Super-Tweeters: Acoustic Information or Phase Information?

spiritofmusic

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Jun 13, 2013
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Easy enough to do. I'll see if I can get a pair on trial approval from Max, and try this idea. I just have to check if my spkr terminals will accept, my main spkr cbls spades are extra chunky Bocchino ones.
 
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microstrip

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(...) Adding another pair firing backwards is an interesting idea. I may pursue as the top of range Wilson speakers also has a rear firing tweeter. (...)

Both the TheSonusFaber (Fenice) and the Aida included two medium and a tweeter back firing units. We can adjust their level according to our preferences, and in the case of TheSonusFaber rotate the whole block of the back units.

Unfortunately, as these units are wired in parallel with the main speaker, increasing their level decreases the impedance in their bandwidth.
 
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microstrip

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I suspect that if each of us sat down for a formal hearing test by a professional audiologist, as I did several years ago, we would be shocked at how poor is our ability to hear much above 12 kHz to 14 kHz, especially if one is above 50 years old.

Sean Casey, founder of Zu Audio, told me that the purpose of a super-tweeter is not to enable us to hear information above 16 to 18 kHz as much as it is to enable us to perceive phase information. The Gryphon Pendragon employs four air motion tweeters per channel to reproduce specifically 18 kHz and above. I am pretty sure the intention is to reproduce primarily or exclusively phase information.

What do you think?

What do you believe is the design purpose of a super-tweeter?

What is phase information?

What does a speaker driver intended to reproduce phase information actually allow us to perceive?

Dave Wilson says something similar - in his opinion accurately timed (phase) high frequency units are needed for "authentic sounding" - see this article: Life In the Rearview Mirror - Wilson Audio for an explanation of what is "authentic sounding". Fortunately , as he says" (I quote) "However, alignment errors of as little as 10 ?s between the tweeter and the WAMM MC’s drivers are quite audible to listeners over 50 years of age (even over 70!). So the ear is very sensitive to even low microsecond range errors. Furthermore, this sensitivity to timing is much less diminished by age than is presbycusis (loss of high frequency spectrum hearing). This is good news for those who want to continue to enjoy recorded music during their retirement years! "

 

DaveC

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Nov 16, 2014
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Phase at supertweeter frequencies is somewhat audible in some cases but mostly inconsequential IME.

The reason why... unless you place your head within a fraction of an inch of the same place and never move it (head must literally be in a vice), phase will change depending on head placement since the wavelengths are so short. Coax drivers may be an exception but they have other issues that are even worse than the issue they are trying to solve.

In my own testing it simply doesn't matter despite many speaker designers coming up will all sorts of reasons it doesn't work, but it seems this reasoning is made without any sort of confirmation via actually listening.

There is certainly a range of frequencies where phase relationship matters A LOT, but this is over a few hundred Hz and under 10 kHz and it makes the most difference near xo frequencies where drivers overlap. People claiming it matters so much at extreme high and low frequencies may have heard some circumstance where it does matter, but IME this isn't for the reasons they assume. With more testing under a wider variety of conditions, room, systems, etc all that stuff simply goes away.

For example the intuitive thought that a rearward-firing tweeter would simply add constructive and destructive interference that would sound horrible in the same way bass frequencies might when you get nulls and peaks is correct in some ways but also almost certainly inaudible despite being able to demonstrate comb filtering using measurements. These measurements paint a bleak picture but luckily this is not how we actually hear. Once again measurements are incorrectly interpreted due to the failure to simultaneously understand psychoacoustics.

There are MANY reasons a supertweeter may not fully integrate in a system but phase and comb filtering are not valid reasons however many times people may claim it to be so.
 
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