RCA K130 Speaker
 

Our RCA K130 was one of my first tube restoration projects over 15 years ago. About 5 years ago I had Hank Brazeal recone the K130 speaker, Hank did a great job, the speaker was perfect. A while back I asked my young son to turn the radio on, he did and turned the volume all the way to max. When the 30 watt radio warmed up, it blarred, he freaked out and ran. I got up and turned the volume down, now the speaker buzzes and rattles badly. If I gently push the speaker cone outward the distortion kind of quits. Is my voice coil warped? Are there any adjustments I can try on the speaker?

Thanks
David

Take the speaker out and check to see what exactly is rattling. Sometimes it might be the outer cone surround, or the inner spider closest to the voice coil, that needs regluing. Not sure how your speaker was redone, but many have a felt disk covering the voice coil and pole piece. Remove that and check all around the gap with a piece of paper...should slide all around without binding. Move the cone in and out with fingers and thumbs of both hands and listen carefully to see if you hear the v.c. rubbing. You can try shimming with several narrow pieces of business card or the equivalent all around the gap and then dampen the cone well and let it sit upright overnight to dry. It might recenter itself. If that doesn't do it you might have to loosen the spider glue with acetone, shim the gap, and reglue.

Reece,

Thanks for the information. I understand all except for the part that states "dampen the coil" I not sure what this means.

Thanks again.
David

That means get some water on your finger or a small soft paint brush and "paint" the coil all over with water, enough to make it all damp (Yikes! This sounds disastrous!) but it's not. Keep from getting any water down in the voice coil. What it does is relaxes the paper somewhat and allows it to take the position that you've imposed upon it by the voice coil shims.

I'd check all the glue points first, though: outer surround, at the spider, the flexible leads to the voice coil.

I think Reece said "dampen the cone", not "dampen the coil" in his first post. He probably meant to say "paint the CONE all over with water" also in his reply.

John

Bingo! let my fingers do the walking. Thanks, jeyurkon..paint the CONE, not the coil! I've had this work on cones that "drooped" out of alignment.