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Discussion Starter #1
I got this amp on a trade so I don't know the history. I don't want to return it either because I got a good deal and hopefully this will be an easy fix. The amp works perfectly until roughly an hour or two of playing. At the clean 2 channel (green) and low volume (9 o' clock or lower) only static can be heard but when the volume is at 12 o' clock, it becomes a loud hum that goes louder and louder like a feedback. In clean 1 channel (green), only static can be heard up until max volume.

In the recording below, my guitar with humbuckers is plugged directly to the amp and I'm slowly increasing the volume from 0 to halfway (12 0' clock). Gain is 12 0'clock on the clean channel 2.


Thanks in advance for your help.
 

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-Dying tube maybe
-mostly sounds like similar issues I have occasionally had with overheating. Either a cold solder joint moves a bit and no longer makes contact, or something else where time + heat creates the anomaly. Can be very hard to detect visually, unless you see a cracked solder joint.
 

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Sounds like a microphonic preamp tube.

I assume we are talking about the DSL40C and not the DSL40CR.

The 40CR has similar circuit-based issues with preamp noise which is why you see a lot of them cropping up on Kijiji already.
 

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Discussion Starter #4
Yes, this is DSL40C not the CR. I hope it's just a tube. I bought a new preamp tube and put it in V1 but same problem. I'll move it to V2 and so on and see. It just takes a while to wait for the tube to be cold to touch, replace then play for an hour again. Thanks.
 

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Discussion Starter #5
I've gone through all 4 preamp sockets using a new preamp tube and problem persists. The problem might be the power tubes. Is there a way to definitely say it's the power tube because I don't have spares and L&M doesn't accept returns for tubes? I just don't want to buy a new set if I'll end up sending my amp to a tech anyway.
 

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Plug your guitar into the FX return jack. Should be somewhat quieter but clear and static free. If so, the power amp section/power tubes should be ok.
 

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I've had the same problem with both bad pre and power tubes. Try those and you'll always have spares.

Sent from my H3223 using Tapatalk
 
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