The Supertweeter

These I don't understand. Human hearing is almost non existent over 20kHz and older folk have switch off much lower than that.

There is nothing on a CD over 20kHz. An LP can't do anything decent up there.

Why add a supertweeter running up to 50KHz? What's the theory, and what psycho-acoustical tests have been done?

 

I had some Tannoy Eyris DC3s and they had a supertweeter. I covered them up once to hear the difference, there was not any!

But I do believe its to do with the way the the high frequency harmonics interact with the fundamental notes in the hearing range, or something like that.

 

Actually, it's 20kHz that human hearing is supposed to cut off (not 30). In theory, we also cannot hear sounds below 20Hz. However, although we may not literally hear them that doesn't mean we are not aware of their presence. In addition, it is certainly true (in my experience) that extending the bass response of a system appears to subjectively alter the balance of the upper frequencies; a similar idea is extrapolated to explain the benefit of super-tweeters.

I must admit though that my own experience of super-tweeters is pretty limited. A friend had a pair of posh Kef speakers that had super tweeters - unfortunately, this didn't stop them from being pretty darn boring to listen to (Kef have now deleted the super-tweeter from this speaker).

 

Of course you are right, and 20 was my typo, now corrected.

 

I think you'd be hard pressed to find anyone who can hear anything at 20khz.

When I was 19 years old I worked in a recording studio. We had a tone generator on the desk for various testing purposes. I played around with it wearing headphones and my threshold then was around 17khz and that was, apparently, quite good.

I would imagine that figure has dropped quite a bit now - 30 years later.

But as has already been alluded to, my guess is that it's not necessarily just about what we can hear, but also about what we can feel. I know this is the case with very low frequencies so presumably it works at the other end of the range???

 

Here is a link to a good test of hearing:-

http://www.audiocheck.net/audiotests_mosquito.php

 

Well, I can hear both those mosquito tests very clearly.

 

IMO extending response way up past 20khz is pretty pointless.

Where supertweeters are useful is operating at the top of the audible range by improving power response in room.

You should be able to hear what the ST is doing - if you can't it is a waste of time and money.

I'd also say that any improvement is largely speaker dependent, and you might get no improvement at all. They also must be properly integrated into the speaker system at crossover- they aren't a one size fits all device that you can just plonk onto any speaker cabinet.

 

The ones in my Tannoys were integrated and made not one bit of difference to me.

 

I thought the idea was that only hoody wearing youfs could hear it - the rest of us could carry on in blissful ignorance?

 

So much depends on the speaker, room and preference of the listener.

The way the BBC designs used a ST is instructive.
The primary tweeter is perfectly ok on axis to around 15khz but falls thereafter.
Off axis you'll also be seeing (and hearing) fall-off at far lower frequencies.
So the ST both fills-in and extends, bringing the balance at the listening position to a point where it is subjectively correct.

Depends entirely what you like.

 

Interesting.

I couldn't hear the unmodulated tone at any volume - although it did produce a low frequency hum from the 'sub-woofer' at high volume - which is not normally present. Very odd???

At first I put this down to either my hearing having deteriorated over the years or possibly the performance limitations of my £80 Logitec PC speakers.

However I could hear the modulated tone, when I turned up the volume, and it was a very unpleasant experience. But no hum this time - I'm confused now (nothing new there).