Checking for electrical interference using a guitar amp

[Gswitz]

Sometimes, I can sit with my headphones on and a project open.

If there is a channel with THU (or any other amp sim) it really amplifies electrical whatever is on the channel.

Turn up your headphones until you hear the hum of the amp clearly and listen for ticks or noise from a fan... 

Using this method I discovered that if I plug in my Roland GR20 backwards I get tiny ticks or from the electrical interference.

The other day, with my Fender Amp (real one not an Amp Sim) plugged into the wall, I could hear interference from the fan. Turned it off and it was quieter.

@Craig Anderton If this isn't in your tips and tricks, you might add it. It's subtle, and takes a while to stumble across it.

[bitflipper]

I used to get intermittent EMI. Attempts to track it down weren't going well, so I went down to the main service panel and started turning off circuit breakers one at a time until the interference stopped. Took forever because, as I said, the noise was intermittent. 

In the end, it turned out to be a refrigerator in the adjacent garage. Which, unfortunately, was on the same circuit as my studio/office/garage. So in the end it wasn't my brilliant methodology that solved the mystery - I just happened to remember that there was a fridge next door and unplugged it. Then I had to go around and set every clock in the house.

[John Vere]

We were just going to sleep and this digital noise kept waking me up. It sounded like a fax machine sort of noise in a short burst. ??

I started looking for our cell phones and turned them off. get back into bed and every 3 minutes there it is. I get up and shut the window.. still,, I'm looking and listening where is this coming from??

I finally tracked it down to the clock radio which was on but off station. But what is that?? Then I remembered that our new ( 1964) house has 3 Smart meters.  Hydro, Gas and Water. They send these micro bursts every 3 minutes I guess.

I also discovered this house shares a transformer with 3 other homes. My old place had it's own and nearest neighbour was a half a kilometer away.  Yiks. Haven't been recording live stuff here yet but I see trouble brewing with electric interference. The old house I had to unplug my electric fencer and hope the bears stayed away while I was recording. By the way, if you hear a ticking that might be an electric fence. 

[Gswitz]

Any electrical device could cause a problem.

My Roland gr20 shouldn't have been possible as a culprit imho.

I guess my point was to take a moment and listen for it. Just because the noise is very quiet doesn't mean it it can be ignored.

In my case, fixing issues has proved relatively easy once i got on the trail.

[twelvetone]

I had a very bad hum whenever I used a particular amp sim.

Took me quite some time to figure out the sim generates amp hum and buzz by design.

[RBH]

I'm moving from a 2006 new construction house. The electrical is very nice in this house, 200 amp, everything grounded, the line in is buried. Next week I'm moving to a 1966 house - everything 2 wire , no grounds. One item on my future agenda is to run new electric everywhere I can access it. I'm getting too old for this stuff anymore. Luckily or not - my studio space is in the basement and running new lines there should be easier.

[LarsF]

Electric fence I have had a lot over the years, having to tilt guitar vertically and turn sideways to a specific spot to get it down enough below -60 dBFs.
Humbuckers are a bit easier than strat sc. I have to tilt slightly forward and search sideway for the spot. But still ok playing position, so I am alright with this.

On Strat my wrist watch came into pickups, so had to take that off - and problem solved.
Can you believe it - every second - again I thought this is electric fence, but no. :D

Then the usuall hum in what direction guitar compared to amp, also tricky in that minimum hum meant more electric fence in some cases. I had to take a longer instrument cable and go out in the hallway.

And one pedal on pedal board needed getting in second place as routed, and own power supply - or some extra noise turning a booster on even digital noise from chips inside the pedal, a steady frequency there. Some pedals need certain order, some impedance thingy as well.

The world of electronics and computers....

[msmcleod]

The way I solved interference from other appliances was to get a pretty large online UPS. It's the kind that constantly runs off its battery and generates its own 240V sine wave. There's no physical connection to the mains, and as it always runs from the battery there's no delay on switch over if the mains is disconnected.

All my computer & audio equipment run through the UPS. My lighting, heater & de-humidifier run directly from the mains.

Not only did it fix the interference issues, there was a noticeable drop in noise on my equipment too.

These things aren't cheap though, especially the more powerful ones. I was lucky and managed to get a new, but discontinued one for 1/3rd of the price. I went for a 3000VA one (2700W) in the end. You can pick them up new for around £750 (yeah, they're not cheap).

If you do go this route, get a meter to measure just how much power you're drawing from the mains. You need to make sure the UPS is capable of delivering at least that, and if it's close to its limit you may have to power your gear on gradually to avoid an initial surge.  When measuring pick a pretty meaty project to test on so your CPU load is high, and it's using as much of the PC's power as possible. Same with your monitors/amps - make sure they're actually doing some work.  

The meter I got is one that just plugs into the socket, so I leave it there so I can keep an eye on it.  The last thing you need is an underpowered PC - that'll cause a bunch of stability issues.

Also, if you're running anywhere near 100% capacity, don't expect much "offline" time if your power goes... You'll only get 2-3 mins to save your project & shut down gracefully before it cuts out.

[bitflipper]

I'm not sure how this is related, but it's what I was reminded of while reading everyone's posts.

I've been remastering and fixing up an album for a friend. It was made in 1980 on analog tape and has never been in a digital format. So we got an original copy, liberated it from its shrinkwrap and found somebody with a high-end turntable to record it. Must have been cheaply pressed, because there were a lot of pops and crackles even though the record had never been played before.

Fortunately, the de-clicker in Adobe Audition was able to remove 99% of the pops, but the few that remained were going to require manual editing. That meant lots of close listening once the most obvious artifacts had been identified and the remaining clicks got more and more subtle. After a while I began to hear tiny pops that I could not see in the editor, and they'd frustratingly occur in different places with each playback. I was beginning to doubt my sanity and/or editing abilities. Then I noticed it was raining outside.

[LarsF]

2 hours ago, msmcleod said:

The way I solved interference from other appliances was to get a pretty large online UPS. It's the kind that constantly runs off its battery and generates its own 240V sine wave. There's no physical connection to the mains, and as it always runs from the battery there's no delay on switch over if the mains is disconnected.

All my computer & audio equipment run through the UPS. My lighting, heater & de-humidifier run directly from the mains.

Not only did it fix the interference issues, there was a noticeable drop in noise on my equipment too.

These things aren't cheap though, especially the more powerful ones. I was lucky and managed to get a new, but discontinued one for 1/3rd of the price. I went for a 3000VA one (2700W) in the end. You can pick them up new for around £750 (yeah, they're not cheap).

If you do go this route, get a meter to measure just how much power you're drawing from the mains. You need to make sure the UPS is capable of delivering at least that, and if it's close to its limit you may have to power your gear on gradually to avoid an initial surge.  When measuring pick a pretty meaty project to test on so your CPU load is high, and it's using as much of the PC's power as possible. Same with your monitors/amps - make sure they're actually doing some work.  

The meter I got is one that just plugs into the socket, so I leave it there so I can keep an eye on it.  The last thing you need is an underpowered PC - that'll cause a bunch of stability issues.

Also, if you're running anywhere near 100% capacity, don't expect much "offline" time if your power goes... You'll only get 2-3 mins to save your project & shut down gracefully before it cuts out.

Yes, it will help also if very unstable voltages like I had before electric company fixed that. I had tube gear that stopped all together when craftsmen worked at the farm I lived then, one drilling machine started and voltage dropped like 30V.

So I got one of these which were way cheaper €200. 

https://powerwalker.com/

A VFI 1000 TG is double converter, constantly running from battery which is constantly charged too - giving perfect condition voltage. Here 230 VAC 50 Hz. For me 1000 VA was enough with good margin, having all gear running below 500W.

Did not do anything about electric fence though, which was due to having fence 2m outside my windows then.

 

Brian May is running a frequency converter to have constantly 234 VAC 50 Hz, which he feels give his Vox AC30 best tone, whereever he goes in the world on tour. That unit goes from 110 VAC to 240 VAC. So these are good for many things, But brand he used cost about £2000 for 1000 VA unit. It's on YT a tour on his gear. So going between continents very practical.

[John Vere]

RBH that's odd your 1960's house is not grounded. Grounding was brought in in the 50's. My fixer upper had all that old paper coated stuff and some was pretty frazzled looking. Looked like a fire hazard waiting to happen to me.  All the outlets were falling apart and brown.  If your basement is unfinished you can do a lot to replace stuff. And in our case we had to open up a lot of main floor walls to get rid of the funky stuff and old insulation ( 2") . Only wires I left alone run to ceiling lights. Someday I brave the attic and replace those too. 

If you do it yourself it only cost me around $2,000 so far including new LED fixtures. I had to add a couple of sub panels to add new circuits for the kitchen. The studio will have it's own circuit but there's no way to isolate it other than what Mcleod is saying.  I had one of those once but it only lasted a few years. 

I try and wire everything I can with balanced cables. And I even got rid of my wireless mouse and keyboard. They didn't get recorded but the noise in the headphones drove me nuts. 

Edited September 20, 2020 by John Vere

[57Gregy]

I was playing guitar the other day and heard a horrible noise.
I stopped playing and the noise went away.

[John Bradley]

I get that a lot. Maybe if I buy yet another guitar, or a new amp...

[Starship Krupa]

On 9/20/2020 at 4:47 AM, RBH said:

Next week I'm moving to a 1966 house - everything 2 wire , no grounds.

Is this in the United States? That seems like at least 10 years too late.

I wonder if it might be like my grandma's place, built in 1950, where the outlet boxes were properly grounded, but for whatever reason the outlets themselves were 2-prong. I had to wonder how that came to be, maybe the regulations allowed for using up old stock of 2-prong receptacles.

It's been years since I've even seen one of those awful 2-to-3-prong adaptors, the ones that were (wink-wink) only supposed to be used in 2-prong receptacles with "a properly grounded" cover plate screw to attach the little wire or tab to. Which caused me to wonder why, if the box were grounded, it would still have a friggin' 2-prong receptacle in it anyway. Then I had occasion to swap out one of the receptacles at grandma's place.

[RobertWS]

Another noise source:  Light/lamp dimmers will broadcast a buzzing sound.

Edited September 23, 2020 by RobertWS

[bitflipper]

Back in the day I worked on large computer systems that were susceptible to EMI. For two years I was part of a team that addressed power quality and environmental issues. My job was to audit computer rooms, test power quality and check for proper grounding. It was a nice break from my other duties that involved sitting at a desk all day flippin' bits.

One day I was called in because a system had been experiencing intermittent crashes that seemed to implicate one of the power supplies. I replaced the main CPU power supply, looked over the wiring, and could do nothing more than wait and see. Sure enough, two days later the system went down. I joked with the system administrator that they could always pay me to sit and watch the computer, since it never crashed when I was there.

No sooner had I made that comment, it crashed. It was pure luck that I happened to notice somebody using a copier on the other side of the glass. Rebooted, used the copier and within minutes it crashed again. It was the frickin' copier! Nothing else was supposed to be on the same circuit as the computer, but the copier installer had unwittingly placed it outside the computer room and plugged it into a circuit that shouldn't have even been available there.

Bottom line is that in addition to proper grounding, what shares the circuit is most important. Ideally, your computer, interface, mic pres and any other electronic gear should all plug in to the same circuit. Extension cords should be avoided if possible. That single circuit should be isolated from other circuits, meaning all THREE wires go straight back to the distribution bus. Things like lights, fans and refrigerators (!) should be on separate circuits. Anything with a motor, anything that doesn't operate on a 360-degree duty cycle, which includes LED and flourescent lights and (shudder) any light with a cheap dimmer.

Granted, we can't all custom-wire our studios, which are probably located in a basement, attic, garage or bedroom. Many of us live in rented digs where the landlord might frown on holes in the wall for installing dedicated circuits.

Here's what you can do, though. Get yourself a power distribution box, basically a fancy extension cord, which might have a surge suppressor (but don't worry if it doesn't, most of them are crap anyway) and/or a toroid choke (better for noise suppression). You can easily make one yourself using inexpensive parts from Home Depot. Make sure it's well-grounded and has enough outlets for all your stuff. It still may have to be plugged into an existing outlet that's on the same circuit as other things in the house, but you'll still have better, of not perfect, isolation from EMI.

If you really want to go all out, go to an electrical supply store and tell them you want an isolation transformer. That's as good as a dedicated circuit, and will isolate your gear from just about all noise that's injected into your home's system from other devices. 

Note that this does not address RFI, just EMI. However, you will probably find that with good grounding you'll also be less susceptible to RFI as well.

 

[Old Joad]

I just got all my gear set up a few weeks ago and the landlord had all the plugs updated to code. now my orange amp and my marshall amp are making a god awful buzzing noise. my guess is they messed up the ground, is there a power strip or something I could plug into to ground the amps?

 

[bitflipper]

I just re-read my post and realized that I said "avoid extension cords" and then proposed an extension cord as a solution. 

That's actually not contradictory. Use all the extension cords you want, as long as no two ground lugs are more than 3-6 inches apart. So yeah, any 3-inch extension cord would be fine.

Old Joad: run down to the hardware store and pick up a cheap outlet tester. Or an expensive one, if you like, which can catch more wiring problems, but usually isn't necessary for troubleshooting most grounding f-ups. Bear in mind that the electrical code does not address power quality at all, only safety. So the wiring could indeed be "up to code" and still be crap.

[John Bradley]

Assuming you're in the US, I highly recommend having one of these (or equivalent) in your arsenal. Especially if you ever take your gear out to a venue -- could prevent some unpleasant shockery if you touch things that are plugged into two different outlets (say, your guitar and a microphone).

https://www.amazon.com/Sperry-Instruments-GFI6302-Receptacle-Professional/dp/B000RUL2UU/ref=sr_1_5?dchild=1&keywords=outlet+tester&qid=1600904662&sr=8-5

Get one, test any outlet you plug your amps into.

 

 

[John Bradley]

Simultaneous recommendation!