is more than ample for a medium to large sized room with average efficiency loudspeakers. And now with several speaker manufacturers such as Klipsch making 100dB “Heritage” designs requiring only very modest power, very high sound levels and deep bass are possible

Ultralinear or Triode?

On request at no extra charge we can convert to pure triode operation.

Remote Control

Remote control of volume with mute facility is available as an option.

REVIEWS

Hi Fi News January 2023