BACK TO THE FUTURE.
A classic speaker returns to the future.
Analyzing the old construction was interesting. It used a 7“ woofer with Polypropylene cone and an underhang coil with a huge magnet, but multiple layers of VC winding to make the whole coil heavy in order to get a sort of roll-off in the response curve of the woofer. The size of the woofer was not following any standard – too big for a 6.5“, but too small for an 8“. But it was a clever choice, because you could get more drive at lower frequencies more like an 8“ and a midband character closer to the 6.5“.
The cabinet itself is using more or less the same volume of the original ES-14. That’s not a big surprise, as the cabinet volume is the result of the driver configuration and the defined bandwidth of the speaker. However, the shape of the cabinet is different. The front baffle is tilted to the back in order to time align the woofer and the tweeter plus it can help with the standing wave mode between front and back. As the design is a reflex system, a port is of course needed. It’s located on the back of the cabinet and the whole shape of the port has been chosen to minimize air flow noise. In order to compensate for the open tube resonance of the port, some openings were added in the middle of the port. To avoid loss of low bottom end, those openings are covered with soft material, tuned to only kill the unwanted resonances of the port.
The cabinet uses a double layer MDF construction, glued together with the latest generation of damping glue. This latest generation is more consistent compared to older solutions and allows easier production. Additional bracing has been used to control the panel vibration modes and reduce the unwanted radiation of the whole cabinet. Only a little damping material is needed internally.
The front plate is an extra part to be glued and screwed on the main cabinet. It has a 45° chamfer around it to control diffraction effect in the 2000-3000Hz region. The first prototypes used square cabinets and it was impossible to get a good frequency response on axis and out of axis. Rounding the corners was not really helping, only the chamfer made the diffraction error a lot smaller and helped balancing the upper midband. An old fashion way, but a useful solution. The speaker comes with front grille, but it is not recommended to use it when listening to music. It’s more a protector when not using the speakers. The tweeter itself is protected anyway and the PP cone is not easy to damage.
The alignment of the box is a flat 4th oder alignment with a tuning frequency of 38Hz. It matches with the bottom end gain of many listening rooms and allows fast and precise bottom end when used in the right position in the room. The binding posts are 4mm banana sockets, mounted on a metal plate. Those banana sockets use very little metal internally to guarantee the best sound – that’s one of the nice ideas of the original design and better than using very expensive “High-End“ binding posts with litte metal but a high price tag. Those single wiring sockets feed the amplifier signal to a crossover that sits on the rear panel of the speaker.
40Hz – 23kHz (-6dB) 33Hz – 25kHz (-10dB)
> 6 Ohm
4.3 Ohm @ 160Hz
87dB @oe2.823V / 1m
0.2% THD @ 1W
High Power 7“, 35 mm voice coil diameter, Hybrid Ferrite and Neodymium magnet, injection molded cone with variable thickness and Mica filling. Low hysteresis rubber surround.
28 mm tweeter with Aluminum/Ceramic compound dome and no Ferrofluid
491 x 250 x 385 mm (HWD)
Stand: recommended height 515 mm
16 kg without stand
Walnut, White semi matte, Black semi matte
Reflex loaded, damped Sandwich panels, one dimensional braces, Low Noise Port, Duo Frontpanel
German made Low Metal Mass 4 mm Banana terminal