Why 3 Tweeter?

[jpetek]

Hi,

I saw that some Loudspeakerbuilder like Vonschweikert or Kharma or others use in their Topmodells 3 Tweeter.

Could me somebody explain why?

Normally you get a lot of problems if you use more then one.

regards

Josef

[Cal Weldon]

Power handling?

[Greggo]

I agree with the above, and though I am not familiar with any reasoning given by the two companies you mention, I believe in other cases like with Dynaudio, a second tweeter was employed but rolled off before it got into lobing frequency, much like the second woofer in a 2.5 way. Just like the woofer example, with a second woofer just helping out in the bass frequencies but not interfering in the mids, I think the additional tweeters are designed to provide support near the crossover point, especially when that point is at or under around 1,500 Hz, so that as you push a tweeter lower, then a second or third tweeter is ready to share the load and help lower distortion and improve dynamic range at those frequencies near the crossover point. it is also my understanding that the additional tweeters could not only be rolled off before getting up around lobing frequency (around 3-5kHz depending on c-t-c distance), but could also be shelved down entirely by 2 or 3 dB, which would also mitigate their ability to distract from the imaging specificity we would expect from a single tweeter.... no expert on this, but something about our natural reflex to cue in on the louder source and that perhaps that makes the phase issues less likely to be noticed..who knows...

[Sonusthree]

Perhaps one or more tweeters are on the rear for ambience?

[Dr.EM]

Is it not to do with directivity of the sound? I remember when reading about planar tweeters this quote "With this tweeter there is no need to manipulate the network or use multiple units to achieve the restricted vertical directivity necessary for home theater applications."
http://www.swanspeaker.com/product/htm/view.asp?id=16

[Greggo]

Yes, pursuit of THX certification being among the many reasons to shape directivity, but I don't think this applies to the high end stereo pursuits as many have commented that achieving the directivity requirements of THX also creates sacrifices on stereo accuracy imaging fronts. Just my guess.

[planet10]

Don't forget the marketing department's influence on a commercial design....

dave

[Tenson]

I have heard that two different drivers working at the same time can reduce IMD.