Super Tweeters

Can cause destructive interference due to to far a distance between drivers and from drivers covering some of the same frequency not to mention the time error. Then you have the very limited efficiency of most ST again not going to match your loudspeaker unless both are designed as a whole. A driver doesn't allow you to hear ranges your not capable of hearing if they could there would be no hearing problems for one could just use a aid and wow you hear normal doesn't work like that. Last I post good luck.

One thing I like about Tannoy ST100/200 is eight selectable crossover points and sensitivity settings. In my application this made them a much better match than the Chinese Lucy ribbons. Correct time alignment can be obtained by varying front-to-back positioning on top of the main speaker. I mount them on an elevated platform to decouple from vibrations across the top of the cabinet.

An ST placed in parallel with the main speaker will change the impedance load on the amplifier. This may effect which amp impedance tap sounds best-- assuming that your amp has the flexibility of multiple taps.

Be aware that whatever cross-over point and sensitivity level is selected, there will be downward embellishment all through the treble region. Tannoy uses a third-order crossover. Their manual includes frequency plots.

Bottom line, the ST is a tool I would not want to be without.

From JohnK - "A driver doesn't allow you to hear ranges your not capable of hearing if they could there would be no hearing problems for one could just use a aid and wow you hear normal doesn't work like that."

What I'm saying is that the super tweeter is the aid. It's helping listeners with high frequency roll-off due to age. It's not like being deaf, where no driver is going to make you suddenly hear. Rather, it boosts up the areas where we are becoming weak in our hearing.

JohnK is correct in his statements though. It's very unlikely that the placement of a super tweeter is going to be time aligned to the regular tweeter as well as the effects from two drivers far apart. This is all true and should be considered upon utilizing such a thing. It is a tradeoff, but most users probably realize this and allow the added/needed boost of highs to outweigh the negative timing and phase effects. Certainly our rooms play a much larger roll in negatively affecting the elusive "flat response" then an added tweeter.

Koestner,
That is true, but there are ways to compensate for that as well. In my case, my speakers are a D'Appolito arrangement with a large horn between two woofers. If I had a super tweeter, I would build a stand for it so that it was level with the mid horn, and placed farther back to compensate for the earlier arrival. There are options if you use a little imagination.