I mayhave found something wrong with my ENGL amp - what does this mean?

[Young Angus]

I heard a while ago on this forum that to help diagnose bad tubes, one thing you could do was to get a pencil with a rubber on the end and tap very very lightly with the rubber on each individual tube and listen for crackles or something. Well i did this to my ENGL for the first time and this is what i found.

I just got a pencil eraser on the end of a pencil and very lightly tapped the tubes inside my amp while it was turned on (with the guitar volume down). None of the preamp tubes seemed to make any noise but the power amp tubes did.

V8 seemed to make a clear echo sortof noise every time the rubber tapped it gently. And this seemed to get louder as i turned the volume up. But the left power tube V7 (left when looking at it front on) didnt make any echo type noise, just a very faint weird noise which i could barely hear, almost like a very very faint spring type noise...you could barely hear it. And this power tube V7 didnt produce any noise no matter what channel or master volume i selected.

Does this mean anything?

 

[Reckless Abandon]

Re: I mayhave found something wrong with my ENGL amp - what does this mean?

Is there a sound problem in your amp? I mean why are you checking the tubes? If it sounds fine it is. If it sounds bad then you have to change BOTH power amp tubes since they should be matched. Ways to diagnose a problem with power tubes is this: Drop in volume, bad distortion, lack of dist. buzzy, does not light up, color is blue, weak sound. Preamp: loss in gain, noisy, weak sound. Preamp tubes can lat 2 years on regular play, power about a year or so. Hope this helps. Tapping tubes can damage them!

 

[jmv]

Re: I mayhave found something wrong with my ENGL amp - what does this mean?

color is blue

not so shure about this one.... check this out.

 

[Robert S.]

Re: I mayhave found something wrong with my ENGL amp - what does this mean?

Blue is not a sign of a bad power tube. All my power tubes in my Marshall and Mesa glow blue. Bright red is a different story.

YA, get that amp to a qualified tech and get it checked/re-tubed. A bench diagnostic will likely run ~$40 and if you need tubes it'll run a bit more. At least you'll know for sure of that amps status. Tubes can be damaged during shipping/transportation and they can last for a year or a day depending on how the tube Gods are smiling at you.

Bad tubes are by far the most common cause of lacking tone and amp failure in a tube amp. Considering how much trouble that amp is giving you tonally it's probably in your best interest to get it checked out by a pro.

 

[Young Angus]

Re: I mayhave found something wrong with my ENGL amp - what does this mean?

As soon as soundclick clears my clips ill have some links to a couple of quick clips i made of the ENGL for all you guys to hear what im talking about.