Mark V possible tube issues?

[bnelly428]

Hey Guys,

Had the V for about 6 months now. I've been noticing if I turn the standby switch on relatively quickly ~30 seconds after power, I will sometimes get a sound that sounds like high pitch that goes to low pitch (sort of like a bomb-dropping sound effect). If I leave the amp on longer it usually is ok. Is this a bad preamp tube or just not letting it warm up enough? I've had 3 tube amps and this is the first time i've encountered this.

Thanks.

 

[eudaimonia02912]

I have that same thing happen when I put my stock power tubes in. However, when I use any other tubes, it doesn't occur.

 

[Barry]

Hey Guys,

Had the V for about 6 months now. I've been noticing if I turn the standby switch on relatively quickly ~30 seconds after power, I will sometimes get a sound that sounds like high pitch that goes to low pitch (sort of like a bomb-dropping sound effect). If I leave the amp on longer it usually is ok. Is this a bad preamp tube or just not letting it warm up enough? I've had 3 tube amps and this is the first time i've encountered this.

Thanks.

Sounds like a microphonic preamp tube problem

 

[bnelly428]

cool i will check out the preamp tubes tonight and switch out if i need to, i hve a bunch laying around.

 

[HeadlessAxeman]

Quoting from Page 51 of the Mesa Boogie Mark V Manual...
Microphonic noise...happens all the time after some useage with tube amps..
For more detailed info, read Page 51 and 52 of the manual.
Hope that helps

You may occasionally experience some form of tube noise or microphonics. Certainly no cause for alarm, this quirky behavior comes with the territory and the Tone. Much like changing a light bulb, you don’t need a technician to cure these types of minor user serviceable annoyances and in fact, you’ll be amazed at how easy it is to cure tube problems...by simply swapping out a pre-amp or power tube!
First may we suggest that you set the amplifier up on something so that you can get to the tubes comfortably without having to bend down. It also helps to have adequate lighting as you will need to see the tube sockets clearly to swap tubes. Use caution and common
sense when touching the tubes after the amplifier has been on as they may be extremely hot! If they are hot and you don’t want to wait for them to cool off, try grasping them with a rag and also note that the glass down around the bulbous silvery tip is considerably less hot which makes it easier to handle. Gently rock the tube back and forth as you pull it away from its socket.