Catching a buzz
 

I've got a 1959 Zenith C730 that I've re-capped, re-tubed and generally fussed over for about a year now. It's my favorite radio and I listen to it a lot, but it has a problem that I'm having trouble tracking down. At anything more than 1/4 volume, I get a buzzing, rattling sound out of the front that -at first- I thought was resonance that was causing the dial lens to buzz. I removed the lens and squeezed it back in with a few small strips of rubber (from an old bicycle tube) but the buzz remained. After that, I began tightening down every screw and nut I could find, including fussing with the plastic tweeter and the brace that runs from the chassis to the top of the cabinet. Still there. This radio has a deep tone that (I'm sure) is adding to the problem, but it's interfering with my listening enjoyment. :no:

Perhaps it's the speaker itself? If so, any tips on where I can find one? It is roughly a 4x6 oval. I have other C730s (and G730s) but don't want to rip apart one good radio to fix another. Is there a vendor on the site that can help?

Nolan, you may want to try hooking up an external test speaker to see if the tone changes (caution, as chassis is connected right to power line).
We have been able to retrofit a modern mini-car speaker (4" or so) into radios that had bad speakers....you many need to make a mounting board for the new speaker to adapt it to the hole.

Chad,

Great idea...in fact, not only did I check the set with another speaker (a big, 8" round Zenith speaker from a junk C845) but I pulled the original speaker and tried it outside of the cabinet too. Just holding them in my hand both sounded fine, but after screwing it back in the rattle/buzz returned. So, obviously, it isn't the speaker.

I'm starting to think the glue joints in the cabinet are loose. I'm a bit reluctant to pry apart and re-glue, because this radio has a veneer covering; not the natural (or solid) wood that some of these radios came in. This is weird; at certain tones (especially a DJ talking or something really bassy) the resonance is so dramatic...and sounds terrible. I'll figure it out, I mean, how hard can it be? At least, I used to think that.

Thanks for the note Chad, always appreciated-