The original poly-ether foam surrounds deteriorate over 15 to 20 years, turning into a sticky, crumbly residue that ruins bass response and threatens to warp the voice coil.

Re-foaming. Do not replace the entire woofer; Cerwin-Vega drivers are unique and hard to replicate.

Identify the old electrolytic capacitors (usually cylindrical barrels). Note their capacitance values ( ) and voltage ratings printed on the sleeves.

Buy Dayton Audio Polypropylene or Audyn Q4 capacitors.

If you found this article, your speakers likely exhibit one of three specific symptoms. Let's diagnose the problem by listening and looking.

The Cerwin-Vega AT-40 is a robust, beautifully engineered slice of audio history. By taking the time to scrape away rotted foam, clean out oxidized controls, and verify your electronic connections, you can easily save these vintage monsters from the landfill. Once fixed, they will happily reward you with another few decades of effortless, room-shaking sound.

The back of the AT-40 features high-frequency and mid-frequency attenuation switches or pots to adjust level outputs. Over time, dust, moisture, and oxidation build up inside these controls.

However, time is the enemy of vintage audio. If you own a pair of AT-40s, you’ve likely noticed that the foam surrounds have turned to dust, the tweeters sound muted, or the bass has lost its punch.