Persistent Hum

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AWR07

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I have read bits and pieces of other posts relating to amplifier hum in an attempt to resolve the one in my amp. It’s constant. It’s quieter when I power up in Tweed mode and maybe a bit louder or more intense when on full power mode. Maybe a little more noticeable still if in 100 watt vs 50 or 10, but only when I flip it out of standby. The hum does appear to be filtered into the sound and through the speaker. The amp is at least 10 years old but was never played. Maybe 10 hours tops. The former owner has no idea if it hummed when he played it and I have no idea if it’s common to Lonestar amps as I have nothing to compare it to. I do know my mark V and Mark V 35 did not hum like this and my most recent amp a Fender Deluxe Reverb didn’t either. I only mention that because at idle all of those were pretty much silent. I am no amp tech and don’t like messing around with tubes and such. I’d hate to think it’s the output transformer, so if I wanted to try to rule out tubes any advice on where to start? Power tubes? preamp tubes. I have already replaced the preamp tube that effects the Reverb. Any advice will help if there is anything I can do to rule stuff out or in fact resolve the issue.

Edit: something else maybe related, maybe not. When I am in Hard Bypass mode for the Loop (which I’d prefer to use) when I power off the amp unless I put it in standby the pop and squeal that this thing makes is unbelievable even if the volume is at what I would call bedroom level. I hate to think that at some point the bias switch got moved to EL34 while it has the 6L6s but I am starting to wonder if this could be the consequence of that.

Thanks.
 
If it wasn't played much for 10 years then the caps might have dried out a bit. Valve amps do need to be played regularly to keep them healthy. A bad tube or tubes could also be the problem but you would need to troubleshoot each tube with a known good tube in order to isolate that. Mesa always have a section in their manuals about how to do this. I personally would take it to a tech and get them to have a look at it. Don't go under the hood youreslf unless you know what you're doing. BTW I have never bought a second hand valve amp I didn't need to take to a tech right away. Usually the last owners had done something that had run them down in some way.

The sound of bad filter caps - hum and ghost notes.
https://www.youtube.com/watch?v=QJUE32vEQNM

Mesa Boogie Amplifier Troubleshooting
https://www.youtube.com/watch?v=wSl-l9aWDHw
 
Thank you for you let feedback. Greatly appreciated. Interesting videos. Can’t quite say I could tell the differences in identifying what hum this this thing may be emitting but it sounds like a trip to an amp tech is in order.
 
If it wasn't played much for 10 years then the caps might have dried out a bit. Valve amps do need to be played regularly to keep them healthy. A bad tube or tubes could also be the problem but you would need to troubleshoot each tube with a known good tube in order to isolate that. Mesa always have a section in their manuals about how to do this. I personally would take it to a tech and get them to have a look at it. Don't go under the hood youreslf unless you know what you're doing. BTW I have never bought a second hand valve amp I didn't need to take to a tech right away. Usually the last owners had done something that had run them down in some way.

The sound of bad filter caps - hum and ghost notes.


Mesa Boogie Amplifier Troubleshooting


My LSC has a similar low hum with the EL34s installed. My LSS and Friedman are relatively quiet. I got the amp second hand but it was still almost new and I play it pretty often. I keep thinking I should take mine to a tech as well.
 

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