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tube amp crackling

post #1 of 5
10/12/07 at 3:55pm
Thread Starter 
Currently I've got a pair of Von VR-1's driven by a Sophia EL-34 tube amp. This is my first experience with tubes. I've been running this setup for about a month now and have been immensely enjoying it. Lately, however, I've been noticing that during warmup when no music is playing, I can hear a crackling/static noise coming from my speakers. Nothing terribly loud, but definitely a noticeable crackling/static noise. It definitely seems like it happens most during the warmup of tubes, but it could be happening later on too, I'm just not sure. Is this is a bad sign? Everything still sounds superb, so I hope this is just a natural tendency of tube warmup? Any ideas?
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post #2 of 5
10/12/07 at 4:02pm
I'm interested in the answer to this to.

I had the same issue. Again new to tubes but there has been crackling during warm up. I would say mien is pretty loud. Lasts a second or two and then gone. No clue what's causing it though.
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post #3 of 5
10/12/07 at 6:30pm
If the sound is something like that which you get when tuning in an old type radio tuner or turning a dirty scratchy pot...

It could be:

Dirty tube sockets, in which case inserting the tubes a few times may help, or you may need to squeeze the little pins that hold the tubes in the sockets so that hey get a good grip in the tube pins. Or it could be the small signal tubes (ie the 12ax7/6N1/6N3 etc or whatever tubes is used for input/splitter) needing to be replaced.

I had this in my amp and I ended up replacing the input tubes and the problem went away. I'd focus on the small tubes first and the EL34s after.
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post #4 of 5
10/12/07 at 6:54pm
not too sure about the technicalities yet, so I wont get into my assumptions (DC steps, current spikes, etc..), but tubes should be used with delay circuits for the first few seconds (or more, depending on the load), and the load should be disconnected once the amp is shut down. It can be harmful to the load. Precautions should be taken, but I'm in no position to make any proper suggestions (but take a look at this for now, which is headphone specific and a DIY solution).

.. for how long do you hear this? (this is not a suggestion to go time it, and be the ill trigger :P ). Also, I'm sure you'll get more responses here soon!
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post #5 of 5
12/17/07 at 9:22pm
Thread Starter 
Update: So after a month more of this crackling going on, I decided to clean off the excess dust on the amp (there was a lot) and reconnect the tubes to see if perhaps a connection was lose. Voila, the crackling was gone. A few days later, however, the right channel decreased in volume to probably about 5% to nothing at all. I turned the amp off and didn't touch it for a few days. I just turned it up again, and the output seems normal, with both channels balanced. Well, it may be my mind but perhaps there is a slight left channel bias. Anyhow, is this indicative of perhaps my signal tubes needing to be replaced? Or something worse...?
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