Crackling Noise In Amplifiers

[orgmorg]

This is starting to drive me nuts.

I've had a Fender Yale Reverb amp (solid state) for a while now and it mostly sounds fine when playing at moderate volume, but whenever I dig in a bit on the strings or turn it up, it makes this annoying crackling noise. Not normal distortion, but a static-ey crackling.

I always just assumed it was the amp, so I recently got an AXL AT-30 (chinese made tube amp,) and it does the exact same thing, exactly.

Tried different guitars, cables, power conditioner, turning off all fluorescent lights and computers, no joy.

Do I have some sort of evil power gremlins or something?

[kpcrash]

Probably - leave them a plate of cookies as a sacrificial offering and see what happens

All kidding aside, you could do what I've done - take your guitar to a music store to "test" a new amp out. Try a couple because it's fun, that way you can at least rule out the guitar. After that, it's time for more scientific tests.FWIW, power conditioners aren't always all that. They can help, but if your whole house has a bad ground or something - it might not produce the desired effect.

[guitar2005]

Could be old electrolytics, a bad solder joint or maybe some bad resistors. Hard to tell without the amp on the bench but if the amp is old, its always a good idea to replace all electrolytics. They have a finite life and as they dry out, their performance degrades to the point where they can short out and/or explode and bring a lot of other components with them.

[orgmorg]

Thing is, it's BOTH amps doing the exact same thing, regardless of what guitar I use.

Maybe I can bring an amp to the music store to try guitars out with.

Think they'd go for that?

Maybe if I brought the cookies?

[kpcrash]

The cookies have gotten me much farther than my good looks at music stores.

Can't hurt to give it a go.

[Tim37]

quit feeding your mogwai after midnight.

[Ripthorn]

Are you running them through the same speakers? If it's not the guitar(s), cable(s), or amp(s), speakers and stompboxes are about the only thing left to check. Is there anything digital in your signal chain? Digital distortion is horrendous. Also, you might just be hearing noise that is there the whole time, but not noticeable until you turn up your amp. You may have to go about this in a more detailed, methodical manner (which translates directly into to time consuming and tedious, sorry).

[orgmorg]

Both are combo amps, and I plug directly into them, no effects. I know, I'm boring.

[westhemann]

Your speakers may be loose in both.Or they may just be cheap speakers and not be able to handle the bass you have going through them.

But that only applies if what you are describing as a crackling noise is actually not crackling.

I had a similar issue when I first replaced the speakers in my Fender Twin Reverb II.I could not reach a few of the bolts to tighten them properly and they would give off a sort of vibration when digging in on the strings.

If it was electrical interference I think you would hear the crackling all of the time,even when not striking the strings.

[WezV]

when i was young i had a buzz in one of my amps - at least that is what i thought it was. nearly got to the stage of buying new speakers as i was sure one had gone.

turned out to be a piece of glass in the front of a gas fire about 1m away vibrating at certain frequencies! first thing i do now is try different location for the amp when i think i have a problem. its not just loose things IN the amp that can be vibrating

but 'crackling' makes me think its electrical problem. dying caps and dirty pots are the usual cause but dont rule out dodgy leads or anything that can be causing interference - again, moving the amp to a different location may help narrow things down

[orgmorg]

I brought the tube amp and a guitar to my friend's store and plugged them in there.

It still did it, but I had to listen hard for it.

My friend heard it too, but it didn't sound unusual to him.

Definitely does it worse here, but maybe a lot of it is just in my head.

No fixing that, I fear.

Screw it, I'm gonna go make some cookies.

Edited March 6, 2011 by orgmorg

[kpcrash]

Told ya - the cookies work everytime.

[KeithHowell]

I would suggest you get your earthing of your electrical supply at your home checked.

I have had a similar problem on a Hi-Fi amplifier which wasn't earthed properly. All sorts of snap, crackles and pops! Earthing it removed the crackling completely. There was a static build up which when it got large enough to overcome the resistance to earth would discharge and cause the crackling.

Keith

[orgmorg]

Tried that, best I could anyway.

Dug up the top of the ground spike, brought out an extension cord, and tested the resistance between the spike and the ground prong of the cord- zero

[orgmorg]

After I posted that, it occured to me that that was the wrong way to test it, since that is just the safety ground.

Tested between the neutral wire and the ground spike and the needle on my multimeter went wacky- oscillating rapidly between infinity and like 1kohm.

I could hear it too, and it sounded about the same speed as the crackling noise.

Looked inside the breaker box and noticed that most of the neutral wires are corroded where they connect to the neutral bus bar.

The ground wire runs from the spike to the meter box, but there is not one from there to the breaker panel.

Time to call an electrician, I suppose.

[KeithHowell]

Tried that, best I could anyway.

Dug up the top of the ground spike, brought out an extension cord, and tested the resistance between the spike and the ground prong of the cord- zero

Yes that may be zero but what is the resistance to ground from the spike? Just because it's hammered into the ground doesn't mean it's a good earth!

You need to check that with a proper earth tester. We always referred to them as "Megas" made by the AVO company which made the AVO (Amps, Volts, Ohms) meters.

This involves hammering a spike into the ground some distance away from the earth spike and connecting the meter between them. You will then be able to get a decent reading of the quality of the earth connection.

Keith

[orgmorg]

OK, well the wacky reading I got was because I was mistaking the hot lead for the neutral- duh!

But in the process of figuring stuff out, I tried running a wire from the ground spike to the neutral bus bar, and when I touched the wire to the bar, there were sparks.

Measured 1.2 volts between them.

Turned off breakers one by one until the sparking went away.

Pulled that breaker, and tested between the hot and neutral on that circuit- continuity.

Unplugged everything on that circuit until I got no continuity.

The culprit- My stereo reciever.

Don't know what the heck is wrong with it, but I get no more crackling from my amps now.

Electricity is weird stuff.

[KeithHowell]

Electricity is weird stuff

Yip but it is all very logical. I think the most important thing is correct grounding! I can tell you quite a few stories about bad grounds on electronic equipment. One case had a few hundred thousand dollars worth of telecommunications equipment destroyed due to a bad earth!

I'm pretty sure you have a earthing problem of your stereo receiver. When I mentioned earlier that the crackles and pops were due to incorrect grounding it was actually the turntable on my stereo setup (this was over thirty years ago) that was not properly grounded.

I also agree: get an electrician to check out your house power supply, corrosion is not good!

Good luck

Keith