HIFI PIG ADVERTISING PROMOTION

ESSENTIAL HIGH END MUNICH 2024 – EPOS

Essential High End Munich 2024 is a series of promotional articles about the HiFi brands you really need to visit at the show. Read on for more about their philosophy, their products, what they are bringing to Munich and, of course, where they will be at this year’s High End Show.

EPOS MODEL ES-28N – THE POWER OF THREE

“All good things go by three“ is a proverb we often use in Germany if something happens the third time.

The new 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 did change his mind?

Nothing! It’s just that a 2-way system doesn’t work 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 meter, 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 we did.

EPOS MODEL ES-28N DRIVERS

BASS

The low-frequency units for the ES-28N are derivatives of the ES-14N woofers. The size is the same, but the moving parts are different. While a straight cone is the preferred shape for a woofer, the ES-14N cone has a radius built in for a better midband. The straight cone is stiffer, and with a larger inverted dust cap, the units work very well in the ported enclosure of the ES-28N. 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 diameter is 36mm in diameter and 18mm long. The coil former is made from non-conductive Epoxy/Glassfiber material to avoid Eddy Current.

MIDRANGE

The midrange unit is based on the ES-7N woofer—a natural choice with only minor modifications to make it a superb midrange unit. It uses a 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 the same as used in the ES14N and ES-7N. There was no reason to use something else. It’s a 28mm voice coil on an Aluminium alloy, ceramic-coated dome with a powerful Ferrite magnet and optimized inter-cavity airflow. The tweeter does not use Ferrofluid in the gap for stable temperature and low compression.

EPOS MODEL ES-28N CABINET

So, the selection of the speaker units was pretty straightforward—choosing the concept for the cabinet was a bit more tricky.

The tweeter position was clear—one meter in height—and the midrange should be placed below in a separate enclosure. The woofers are placed close together in the cabinet but not too high so we can better control the floor reflection.

For a bigger 3-way, thinking about the best way of balancing the speaker is always necessary. Making the response curve flat in an anechoic chamber would result in a boomy, heavy-sounding speaker. So, it’s required to let the speaker fall off to lower frequencies from the lower mid-band already. Careful listening was needed to find the right compromise between a fast, clean bottom end and enough weight for all kinds of music.

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 eightcentimetre 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 equalizing 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.

EPOS MODEL ES-28N MEASUREMENTS

The response curve shows a falling character toward low frequencies from about 300Hz, the corner frequency of the so-called baffle step. The ES-28N is voiced slightly differently from classic designs, taking into account that the woofers are close to the floor. Together with a low tuning of 30Hz, a very deep and tight bottom end results. The impedance is compensated in the midband for better working with tube amplifiers.

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

The distortion curves, measured at 86dB SPL show an average level of below 0.2% between 100Hz and 10kHz.

EPOS MODEL ES-28N TECHNICAL DATA

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 Frontpanel

Terminal Custom made Low Metal Mass 4 mm Banana terminals

Hear the new EPOS loudspeakers with FinkTeam and EPOS in A 4.1, E121

Keep up to date with all our High End Munich 2024 coverage here