Epos ES-28N

Epos ES-28N

The new Epos ES-28N is the third model in the current EPOS line-up, and on top of it, it’s a 3-way loudspeaker made by a designer who is well known for doing 2-way systems even with bigger woofers.

So what changed his mind?

Experience! It’s just that a 2-way system is not working so well in a configuration with two woofers.

OK, there is the typical D’Appolito configuration with a woofer above or below a tweeter, but as the tweeter should be sitting around one metre, the speaker would end up as a huge tower.

Mounting the woofers below the tweeter would need a so called 2.5-way configuration.

In such a configuration, one of the two woofers stops working in the lower midband, and the second woofer covers the rest of the midband to connect to the tweeter.

That sounds like a good idea, but unfortunately, the main radiation axis for those two woofers would be tilted downwards, so it is difficult to manage the mid-frequency energy properly. So why not make it 3-way? OK, that’s what they did.

Epos ES-28N Cabinet

Similar to ES-14N, the cabinet of ES-28N is slightly tilted to get better time alignment for the drivers.

The two woofers sit in a Bass reflex compartment, carefully braced for low cabinet colouration.

For the same reason, the whole cabinet is made from a sandwich construction with a layer of high-damping glue beside two MDF panels.

The front plate is 50mm thick and made from two 10mm sandwich panels and a separate chambered MDF panel of 30mm.

The midrange has its own compartment with a triangular backside to avoid reflections.

The remaining part behind the tweeter takes the crossover, so the components are isolated from high sound pressure levels.

The port tube opening is located on the bottom.

That allows an eight-centimetre diameter port in a length that gives the lowest possible output of resonances from the cabinet and the highest maximum output of low frequencies.

In addition, the port is equipped with pressure equalising holes in the middle to avoid the tube resonance of the port itself.

The opening in the socket is big enough, so even in cases where the cabinet is standing on the floor without spikes, the bass performance is not compromised.

The 30cm long port tube output reached its maximum at the tuning frequency of the cabinet/driver combination, 30Hz.

The graph shows the difference between a standard port and a version with the pressure-compensated EPOS design, which removes the double-sided open tube resonance by almost 10 dB.

Thanks to the correct position in the design, the cabinet’s standing wave modes do not escape through the port tube.

Bass driver

The two 7“ woofers share the magnet system and basket with ES-14N but use a straight cone instead of a curved cone.

A straight cone is the best solution for the bottom end.

A large inverted dustup makes the cone even stiffer for fast and powerful bass.

The magnet uses aluminium demodulation rings to stabilise the inductance of the voice coil, so there is no modulation of the crossover, low harmonic distortion, and low intermodulation.

The coil is 36mm in diameter and 18mm long. The coil former is made from non-conductive Epoxy/Glass-fiber material to avoid Eddy Current.

Midrange driver

The midrange is based on the design of the ES-7N woofer – Mica-filled polypropylene cone material made with injection moulding.

A low hysteresis rubber surround and a Nomex high-temperature capable spider ensure the suspension is linear with good control of higher excursions.

The 30mm voice coil with glass fibre/Epoxy former works in a magnet system with an impedance control ring to minimise distortion and intermodulation. A double magnet compensates the stray field and increases the force of the coil.

Tweeter

The tweeter is identical to the tweeter of the ES-14N and ES-7N, giving the new model the same top-end quality.

It’s a 28mm voice coil on an Aluminium alloy, ceramic-coated dome with a powerful Ferrite magnet and optimised inter-cavity airflow.

The tweeter does not use Ferrofluid in the gap for stable temperature and low compression.

Epos ES-28N specifications

Frequency Response: below 30Hz – 25kHz (in room)

Average Impedance: > 6 Ohm

Minimum Impedance: 3.9 Ohm @ 16kHz

Sensitivity: 86dB @ 2.823V / 1m

Distortion: average below 0.2% THD @ 86dB between 100Hz and 10.000Hz

Crossover Frequency: 330 Hz, 2700 Hz 2nd order LKR and 4th order LKR

Bass Unit: Two High Power 7“, 36 mm voice coil diameter, Hybrid Ferrite and Neodymium magnet, injection moulded straight cone with Mica filling. Low hysteresis rubber surround.

Midrange unit: 5.25“ (130mm) midrange, 30mm voice coil diameter, Ferrite double magnet, Mica filled PP cone. Low Hysteresis rubber surround

HF Unit: 28 mm tweeter with Aluminium/Ceramic compound dome and no Ferrofluid

Dimensions: 1050 x 250 x 360 mm (HWD)

Weight: 35 kg

Finish: Walnut, White semi matte, Black semi matte, Jade green

Cabinet: Reflex loaded, damped Sandwich panels, one dimensional braces, Low Noise Port, Duo layer Front panel

Terminal: Custom made Low Metal Mass 4 mm Banana terminal