The ambition of this project is to offer a high-end kit that even beginners in loudspeaker building can cope with. Thus a two-way loudspeaker with state-of-the-art drivers, a fairly simple crossover and a cabinet that is easy to construct. The cabinets must be rugged and well braced, but it doesn't have to look nice to sound good.
The kit is built around one of the best drivers Danish loudspeaker industry can offer, an 18H52 driver from the hands of Per Skaaning at AudioTechnology, the company that carries the fruit of all experiences gained by his father, Eivind Skaaning, from participating in the development of ScanSpeak and Dynaudio companies.

The 18H52 driver used here is made to my specifications and is proprietary to Jantzen Audio. Do not buy a standard 18H52-15-06 driver from AT. It is different with regard to materials used and voice coil impedance and the crossover shown below won't work properly. The 18H52's copper clad magnet polepiece provides an almost flat impedance profile and reduces non-linear distortion. The chosen voice coil impedance makes this construction well suited for valve amplification although not for 5-10 watt SET. 25-40 watts PSE or push-pull is recommended minimum. Obviously high-quality solid state amplifiers may perform well too.
Please do no ask what the difference to the standard units is, because I won't tell you (had the question numerous times already).

Like all planar tweeters the SWANS RT2H-A holds an extremely low moving mass, and the large diaphragm coupled to a well constructed die cast waveguide, makes excellent horizontal dispersion. Like all planars, vertical dispersion is limited and tilting the speaker a little leaves a comfortable listening window. The end result is speed, resolution and dynamic integrity that leaves conventional soft domes behind. Listening to cymbals and other instruments with high frequency content, makes you wonder whether you have ever heard something similarly natural from conventional domes.
Hand clapping (applause) from an audience on live recordings is a powerful tool for evaluating driver integration and treble quality, and this speaker excels over any other speaker I have made, and based on experience I know this is mostly due to the planar tweeter.

The RT2H-A planar tweeter used here is a standard unit, but it has been slightly modified (changing of damping materials behind diaphragm), the drivers are paired to +/- 1 dB SPL from 3-10 kHz and all units are tested in the final AT-SW speakers before release. I hope this will overcome the common sceptisism toward Chinese produced products. The diaphragm, by the way, is produced in Canada.

The basic characteristic of this construction is transparency above all and a surprisingly powerful bass considering the size of the bass driver. A seamless integration of drivers provides enhanced insight into the music and the bass reaching down to 40 Hz delivers a solid foundation for any source material. The AT-SW kit provides sensitivity of 86-87 dB/2.8 volts/1meter. Cabinet dimensions are 250 x 450 x 325 mm (W x H x D) if you want to build your own cabinets. US builders may use PartsExpress #302-730 cabinet, e.g. piano black finish as used for the prototypes here.
I do not suggest anything other than the very best capacitors for this speaker, thus Superior Z-caps used in this construction.

Amplifier requirements: I have run these speakers with different amplifiers, from class B solid state to NFB single ended triodes and feel sure that AT-SW will deliver more and more the better the amplifier and associated equipment. The best sound I had was from my 5687 line stage and modified Audio Mirror mono-blocks, but 20 watts is on the low side unless you never play at significant sound levels.

Further information on cost, shipping and payment at contact@jantzen-audio.com

Cabinet damping is very important for obtaining the best results, although different materials can be used. The prototype test cabs were damped with 30 mm egg crate foam on all sides plus a folded layer of acoustilux/MDM3 on top of the crossover - behind midbass driver.

Whether bitumen pads should be used on internal panels is up to the overall rigidity of the cabinet. If well braced, bitumen pads may be omitted. Please note that bitumen pads does not reduce sound reflections, it damps vibration of cabinet panels. I have seen some confusion over this.

Alternatively 10-12 mm felt pads may be placed on all in internal panels followed by acoustilux/MDM3 as suggested on drawing. In addition to this, a folded layer on top of the crossover placed behind the AT driver.

Also try tilting your speakers while sitting in your favourite listening chair. The tilt will depend on your height, your chair and the distance to the speaker.

I find the best sound from the AT-SW by toeing in the speakers to listen almost on-axis while still being able to see inner side panels from my listening position.

If you want to thoroughly evaluate the many hours going into your project, move the whole set to another room and hear what happens. Next, try various amplifiers and source material, CDs and vinyl set-up if available. I've recently compared the AT-SW driven from an "average" power amp (Rotel) and a 2 x 80 watts class A solid state amp (Jungson) and the test was devastating for the Rotel. Feel sure the AT-SW will deliver the details from the very best equipment available.