2. speakers
  3. 1426560878

soft thump and driver moves...even with no signal

Anyone experience anything like this? Was listening to Spotify when I noticed a slight noise in between tracks. Saw the left driver move slightly then again maybe 10 seconds later or even less. No music was playing at that time. Turned volume down completely but still had the periodic movement. Similar to what you might see with a warped record. Shut things down for the evening. Hoping it's just some old tubes finally failing. Plan to change out power tubes tomorrow. Let me know if you've any insight into what might cause such a thing. Thanks in advance.
128x128ghosthouse
czarivey
5,946 posts
 
it happens on certain records that may rumble.
atmasphere's avatar
atmasphere
11,784 posts
 
Hoping it's just some old tubes finally failing. Plan to change out power tubes tomorrow.

Based on the description this is quite possibly a bad tube in the signal chain somewhere after the volume control. Its likely not a power tube.
ghosthouse's avatar
ghosthouse OP
4,306 posts
 
Thanks Atmasphere. That's helpful (look downstream of the pre-amp). In addition to a quad of 6CA7s, these amps each run a pair of 6922s + one 5687.
atmasphere's avatar
atmasphere
11,784 posts
 
If this occurs fairly often, first thing to do is swap the interconnects from the preamp left for right and see if the problem moves to the other channel. If so, the problem is in the preamp. If not- its likely one of the driver tubes.
More to discover