DSL20HR weird thump in 20 watt mode

[TCF805]

Hi everyone,

I love my DSL20HR, but every time I put it in 20 watt mode, I get a weird thump that sounds like someone knocking on a door through the cab. I guess it's somewhere in the power amp, but I'm not sure. I got both amp and cab used. Anyway, hopefully someone has experienced this issue, too, and can help troubleshoot.

 

[fitz]

Hi everyone,

I love my DSL20HR, but every time I put it in 20 watt mode, I get a weird thump that sounds like someone knocking on a door through the cab. I guess it's somewhere in the power amp, but I'm not sure. I got both amp and cab used. Anyway, hopefully someone has experienced this issue, too, and can help troubleshoot.

Just to clarify:
Power on, standby in off (middle position), and you get a thump when you go from standby to 20w, but not standby to 10w?
Guitar and front end effects are plugged in?

 

[TCF805]

Forgot to hit reply!

 

[TCF805]

Just to clarify:
Power on, standby in off (middle position), and you get a thump when you go from standby to 20w, but not standby to 10w?
Guitar and front end effects are plugged in?

It's while I play in 20 watt mode no matter the volume level. So, not like a continuous knocking sound when I take the amp off standby, just when I play. It happens no matter the volume level in 20 watt mode, but It does not happen in 10 watt mode no matter the volume level.

 

[fitz]

It's while I play in 20 watt mode no matter the volume level. So, not like a continuous knocking sound when I take the amp off standby, just when I play. It happens no matter the volume level in 20 watt mode, but It does not happen in 10 watt mode no matter the volume level.

Knocking while playing in 20w, not 10w.
Sorry, I've never had something like that happen to mine, but someone else may be of more assistance.
Given no other info, I'll still suggest pull & reset all tubes, and try different speaker cables if you have any.
Remove any pedals from the front end & loop, if applicable.
Try to eliminate common, easy to fix stuff, before looking into circuit issues, or taking for service.
If it's a new amp with warranty, find the paperwork....

 

[TCF805]

Thanks! I've only played with pre-amp tubes. Power amp is next!

 

[scozz]

Knocking while playing in 20w, not 10w.
Sorry, I've never had something like that happen to mine, but someone else may be of more assistance.
Given no other info, I'll still suggest pull & reset all tubes, and try different speaker cables if you have any.
Remove any pedals from the front end & loop, if applicable.
Try to eliminate common, easy to fix stuff, before looking into circuit issues, or taking for service.
If it's a new amp with warranty, find the paperwork....

This^

 

[Max Gahne]

I had a different amp that used to do something like that. So I had the chassis out while playing it and could see a little flash out of one of the power tubes when I heard the thump. In my case it was a tube failing.

The reason I had the chassis out is because a knock like that is often a spark. I had the chassis out and the lights off in the room to see if I could see it.

 

[TCF805]

I had a different amp that used to do something like that. So I had the chassis out while playing it and could see a little flash out of one of the power tubes when I heard the thump. In my case it was a tube failing.

Thanks! I'll give that a shot. I got the amp used and didn't think to check the power tubes.

 

[SkyMonkey]

Don't touch anything inside the chassis circuit board though. You could get a killer shock. Only remove/reseat the tubes.

 

[TCF805]

Don't touch anything inside the chassis circuit board though. You could get a killer shock. Only remove/reseat the tubes.

I appreciate you not wanting a stranger to get electrocuted.

 

[SkyMonkey]

You're my 'Marshall' brother, so it goes without saying!

 

[TCF805]

You're my 'Marshall' brother, so it goes without saying!

Haha music is thicker than water. Thanks, man!

 

[Chris-in-LA]

New Forgot to hit reply!

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