I just purchased a new Ampeg V4B RI with a 212av cab from guitar center. Love the all tube tone, however, at certain frequencies (when i play a G# or A on the A string or E string), something inside the V4B was rattling. Took it back to GC and they got me a replacement unit. Unfortunately, with the replacement unit I had the same exact issue. Its not coming through the speaker, so pretty certain its not wiring/electrical issue. It is definitely a vibration induced rattle. Really dont want to return the amp because I otherwise love it, but having a hard time justifying the money I spent on this for it to not be absolutely perfect. Also dont know that swapping for another from GC would be worth it since both units I got had this issue. Has anyone else had this issue and know what might be going on? All replies appreciated! I have a local Ampeg tech who can fix it under the warranty if we can diagnose the issue. Thanks!