Damn Amp Noises (updated)

[Psyre]

So I finally got a cab for my bassman (yes proper watts/ohm matching) and was playing today and occasionally I get the ole wind blowing noise. I know this can be caused from bad solder joints, caps, or resistors but it seems to be more from vibrations (maybe agitating the problem spot?) however I can't get it to do it all the time just occasionally. Is it possible that the sound is simply the vibration caused by the cab? If I put the cab cover underneath the head it didn't seem to produce it or at least way less if it was at all.

Also I tapped on the tubes with a wood pencil and could not reproduce the sound.

[dubkitty]

it's entirely possible that it's the vibration making something rattle. my Laney has a funky preamp tube socket that sometimes makes V3 issue a variety of sounds ranging from a loud hiss to an excellent imitation of a microphonic tube no matter what tube is installed, and i've had the chassis out and can't find anything visibly wrong. and if you've got something that's on its way out--say, a tube or a bad solder joint--rattling it with a big old cabinet certainly isn't likely to help.

[Psyre]

I just had it gone through by a tech and he said it looked really good for its age and was impressed that it still had the original caps etc so I'm prone to believe him, he is one of teh best known techs in Arkansas and been working on amps for 60 years. I'm just want to take good care, I have a show this weekend, so before I commit to using it I will see if padding the top of the cab kills some of the vibrations.

[Gone Fission]

If you must stack the head on the cab, isolating vibrations is a very good idea. Best move is to have the head not stacked on the cab and to still decouple the head from the ground. Prolongs tube life, reduces microphonic feedback issues.

Of course, it could be something else around in the room that's suddenly on a rattling kick. If this is the loudest rig you've run in that room, it's quite possible, or maybe the rig is just tuned to rattle the room.

[Psyre]

Thanks Fission, that does make a lot of sense. Also if I pick the amp up for just put tension on the handle it stops immediately so it must be the vibrations I just want to make sure I'm not just using poor judgement by wishful thinking.

[rfurtkamp]

This sounds like an excuse to buy an Echoplex or Space Echo or other amp-top unit to 'dampen the vibrations.'

[Zander]

Did the tech put the amp on an oscilloscope and hook up a signal generator? If there's anything wrong with the electronics, doing that would make it show up real quick. If he's as good an amp tech as you indicate, he should be able to use the o-scope to isolate the bad part or the vicinity of the bad solder joint.

If he did put the amp on an o-scope and it showed no issues, then yes, it does sound like there's a sympathetic vibration somewhere.

You would also be well served to check for loose amp chassis bolts, transformer bolts, tube socket screws, turretboard mounting screws, speaker mounting screws, or maybe even loose bracing. These can all make the possibility of a sympathetic vibration more likely.

[Psyre]

Space echo!!!!!!

I check all the mounting screws and tube sockets etc already, I brought home a mouse pad from work yesterday and cut it in half and stuck in underneath and played for about an hour with no noise. I think it's because Fender has a handle on the top of the cab (which it was on the side like the old ones) and it appears to be sitting unlevel due to that.

[rfurtkamp]

Space echo!!!!!!

With genuine coily cable, black from sin and strangling babies.

I check all the mounting screws and tube sockets etc already, I brought home a mouse pad from work yesterday and cut it in half and stuck in underneath and played for about an hour with no noise. I think it's because Fender has a handle on the top of the cab (which it was on the side like the old ones) and it appears to be sitting unlevel due to that.

Could be, I ran my Bassman on uneven amp surfaces (same handle as you describe) without issue generally. I'd bet personally you'll be replacing a preamp tube soon though if my experience is any good. Bring spares!

[tuffteef]

does it sound like rustling newspaper ?

then just stops?

[Psyre]

Could be, I ran my Bassman on uneven amp surfaces (same handle as you describe) without issue generally. I'd bet personally you'll be replacing a preamp tube soon though if my experience is any good. Bring spares!

Did you bassman have the piggyback brackets on it? I'm starting to thin thats what it is, No matter where I put the head the metal brackets are resting on the metal from the cab handle. I turned the cab horizontal and only the rubber feet were touching the cab (a good inch of space between the bottom of the amp/top of the cab and I could not replicate the sound (usually happends when holding the low E on the 6th fret) I then rotated it back and immediately could replicate the noise. I think it may be the metal on metal vibrations.

However I do need to get spare tubes.

[Psyre]

does it sound like rustling newspaper ?

then just stops?

Yes, but only stops if i apply pressure on the head or applying pressure on the handle (picking it up just a hair)

[tuffteef]

does it sound like rustling newspaper ?

then just stops?

Yes, but only stops if i apply pressure on the head or applying pressure on the handle (picking it up just a hair)

dude i have this shitty problem aswel
talk about ruin all my recordings


i think its some kinda cap or joint problem after googling around
but my entire amp is pretty out of service anyway

[Psyre]

Ughh not what I wanted to hear tuffffff

I'm gonna take the piggyback brackets off tonight just to see, like I said I played it for about an hour with the cab turned so the handle wasn't underneath and it eliminated any sound that was there before, so I'm being optimistic. I just don;t want to develop blind optimism and denial.

[Psyre]

After further testing I don't think any of my powertubes are microphonic, the only one that would make the swoosh swoosh sound was V2 if I pushed on it a little (which isn't good for me to do obviously) I used it at practice tonight and it was silent as can be for the 2 hours. I'm using RCA 7025's which are said to be slightly microphonic anyways. I think removing the piggyback brackets fixed the issue I was having.