Dali Opticon 6 - don't hear hybrid ribbon tweeter

[brinta]

I have purchased these Dali Opticon 6 loudspeakers a bit more than a month ago and they sound breathtaking.

However I have noticed that I cannot hear any sound coming out of the top part of the hybrid tweeter (the ribbon). I do hear sound from the soft dome tweeter.

 

According to the specifications from Dali from their website about the ribbon tweeter:

Gently rolled in above 10 kHz, the ribbon reaches full contribution from 14 kHz to well beyond 30 kHz, far above the audible range.

 

So I thought it might be because I just don't play music in these high ranges. Or it might be because my crappy receiver; an Onkyo TX-SR606 which doesn't operate at 4 Ohm. I know this the next investment I need to make.

 

When I hear very close separating the soft dome and the ribbon tweeter with my hands than these ribbons are completely silent.

 

Do you experience the same thing? How can I test this using a test file operating at higher frequencies?

 

Any suggestions are welcome, also a bit of technical background for me to understand.

[audio.bill]

On some of the DALI models using their hybrid dome/ribbon tweeter, the tweeter is crossed over as high as 14kHz. In such an implementation many listeners (especially males middle age or older) will not be able to hear significant output from the ribbon driver. It is designed to provide extension beyond the normal range of human hearing, which may still impact what we do hear by providing the upper harmonics of frequencies within our hearing range. Some studies have shown that when such high frequencies are missing it does affect our perception of the music even though we may not be able to hear some of those frequencies on their own. Hope this helps, and enjoy your new DALI speakers!

[Bikutoru]

I've had Dali Ikon 2s for years and they have ribbon tweeters. I tried to put my ear to them to hear any sound, but couldn't. However, when I get some opera or jazz recording with 'extreme' high frequencies, these speakers are able to re-produce, beyond my wildest dreams. It might be just my personal believe, but somehow I have never heard that level of high frequencies reproduction from my previous speakers. So, I just stopped worrying about hearing ribbon tweeters in isolation, but I'm sure I do perceive them when it comes to real music re-production, from a well engineered recordings.

[Snakeoildrinker]

I have the rubicon 6's for a few years now and have done very extensive testing with all kind of equipment and even brought my 11 year old niece (who has very good hearing) into it to test it. 

 

My conclusion is that both ribbon tweeters just don't do anything. 

 

The only thing that I may do next is open up the speakers to check what they are actually hooked on to. 

 

How it went:

I bought them new in a respected hifi shop in the Netherlands, because after the testing sessions I really liked their sound. 

 

I got my speakers new out of the box, so not the demo set. After a while at home I got the impression something was missing on one side and started testing and fiddling with the cables etc. But to no avail. Other speakers had no trouble on the same amp setup. 

Also there was a visual inconsistency in the plastic wires in front of the ribbon tweeter. It was probably purely cosmetic but I didn't know that at the time and therefore went on a hunt for the cause of the problem. 

 

After a lot of hassle I switched both my units out for a similar, new pair out of an open box. 

Came home with those, ran the same tests and voila: also nothing coming from the ribbons. 

 

Bring in the aforementioned little niece and a digital tone generator again for more details.

Because I read all the fora full of people saying that their hearing is lacking and certainly not their equipment I wanted to make sure I was not going to be caught with these biased arguments. 

Her hearing is amazing and goes well into 19k+ hz range. This was professionally tested at a hearing aid shop when she joined our grandpa when he went to get his. 

 

(this is really turning into a long story...) 

 

According to her the sound just stops at around a little bit over 15k hz. We also tried my kef LS50's and those went up to 18k hz. I did all the tests with the yamaha cx-2 + mx-2 amp setup with audioquest slip 4 cables BTW. 

The volume was max on the end stage and upto 40% on the pre-amp. This is more than loud enough to say 'it's very loud'. So if it doesn't play high frequency then it's surely the speakers and not the ears. 

 

So again: my conclusion so far is that the ribbon tweeters add literally nothing to the great sounding Rubicon 6 speakers. They're simply not needed. But you do pay extra for the idea. Amazing marketing... 

[semente]

This is the on-axis response of a Rubicon 8. Considering that the dome tweeters are crossed at 14kHz the ribbons surely are doing "something"...

https://www.stereophile.com/content/dali-rubicon-8-loudspeaker-measurements

 

The "problem" is that Dalis are designed for no toe-in and the ribbon has a very narrow directivity, meaning that the response will be down considerably above 14kHz at 45º or even at 30º off-axis:

DALI Rubicon 8, anechoic response on supertweeter axis at 50", averaged across 30° horizontal window and corrected for microphone response, with complex sum of nearfield responses plotted below 300Hz (black); anechoic response 20° to side of supertweeter axis at 50", corrected for microphone response (blue).

 

A strange design choice.