DLS IR 15 subwoofer

Absolute Sound
Subwoofer Chassis

Top Gun

DLS literally wants to pile on the pressure with the top model from the Iridium series. So just what is the 15 incher capable of?

The precious metal iridium is heavy, hard and brittle – far rarer than gold or platinum and in chemistry it is the element with the highest density of them all. It comes as no surprise therefore that the Swedish high end manufacturer DLS has picked out iridium as the name of its state-of-the-art speaker from the Ultimate series – it exhibits qualities similar to this luxurious metal.

Editors were already impressed by the qualities of the Iridium 6.3 three way compo system back in autohifi 1/2004. Now the top model of the brand new Iridium subwoofer, the Ultimate Iridium 15, is to be added to its excellent performance.

Priced at a hefty 730 Euros, the woofer will certainly remain somewhat of a rarity. However, those who decide to take the plunge will be rewarded with a solid chunk of subwoofer technology. Weighing in at 13.4 kilograms, the 15 incher still passes as a light-weight – after all, many competitors tip 30 kilograms or more on the scales.

The stable basis for this Swedish delicacy is constituted by a tried and tested basket design made from die-cast aluminium with four large struts, which has been a common sight for years on the Auto-HiFi scene and is used by many manufacturers.

However, the 28 round openings which are 5 mm in diameter and are located on the lower edge of this basket are new. The openings firstly serve to cool the 3 inch sized double voice coil; secondly they ensure that the air cushion behind the Nomex centring spider can escape during operation. This technical trick keeps mechanical loss at a very low level, which for good bass reproduction should be as low as possible.

The obligatory pole vent is located on the rear of the DLS subwoofer to provide further cooling, which just like the yoke is forged from a single piece.  The vent has a diameter of 35 millimetres and features an optimised flow outlet.

DLS has arranged a further twelve 5 millimetre sized bevelled openings around this vent, which ventilate the voice coil gap and thus the voice coil itself. Thanks to all these cooling methods, the Iridium sub will rarely get too hot around the voice coil core.

Between the two yokes there are two ferrite magnet rings, each with a diameter of 220 millimetres (which are protected by a rubber ring) that serve as the motor for the voice coil. The cone material for the Ultimate Iridium 15 is treated paper which is coated on the front with a fine structure, slightly enlarging the effective cone surface.

Last but not least, speaker cables find secure hold on the powerful, gold-plated screw terminal. There is also another interesting detail to be discovered here: instead of the standard soldered connectors, which are known to often break after many hours of running, the conductors for the voice coil feed on the DLS subwoofer are protected by shrink wrap casing and are fitted with cable lugs, which are in turn firmly screwed to the terminal, making breaks almost impossible. Brilliant solution!

A glance at the Thiele Small Parameter shows that that the Ultimate Iridium 15 will feel at home in really small cases – “small” of course always relative to the 15 inch subwoofer format. While some 45 net litres would be needed for usage in a closed case, the DLS in the ventilated bass reflex variation makes do with a surprisingly trim 50 litres net. Therefore, autohifi decided to measure and listen to the second variation of the noble sub.

In the TestFactory measuring lab, the Swede was allowed to run riot with the Boulder amplifier - and both the sub and the testers had their fun. The Ultimate Iridium 15 was already going hell for leather at 90 Hz and delivered an impressive 119 dB. That this was not everything it had on offer was proven by the measurements at 50 and 70 Hz, with the DLS packing out yet another 4 dB – making a total ear deafening 123 dB.

Freezer: A total of 28 openings provide ventilation behind the centring spider and cool the voice coil.

A work of design: The plastic grill not only looks good, it also protects the DLS sub’s cone.

The tension began to rise: what would the candidate fare now in the king of all disciplines - low range bass reproduction? Supplied with a 30 Hz signal, the Swede did not show any signs of weakness and thundered 110 dB into the measuring mike. Awesome!

After this successful performance in the measuring lab, the Ultimate Iridium had to put its power to the test in the editor’s Golf. Competitor: the 38 point reference Emphaser Em 12 NEO. After just a few seconds of the track “Flying” from the Alpine-F1 CD, it was already obvious here that a precision motor-minded person had taken care of the lowest frequency spectrum. The DLS effortlessly reproduced the demanding bass patterns of this track and followed every turn of the speaker control without complaint, while the Emphaser was already begging for mercy.

This picture did not change with the dynamic bass tracks which can be found on the ultra brutal Fear Factory CD “Demanufacture” (Death Metal/Industrial). The Ultimate Iridium 15 socked out the bass drum kicks into the interior, creating the ultimate of booms. The subtle upper bass overtone also made a powerful contribution in the frequency range.

DLS also showed that it can also deal with gentler tones in the strings track “Walking on the Moon”, interpreted by the Dutch jazz combo the Yuri Honing Trio. The acoustic bass and the drums which were recorded without a compressor and gates were bafflingly realistically reproduced by the sub – playing its way into the subwoofer elite with this excellent performance.

Verdict: DLS has succeeded in creating a magnificent subwoofer with the Ultimate Iridium 15 - it kicks out power, sounds amazing and entirely justifies its high price.

Black hole: the pole vent and twelve openings in the air gap ensure thermal balance.

DLS Ultimate Iridium 15

Price: 730 Euros
Sold by: DLS
Hohenzollernstraße 11 – 13, 40211 Düsseldorf
www.dlsmobil.de

autohifi measuring results

Frequency range autohifi         

Clean tuning with more than enough low-range and high performance

Maximum acoustic pressure autohifi         

Despite the relatively small case of 50 litres surprisingly high level profile over the entire bass range.

Nominal impedance
Minimum impedance

External measurements
Built-in measurements

Thiele Small Parameter

Effective cone
Effective cone surface

Case
Acoustic sound level
Maximum acoustic sound level

Equipment: Die-cast aluminium case, coated paper cone, stable rubber support, double centring, double voice coil, multi voice cone ventilation, double ferrite drive, magnet protector, powerful gold-plated screw terminals.

Rec. amplifier output
Rec. cross-over frequency

autohifi rating (max. 100 points)
Sound
Maximum acoustic pressure
Finishing

autohifi test verdict

Absolute top of the range 77 points

Price/performance 4/2005

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