In reply to:
I'm really interested in the concentric tweeter and how the imaging and soundstage compare to, say, the Axiom or Monitor Audio dome tweeters.
The reason I ask is that quite a few years ago, KEF introduced a series of speakers with concentric tweeters. In tests, the KEFs were very coloured by comparison to speakers from several Canadian manufacturers that used dome tweeters. I had this theory that the woofer cone caused cancellations and reinforcements of the tweeter's output, in effect horn-loading the tweeter with unpleasant results.
I never had a chance to do tests on Tannoy speakers that used concentric tweeters, or on any Tannoy speakers, hence my interest.,
This is an interesting question Alan.
I've actually A/B'd the Axiom M60s with these Tannoy Definition D700s before, in a blind fashion, using a switcher, a friend, and a Parasound Halo A23 amp which gratefully had indivdiual gain knobs on the backside for each speaker channel. This made for a great comparison using all the same equipment and being able to adjust for SPL differences between the speakers.
We played music in mono mode and placed the speakers about 10' in front of a single cushy chair.
The person listening used a blindfold and would ask to switch between the speakers at will. The listening distance was set perfectly such that neither of us could tell which speaker was playing at any time based on left or right ear orientation. We each took a turn listening to the switching routine and taking our time with some standard test discs we made back when my friend was looking for speakers. We both got so good at understanding the sound of the two speakers that even by madly switching between the two, the listening person could correctly guess which speaker the switch had on at a particular point.
The primary differences noted between the M60 and the Tannoy were as follows (and we both scribbled similar conclusions on this):
The Tannoys had more bass but not an overbearing bass, just heavier. They had more clarity in the upper end which was something i found surprising. The first time i heard the two i guessed that the Axioms were the ones with that sharper clarity and i was wrong. The Tannoys also were king in the soundstage area, but considering the difference in driver size and speaker widths, this may account for such a large difference. The Tannoys were extraordinarily easy to place and even putting them a toe in or out a couple of degrees, shifting upward or downward, did little to change the overall sound.
However, the M60s had more forward presence, felt like the sound was closer to the sitting area, more live. Their bass was, for lack of a better description, 'fast' bass. The drivers seem to recover much faster and bass didn't linger as long. This probably should not have been a surprise either since the Tannoy is using a 10" polypropylene cone while the Axioms use a 6" aluminum. Big difference in size and stiffness. I like both types of bass. One seems to sound more accurate, but perhaps thin, while the other creates more presence in a larger room where no sub is required. The Tannoys do have port bungs to help control some of the bass output and i only have 1 of 2 bungs in each speaker.
Unfortunately i do not remember much about the midrange and i lost the notes i took that day. I want to redo the listening test again now that i have a room far more conducive to listening to material.
Against a speaker that retails at 6k+ Cdn, the Axioms hold their own quite well. I've mentioned before that i prefer this Tannoy sound (ever since this A/B audition really) and for me, the extra price for the Tannoy is worthwhile. Specs on the series can be found in
this pdf file. The fact that i got them used and in near mint condition for only 4k certainly helps.
I cannot comment on how KEF may have designed and introduced their concentric drivers, but i do know of the KEF i last heard, i was not very impressed. It did sound like a horn loaded speaker but it was using a normal dome tweeter. Compared to the M60s, which we had next to the KEFs but w/o a switcher, they did sound coloured, but this was some time ago so maybe they were just different. Nonetheless, I'm not a fan.
If i can get Bren and BruceH over here, the M60s and the Tannoys are on the block, hopefully with Bruce's MonitorAudio GR60s for a head to head comparison. I do not have the Halo amp anymore though, so our options for switching between speakers using the exact same equipment AND having the speakers matched in SPL is going to be a bit of a trial. I'm working on getting my gain controlled speaker switcher running by then, but i'm in a design phase looking for some better parts. I want to change out the pots for a different type and i need to drill then solder some banana jacks on the rear, removing the present, horrible little hookups that exist.
If they don't come over, i will probably end up doing this test again anyway at some point. Stay tuned....
. Can we agree that it would be a Saturday? 
