I guess I have to sell my Tekton Enzos

@kdude66

From about 4 to 15 KHz in the case of the tweeter. 4Khz is about 3 inches and 15KHz is about 1 inch in wavelength.

As an example imagine two tweeters spaced 6 inches apart. The combined reflected energy they give out will produce total cancellation at roughly 4KHZ, a reinforcement peak at 8Khz and a cancellation at 12Khz etc. The combined sound directly in front and equidistant from both tweeters will be the only signal in the room without these effects (the direct sound)

Generally what you hear is roughly 60% direct and 40% reflected if you sit in a farfield position and maybe 75% direct and 25% reflected in a nearfield situation.

Here is a plot showing the effect of 1 msec delay - equivalent to about 12 inch spacing of the drivers that produce the same signal.

http://digitalsoundandmusic.schwartzsound.com/wp-content/uploads/2014/05/Figure-4.32-Comb-filtering-...

Basically comb filtering changes the timbre of the sound (often described as a thinner or hollow sound) as well as creating a wider Soundstage.

More examples of comb filtering - hopefully you now know what to listen for - it is certainly not always a bad sound - quite often it is desirable in pop/rock and electronic music. The faux stereo effect is perhaps the most impressive demo on the link below

https://m.youtube.com/watch?v=Zic2eNbxNmY

@kdude66

If you are familiar with panels then you will know the sound of comb filtering. If you use a flanger or reverb on a guitar you will be familiar with the effect too.

It is hard to describe but comb filtering makes the sound seem to come from a wall of sound rather than a defined point and of course this would only happen in the upper treble with the Teckton DI design. It gives a bigger Soundstage. Large ribbons do this too.

Here is a demo - notice how the sound shrinks as comb filtering is removed (microphones close) and how it feels expansive (microphones apart). These effects are on recordings already but a speaker that naturally does this will add a bit of this characteristic to all music played through them.

https://m.youtube.com/watch?v=6JK721OpLko

It is hard to judge but the distance of about 9 inches separation on the video is the sort of enhancement you might expect with the DI. It is a very pleasant enhancement and no surprises it is used a lot in music production!

Here is another example of how comb filtering effects drum sounds (in this case the sound is bouncing off the ceiling and combining with the direct sound to produce a comb filter) In fact any two devices recording the same sound or producing the same sound will produce these effects if they are physically separated a greater distance than the audio wavelengths concerned)

https://m.youtube.com/watch?v=4qgmY8jIGi0