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Checking Preamp Tubes - Is it Dangerous?


R Anderson

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I am NOT one to mess with the tubes in my amp. Terrified I will either do something wrong or be on the receiving end of a lightning bolt.

 

But, I picked up a rack mount H&K Tubeman preamp that has a hum. Could it be a tube? Can I open this baby up and check the tubes with out fear of electrocution?!

 

Thanks

R

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Yeah...you can check the tubes safely.

But do you know what you're checking for?


I just checked mine....by having an extra pre and replacing each one until I found the bad one. (patience...turning the amp off and on with each check.)

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Originally posted by R Anderson

I am NOT one to mess with the tubes in my amp. Terrified I will either do something wrong or be on the receiving end of a lightning bolt.


But, I picked up a rack mount H&K Tubeman preamp that has a hum. Could it be a tube? Can I open this baby up and check the tubes with out fear of electrocution?!


Thanks

R

As mentioned,worth a shot but it could be other things. Did you check all cables,including the short patch ones? You are using shielded cables,right? Is it close to a TV/monitor or other item that could be sending interference? Is everything in the chain hooked to the same circuit? All grounded? I'd be more inclined to think it is a ground loop power related problem unless there are technical issues with the unit.

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Again, thats for all the good input. I will take a fresh look at all the cords, power etc..

When I remove the Tubeman and put a similar item (Seymour KTG-1 tube preamp) in it's place I have no hum or noise which is why I am inclined to think the problem is in the unit.

I am actually hoping it is a tube rather than having to take it to someone for something more hi-fi.
R

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Originally posted by R Anderson

Darn it. Changed out the tube for a new one. Still hums. I like the sound of this thing but that hum will never do.


R

 

 

I'm not familiar with this preamp....

 

 

Does it do with nothing plugged in?

 

Does it do it on both(all) channels or settings? IS the gain all the way down?

 

 

Is there a "ground lift" switch?

 

Put an adpter on the power plug and see what that does.

 

 

I assume you've alread chnaged cords, checked the amp it's plgged into, and your guitar?

 

 

If that doesn't do it, it may have to see the tech. I know you don't want to take that hit, but you might lose money selling it as is.

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