[Ronin61]

Philco 42-380 has been recapped and resistors replaced but there is a lot of speaker vibration. The bass and treble controls work fine as does the volume control. Any suggestions or ideas for a cause and a solution.

[morzh]

What is the "speaker vibration"? Mechanical?
Maybe it is just loose? ???

[Ronin61]

I have removed the the speaker and put it back in and all hardware is snug. The vibration remains.

[morzh]

I mean, how does it manifest itself? Sound, or the cabinet walking all over the floor, or...? The very word "vibration" does not tell much. The sound the speaker makes is itself a vibration.

Can you describe it?

[Ronin61]

As I turn the volume up the vibration begins and it is most apparent when music is being played. I adjust the bass and treble and the vibration / distortion is less but persists. It is sound not rattling the cabinet is stable and is sitting on carpet.

[morzh]

I think I know what you are describing.

I would say check your decoupling caps but you said you have replaced them.
Output Tubes?

Also: have you checked that your output transformer is good all the way? From the centertap to each end? Are teh voltages on both tubes anodes (plates) correct?

[Ronin61]

Great advice I will check those things and post my results.

[Ronin61]

Thankyou morzh.

[morzh]

And the last thing (not likely but) - the speaker itself. Just for giggles if you have a similar speaker, you might connnect it and see if the same thing is happening.

First if the speaker has the transformer attached you will be eliminating both at the same time, and then if it shows improvement, you can then try to see which one of the two is the culprit.

[NostalgiaRadioTime]

I had a similar vibration problem on my 48-1253. By mid volume, the vibration was very noticeable. It turned out there were some teeny tiny little round moth holes in the speaker cone. Once I sealed those up with liquid tape, the vibration stopped. Not saying that's the case with Ronin61's set, though.

[Radioroslyn]

Give the cone a good looking over. Make sure that the paper is glued down at it's edges. At the frame and the voice coil.
Terry

[codefox1]

I once found a loose cabinet seam in a vintage Altec speaker which sounded like a bad driver to me and was disproved by swapping out the driver. Couldn't tell from outside and damage probably ocurred when it was shipped to me.

Anyway I patched up the seam and put reinforcement blocks on all four corners, and did the same to its mate. Fixed!