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Icon Audio Stereo 40 MkIV Integrated Valve Amplifier


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Enquiry/price check? Click here SKU: IAS40M4
Ex VAT: £1,915.83

RRP: £2,499.95


Stereo 40 MkIV, supplied with EL34 or KT88 valves, features an Easy Bias Meter, Remote Control, Record Loop and Choke Power Supply delivering 2x 50W/30W of power.

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RRP: £2,499.95


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Warranty length 1 Year
Brand Icon Audio

Tech Specs

- Class A, all Triode front end
- Circuit: Ultralinear or Triode switchable
- 4x EL34/KT88 matched for best performance
- Valve/phase splitter: 4x 6SN7 (1st stage)
- Output: 2x 50w per channel Ultralinear
- 2x 30 Watts in Triode mode
- Signal to noise level: -90db
- Freq response: >20hz-20kHz (0, –1dB)
- Power bandwidth: 30Hz-30kHz (-3dB)
- THD: 0.2% at full output


- Input sensitivity: 250/800mv (high/low)
- Silver PTFE audio cable
- Gold plated Input & speaker terminals
- Line inputs: CD, Tuner, Aux plus Tape
- Tape monitor circuit: ‘Record Out’
- Suitable for 4 to 16ohm loudspeakers


- Remote control: HQ ALPS motorised vol
- Solen caps, Jensen copper foil (paper/oil)
- Supplied with valve cover
- Choke regulated power supply
- Custom hand wound Tertiary transformers


- Standby switch: save valve life/power
- Power requirement: 230-240v (117v adj)
- Max Power Consumption: 240W
- Cont Power Consumption: 76-140W min
- Compliance: CE, ROHS and WEEE
- Dimensions (WDH): 390 x 410 x 230mm
- Weight: 22kg

Product Description

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

Headphone Socket

Following customer feedback the new model now features a headphone socket giving greater flexibility of use.

Improved Power Supply

In conjunction with the 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.

Redesigned Driver Circuit

Using a “cascode” configuration for the first stage enables Icon Audio 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. Since too much feedback can spoil the sound of an amplifier, only a small amount is used in the Stereo 40 MK IV.

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. The large handmade output transformers are believed to be amongst the finest available. They are more expensive and difficult to make but worth the effort.

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. A majority of customers use the Triode Facility most of the time therefore this model is upgraded so the Triode power is now 30 Watts enabling use of all but the most inefficient speakers.

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 the new David Shaw types or new production and vintage USA/Russian types.

Remote Control

HQ ALPS motorised volume pot remote control is useful to get exactly the right volume in your listening position and 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. Icon Audio can offer a range of upgrades including Shuguang “Treasure” valves and Russian types. As well as the superb Jensen “oil in paper” capacitors.

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Contact Details

UK Local Rate Number
0844 50 403 50

Sales Landline
0121 224 7300/7401

Customer Services Landline
0121 224 7350/7351

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