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Another tube amp problem. sigh!

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  • Another tube amp problem. sigh!

    I just replaced my Crate Powerblock with a Carvin TS100 Power amp. What a difference!! A GT-8 patch (based on a Marshall model) that used to sound bassy and lifeless through the PB, sounds crispy, clean and with enough presence to make me drool

    Anyway, that is where the good things come to an end. After a few minutes of playing, the speakers go "BURRRRRRRRRRR" and dont stop doing that even if I reduce the volume on the Poweramp. I have to put it into standby to make it stop. If I start playing, again after a few minutes it does the same thing.

    Does this sound like a preamp tube or a power tube problem? Also, if I turn the power off completely, when the amp shuts off, there are few "pop" sounds that I hear. If the power tube(s) is busted, will there be any sound coming out?

    thanks
    sam
    Sam

  • #2
    Soundclip? It's hard to tell what you mean by "BURRRRRRRRRRRR"

    Pops when turning off the power is normal, or every tube amp I've had has had problems.
    Scott

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    • #3
      Mine did something similar and it turned out to be a preamp tube. The way I tested it,(like a caveman) was I fired the amp up, turned up the amp with the guitar volume off.

      I then took a pen and tapped the tubes one at a time. You should hear no noise if they are good. But I came accross one that when I tapped on it I heard the tapping throught the speakers. Bingo. I replaced the 12ax7's with new ones. No more problems.
      Scott
      Be without fear in the face of your enemies. Be brave and upright, that God may love thee. Speak the truth always, even if it leads to your death. Safeguard the helpless and do no wrong.

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      • #4
        Originally posted by Spivonious View Post
        Soundclip? It's hard to tell what you mean by "BURRRRRRRRRRRR"
        think of the sound as a blender just turned on. :ROTF:

        Originally posted by StukaJU87 View Post
        Mine did something similar and it turned out to be a preamp tube. The way I tested it,(like a caveman) was I fired the amp up, turned up the amp with the guitar volume off.

        I then took a pen and tapped the tubes one at a time. You should hear no noise if they are good. But I came accross one that when I tapped on it I heard the tapping throught the speakers. Bingo. I replaced the 12ax7's with new ones. No more problems.
        Nice!! I hope its a preamp tube problem too. But today, I am going to pull all the tubes, clean the filaments with contact cleaner and test it out.

        So, will there be any sound coming out of the amp if any power tube dies?
        Sam

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        • #5
          ok, here's the thing. even with no input, when I turn on the amp, there is this loud sound. but I still tapped all the tubes and I could not hear the tapping. but the loud sound is still there.
          Sam

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          • #6
            Is everything grounded correctly? Also did you check to make sure all your tubes were in tight? Loose tubes can make some odd noises.

            Comment


            • #7
              I and my brother pulled out all the tubes, used the contact cleaner on the pins and socket and reseated them after drying. There is still the ugly loud noise coming out.

              The thing is, the when the loud noise comes on, the volume control has no effect on it. The only way to make it go away is to turn the amp to standby.

              I need to contact some ts100 users.
              Sam

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              • #8
                Send Pete (twisteramps) a pm and ask him to check this thread. He is a great guy and can off help.
                Scott
                Be without fear in the face of your enemies. Be brave and upright, that God may love thee. Speak the truth always, even if it leads to your death. Safeguard the helpless and do no wrong.

                Comment


                • #9
                  I just did. thanks for the tip. Tomorrow I am gonna contact carvin tech support and see if they have any inputs.
                  Sam

                  Comment


                  • #10
                    Since it only happens when full power is going to the tubes, I'd guess it's a problem with the power section of the amp. The sound tells me that it's a grounding problem, or maybe something with the transformer? Hopefully Pete will shed some light on this.
                    Scott

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                    • #11
                      The strangest thing happened. I am on the call with carvin tech and I am unable to reproduce the problem. It seems to have gone away. In the past two hours I have fired up the amp 5 times or so and the loud sound hasnt come up. An hour ago, there were a series of loud popping sounds when the amp was powering down. But now even that seems to have gone away. If I hear popping sounds, its definitely a tube problem right?
                      Sam

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                      • #12
                        Regardless of what kind of tube amp you own, diagnosing tube problems has never been explained better than is was here:

                        http://www.mesaboogie.com/manuals/ExpressSers.pdf

                        go to page 19 of 34, or page 15 depending on how you want to look at it... it's called "diagnosing tube problems"
                        "Wow,... that was some of the hardest rockin ever. Hardest to listen too."
                        --floydkramer

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                        • #13
                          Thanks for the document spike. I used to own a mesa boogie manual long time ago and forgot how informative they were.

                          Reading the manual, this section seems relevant to my case in hand

                          The severe short is not nearly so benign. In the worst cases, a major arcing short occurs between the plate and the cathode with visible lightning inside the glass and a major noise through the speaker. If this is seen to happen, IMMEDIATELY turn the amp to STANDBY. By this time the fuse probably will have blown. Such a short is usually caused by a physical breakdown inside the tube including contaminate coming loose or physical contact (or near contact) between the elements. Replace it and the fuse with the proper slo-blo type and power up the amp using the power up procedure as we described earlier in this manual.

                          However, the problem seems to have gone away. In the last two days, I have played a couple of hours on the amp and the noise is not there anymore.

                          I emailed Bob from eurotubes and he says that it could either be a bad power tube or a capacitor. And my brother says that if a capacitor is nearing its dying stage, it may act weird on and off. So, all I can do is to change the tubes when i get a chance and hope its not a capacitor that's blown.
                          Sam

                          Comment


                          • #14

                            Glad you dig the link.
                            Chances are, it's a tube.
                            Keep us posted brother.
                            "Wow,... that was some of the hardest rockin ever. Hardest to listen too."
                            --floydkramer

                            Comment


                            • #15
                              ok, after 12 days of no "loud" unwanted sounds...today it did it again. But after I switched the amp to standby and turned it on again, it disappeared for almost 20 mins that I played. so, I'm pretty sure now that its a tube problem...

                              someone please tell me...if the amp makes loud "pop" noises while turning off, is that a preamp tube(s) problem? I think I read that somewhere.
                              Sam

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