Musical Fidelity M6x 250.7 Multichannel Power Amp Class Wars

Class Wars

While Musical Fidelity's 7-channel M6x 250.7 and Primare's 8-channel A35.8 [HFN May '22] share a common 150W/8ohm specification, that's about the end of the comparison! Under their respective hoods are two very different amplifier technologies – while the A35.8 utilises a switchmode PSU, with dual APFC (active power factor correction), feeding eight Hypex NCore NC500 Class D modules as four separate 'stereo' banks, the M6x 250.7 combines a pair of 550VA toroidal transformers feeding linear PSUs mounted onto seven mono, Class AB amplifier cards. Because MF is using seven mono amps (eight would not fit within the 450mm width of the M6x cabinet) this means the two huge AC transformers are feeding three and four mono cards, respectively.

Neither the A35.8 nor M6x requires fan cooling but while the latter incorporates extensive alloy heatsinking on each card, the A35.8 directly benefits from the efficiency of Class D operation without excessive heat or heavy casework. Hence the A35.8 weighs in at just 15kg and draws 1.33kW from the wall at 8x150W/8ohm (95% efficiency) while the more 'traditionally' engineered M6x 250.7 weighs a hefty 35kg and pulls 1.62kW at 7x150W/8ohm (66% efficiency). See p55 for more on amplifier efficiency. PM

Audio Tuning Vertriebs GmbH
Supplied by: Henley Audio Ltd, UK
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