Shaky Metal Sound coming from Amp

[shredhead72]

Hi All,

I think... since I started playing in 45 watt Tweed mode on channel one with the Master at about 11 o'clock, I started hearing this metal jangling sound. Almost like there is a box of paper clips on top of the amp. I'm assuming it's a loose tube or something, but I'm not sure. I'm not very amp savy yet, so I'm worried about screwing something up.

Any advice or troubleshooting steps.

I also feel like there is a noticeable hum coming from the amp that wasn't there when I got it a year ago on channel 3 (45 watt Mark 4)

\m/_

 

[Jackie]

My dad has a Marshall Class5 who had crappy power tube in it. You could hear the INSIDE COMPONENTS of the tube rattle and it was annoying as **** if you played it loud, so I replaced it and it went away. Is that what you're hearing? This kind of glass-on-metal jingling? If so, it's probably a tube as you suspected. Can't say if it's power or preamp since the Class5 has only 1 poweramp tube.

 

[shredhead72]

I figured as much. I was just hoping someone would say, "just tap on the amp three times and it will be fixed with magic."

I'm assuming this is normal wear and tear...

 

[Jackie]

Well since you mentioned tapping, try this old routine - take a pencil or chopstick or any wooden stick-like object and tap each tube (gently) while the amp is on. No tube should emit a loud noise when tapped on. If one does, that one is the culprit.

 

[shredhead72]

I was going to call Mesa. Is that what they're going to tell me to do? lol

 

[K-Roll]

this may sound funny but the last time I had this problem in our rehearsal room I found out that this noise was made by a set of ceramic teacups and small ceramic plates that were placed in one of the shelves.. the girl who'd occasionally come and play her drums loved to make her some tea so she brought her mum's tea-set each time I brought my amp to the tech it was dead silent.. one day I decided I've had enough so I sold it.. and bought a new amp the problem remained the same until I found out that it wasn't the amp causing these ringing metal sounds heh

 

[SonicProvocateur]

1) It may be the control or screen grids inside the power tubes rattling. Some of my power tubes do this more noticably than others. It is perfectly normal and fine if the sound is only very light. Preamp tubes should be dead quiet, but some can make a little rattle but not like you're describing, it would make the amp sound like garbage. Playing with the amp off the cab can remedy it to some degree depending on how loud you're playing (if it's a head). If you have a combo, use a separate cab and see if it doesn't stop; combo's are pretty notorious for tube rattle in general (although Mesa's are pretty good).

2) If you have a tremolo guitar, you may be hearing the springs vibrating back up through the guitar. A couple of my Ibanezes and my PRS make this sound. You can hear it most when palm muting. I fixed the tremolo noise by putting some cloth against the springs.

3) As K-roll said, sound will make EVERYTHING vibrate. Air conditioning vents, lamps that hang from the ceiling, loose screwdrivers laying around, a snare drum your drummer left laying around...you never know until you start cranking! It could be alot.

 

[shredhead72]

Thanks guys,

I'm 95% sure the rattle is coming from the amp. I've moved everything else in the room to be sure already. I haven't gotten around to troubleshooting the tubes yet. But its a combo and the guitar is a Les Paul Traditional (so no trem).

I'll post back once I solve it.

 

[SonicProvocateur]

Also, check your preamp tube shields. They have a small spring in them that could potentially rattle against the tubes if not on tight.

 

[iceman]

I get tube rattle from some tubes at certain frequencies. You can tap on the tubes with a pencil or something to see if you can isolate it to a tube. I also get a rattle from within the amp chassis ( near the rear corner on the side where the slave out is) Something is lose or wires are sitting next to something because it will start usually after I move my amp, and then stop once I " shake" it slightly and then isn't a problem till I move it again. I should get it fixed but it hasn't bugged me enough todonsomething about it.

 

[shredhead72]

Hey all,

I played for an hour last night literally sitting behind the combo and taping on tubes with a pencil. I think I was hallucinating after a while because when I shut the fan off, I didn't hear the sound anymore... but when I turned it back on.. I STILL didn't hear the sound.

I removed the back panel that has the footswitch case and looked for any issue with the speaker, but I couldn't find anything. It seems like the noise is coming from the fan "area".

Also, the rectifier tube (5U4) doesn't light up all that much. Not as bright as the 6L6's. It has a very faint light at the tip of the tube. I was running all channels in 90 W mode. Picture here: http://i1221.photobucket.com/albums/dd471/edwa72/photo6.jpg

Any other thoughts.

 

[iceman]

I fixed my rattle, it was a loose screw holding the transformer next to the foot jack. One trick I've used in the past on amps and cars, is to use a piece of tubing to help locate the area of the noise you are looking for. Put your ear on one end and start searching, it really narrows the space of where the noise is coming from. With just your ear there is a wider field that the noise can be in. Sounds odd but it works. :?