This depends a lot on the loudspeaker design. Paul uses Infinity IRSs, which are line source, planar magnetic drivers for the tweeters and midranges and they are designed to be used the way he uses them.
In yesterday’s post, we looked at long wavelength bass notes—some exceeding 50 feet in length. Today, let’s have a look at their shorter cousins, high frequencies.
Where bass frequencies are typically multiple feet in length, higher frequencies are generally in inches or fractions of an inch. 1kHz, for example, is right around 1 foot, while 10kHz is a little more than an inch.
When it comes to system setup what makes these frequencies challenging is their very short wavelength. You can imagine toeing in or out one channel’s loudspeaker a “skosh” and making a very big sonic difference.
The short wavelengths of higher frequencies are one reason I have long been an advocate of relying upon the off-axis response of the system for best imaging (as opposed to pointing tweeters directly at your ears). In my setups you’ll almost always notice the left and right speakers are nearly without toe-in, pointing instead almost straight ahead. The energy distribution of the off-axis response is much smoother and less prone to laser-like problems we get when we rely instead upon a perfect triangulated setup of speakers.
Fractions matter when it comes to higher frequencies but one can mitigate some of this specificity by relying instead upon speakers with excellent off-axis response.