Author Topic: Practical pros & cons of concentric drivers (Tannoy, KEF etc)  (Read 688 times)

Offline greatwhite

Practical pros & cons of concentric drivers (Tannoy, KEF etc)
« on: October 28, 2020, 09:09:36 AM »
I've always been a fan of concentric tweeter/bass driver concept as employed by the likes Tannoy and KEF (and now Fyne Audio) from a point of view of the full frequency range emanating from one spot. As I've read on various sites that there are a number of technical challenges that go with building such drivers which might by why so few manufacturers bother with them, but I was hoping for some insight from people that have had these type of speakers on the typical strength and weaknesses in day to day use e.g.
Are there consistent areas where these unit have difficulty? Sonically, setup, mechanical...
How does their reliability compare to conventional separate driver speakers?
If they do fail, my understanding is they are more difficult to fix. Any experience in this regard? Typical pitfalls if any?
Apart from the 'single' sound source are there other advantages people have found?

Thanks in advance

Offline Nchebe

Re: Practical pros & cons of concentric drivers (Tannoy, KEF etc)
« Reply #1 on: October 30, 2020, 09:19:33 AM »
Having owned a pair of Tannoy 611s and now the D700s, I can say that the one advantage is the tweeter domes are a fair way away from pokey little fingers!!!
:sd:
Can't say the same for KEFs...

Offline Timber_MG

Re: Practical pros & cons of concentric drivers (Tannoy, KEF etc)
« Reply #2 on: October 30, 2020, 10:04:12 AM »
The issue is that the depth of the phase plug and stub leading into the cone acts as a 1/4 wave resonator for the woofer (not necessarily or the tweeter which loads the horn at the throat) and the resultant dips in response are always a feature that overwhelmingly favour very awkward filters.

Offline Katji

Re: Practical pros & cons of concentric drivers (Tannoy, KEF etc)
« Reply #3 on: October 30, 2020, 02:35:38 PM »
Awkward as in complex / problematic?


What about these - Coral 10TX-70 - car coaxial style?  Even more bad issues?


Offline Agaton Sax

Re: Practical pros & cons of concentric drivers (Tannoy, KEF etc)
« Reply #4 on: October 30, 2020, 03:41:55 PM »
Awkward as in complex / problematic?


What about these - Coral 10TX-70 - car coaxial style?  Even more bad issues?


Oh dear,much,much more wrong. All the negatives of dual concentric plus many more.

Mind you there are those legendary East German monitors that use this sort of concept (Geithain). Only one I can think of who may have heard them is Achim. Maybe we can drag him away from his downstairs neighbour for long enough to comment?



Dammit,come to think of it,this is exactly what my speakers are. Bloody good idea then. All speakers should be built this way.
« Last Edit: October 30, 2020, 03:47:57 PM by Agaton Sax »

Offline Katji

Re: Practical pros & cons of concentric drivers (Tannoy, KEF etc)
« Reply #5 on: October 30, 2020, 03:59:51 PM »
?  Maybe I should look at that last pic of yours again.  I know the room horn doesn't have a tweeter suspended in it.....or maybe I'm just confused.

Coral did a lot of experimentation...including some compression driver tweeters.  But the most common and most liked seem to be the plain coaxials, in boxes that seem to be folded horns - for some reason[?] I've never seen any pics of the insides of them.  Boxes according to that traditional Japanese style...coaxial full-range mounted at the top of relatively large wide baffles.

Offline juventino

Re: Practical pros & cons of concentric drivers (Tannoy, KEF etc)
« Reply #6 on: October 30, 2020, 04:14:19 PM »
Only one I can think of who may have heard them is Achim. Maybe we can drag him away from his downstairs neighbour for long enough to comment?

 :BWAHAHAH:

Offline Agaton Sax

Re: Practical pros & cons of concentric drivers (Tannoy, KEF etc)
« Reply #7 on: October 30, 2020, 05:00:29 PM »
?  Maybe I should look at that last pic of yours again.  I know the room horn doesn't have a tweeter suspended in it.....or maybe I'm just confused.

Coral did a lot of experimentation...including some compression driver tweeters.  But the most common and most liked seem to be the plain coaxials, in boxes that seem to be folded horns - for some reason[?] I've never seen any pics of the insides of them.  Boxes according to that traditional Japanese style...coaxial full-range mounted at the top of relatively large wide baffles.

You talking about me? Sorry can't resist that one. You mean my system?

This shows the system to be conceptually not that far from the Coral



The initial idea was to have the horns deep in the basshorn throat a la Altec 604 or Rene Simmond's system



However that lasted all of 5 minutes as the colourations introduced by the bass horn flare were simply awful. It only became acceptable once the smaller horn throats either cleared or were very shallow in the mouth-a la coaxial.

I think that demonstrates the problem with  Tannoy , the Altec 604 or the Urei. I am a huge Altec fan but much prefer the non coaxial arrangements. I am sorry but I also do not buy that long standing Tannoy boast that the cone of the bass driver extends the tweeter horn. That is as bad as claiming the room corner extends the natural flare of the Klipsch basshorn.

My experience with coaxial,mainly a truly dreadful Goodmans (I forget the model) turned me off that approach too-that is until I realised I have done that very thing.


« Last Edit: October 30, 2020, 05:02:55 PM by Agaton Sax »

Offline jlaubza

Re: Practical pros & cons of concentric drivers (Tannoy, KEF etc)
« Reply #8 on: November 10, 2020, 05:38:25 AM »
The issue is that the depth of the phase plug and stub leading into the cone acts as a 1/4 wave resonator for the woofer (not necessarily or the tweeter which loads the horn at the throat) and the resultant dips in response are always a feature that overwhelmingly favour very awkward filters.
I owned a Kef Q300 bookshelf speaker set. If you look at pictures of the Kef dual cone unit, you can see that they avoid the above mentioned issues through their design. The Q300 in fact has a very simple crossover (I think first order).

Sound wise, I could not say that it sounded any better than competitor, separate woofer tweeter products. Their really expensive speakers might have a sonic advantage but for me, the coaxial setup is simply an alternative approach, useful perhaps for space restricted installations.

In my 5 years of ownership of the Q300s, I had no problems with them.