Even ideal equalization degrades off-axis response and can amplify distortion and noise

Evidence

However, one must remember that the equalized magnitude responses shown are valid only along the main axis of the loudspeaker in a free field, and that in other directions the response may be worse than the original unequalized one. In addition, equalization increases the movement of the loudspeaker diaphragm at amplified frequencies, which may also amplify some non-linear distortion components. Furthermore, in some cases, such frequency-specific amplification may also amplify unwanted noise originating from some earlier part of the signal chain. — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 523

Categorization

• XREF: Connects to the reader’s standing interest in how idealized signal-processing fixes carry real-world side effects, echoing audio engineering tradeoffs in loudspeaker design literature.