June 2023 | Newsletter No. 48

The story behind the German Physiks Unicorn

Welcome to the June 2023 German Physiks newsletter.

In our newsletter number 5 in August 2019, we explained the technical background to our Unicorn loudspeaker.  This unique design uses just one of our omnidirectional DDD drivers coupled to a complex horn  to cover the entire audio range.  Just as interesting is the story about how this design came to be put on the market, because without two chance interventions, neither the Mk I nor Mk II versions would have seen the light of day.

The Unicorn Mk I

Even in the early days of German Physiks, the designers wanted to make a loudspeaker that used just one DDD driver to cover the full audio range.  They eventually settled on a design where, rather than start to roll-off the low-end range of the DDD driver around 200Hz, as is the case in all other German Physiks loudspeakers, the DDD driver was allowed to run well below its normal 100Hz lower limit.  The additional low frequency radiation this produced was fed from the back of the DDD driver to a high gain horn, coupled with a tuned bass trap.  The bass trap kept mid-frequency energy out of the horn. This would otherwise have caused smearing due to time differences between the DDD driver’s direct radiation and radiation from the horn. It would also have caused a lift in the mid-frequency response.  To achieve a completely even low-frequency response from the horn system, a small amount of equalisation was applied to the input signal using an externally housed passive network.  

To help them make a loudspeaker that was as transparent and faithful to the original source as possible, a concert pianist was invited to the factory to listen to the prototypes and give his opinion.  This gentleman was unfortunately blind, but a consequence of this was that he had very highly developed listening skills.  As a source they used CDs of his performances with a piano that he was very familiar with.  

Over the course of a number of listening sessions, several prototypes were tried until finally the pianist was satisfied that they had a loudspeaker that was reproducing his piano as he knew it should sound.  Special attention was paid to the bass response, as he commented that most of the loudspeakers he had heard elsewhere tended to have an overstated low-end response.  This bass tuning was adopted on all subsequent German Physiks loudspeaker designs.

Other classical musicians were then asked to listen to the prototype in order to get the new design reproducing their instruments correctly.  

Rather than make the design with a completely inert cabinet, it was found that the best approach to get the sound they wanted, was to let certain panels on the cabinet vibrate to some extent.  To refine this idea, the designers consulted a musical instrument maker who was able to give advice on  how the vibration on panels could be controlled in order to achieve the sound that they were seeking.

The DDD driver used was the original titanium version. The first iteration of the carbon fibre DDD driver we now use would not appear for another 10 years.

A chance conversation

“… pleasures and treasures await.”

Audiophiles in Japan, where they had long appreciated the benefits of horn systems, quickly took to the Unicorn.  They loved the top to bottom coherence of the sound; the exceptional speed and resolution of the DDD driver and the outstanding timing of the bass.   With the Unicorn there was no sense that the bass was not quite in time with the rest of the frequency range.  The Unicorn’s unconventional styling was of secondary importance, as in their eyes, or rather in their ears, the exceptional sound more than made up for any concerns they might have had about the looks.  This was helped by the fact that the Unicorn’s cabinets were available in a wide range of very high-quality veneers.

In 1999 Dan Sweeny wrote a review of the Unicorn Mk I that appeared in issue 120 of The Absolute Sound.  The following quotes summarise his thoughts. 

“Another bass instrument virtuoso given full justice is contrabassist Ludwig Streicher on the Telefunken recording of his Bottesini concert Speilt Bottesini [642230 AS, heavy vinyl reissue].  Like many bass soloists, Streicher has the hand strength to play his big fiddle like a cello, and the score demands that he continuously swoop and soar from soprano to subsonics to the accompaniment of Norman Shetler’s extraordinarily agile piano.  The Unicorn not only resolves the acrobatics perfectly, never once rephrasing Streicher’s rambling meditations into the monotonic low bass of too many systems today, but preserves the singing tone and the incidentals of wresting music from this hulk.”

“It Is not customary to speak of a noise floor in regard to loudspeakers, but the Unicorn seems to lack the kind of ongoing sub-audible disturbance that occurs in conventional loudspeaker systems and obscures the lowest level of sonic detail on a recording.”  

He concluded:

“The Unicorn is a special product.  Bass horn omnis are almost as rare as the unicorns of legend, and I’m sure that many, contemplating its enormous enclosures, will shake their heads and turn away.  But for those undaunted by defiant eccentricity, pleasures and treasures await.”

Unicorn Mk II

Over a number of years, further work was done on the design, resulting in the Unicorn Mk II. The main changes were an improved bass response and a revised cabinet with a forward-facing horn mouth that made it easier to position the loudspeaker in the room.

As the Unicorn Mk I was selling steadily, mostly in Japan, the updated version was not put into production, but was used in the factory as a reference for transparency against which other designs were judged.

In 1999, a Japanese audio reviewer, the late Okihiko Sugano, was visiting the German Physiks factory, when he heard the Unicorn Mk II.   He was already very familiar with the Unicorn Mk I, but after hearing the improvement that the Mk II offered, he strongly advised German Physiks to put it into production.  At that time, Mr. Sugano was the top reviewer for Stereo Sound, the most influential high-end audio magazine in Japan.  It also had a significant readership in several other Far East countries, so his strong suggestion was not to be ignored.

Initially the Mk II was fitted with the same titanium DDD driver used on the Mk I.  With this the frequency response was flat between 55Hz and 21.5kHz.  With the current carbon fibre DDD driver, the response limits have been significantly expanded and it is now flat between 40Hz and 24kHz. 

Latest improvements

The most recent update to the Unicorn Mk II has been the replacement of the passive equalisation network with a small DSP based equaliser that is connected between the preamplifier and power amplifier.  This provides improved transparency and dynamics, together with better bass control, as the power amplifier is now directly connected to the DDD driver.

The passive network is still available for customers who want it.

Conclusion

One can consider the Unicorn a lucky loudspeaker, as without a couple of chance interventions by people outside German Physiks, the two versions would never have gone into production.

While the limited ultra low bass rules the Unicorn out for devotees of death metal, its exceptional coherence, clarity and speed enable it to provide a wonderfully involving and enjoyable musical experience with jazz, female vocal and small to medium scale classical music. Many Unicorn owners have told us that the clarity and agility of the bass leaves them with no feeling that there is anything missing in this department.

If you want a demonstration of this, please look at this You Tube clip from High End Munich 2012, showing two visitors to our room seriously getting in to a pair of Unicorn Mk IIs doing a very good job with Pink Floyd’s iconic track Money.

The essence of the Unicorn has best been summed up by the late Wes Philips, who wrote about the Unicorn Mk II in his CES 2009 report for Stereophile magazine:

“I initially listened to the Unicorns waaay over against the wall, but I still got a coherent, solid soundstage. When I sat in the sweet spot, I essentially heard what I'd heard over to the side—only a tad more of it.
 

The more I learn about hi-fi, the more I find I need to unlearn. I always thought I didn't like 360° speaker designs, but it was specific designs I didn't care for. The Unicorns were fast, focused, and convincing.”

Thanks Wes …

Visit the Unicorn Mk II web page.

Visit the DDD driver development web page.

A selection of Unicorn Mk II reviews is available on our web site.

Until next time

Thank you again for signing up to our newsletter and thank you for your interest in our products. Please don’t forget to visit our Facebook page.

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.

Holger Mueller | German Physiks