Icon Audio launch mighty new flagship limited special edition MB81 monoblocks
Has Icon Audio founder David Shaw designed the ultimate triode amplifier? Previewed at September’s National Audio Show and lovingly created to fulfil a personal ambition, these gargantuan amps will be sold in limited numbers as a very special edition.
“If I’m completely honest,” says Shaw, “for much of the past year I’ve been building my own birthday present – and this is it!”. After discovering a quantity of ‘new old stock’ Russian GU81 transmitter valves, Shaw began to work on a prototype amplifier that would achieve a long-held goal: to effectively drive any modern lowefficiency high-end speaker to realistic levels.
At 260 mm tall, 100 mm in diameter and weighing in at 1 kg, the GU81 is a truly majestic valve. Although the GU81 remains in production, Shaw still favoured the ‘new old stock’ valves for the MB81, hand-picked for their combination of fine resolution, enthralling musicality and immense power.
Shaw has long been a fan of triode operation, being the purest form of valve amplification. But triodes typically have a downside: limited power output, which to overcome presents real a design challenge. Says Shaw, “Our pursuit for making ever-better amplifiers often leads us into uncharted territory. This is such an example and it’s been a genuine labour of love. I’ve spent many, many months designing and listening, listening and redesigning.”
Happily, his efforts have more than delivered, if reactions to the prototype previewed at September’s National Audio Show are anything to go by.
In the Icon Audio MB81, Shaw has produced a triode monoblock that can deliver an astonishing amount of power into even the most demanding of loads. These massive amps are about 50% bigger than the current Icon flagship MB845MkIIm and weigh around 100 kg per pair. The specification is incredible: 250 watts RMS continuous output into an 8 ohm load. Complex tertiary output transformers minimise distortion while allowing unbeatable bass power and authority.
“Following our work with other big triodes, we wanted to build an amplifier that would deliver plenty of power to drive the largest inefficient speakers with ease in pure triode mode, in very large rooms,” explains Shaw, who finds it curious that loudspeaker manufacturers rarely specify the types of amplifiers that their speakers are designed for, and believes that the intimate synergy between the two is crucial to make or break a good sound system. “Although many large speakers are generally efficient,” he adds, “their complex crossovers full of capacitors and inductors often present a difficult load for an amplifier, especially if it’s running with less than ideal power.”
Always keen to break new ground, Icon Audio believe the MB81 to be the world’s first ever push-pull GU81 amplifier. While it was initially developed as a personal gift for Shaw himself, he plans to produce a small number for sale as a very special limited edition. “This is probably the most amazing amplifier we’ve ever made,” says Shaw, “so it would seem churlish not to share it”.
Whether you’re in the market for a £12,500 pair of monobocks or not, you might just want to arrange a listen anyway – for the pure joy of it. Happy birthday, David Shaw.
Icon Audio MB81 key features
250W RMS continuous output per amp into an 8 ohm load.
Pure Class A triode front end.
Triode GU81 push-pull output stage.
The GU81s can be user-calibrated using Icon Audio’s built-in ‘Easy Bias’ meter.
All hand wired with silver plated pure copper PTFE audio cable to optimise sound and reliability.
Low distortion tertiary wound output transformers, potted to reduce noise.
Solen/SCR audiophile quality capacitors.
Jensen copper foil on request.
Silver-plated pure copper PTFE audio cable.
Gold plated input and loudspeaker terminals.
Technical specifications*
Output power 250 W RMS into 8 ohms continuous
Valve complement
1 x 6SL7 & 2 x 6SN7 first stage valves
2 x EL34 driver valves
2 x GU81 output valves
Frequency response 20 Hz – 20 kHz -1 dB
Suitable loudspeakers 4 Ω to 16 Ω (min 1 Ω max 100)
Sensitivity
600 mV sensitivity (low feedback) for full output
1.6 V sensitivity (medium feedback) for full output
Signal to noise ratio -100 dB
Total harmonic distortion Typically 0.3% 200 W
Damping factor 7
Input impedance 100 kΩ
Power consumption (pair)
220 / 240 / 115 V:
900 watts typical (up to 50 W output)
1,900 watts max ( @ 250 W output)
Dimensions 315 mm (w) x 385 mm (h) x 660 mm (d)
12.5” (w) x 15.3” (h) x 26” (d)
Weight 55 kg / 122 lb each
Warranty 1 year (including valves)
* Typical figures @ 235 V / 117 V; provisional specifications subject to change.
Pricing & availability
Icon Audio MB81 (inc. VAT): £12,500 per pair.
Launch: February 2015
About Icon Audio
The Icon Audio philosophy is to create audiophile products that sound good, look good, are easily affordable and will last a lifetime.
Each Icon Audio amplifier is designed in Leicester, UK, by the company’s founder, David Shaw. The amplifier chassis are then manufactured in China, with production and quality control being closely managed by Shaw himself who regularly travels to China to ensure that the performance and quality on which Icon Audio have built their reputation are fully maintained. Final product assembly, custom modifications and extensive testing then take place in Icon’s premises in Leicester, UK.
Everything in an Icon Audio amplifier is serviceable and replaceable, from the valves themselves to substantial components such as the transformers. All Icon Audio products are available for demonstration by appointment in Leicester and also via a selected dealer network.
