Guitar amp buzz even with balanced power supply. Help!

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JohnRoberts

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I hope your "irrelevant" earth ground is at least connected to earth ground, or whatever your Code is. If I were playing a guitar and it hummed strangely, I'd fear being part of an undetected fault; you are assuming the pickup is the only possible source of guitar noise. A human is a fairly large capacitor plate to everything nearby. If your balanced power is floating you may not have touched the wrong thing yet. If you've already answered this question please pardon me.
A couple years ago I designed an outlet tester that used the human body as the relative 0V reference (not actually 0V).
===
Not to get to far off the road, what changed a couple weeks ago?

JR
 

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Paul Wolff
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Something appears to have changed from your discussion. Some times things break, and sometime new sources of interference pop up... 5G anybody?

Apparently 5G interferes with aircraft avionics so they are still trying to sort that out.

JR
Apparently it's in all the vaccines too, funny though, the schematic is the same as a Boss distortion pedal.
 

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Paul Wolff
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There are a couple of things to help with guitar buzz. You are basically walking around with a hi-z unbalanced coil thats plugged into an amplifier.

The noise in the amp is not from any other source except the pickup. Sometimes flipping the ground switch helps (if the amp has one) but for the most part it's the pickup. Fenders are worse because they are s single coil. Gibsons are better because they have two coils out of phase with the magnet in the middle, so the string gets picked up because it's in the filed, but the outside interference is reduced because of the common mode effect of the coils (see earlier threads about that).

Most light dimmers for incandescent bulbs dim the light by chipping off part of the sine wave with an SCR and a phase shifter controlling the SCR. This creates sharp spikes that have harmonics to eternity and back. Even when full up, they can still buzz.

Light dimmers that are used in both LED and incandescent bulbs work the same way. LED only dimmers may not do it as bad. This is why they put various in the walls of studios. They are variable AC transformers that lower the voltage by turning it down.

Florescent and neon lights/signs emit a lot of noise because they are basically creating sort of an arc inside the tube that ionizes the gas and light comes out. If it were DC, there would be no noise, but they are 60Hz (or 50).

If the buzz is constant and doesn't seem to "rotate" like a very slow phase shifter, it is coming from something AC. If the buzz slowly rotates, you are getting interference from a TV signal, as a TV transmitter has a 59.97Hz vertical component in it, which beats against the 60 in the wall. Those are becoming less and less problematic as the TV transmitters have moved to HD.

You may have a bad power supply in a piece of equipment that is radiating.

IF the noise is 60 (50) Hz and pure, it's a ground loop. If it's 120 (110) it's a power supply issue, if it sounds hummy and fuzzy, it's a combination of a ground loop and or PSU and or interference. If it's a sharp buzz, it's interference.

First tip:
Locate the source of the buzz bu walking around the room with the guitar and seeing if it's coming from a lamp, or some other device. Location the source and turn it off during the takes. In a live venue, you're toast. Use a gate out expander.

Second Tip:
Make a guitar cord or buy one that is marked GUITAR END and AMP END. These are balanced mic cables that at the AMP end, have the HOT tied to the tip, and the SHIELD AND LOW tied to the GND. At the GUITAR END, isolate/insulate the SHIELD (not used) and hook HOT to the TIP and LOW to the GROUND. This will balance the pickup so some degree. It helps a lot.

Third Tip:
Get a thin sheet of Mu Metal (Nickel) and cover it with contact paper so it doesn't scratch the guitar. Tape it to the back of it. It will block a lot of the interference. You can sandwich Nickel, Copper and Steel, insulating the Nickel and grounding the Copper and Steel to the guitar jack.

Forth Tip:
Have the guitar player rotate until he finds the null point and stay there.
 

JohnRoberts

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This is why they put various in the walls of studios. They are variable AC transformers that lower the voltage by turning it down.
Variacs..

===
The OP mentioned a new guitar amp noise but did not mention what guitar amp.

Some old school guitar amps with two wire line cords used stinger caps to "ground" (cough) the amp chassis cap coupled to the presumably quiet neutral. With balanced power that neutral will not be very quiet, but that would cause hum not buzz, so never mind.

JR
 

Youngwhisk

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Have you tried a different cable? Maybe there is an open shield? If you have one, put a guitar plug (no cable) without cover into to the amp and short tip and ring.
 

nielsk

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Try to find someone with an RF scanner, look at the guitar / amp noise on a scope and compare the results.
Of course, the correct way to troubleshoot this sort of problem is to turn off every circuit breaker in the building except the circuit the amp is on, then try a different guitar, then a different amp, then a different circuit.
Then try the amp & guitar in a different building.
Eliminate the variables.
Experiment with some shielding materials.
It does seem that this is likely a new airborne noise pollution with a very broad coverage, or a bad connection on the power mains or transformer (I have seen this several times).
In the US your power company is responsible for everything up to your meter base, get them to check all connections back to the transformer.
As to balanced power, the goal is to reduce common mode noise on the AC power system and it does work well for that, given that the secondary CT is properly bonded to technical earth (there is no consistent balance without this!)
 
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I'm located in more of a suburban area. I haven't noticed any new cell towers or anything in the area. However, assuming something like that is the case, what's the solution? I'm already using an isolation transformer/balanced power supply.
I think it’s worth looking into what Ike is talking about just to rule it out although it does sound more like 60Hz related.
There might be cell phone antennas around you that for years have not been causing you any issue but as soon as they switched to 5G in the 600MHZ range all hell breaks loose.
you can download a cell tower location app that will also tell you what frequencies they are transmitting at.
Try rotating the amp 360 degrees to see if there is a null in the noise.
It definitely might not be that but it’s easy to check. I now look into this possibility whenever a client brings up a new noise issue.

good luck!

Corey
 

DKatz

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Where are you located? If you are in the US or Canada, you could be picking up RF from newly deployed 600 MHz range cellular services. I have dealt with several studios that have had issues with this getting into condenser microphones and it wouldn't surprise me to see it getting into guitars. Are you in an urban area? If so have a look at nearby rooftops and see if they have new looking cell towers on them. The fact that the level stays the same when you move around the room does speak to something with broader coverage.
Listen to the recording. That's no cell signal.
 
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About 2 weeks ago I noticed a new guitar amplifier buzz in my studio. I have since tried multiple amp & guitar combinations and they all have this nasty buzz. We have dirty power in my area so I've been using a Furman P2400 AR & IT for balanced power or a Tripplite isolation transformer. This setup has been working great for the last 4 years, then 2 weeks ago this buzz started. Occasionally an amp will pick up a very faint radio signal too.

From what I understand, I shouldn't be getting any sort of power line interference with balanced power so I'm not sure what to look for next. Any ideas what could be causing a buzz when I'm using balanced power?

The buzz seems to be roughly around 1khz. It does go away when I turn down the guitar. I have moved the guitar all around the room and the buzz does not change like regular guitar buzz.
There are no power lines or anything obvious that could be causing enough EMF/RFI that would cause this buzz. I have disconnected everything one the circuit other than the guitar amp and the buzz is still there.
Here's an anecdote that I think is probably spot on for your situation. I was working as a tech at a major destination studio that was made up of a couple of wings of an estate. The native power condition in the area wasn't fabulous, but also not particularly bad. Never the less, the studio in question was entirely served by balanced power. It developed a buzz like the one you are describing. It was my job to figure out what was causing the interference and put an end to it. I set things up so that the studio was powered by an independent gas-powered generator. Then, got a Fender Precision bass that was known to be fairly sensitive to stray inductance and positioned it in the room for maximum buzz. I then proceeded to turn of the circuit breakers that served that wing one by one, beginning with the most logical ones: heating, AC, lighting, etc. None of these had any effect. I was finally down to one remaining breaker - for a bedroom at the other end of the wing. There was nothing in that room that should have been causing interference, but when I flipped the breaker, all went silent. I ran down to the other end of the building and peered into the room. There was a laptop computer with a charger plugged into the wall. I unplugged the laptop, turned the breaker back on, and the studio remained silent. What I learned from this was that noise induction is a LOT more insidious than I had previously thought. And that maybe a totally quiet studio was more of a mysterious blessing than one you count on in a premeditated way. The implication for you are that the EMI you are experiencing may have its origins in your neighbors house, or perhaps a local business.

If the nature of your buzz is that it is near 1KHz, that is pretty near 960Hz, which is a distant harmonic multiple of 60 Hz. And no, I don't have a sure-fire cure-all for this situation. In the case I've just described, we made it policy that any device with a wall-wart charger had to be preceded by power filter of some kind (could even be a power strip with a built-in filter). This did not totally eliminate the EMI, but it brought it down to a workable level.

So...good luck.
 

Newmarket

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Variacs..

===
The OP mentioned a new guitar amp noise but did not mention what guitar amp.

Some old school guitar amps with two wire line cords used stinger caps to "ground" (cough) the amp chassis cap coupled to the presumably quiet neutral. With balanced power that neutral will not be very quiet, but that would cause hum not buzz, so never mind.

JR

Yeah - you USA guys with your odd approach to AC Mains earth 🙄
 

CJ

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could be fallout from Hanford washing down the Columbia,

make sure you are not using a speaker cord for the guitar,
 

Ike Zimbel

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Listen to the recording. That's no cell signal.
I just did. It's not the "Morse code" DTMF tones that you will often hear if someone has a phone sitting on sensitive electronics and they get a call, text etc. but the noise that the new cell services cause, at least in condenser mics, doesn't sound like that either. I can't think of a good way to characterize the sound that I was hearing from the condenser mics, but when you think about it, the fact that an RF signal that is being transmitted at between 618 and 650 MHz (in 5 MHz swaths, no less) is coming out of a device that lives in the 20 Hz - 20KHz range, all bets are off as to what that will be demodulated as.
 

Mixermend

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It is now common to find systems producing noises that are 'floating' - or not tied to mains earth.

Think of a lap top connected to an audio interface fed with a guitar possibly via a DI Box.

These are all powered with external 'wall wart' PSU's - so nothing is connected to mains earth.

Often simply touching the sleeve of a jack plug to a water pipe or radiator - produces silence.......
 

fazer

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Maybe some body said this already but have you tried the amp and guitar on a normal circuit without balanced power? (Furman bal pwr should be turned off for test). Or other circuits in the house should be used with amp/guitar for testing noise pickup? Furman balanced power units a have built in displays that might be creating a buzz into the circuit they’re monitoring if they go possibly bad. Just a thought,
 

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Paul Wolff
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I guess no one read my post. and yes "VARIAC" sometimes spellcheck know better...

Most noises from a guitar have little to do with the AC gnd. The old "stinger" ground switch that John is speaking of actually worked well, though didn't make it any safer...

I explained how to make a balanced guitar cable. make one or buy one. It does help a lot.

Most cell phones won't cause interference in a piece of audio (they may right next to the guitar), their used to be an issue with AT&T or anyone with a similar network, where they used a sub carrier for tower communication, which was pulsed (that BDDT BDDT BDDT BDDT BDDT BDDT BDDT BZZZZZT sound). They used the pulsed or intermittent transmission of the data because the FCC has relaxed requirements about over modulation of intermittent transmissions, so they would over drive the transmitter to get a little more range, spraying harmonics everywhere, and they would show up in audio stuff.

Try the guitar cable, but first walk around the room with the guitar as a wand and find the source.

Also, make sure the bridge, nut, strings, the tension rod, the jacks, pickups and the pot covers are all grounded together.
 

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Paul Wolff
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By the way, you can do a much better power system than a "balanced power" system in the US. The European system is clean because it's balanced and has a clean ground. Here the power comes in balanced-ish, and then we screw it all up. Spending the money on balanced power is a waste, as a simple ISO transformer will accomplish the same thing. I previously wrote about how to wire your studio, (with an electrician's help) that can be as low as free to a few thousand dollars. I recently did the power system for a well know LA producer/writer, and for $2000, he cot everything he needed to make a clean studio. It was a 220 to 110 transformer, so all his outlets were on the same feed. Read the previous thread, and don't waste your money on balanced power systems.
 

Ike Zimbel

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Another thought and a couple of anecdotes:
When you say "there's nothing new" in the house, are you sure there's absolutely nothing new? No new light bulbs, appliances, public utility changes like them installing remote metering of electricity, water, gas consumption (all of which use cellular connections), alarm system, WiFi infrastructure etc?
Anecdote #1, big: I have a client who owns a recording studio in Halifax, Nova Scotia. Big, professional set-up with a Neve V 48 channel console, Studer tape machine etc. A few years back he reached out to me to say that the noise floor in the console had jumped dramatically over night. After a whole lot of "check this, look at that" back-and-forth I remembered that when I commissioned the console, it really didn't settle down until I connected the central ground point on the desk to the studio technical ground, a copper bus bar in the machine room that was tied to the building (an 1800's vintage warehouse) service entrance ground with #4 or #6 insulated copper wire. I asked the owner to verify the desk connection to the bus bar...all good. Then I suggested that he verify the run to the service entrance (which was three floors below) and, Bingo! There were some trades doing some renovations in the basement, and they had cut the ground wire because it was in their way :(. Reconnecting the ground wire fixed the noise issue.
Anecdote #2, small: I had a client who bought an Aurora Audio GTQC Rev Ten from me (that's the channel strip...mic pre, Eq and comp in 1-U), brand new (I'm the Canadian dealer / service rep). After he started using it, he reported a noise issue. This was a few years back and, again, I'm having a hard time characterizing the noise...it was faint, but it was there. He had bought that unit because he had a friend / mentor who already owned one so they exchanged units to see if the fault moved with the unit. The new unit was totally quiet at the friend's studio, and the friend's unit was totally quiet at his studio, and yet still exhibited the noise when he got it back. Well, this was enough to cause me to go and do a house call at his "studio"...the basement of his parent's home. As I was getting set up, I was looking for a convenient outlet to plug in my test set, while we were listening to the noise. There was some little white box plugged into the nearest outlet to his set-up and I asked if I could unplug it to power up my stuff. He said "ok", and the noise stopped as soon as I unplugged it. "It" turned out to be a shitty little WiFi booster that he was using to get better coverage down in his corner of the basement. Now, the reason his friend's unit was quiet when he tried it is that the friend had an earlier version of the GTQC...the Rev ten version has a "Blend" control on the front panel which the earlier version lacked. The Blend control requires an extra amplifier stage and the noise was getting into that amplifier.
So, the moral of both stories is: Sometimes changes happen that you didn't do, and sometimes things that you do not associate with your audio set-up (iow: not part of the signal path) are the source of your audio problems.

Since Paul's latest post came in while I was writing this, a couple of notes:
1) The OP has already stated that unlike the usual noise issues you get with guitars, walking around the room with the guitar does not change the level of the noise.
2) That he has tried multiple guitars, with hum-bucking pick-ups, so that tilts away from loose nut and other hardware issues on the guitar (although I'm a big fan of tightening hardware when noise issues arise so it wouldn't hurt to check that on ALL his guitars).
 

abbey road d enfer

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The European system is clean because it's balanced
in France, last remnants of balanced 2x110V were replaced with the standard unbalanced 220 (now 230 Eurovoltage) in the early 70's.
There maybe countries where it still exists but it's certainly not the case for new installations.
and has a clean ground.
At least in UK, France, Germany and Italy. I've read about horror stories in Scandinavia; in some places, the soil is hard stone, so the earth tag on sockets is strapped to neutral.
 

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