Guitar amp buzz even with balanced power supply. Help!

[murrayatuptown]

4 guitars.
I might have missed if you said you did, but were different instrument cords tried also?

I have no experience with balanced power as a product feature, but had hum with an integrated amp many years ago. I found using (not recommending) a 3-2 wire ac plug adapter to lift the ground of the integrated amp, which in those days was the only piece of gear I had with a 3-wire cord no hum.

I added an 8' ground rod under a rain gutter connected to the smaller diameter (and surely shorter) existing one. I dumped some rock salt around the new ground rod.

Nothing changed, so I figured it was a quirk of the integrated amp.

Until we had our home's AC service upgraded from 60A (Edison base screw-in fuses!) to 150 A. That required a new service 'drop' cable from the utility pole.
The electrician said the ground wire from that was corroded and only hanging on by a few strands. He was surprised it was in that condition.

I tried the integrated amp with its grounded cord and the problem was gone.

I think the moral there is not what specifically had degraded, but that something did which was just fine previously.

Seeing other comments about interference from seemingly unrelated electronic devices, I'm reminded that SMPS type devices, which include a wide variety of hf converters and integral ballast bulbs (fluorescent and LED), motor drives, etc, experience degradation of electrolytics on the hf converters more frequently than the offline (60 Hz source, 120 Hz ripple) rectifier filters. It's common to not know until the power supply is working poorly or not at all. I wonder what secondary features degrade before the SMPS device completely fails (any type of EMI/EMC changes due to interaction between the line freq. and hf ripple).

What you CAN check in the Vox amp (after confirming safe discharge of HV/HT) is that grounding hardware hasn't loosened.

 

[JohnRoberts]

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.

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.

It is worth repeating that "bootleg grounds" (to neutral) can be dangerous. If that neutral path inadvertently opens up, that chassis and anything connected to that safety ground will be energized by current flowing from the mains trying to get to a lower potential.

Using neutral as an appliance ground was common practice (my house does not have safety grounds). As I recall several years ago when I installed my new wall oven the instructions advised the "bootleg" connection when a separate safety ground was not available.

JR

 

[Ike Zimbel]

Until we had our home's AC service upgraded from 60A (Edison base screw-in fuses!) to 150 A. That required a new service 'drop' cable from the utility pole.
The electrician said the ground wire from that was corroded and only hanging on by a few strands. He was surprised it was in that condition.

I tried the integrated amp with its grounded cord and the problem was gone.

I think the moral there is not what specifically had degraded, but that something did which was just fine previously.

Seeing other comments about interference from seemingly unrelated electronic devices, I'm reminded that SMPS type devices, which include a wide variety of hf converters and integral ballast bulbs (fluorescent and LED), motor drives, etc, experience degradation of electrolytics on the hf converters more frequently than the offline (60 Hz source, 120 Hz ripple) rectifier filters. It's common to not know until the power supply is working poorly or not at all. I wonder what secondary features degrade before the SMPS device completely fails (any type of EMI/EMC changes due to interaction between the line freq. and hf ripple).

What you CAN check in the Vox amp (after confirming safe discharge of HV/HT) is that grounding hardware hasn't loosened.

Both good points. With the power company, everything is fine until it isn't. I have seen crimp connections (this is how it connects from their wires to the mast outside your house) fail on one phase and fail on the neutral. And in one studio that was in an old one-room schoolhouse out in the country, no ground connection at all. Having said that, if it was a failed or bad connection on a phase or the neutral, you would probably be seeing it on other devices / appliances / lighting in your house. A degraded ground connection, not so much.

 

[Newmarket]

This may not apply to the OP's situation. But it's always worth thinking about problems coming from an adjacent room whether part of your property or otherwise.
It's just easy (I speak for myself !) to ignore stuff that can't be seen. I recall playing (Bass/Drums/Guitar) in a friend's house where the guitar amp would glitch every few seconds or so. Having tried tracing it to anything in the room and our phones etc. - eventually thinking 'outside the room' led to the culprit being a TV Satellite box thingy downstairs not even in adjacent room.
But SCR dimmed lights can be in the room directly below. And if that room is a separate flat then you're a bit stuck to confirm it.
Also - the LED lighting can be problematic depending on the type and design. I have an 'EMC' friend who did a lot of testing on this and showed severe CE EMC non-compliance issues. But appetite for enforcement or remedial action is low - in UK at least. As for WiFi over mains cabling...don't get me started !

Back to the OP - it would be good to hear back how the cable configuration suggested by @FIX works out in this situation.

 

[Ike Zimbel]

Here's another idea: Do you have a DI, preferably a good quality, active DI that you can plug your guitars into and record the result? That would take the amp completely out of the equation. If so, and the noise persists, then it would be time to try some more advanced cable options, as suggested by Paul Wolff.
The condenser mics having RF issues that I mentioned earlier all improved when connected via a StarQuad cable with a Neutrik EMC connector on the female end. I'm thinking that such a cable with XLR-1/4" adapters on each end might work...but, the adapters might negate the good work that the EMC connector is doing. You could also try ferrite clamps around the guitar cable at the guitar end, or even both ends.

 

[Timjag]

Is the neutral tied to ground on American power these days, like in the UK? Seems to me you can never really escape it. I do get that sound on guitar amps here, it’s intermittent. I think it’s a dimmed LED lamp from the practice room next door because it’s worse when he’s teaching in there.
It’s annoying but given the volume guitar amps run at it doesn’t cause me problems, but yes it’s bugs

 

[JohnRoberts]

Is the neutral tied to ground on American power these days, like in the UK? Seems to me you can never really escape it. I do get that sound on guitar amps here, it’s intermittent. I think it’s a dimmed LED lamp from the practice room next door because it’s worse when he’s teaching in there.
It’s annoying but given the volume guitar amps run at it doesn’t cause me problems, but yes it’s bugs

In the US safety grounds are bonded to neutral only at the breaker panel.

Inadvertent ground-neutral shorts can contaminate grounds and are discouraged.

JR

 

[Newmarket]

TMI ???

https://www.google.com/url?sa=t&sou...0QFnoECDwQBQ&usg=AOvVaw26kelTDntsYVAxlP3FoPhX

EARTHING: YOUR QUESTIONS ANSWERED

 

[JohnRoberts]

TMI ???

https://www.google.com/url?sa=t&sou...0QFnoECDwQBQ&usg=AOvVaw26kelTDntsYVAxlP3FoPhX

EARTHING: YOUR QUESTIONS ANSWERED

That article references some UK or EU? regulations (they don't say which).

Ground bonding to copper plumbing is archaic as most modern construction uses non conductive pipes. I added ground wires between my copper and fuse box (old house) because several years ago I was getting shocks from my hot water heater when it tried to kill me.

JR

 

[Newmarket]

That article references some UK or EU? regulations (they don't say which).

Ground bonding to copper plumbing is archaic as most modern construction uses non conductive pipes. I added ground wires between my copper and fuse box (old house) because several years ago I was getting shocks from my hot water heater when it tried to kill me.

JR

UK - It refers to BS 7671 (BS = British Standard) and is from the IEE - although that doesn't now exist in its own right. It's now part of the IET.
As it happens I'm a member meaning that I think I can get a free coffee and can access the facilities in central London. But as it's usually a Mon-Fri office hours thing I never do.

Agreed that relying on conductive plumbing is fraught with danger. There are quite a few tales of bonding to copper pipes - then some plumbing further down the line gets replaced with 'plastic'...

 

[JohnRoberts]

I abandoned my membership in IEEE and AES last century. I had piles of unread journals that I told myself I would read when I got old... then I got old and said nah. I ended up shipping about 20 pounds of old journals to PRR, the only forum member who expressed any interest in them. One of the boxes apparently broke apart during shipping and several journals that still had mailing labels on them came back to me like bad pennies.

JR

 

[radardoug]

I think this topic has gotten off track. Like most problems with noisy guitars, its the guitar that is the problem. It has nothing to do with earthing. If you wave a coil around in an electrically noisy environment, it will pick up noise.
So could the OP please do the following tests and advise of the results.
1/ Turn on amp with all volumes down, and no guitar plugged in. Is it noisy?
2/ Plug in the guitar but with volumes down, is it noisy?
3/ With volumes on the guitar down, turn up the amp volume. Is it noisy?
4/ Turn up the volume on the guitar.Is it noisy?
His answers will clearly show us where the problem lies.

 

[Newmarket]

I abandoned my membership in IEEE and AES last century. I had piles of unread journals that I told myself I would read when I got old... then I got old and said nah. I ended up shipping about 20 pounds of old journals to PRR, the only forum member who expressed any interest in them. One of the boxes apparently broke apart during shipping and several journals that still had mailing labels on them came back to me like bad pennies.

JR

Yes - UJS - "Unread Journal Syndrome". Just to be clear IEE/IET is a different organisation to IEEE.
There are just to many "E"s in all these institutions. But as I write there's an unopened IET magazine in the hall...
wrt AES - I was never a member when I actually worked in Pro-Audio. But I was an Associate member for a while after that. The UK end used to have regular events / presentations in London.
Some were very good. Others not so much - well I'm not really interested in audio for Video Gaming.
They were generally open to public but it felt polite to have some sort of membership and also have access to some resources. I'm not sure what the situation is atm. Pre-Covid they had already tended to have events outside London - esp Southampton and York IIRC. Hard to argue against that tbh but I used to work near Gatwick airport so it was just about practicable to make some events in London. I work further away now so probably wouldn't get to them anyway. But maybe I'll check it out anyway.

Yes - I know this is way off OP topic !!!

 

[abbey road d enfer]

I think this topic has gotten off track. Like most problems with noisy guitars, its the guitar that is the problem. It has nothing to do with earthing. If you wave a coil around in an electrically noisy environment, it will pick up noise.

I disagree; guitar pick-ups are high-impedance, so they are also sensitive to electrostatic fields. An ungrounded guitar rig may result in establishing a significant electrostatic field between guitar parts and objects that are grounded.

 

[Brian Roth]

I don't recall if this suggestion has been mentioned in this thread. Use a battery operated radio that covers the AM/"medium wave" band. That would cover 530 KHz to 1.7 MHz in the USA....the band with all the local Talk radio programs. Tune around at the low end of the band to find frequencies that aren't occupied with the local Taking/screaming yahoos and see if you hear similar noise problems (besides the screamers....lol!).

Radio must be battery powered for this test. I've used the radio in my car a few times to verify "something is in the air".

Bri

 

[radardoug]

I disagree; guitar pick-ups are high-impedance, so they are also sensitive to electrostatic fields. An ungrounded guitar rig may result in establishing a significant electrostatic field between guitar parts and objects that are grounded.

Noisy environment is magnetic AND electrostatic fields. And I think you will find if you follow my testing suggestions, that problem will show up.
But most guitar problems occur with magnetic fields.

 

[[email protected]]

Ridiculous claim.

I was repeating what I had been told. I may have misunderstood.

 

[[email protected]]

Hey everyone, thanks for all of the advice. I didn't have time to continue troubleshooting the buzz for a few days but when I went down to the studio today the buzz was miraculously gone. Everything was plugged in just as I left it when the buzz was there. I may never know what the cause was but I hope it stays away. A neighbor did tell me that he saw some power company trucks a few blocks away doing work around the time this started.
Anyway, I'm definitely bookmarking this thread in case it comes back. Thanks!

 

[JohnRoberts]

maybe you scared it away..... It may return, but now you have more tools.

JR

 

[FIX]

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.

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.

Yes, the real "ground" has to be conductive... We supplies remote mic pres to record OASIS at Wembley in 1997, their was a buzz in the all mics, turns out that because of noise here, we lift pin one from the AC ground and let the Truck ground it, but over there when we tied pin 1 to Earth, the noise was gone. The truck (Manor Mobile) used earth for mic ground returns. Now thats how it's done...