magantone 431 chirping when vibrato is on

[randomair]

my old magnatone 431 is chirping when the vibrato and tremolo is engaged? any clues? i checked and changed the tubes, but the chirping still persists. it seems to get louder as i turn the tremolo or vibrato up...thanks.

[capnjuan]

Hi randomair; is this your amp? http://www.vibroworld.com/magnatone/431.html Didn't find schematic; only chirps when vibrato and tremolo on? The text says it is 'switchable from vibrato to tremolo' suggesting the circuit and switching are set up to make the two features mutually-exclusive. If true, your amp shouldn't be able to do both simultaneously but, if it is, it might be the controls; dirty contacts inside a footswitch if the amp uses one, dirty input jacks, or whatever your amp uses to switch from one to other. J

[randomair]

that would be the one!!!

http://www.prowessamplifiers.com/sch...brato_amp.html

here is a schematic for my amp...i have changed those .047mf caps that go from the 12dw7 and to the 6hu8, no change in the chirping. and yes it does it in both modes (tremolo and vibrato). i have dry and wet cleaned all tube sockets, tried all new tubes save for the 6hu8.and checked all grounds. i just cant pin this sucker down. i will try your suggestions and promptly get back to you. thanks!

i forgot to mention when the reverb is turned up it buzzes like crazy. i checked the pan and the cables and those are all fine.