Stereo 40 MkIV

EL34 or KT88 valves

“Easy Bias” Meter

50+50 Watts rms*

30+30 Watts Triode

Remote Control, Record Loop

Choke Power Supply

 

The Icon Audio ST40 MKI was our first design in 2001 and has always been a special product to us. Since that time we have substantially improved it over the years and its latest guise, the MK IV has several improvements making it exceptional value.

 

Headphone Socket.

Following customer feedback the new model now has this feature. Giving greater flexibility of use.

 

Improved Power Supply.

In conjunction with our re-designed output transformers, the Ultralinear Power is now over 50 Watts. This gives greater instantaneous power available for heavy transients, and a more solid bass.

 

More Triode Power.

We know that majority of customers use the Triode Facility most of the time. The Triode power is now 30 Watts enabling use of all but the most inefficient speakers.

 

Re designed driver circuit.

Using a “cascode” configuration for the first stage enables us to use the venerable 6SN7 valve for all the driver circuit functions. This gives better definition whilst improving the frequency response at lower volumes. This also simplifies valve replacement as the amplifier only uses two valve types.

 

The Stereo 40 MK IV is packed with high end features:

 

Choke Regulated Power Supply

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

Tertiary Transformers have an extra (third) winding which reduces distortion, using less global feedback. We believe our large handmade output transformers to be amongst the finest available. They are more expensive and difficult to make, but worth the effort.

Low Feedback Too much feedback can spoil the sound of an amplifier. We only use a small amount in the Stereo 40 MK IV.

Wide range of valves

The Stereo 40 is designed to work with a wide range of output valves. You can choose between EL34 or KT88 (or even KT66/77/90, 6CA7, 6550). So you can experiment in the future.

Ultralinear or Triode?

For sixty years hi fi fans have argued which sound is better. With the Stereo 40 IV you have the choice of both at the flick of a switch. It is like having two amplifiers in one! Most hi fi fans prefer the sound of triode operation.

6SN7 (CV181)

More relaxed than their miniature cousins, these larger driver valves are the best in their class for their musical sound and longer life. Try our new David Shaw types or new production and vintage USA/Russian types.

Remote Control

Useful to get exactly the right volume in your listening position. Allows fine adjustment of the right sound level.

Plenty of Power

50 watts of power is enough to fill a medium to large room with a high volume of musical excellence.

We can offer a range of upgrades including Shuguang “Treasure” valves and Russian types. As well as the superb Jensen “oil in paper” capacitors. Ask us for a quote.

 

Specifications and Features

• Comprehensive manual supplied
• Remote control: HQ ALPS motorised volume pot
• All hand wired point to point
• Class A, all Triode front end
• Output circuit Ultralinear or Triode switchable
• 4x EL34/KT88 matched for best performance
• 4x 6SN7 for first stage valve and phase splitter
• Standby switch to save valve life and power
• 2x 50w per channel Ultralinear output
• 2x 30 Watts in Triode mode
• Signal to noise level -90db
• Freq response better than 20hz-20kHz +0 – 1db
• Power bandwidth 30Hz-30kHz -3 dB
• Total harmonic distortion 0.2% at full output
• Suitable for 4 to 16ohm loudspeakers
• Supplied with valve cover.
• Choke regulated power supply
• Solen audio caps, or Jensen copper foil in paper and oil
• Silver PTFE audio cable
• Custom hand wound Tertiary output transformers
• Gold plated Input & speaker terminals
• Four line inputs: CD, Tuner, Aux plus Tape
• Tape monitor circuit with ‘Record Out’
• Input sensitivity 250mv.(high). 800mv (low).
• Power requirement 230-240volts (117v adjustable)
• 76 Watts standby, 140 W Min, 240 W
• CE, ROHS and WEEE
• 39cmW, 41D, 23H, 22kg (allow for ventilation)

(Specifications subject to change) *(Root Mean Square = continuous output)

REVIEWS

Hi Fi News May 2019
Hi Fi World August 2019