The Dayton Audio B652 speaker was a fantastic budget audio speaker.
The B652 Air took it for a giant leap forward.
My hot-rodded version includes the following modifications:
Stock electrolytic capacitor replaced with an audiophile quality Jantzen cross-cap.
Stock resistor replaced with a Mills audiophile resistor.
Stock fiber replaced with Acousta-Stuff fiber made for speaker enclosures.
Stock sponge feet replaced with 3M brand elastomer isolators.
Deeper bass and smoother midrange over the stock B652 Air.
These are currently listed on Audiogon.