Epos ES25 Loudspeaker

MS10 Loudspeaker

Classic 50 Loudspeaker

Epos ES22 Loudspeaker

MS30 Loudspeaker

Epos Cabinet & Rear Baffle Detail

MS CS-1 Loudspeaker

Epos Cabinet & Front Baffle Detail

After graduating from the University of Southampton, I joined Mordaunt-Short and Epos Acoustics in 1992 as a Loudspeaker Design Engineer. Mordaunt-Short was bought by TGI PLC in 1987 which already owned Tannoy and Goodmans Loudspeakers Limited (GLL), forming the largest loudspeaker manufacturing company in Europe.

I learnt the practical skills of loudspeaker design from Robin Marshall who had founded Epos Acoustics in 1983. Robin sold Epos Acoustics to TGI and became the Technical Director for Mordaunt-Short and Epos Acoustics.

As part of a small engineering team, the drive units and systems for the Epos ES22 and ES25 loudspeakers were developed and launched. All of the component parts were manufactured in house.

Transducer Design

All loudspeakers and drive units were designed and hand-built in-house at the Havant headquarters shared with GLL.

The 25mm tweeter domes were formed from aluminium alloy and used a polyamide suspension. The dome is acoustically loaded by a separate rear chamber, and vents in the coil former equalise the pressure on the voice coil to eliminate asymmetric pressure distortion.

The 165mm midrange driver is built on a die-cast aluminium chassis. The injection moulded polymer cone, nitrile rubber roll surroundad and central phase plug provided a well behaved roll-off characteristic. The voice coil was wet-wound on an aluminium former with high-temperature wire. The powerful resin adhesive was used in preference to the more common solvent bonding to provide higher power handling and reliability. The magnet assembly had a centre pole that extended beyond the top plate to linearises the magnetic flux around the voice coil and provide a higher inductance to roll the driver off smoothly.

The bass drivers used injection moulded polymer or thermo-formed Cobex cone pistons with an integral dust-cap designed to increase its stiffness. The massive magnet systems were designed for long-throw, linear performance. The ES25 bass unit used a dual rear suspension system was used to provide balanced excursion in both forward and reverse directions.

Enclosure Design

All the cabinet enclosures were manufactured in the UK from balance veneered MDF. The cabinet panel thicknesses varied to disperse the resonance frequencies and extensive internal bracing was used to increase the rigidity of the enclosures and minimise panel vibration.

Crossover Design

One of the Epos fundamental principles was that the best sounding crossover is NO crossover. The midrange driver is directly coupled to the power amplifier for transparency and detail. The bass driver and tweeter use single component networks to integrate with the midrange unit. the internal connections were hard-wired rather than the more common and less expensive method of mounting components on a PCB.

Skills