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Review & Visits

 High End Show 2010 in Munich

Ground Sound was exhibitor at the High End Show 2010 in Munich ( Halle 4 stand G03 )
- here is a short report and some pictures


 Elektor Audio Special - XT612 & XOverWizard II


Contents of the Elektor Audio Special 3

The Do-It-Yourself loudspeaker project XT612 powered by our active amplifier Coolback II 600 has been in the media again. The article also talks about the new XOverWizard II software, which includes measurement, optimizer etc.

Here is the conclusion in German:

Über den Klang

Zu sprechen, ist angesichts der diversen Einstellmöglichkeiten bei dieser Kombination eigenlich hinfällig. Es ist ja gerade der Vorteil einer derart aktiv betriebenen Box, dass sich der Klangcharakter in weiten Grenzen an die eigenen Vorlieben anpassen lässt. Bild 6 zeigt die parallel mit Clio gemessene Eigstellung, die wir für den Hörtest vorgenommen haben. Beim Hörtest ist schell deutlich geworden, dass die Verstärker mit den Lautsprechern keinerlei Probleme haben. Der Bass bleibt jederzeit straff and kontrolliert, die Mitten verfärbungsfrei und die Höhen klar und präzise. Die Groundsound-Elektronik präsentierte sich als solid, technisch einwandfrei aufgebaute und klanglich hervorragende Lösung zur Aktivierung auch von edelsten Lautsprecherkombinationen. Preislich sicher kein Mitnahmeartikel, aber angesichts von Leistung und Qualität absolut empfehlenswert für jeden, der schon immer mal seine Lieblingsbox aktivieren wollte.



 Review in K+T 3/09 of XT612 / Coolback II 600


The Do-It-Yourself loudspeaker project designed by Kurt Hansen and Robert GS have been review together with our active amplifier Coolback II 600 which is powering the loudspeakers.



 Robert attended the Gelsenkirchen Messe 2008


The traditional DIY Messe is housed at Hotel Lichthof in Gelsenkirchen, Germany. At the fair Robert made a daily presentation of our electronics for activating loudspeakers. The presentation included a tutorial of the XOverWizard software and some background information of Ground Sound, products and Robert. The newly developed loudspeaker kit XT612 (pronounced X - T - Six - Twelve) was also demonstrated and listened to. The XT612 is developed by Kurt Hansen and Robert GS.

It was nice to meet current and future customers - thank you all for your interest and positive feedback.


Peter Strassacker presenting loudspeakers at the fair
in a relaxed and nice atmosphere
Ground Sound active modules
next to passive components


Iris Strassacker, owner of LautsprecherShop.de
and employees Daniel Gattig and Philipp Zukowsky
Dennis Frank
development of loudspeaker kits



 Visit at K+T's Hörtest at the 21. June 2008


The A/O loudspeaker were "activated" with our electronics = Chassis1503. The new compact CoolbackII600 were displayed. The development amplifier code name OP were used with some of the passive K+T project loudspeakers. A sample of our modules and a proto type board of the DCN28DAV were also displayed. The A/O is a Wilson Watt/Puppy inspired Klang + Ton loudspeaker project published in issue 6/2007 + 1/2008 + 2/2008.



 Review in HIGH fidelity of Chassis 1503

Click here to see the test in Danish - some paragraphs are translated to English

44 From the technological front line * "Ground Sound Chassis 1503, 3 channel power amplifier and DCN23 crossover is sophisticated electronics with wealth of possibilties."

  Same review in Swedish



 Test in Elektor of PA3CC

Click here to see individual review of PA3CC Click here to see the test summary


Click here to see the results of all measured modules


 Review in HOBBY HIFI of Chassis 1503

Content page of the magazine in German
Digital Optimum

"When active, then it is also correct. Ground Sound has developed some universal electronics, which can be programmed ingeniously simple with extreme flexibility and high performance. We digitized our reference project Optimum - and were enthusiastic."


Click here to see the test in German - some paragraphs are translated to English
The very first review of Ground Sound products
- and actually a very fine one!

The review has been performed by Rolf Hähle (a long time reviewer and spec. tester for this and other magazines).
You'll find the technical data measurements on page 47. How about this kind of power 2 x 1090W burst 1kHz!!



 KLANG + TON - News 2007/5

View the news article - German
New and better Electronics from Ground Sound

"The Danish DIY Electronics manufacturer Ground Sound has upgraded some products and developed a new multi channel amplifier “Coolback 300”. This is a smaller version of the “Coolback 600” and has 3 x 100W (8ohms) output power which is more than enough for most active projects. The dimensions of the basic aluminium profile could be lowered on 15 x 55 cm, the deep amount to 7.5 cm. ...."



 KLANG + TON - News 2007/1

View the news article - German
New chassis from Ground Sound

"Ground Sound - offers very versatile and extremely high-quality electronics components for the activation of loudspeakers (we reported in issue 4/2006 p. 11) - now two new housings variants are offered for the products. The housings are named “Chassis 600” and “Chassis 1500” taking up to three amplifier modules per chassis including the digital crossover and the complete power supply of the system. ...."



 Visit at HOBBY HIFI at the 13. April 2006

The residence of Hobby HiFi
At the visit to Germany, I also visited the residence of Hobby HiFi. They “live” in a very nice building with supreme arranged rooms – I can imagine that it is easy to accomplish good designs under such nice conditions and the surrounding landscape also add to inspiration level.
I was welcomed by a man who had done his “homework”:

Dipl.Ing. Bernd Timmermanns
(former editor of Klang + Ton).


The Control Room at Hobby HiFi - nice and tidy - PC with MLLSA measurement system!
View toward the Control Room in the measuring room - notice the not yet finished reference loudspeaker Optimum


A look in the Measuring Room of Hobby HiFi - very large - perfect to get good measurements
The measurements of the loudspeaker that were to be activated were ready – the only thing we had to do was a setup in the XOverWizard and a cable adaptor from amplifier (SpeakOn) to loudspearker (Usual speaker terminals). The system was up and running in no time – we even managed to make a check measurement in their measuring room. Smooth and easy, just like the sound of the Topas. The Topas isn’t a big speaker, but for the size it will fit smaller living rooms and then all adds up. Normally I’m used to a much bigger loudspeaker system and this gives me the need to have an extended lower range to like the sound of a loudspeaker. I would definitely add a subwoofer to the Topas system, if I was the owner.


Transmissionline loudspeaker Topas - design by the boss himself: Bernd Timmermanns
A considerably more my kind of style loudspeaker was the unfinished reference project Optimum (2 x 15” + 2 x 8”” and an Expolinear tweeter), which was located in the measuring room. I would have loved to activate these loudspeakers right away, but as you can imagine, it would have taken too much time for this afternoon session. You can read the review of the activation of this Optimum loudspeaker accompanied by our Chassis 1503 – ideal partners I would say!

"Small, slim and beautiful"
This isn’t referring to a woman, but the Topas loudspeaker.

Download the setup for the active Topas


Listening Room at Hobby HiFi - before the listening of the active Topas
Screen shot of the Topas XOverWizard setup



 Visit at Klang + Ton at the 12. April 2006

The Clio measurement system at Klang + Ton
“Surprisingly good sound”

To promote our DIY products we paid Klang + Ton a visit in Duisburg, Germany. Before the visit, we had agreed on the phone to activate one of their loudspeaker projects. It appeared to be the Mivoice 3 in raw MDF, which seemed a bit cheap! The name comes from the used drivers!! - Mivoc.
The measurements were made in their very big room which actually is an old gym. This room is very suitable for measurements as it gives the opportunity to place the microphone at a considerably larger distance without interference from the room. The measurement system was Klang + Ton’s Clio system.


Elevated loudspeaker measurements - an easy way of getting better results
We (Christian Gather K+T and Robert GS) made measurements of each driver – one at a time. By importing the measured data into the XOverWizard, we could design a setup, programmed the parameters to the DCN23 filter and performed a check of the total setup. When all added up, we moved the gear to the listening room at Klang + Ton.


Maybe the Mivoice looks cheap, but the final result actually appeared to be a pretty good design - which I liked
Christian Gather - Klang + Ton - editor


A shot of the Mivoice 3 from behind - notice the bypassed passive crossover
When the system was up and running - Holger Barske (editor of LP and HB web) joined us for the listening session. Both Christian and Holger were trilled about the new active sound of Mivoice 3. I too was really surprised about the performance of this “cheap” loudspeaker setup. At the sound check we used two CD players and the very big turntable in the background. On the top of the rack the preamplifier can be seen. During the session, Holger and Christian talked together and later it appeared that they might look into an opportunity to upgrade the K+T reference loudspeaker project Duetta with our electronics. Duetta is a 3-way loudspeaker in two boxes and Eton drivers. The current version can be both passive and active. The active version has been equipped with electronics from SAC. This solution can easily be substituted with our similar Coolback303. Our Coolback303 has a bit more amplifier power. When comparing the SAC analogue electronic filter to our DSP based digital crossover – there will be much more flexibility to adjust the loudspeakers in terms of driver correction and room conditioning.


Screen shot of the Mivoice 3 XOverWizard setup
At the moment I (Robert) can’t tell when or if the upgrade will take place – Klang + Ton has a set of our Collback603 which is intended to power the revised active Duetta. Hopefully more to come…

Download the setup for the active Mivoice 3


Setup in the Listening Room at K + T - notice the very big turntable in the background
Another shot of the setup - Ground Sound Laptop ready to make adjustments to the sound if needed



 KLANG + TON - News 2006/4

View the news article - German
Active Electronics from Denmark

"Robert Sorensen of Ground Sound from Denmark has signed in for the job of activating loudspeakers. He offers a microprocessor controlled digital crossover, two (analogue=Class AB) output stages and power supplies, with which full-active systems can be build. The software for the digital crossover makes a convenient control of the filter functions, with all kinds of thinkable filter functions. ...."



 HOBBY HIFI - News 2006/3

View the news article - German
Modules for active loudspeakers

"From Denmark comes not only B&O, great cheese and good soccer players (not lately red.), but since short time also electronic modules for DIY audio. Ground Sound has worked for some years within the range of professional amplifier assembly and now developed a digital crossover. Now this technology will be available for the DIY audio market. With the digital crossover DCN23, which is based on A/D and D/A converters with 24 bits and 96kHz Burr Brown, two amplifier modules PA3CC and PA6CC with 300 and 600 Watts of maximum power output as well as the power supply PSU12SA. ...."



 HIGH fidelity - News 2006/3

View the news article - Danish
The very first talk of Ground Sound products in the media

Modules for active loudspeakers

"If you can spend serious money on DIY, then Danish Ground Sound has developed some exciting products. It’s a digital crossover, two Class AB power amplifiers at 300W and 600W plus power supplies and other necessary components.
The digital crossover addresses people with knowledge of both HiFi and computers. ...."



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