No, I am not making a home cinema setup (hmm?) !!! You just know something is up when you are turning your system left to right, up and down, forwards and backwards. Adding dampening material, removing it, close the compartment or open it up again. Something is not right. Lately I have been feeling this about my speakers. The bass is tight, but missing something. Mids are good, but you never feel as if it is alive. The highs; well, you've actually gotten used to not having them...
What are friends for? Mattijs let me listen to his horns on a short visit and at the Triode Festival. It took a while for his Oris 103 to get tuned and tweaked, but it played! I had my Oris 150 and LaScala's next to them but they did not get a lot of air time, they were beaten, flat out! The LaScala's couldn't fill the room, bass was way too dry. Okay, this is a different situation than at home (smaller space, more carpeting etc). The Oris however let me see the darkest side I have so far from this system. We couldn't get it playing as it should. Too much coloring in the mids, no highs at all. Was it the room?
Just got the results in from Bert on a new idea (thanks David!). It is an Altec 291-16A compression driver front loaded with an Oris horn, but in a very special way. The compression driver is not used in the conventional way, but the rear cover is removed and the 4" diaphragm now acts as source instead of the 2" compression horn-mouth.
We tried this out just for fun to see if it would actually work. Efficiency drops quite a bit (as expected) with about 10dB compared to the "propper" use of this driver. The benefits are that it no longer needs an extensive correction to get the entire response flat. The response is now from around 250Hz to 12kHz within about 3-5dB. This is very good considering that my Lowther does the same but with peaks/dips of upto 10dB.
As you can see there is a big dip at 6kHz, Bert's looking into this and hopes to solve this.
The two adapters for the drivers/horns were finished today. I brought my Altec drivers to Bert so we could have a listen to them. Exciting stuff!!! We hooked them up, sat down, turned on the music... Hmmm, sounds nice, very crisp and open. First impression was very good. After about 15 minutes we turned up the volume a bit. Was that some noise in the background? Ah, we forgot to filter the bottom end, the Altec doesn't handle the lows quite well so we put in a 12dB filter at 200-250Hz. This improved the distortion we got, but there was still that annoying sound. On voices, the F clearly let us hear the material of the dome, piano wasn't alive or "real".
After not even an hour we turned them off an put back the Oris 150 with AER's. Much nicer!!!! In conclusion, not all experiments end up with a better result. The idea behind this was very nice: use a high efficiency speaker without the down-side of the compression and accompanying phase problems. What we got in return was another set of problems that might even be worse. Ah well, at least I know what else I don't want :))) Needless to say this speaker will not make it into my setup anymore.
The complete unit, just 10cm longer than the Oris 150 system
The driver mounted to the horn, and clip-leads ofcourse !
Data sheets for these units can be found in my download section...