Here I am all happy with my 8 day old Fyne F500 speakers.
Then Danny from GR Research comes along with this video:
Wow! I am simply not hearing all of the problems he describes. Many reviewers have also reviewed the F500, and did not mention any problems.
What gives?
You have to be really careful about buying coaxial speakers. It is inherently a very good idea, as done well it can result on excellent phase coherency. They are especially attractive for center speakers.
The design problems were highlighted by Paul Klipsch sixty odd years ago, and he contributed greatly to the knowledge base by highlighting the problems in a number of academic papers.
One particular problem is interference of the tweeter output by the large cone, causing peaks and troughs in the output. This is certainly seen in the FR of the speaker under discussion. The best solutions come from Andrew Jones during his time at KEF. The Tannoy dual concentric also has to get a very honorable mention. I know of no others that are not a disaster, and clearly the speaker under discussion adds to the list.
When I designed my center speaker, I wanted a coaxial design. It was an enormous challenge. I used a SEAS unit made under license from KEF.
I did have to "cheat" a little. I used two drivers. I used the large cone of the lower driver for active baffle step compensation. and I used the tweeter in that driver, to fill in the major response null from the cone reflections. The end result turned out to be excellent in the end, and it has made a really good center speaker. Speech is really natural, music is excellent and it has very even coverage over the whole listening area.
In the speaker infer question, I see a parallel sided main cone, with a tweeter set deep within it. That would produce just the sort of response which was documented in that YouTube video. So, yes and abject disaster.
