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German Physiks Newsletter No. 21 $$PLAIN_TEXT_PREVIEW$$
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February 2021 | Newsletter No. 21
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Limited to Unlimited to Ultimate
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Welcome to the February 2021 German Physiks newsletter. Casting around for ideas for this month’s newsletter we decided to describe the evolution of one of our most popular models, the Unlimited. This has also been one of our most successful models in terms of major magazine awards, achieving two Absolute Sound Golden Ear awards and three Absolute Sound Editors’ Choice awards so far.
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Until 2011, our cheapest loudspeaker was the HRS-120 - shown below. This was the forerunner of the current HRS-130. The HRS-120 started at Euro 16,900 without tax – about US $ 23,500 at that time. Dealers were telling us that they needed a lower cost model in order to attract more customers, but producing a cheaper loudspeaker was not so simple.
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The design brief was to produce a simplified version of the HRS-120: a floor standing loudspeaker, with a DDD driver on the top and a downward firing woofer in the bottom. A significant part of the cost of our loudspeakers is the DDD driver. We build these ourselves by hand and this is a time-consuming process. There is no way to reduce costs here without seriously compromising performance. The only area that we could look for potential saving was the cabinet. The HRS-120 cabinet is quite complicated and therefore expensive. It is octagonal, a more difficult shape to manufacture and apply a finish to than a simple “square box”, as it has more panels and more edges. In addition, it had the internal cavity required by the Helmholtz resonator that tunes out the resonant frequency of the base enclosure. The HRS-130 and Borderland also use this technique. The first part of the solution for the new design was to use a simpler square section cabinet and dispense with the Helmholtz resonator. The cabinet was further simplified by eliminating the base plate used on the HRS-120 and the castellations at the bottom of the cabinet that this was attached to. The bass driver was the same 8-inch unit used in the HRS-120. This was a good quality unit we were familiar with and by being able to buy it in larger quantities, we could achieve a saving.
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Putting a high-quality finish on a cabinet, whether veneer or paint, is expensive. Time has to be spent to carefully prepare the surface before applying the finish. Time also has to be allowed for each layer of lacquer or paint to fully dry before it is polished and the next layer applied. On our high-polish veneer finishes, at least 4 layers of lacquer are applied. With some veneers, up to 16 coats of lacquer have been used. The solution was to use a finish we christened “acoustic vinyl”. This is actually flooring vinyl. Whilst it costs more per square metre than most of the veneers we use, less time needs to be spent on the initial surface preparation and beyond trimming the edges, no additional finishing after application is required. This saving in time produced a useful saving in manufacturing cost. This material had two additional benefits. It consists of two layers. An outer layer that is very durable and resistant to damage and an inner sound absorbing layer. This inner layer, depending on the material used, can provide up to 19dB reduction of impact noise and so provide useful damping of the cabinet’s panel resonances.
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The new design was called the Limited 11 and was launched in early 2011. To help reduce costs further, it was only made available in one colour – grey. The Limited 11’s carbon fibre DDD driver covered the range from 200Hz to 24,000Hz, while the 8-inch woofer took the bass down to 32Hz. With a foot print of only 240 mm x 240 mm (9.5” x 9.5”), it was ideal for small rooms down to around 10 sq m (106 sq ft) , but could also fill medium size rooms up to around 55 sq m (580 sq ft). 100 pairs were manufactured and we introduced the product as a limited production run, so that we could test the market.
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The 100 pairs of the Limited 11 sold out much more quickly than we had expected. Dealers and customers asked for more, but also for more colours, so we brought the design back later that year, still using the acoustic vinyl finish, but now in black, white, brown and the original grey. As the product was now a regular part of our product range, it was renamed the Unlimited Mk II. It was called Mk II, as we had used this name on a model with a different design 10 years earlier.
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“… offering a slice of sonic heaven at a fair price.”
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A major crossover revision in 2013 produced a significant improvement in bottom end extension and stereo imaging. The following year the Unlimited Mk II was reviewed in the US audiophile magazine The Absolute Sound by veteran reviewer Dick Olsher. Dick’s conclusion made us very happy indeed: “There are many good speakers out there that fail somewhere on the road to greatness. That’s not the case here. The Unlimited II scales that elusive performance summit. In hindsight, this review experience feels much like a coronation of the DDD as the king of Walsh-type bending-wave transducers. The DDD technology brings one closer to the live experience by virtue of conveying the immediacy, drama, and coherence of the real thing. In musical enjoyment, it leapfrogs a host of expensive box speakers that are forever constrained to sound like canned music, offering a slice of sonic heaven at a fair price.” Read the full review in The Absolute Sound here
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When we were setting up the Unlimited Mk II up our room at the Rocky Mountain Audio Fest in 2014, we had got the sound almost right, but needed just a little more bass. Moving the loudspeakers nearer to the rear wall gave us more bass, but we also lost a bit of the sense of air in the stereo image. We were sharing the room with a US company called BDR Sound, who made a range of carbon fibre isolation products. One of these was a carbon fibre puck intended for use under loudspeakers. The height of the spikes supplied with the Unlimited had been chosen by the designer to give the level that of bass that he wanted and we were sure he would not have appreciated anyone modifying his design. As we were running out of time to finish the set-up, we thought we would see what would happened if we put some pucks under the Unlimited’s spikes, thereby raising it further from the floor. Hey presto, we had the amount of bass that we wanted, without affecting the stereo image. Visit the BDR Sound web site
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Whilst strictly speaking this is not a tweek, we included this picture because it shows an interesting use of the Unlimited Mk II, where the customer has taken advantage of the DDD driver’s omnidirectional radiation characteristic to create what they described as “the best open back headphones”. We have tried this and it does work very well. It is an interesting option when you don’t have much space for your listening room.
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In 2014 two more versions of the design were introduced. Unlimited Ultimate: In response to requests for the Unlimited Mk II design in a more colourful and luxurious finish, we introduced the Unlimited Ultimate, finished in high polish polyester black, white, red and yellow. Unlimited Carbon: A customer in Hong Kong requested a custom version of the Unlimited Mk II finished in carbon fibre. When the distributor there saw it, he liked it so much that he placed a large order for a good number, so we decided to make this version part of the regular line up. By 2017, the bulk of Unlimited sales were accounted for by the Unlimited Ultimate, so the Mk II version was discontinued. Further improvements to the crossover have been made since 2013 and these have enabled the Unlimited to stay at the top of its class and also accumulate an impressive number of important awards. Visit the Unlimited web page Read Unlimited reviews in the Reviews Library
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A review of the Borderland Mk IV loudspeakers. Print and video reviews of the Emperor integrated amplifiers. A video review of the HRS-130 loudspeakers.
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Thank you again for signing up to our newsletter and thank you for your continued interest in our products. Please don’t forget to visit our Facebook and Instagram pages. If we can be of help with anything at all, please do not hesitate to get in touch with us here. You can find your national distributor here.
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Holger Mueller | German Physiks
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