We (Ulf Weidhase and Siegfried Nitz) began approximately 5 years ago to skip from classical multidrive sytems and electrostatic speakers to horns.
At that time we tested an Audivector with Lowther PM4 and PM2a and we both for first time heard music in a way we never heared before. There was more dynamics, emotion, an atmosphere similar to life concerts. But the Audivector was not an easy DIY project to realize by ourselves. Therefore we searched in the internet for alternatives and immediately the Oris 150 from Bert became our favorite.
It was not complicated to set up, and the support from Bert was excellent. At that time we combined the Oris 150 ( driver was a PM4a) with a Klipsch horn and the first results were fascinating. The Oris has the capability to reproduce the emotion and the right atmosphere of music, much better than the Audiovector.
And the Klipsch?? Individually, the bass response was very good, but not in combination with the Oris. Time alignment because of the large folded Klipsch horn in our opinion was the problem. Therefore we constructed an Onken similar to the one described by Hiraga, using an Altec 416A. And there it was, almost perfect matching with the Oris.
The ultimate we got when we replaced the PM4a and installed the AER MD3 from Filip Keller. Wow!!!
This was again a big step in the right direction. Harshness of trebles, typical for the Lowther driver dissapeared, specially when listening to classical instruments like violins.
It is needless to say, that in our opinion, the best performance of this combination is achieved with tube amplifiers. First we began with commercial ones, later we replaced them one by one by our own constructions.
For the Oris we constructed an amplifier with the famous Siemens F2a (in SRPP), driver tube is the C3m ( also in SRPP). And for the Onken we setup an amplifier using the Russian tube 6C33 (also in SRPP), driver tubes are in the 1. stage also C3m and in the second stage a EL84. The output transformers were calculated and realized by Reinhöfer, he delivers excellent quality at an affordable price. And the story didn´t end at this point. What about a good tube preamplifier? The Accuphase I had very soon was outperformed by a preamp. we constructed by again using the 6C33 (in SRPP). After 5 years spending a lot of time for experimentation and after endless listening sessions we believe that we achieved what we always were looking for: absolute perfect reproduction of any kind of music material, in imaging, musicality, dynamics, even at high listening levels.
Thank you Bert !!