The Icon Audio MB25a

The ultimate listening experience?

Excellent mono block power amplifiers bases around the ancient 1930s triode, First developed for cinema sound.

The 300Bs are virtually without equal and almost defy description. Even their power is deceptive. Twenty eight  watts may not sound a great deal but couple a pair of MB25s with a quality input source and moderately efficient speakers and they are capable of illuminating your listening room with stunning rich musical sounds and uncanny presence. Yet unlike transistor amplifiers, they are completely without any harshness or listening fatigue, despite their ability to reproduce that ‘rasp’ of trumpets, that ‘edge’ to strings and inner detail of complex vocals, with real bass power if called for.

The sound is warmer, and more involving than solid-state counterparts. The sweeter treble makes for very easy listening, whether jazz, classical or dance music. The bass is not ‘woolly’ and is capable of delivering bass power down to below 10hz. You can expect to hear a more detailed three-dimensional soundstage with less confusion in complex passages.

What is our secret?
In order to get the best out of these valves we have provided a generous power supply, DC heating and a large output transformer. We have also opted to use older design double triodes 6SN7 and 6SL7 for the 1st stage and phase splitter to keep an all triode sound.

Pre-Amp

The MB25s are mono-block power amplifiers with a sensitivity of 2v, which will normally mean a pre-amplifier is needed. Almost any good quality unit would be suitable. Our LA3/LA4 makes an ideal partner (see separate leaflet). CD only users may find they are able to connect directly and use their CD volume control or a passive unit.

Construction

At Icon Audio we believe that the build quality adds to listening experience. Therefore the MB 25 is built to a very high standard and is very solid. The chassis is polished stainless steel, chosen for its non-magnetic neutral sonic qualities. The front plate is 10mm solid anodised alloy plate. The output transformer is resin sealed in an enamel crackle finish steel housing. With the oversized power transformer mounted at the rear.
Inside the chassis the valves holders are mounted on a painted steel sub chassis.

The chassis structure is resistant to unwanted vibration. Unlike amplifiers with printed circuit boards, all major components are secured to the chassis.

Note the use of ‘Hard Wiring’ ‘Point to Point’ and not printed circuit boards or even tag boards that some of our more expensive competitors use.

This method of high quality construction ensures the shortest signal paths. This has many benefits including low impedance, low capacitance and low inductance. This helps minimise noise and hum also promoting clean sound quality. Nothing gets hot under the chassis and therefore component life is prolonged.

This gives you an amplifier with excellent performance that has superb build quality, is easily upgraded and should last a lifetime.

Input terminals are gold plated, as are the large speaker terminals, which will accommodate the largest of cables as well as banana plugs. 4 & 8 Ohm speaker matching is provided.

Only two audiophile polypropylene capacitors are used in the signal path (one driver and one per 300B). Resistors are oversized 2&5w metal oxide.

Specifications and Features

• All hand wired point to point
• No printed circuit board or tag board
• All Triode design
• 2x 300B power triodes
• 6SL7 1st stage &1x 6SN7 phase splitter valves
• Optional Heater delay to prevent cathode stripping
• 28 Watts RMS per channel
• Signal to noise level -89db
• Freq response 20hz-20khz + or -1db
• Total harmonic distortion 0.2% 1khz
• 4 and 8 ohms output taps
• EI transformers using Japanese Z11 fine grain annealed steel, with low oxygen copper
• Attractive cover included in the price
• Minimal feedback used
• High quality 2&5w metal film resistors
• Blue LED mains indicator
• Polypropylene audio capacitors
• Internal audio wiring using audio grade silver cable
• Valves carefully matched & burnt in
• Ceramic valve holders for minimum leakage
• Centre tapped heater circuit for minimum hum
• Drivers 6.3v heater circuit floated at 60v to minimise heater-cathode leakage
• Polished stainless steel chassis
• 10mm solid aluminium front plate
• Gold plated Input & speaker terminals
• 1.9v input sensitivity.
• ‘Soft Start’ for added protection.
• 240volts, 180watts each
• C E certified
• 180W, 230H (330), 530D (590), 20kg (figures in brackets allow for rear connections & ventilation)

Total price of the MB 25s £1799.95 (pr without options)

Downloads

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

PDF Word.doc