How to Open RCA 40-5022 Speakers

The RCA 40-5022, sold as the STS-520, is a sealed two way bookshelf speaker with a glued cabinet, so it does not come apart at the seams. You get inside through the front. Take the grille off, remove the screws holding the 5 inch woofer, and lift the driver out. Everything inside the box is reachable through that opening.

People look for a back panel to unscrew on these and there is not one. Mass market bookshelf speakers of this type are built as a glued MDF box with the drivers fitted from the front, because it is cheaper and because a glued cabinet is more rigid than a bolted one. Trying to split the seams destroys the speaker.

What you are working with

The 40-5022 is RCA’s catalog number for the STS-520: a 5 inch high compliance woofer, a 1 inch dome tweeter, 8 ohms nominal, rated around 40 W RMS, with a claimed response of 80 Hz to 20 kHz. A simple passive crossover sits inside, usually a capacitor on the tweeter and little else.

RCA never published a service manual for these, which is normal for consumer speakers at this price. There is no factory disassembly procedure to follow, so what follows is the standard approach for a glued cabinet with front mounted drivers, which is what this is.

Tools

A Phillips screwdriver, a thin plastic trim tool or an old credit card, and something soft to lay the cabinet on. If you plan to reseal the woofer, add a tube of non hardening butyl sealant or a roll of foam gasket tape.

Do not reach for a flathead screwdriver to lever anything. Vinyl wrapped MDF chips at the edges and it never looks right again.

Removing the grille

Lay the speaker face up on a towel. Work your fingers under one corner of the grille frame and pull straight out, not sideways.

Most grilles of this era are held by four push pins that press into rubber grommets in the baffle. They release with a firm, even pull. Take opposite corners in turn rather than levering one side, since the thin frame will crack if you twist it.

If the grille will not move at all, check the perimeter for a bead of adhesive. Some units left the factory glued, and on those the grille cloth frame has to be cut away and remade if you want it back. Slide a plastic tool around the edge to break the adhesive line before pulling.

Set the grille somewhere it will not get stood on. The frames are brittle after thirty years.

Getting the woofer out

1. Remove the four screws around the woofer’s flange. They usually go into MDF rather than threaded inserts, so back them out slowly and keep them together, since the holes will be worn and a different screw may not bite.
2. Break the gasket seal. The driver is bedded on foam tape or sealant and will feel glued in. Slide a plastic trim tool under the flange and work around the edge, lifting gradually rather than prying at one point.
3. Lift the driver only an inch or two. Two thin wires run to the terminals on the back of it and they are shorter than you expect.
4. Note which wire goes to which tab before disconnecting. Photograph it. The positive tab is usually marked with a red dot or a plus, and getting this backwards on reassembly puts the woofer out of phase with the tweeter, which hollows out the midrange.
5. Pull the spade connectors off with your fingers, straight back. If they are corroded, grip the connector body with pliers, never the wire.

What is inside and what you can do with it

Through the woofer hole you can reach the crossover, which is usually mounted to the inside of the baffle or to the terminal cup at the back, and the polyfill or fiberglass wadding lining the cabinet.

The common reasons to be in here are all straightforward. A tweeter that has gone silent while the woofer still plays usually means a failed crossover capacitor, and replacing it with a non polarized film capacitor of the same value costs a few dollars. Loose wadding that has fallen to the bottom of the cabinet can be teased back into place, which restores the damping the designer intended. A crackling or intermittent channel is often just corroded spade terminals, cleaned with contact cleaner and a fiberglass pen.

If the woofer surround is crumbling, that is a refoam job rather than a replacement, and the driver is already out so you are most of the way there.

If you are opening the speaker to diagnose rather than to repair something you have already identified, run the electrical checks first. Our guide on how to tell if your speakers are blown covers the multimeter readings that tell you whether the driver or the crossover is at fault, and it will often save you taking anything apart.

Putting it back together

The seal matters more than anything else on reassembly. A sealed cabinet only works if it is sealed, and air leaking past the woofer flange raises the resonance and thins out the bass audibly.

Scrape the old gasket material off the baffle, lay a fresh strip of closed cell foam tape or a bead of butyl sealant around the opening, reconnect the wires the way you photographed them, and seat the driver.

Tighten the screws in a cross pattern, the way you would a wheel, and stop as soon as the flange is compressed. MDF strips easily and an over tightened screw spinning in a stripped hole is a much larger problem than a loose one. If a hole is already stripped, a sliver of wooden toothpick and a drop of glue gives it something to bite into.

Check both speakers play in phase before the grilles go back on: put on something with a strong central vocal and confirm it sits between the speakers rather than spreading vaguely across the wall.

Frequently asked questions

Can you open RCA 40-5022 speakers from the back?

No. The cabinet is glued MDF with no removable back panel, which is standard construction for bookshelf speakers in this class. The only access is through the front, by removing the grille and then the woofer. Attempting to split the glued seams will damage the cabinet and is not recoverable.

How do you remove the grille on RCA bookshelf speakers?

Work your fingers under one corner and pull straight outward rather than sideways, taking opposite corners in turn. Most are held by four push pins seated in rubber grommets in the baffle. If the grille does not move at all, run a plastic trim tool around the perimeter first, because some were assembled with a bead of adhesive as well as the pins.

What is inside the RCA 40-5022?

A 5 inch woofer, a 1 inch dome tweeter, a simple passive crossover and a loose fill of polyfill or fiberglass wadding. The crossover is typically one capacitor feeding the tweeter with little else, which is why a dead tweeter on these speakers is so often a failed capacitor rather than a failed driver.

Do I need to reseal the woofer when I put it back?

Yes. The cabinet is sealed, so any air leaking past the woofer flange changes how the driver behaves and audibly thins the bass. Scrape off the old gasket, lay fresh closed cell foam tape or a bead of non hardening butyl sealant around the opening, then tighten the screws in a cross pattern just until the flange is compressed.