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AC Power Crackle


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Hey, hey!


My new apt has an crackle in the AC that will come through any audio device at higher volumes but especially a tube amp or a modeler on a gain setting.


My friend found me a decent Power Var 3 stage toroidal conditioner at Goodwill but it doesn't touch the crackle.


I was thinking going with something like APC battery backup unit to hopefully go off of pure, buffered power.


I've made custom notch filters to deal with 60 cycle matters but this crackle is to erratic for something like that.


Any ideas really appreciated. I'm also amazed how the even some of the nosiest tube amps at many G.C.s remain pretty quiet even with single coils. Anyone know what they are doing with their power?





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Wow, I hate AC problems like that! I ran into something like that just the other day playing a benefit in an old building with some new wiring, and some old... ! Weird modulating noise and "static-y" crackling on top of extreme AC hum. A basic outlet-tester checked OK; switching to another outlet via an extra-long extension-cord made the worst of it go away, enough that I could use my amps if I switched 'em out in-between songs, etc., but there was still an exceptionally loud, annoying hum... :rolleyes:



Have you tried all of the outlets in the apartment?



Is it possible that it's not the AC, but some other kind of interference, like RF?

Ask yourself- What Would Ren and Stimpy Do?


~ Caevan James-Michael Miller-O'Shite ~

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I use heavy-duty power strips, w/RF filters to help eliminate noise, and here in the D.C. area, there are plenty of buildings like Caevan describes, with a mix of old and new wiring. A battery-driven power supply would isolate your rig from whatever is happening in the walls, but I'd wonder if there's an issue that could also affect other electronic equipment in your home. Tube amps are much more forgiving than IC's when it comes to power spikes and transients.

"Monsters are real, and Ghosts are real too. They live inside us, and sometimes, they win." Stephen King





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If it's an old apartment building maybe there is no ground connection. Ground loops are the electronic tech's devil to trouble shoot! I hesitate to make suggestions since you're now dealing with not only 120 volt wiring but you don't own the place. Talk to the owner, see if they'll get an electrician to check your circuits. Hey if nothing else, "AC Power Crackle" would be a great name for a band!! (Pink Jimi you out there?)
I was born at night but I wasn't born last night...
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Crackle is different than most common power issues. It would have to be cause by a poor connection either in the line itself, or something large connected to it. See if you can verify if it exists on all the circuits in the building. There is no way to filter that, other than a Battery/power inverter. A UPS may not work because they only kick in when the power is disrupted. You'll have to find the offender.



Acoustic/Electric stringed instruments ranging from 4 to 230 strings, hammered, picked, fingered, slapped, and plucked. Analog and Digital Electronic instruments, reeds, and throat/mouth.

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Crackle is different than most common power issues. It would have to be cause by a poor connection either in the line itself, or something large connected to it.


Actually it's more commonly caused by an inductive load on the service. Refrigerators & microwaves turning on elsewhere in the building would be the likely suspect. I had a neighbor about 5 houses away who used to do arc welding in his garage. That caused mains-borne garbage even though he was on a completely separate service from me. I finally installed an Equi-Tech power conditioner & that took care of all of my AC line noise issues. It's very expensive, not exactly portable, & it works.

BTW, inexpensive fixes, things like the Furman PL 8 rackmount power strips, which supposedly filter line noise, do exactly nothing to relieve this sort of mains noise. There's no band-aid.

Scott Fraser
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