Wired Speakers Hum When PC Sleeps

Dell / Xps 8930
April 18, 2020 at 08:19:23
Specs: Windows 10, I5-9400
I have a set of wired speakers connected to the head phone jack of my Dell XPS 8930 tower.

When the PC enters sleep mode, the speakers begin to hum. This happens with both the front and rear panel jacks.

Is there a way to eliminate this hum, other than turning off the speakers or buying a pair of Bluetooth speakers?

Thanks!

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#1
April 18, 2020 at 08:57:28
Sounds like a ground/earth loop effect; or possibly due to a slight imbalance across the two phases of your house electrical distribution system.

Is the Dell plugged directly into the wall socket; or is it via an extension block or similar?

Similarly the speakers - are they mains powered too; and if so how are they connected to main - as above re' the Dell itself?

Is there any way to determine what else is plugged into the cct. which also controls your Dell tower?


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#2
April 18, 2020 at 10:23:44
Yeah, I kind of figured it was a ground loop issue. I know that I can buy either inline or clip-on eliminators. I may try that.

As far as incoming power, the speakers are plugged into a wall receptacle, the tower is on a power strip off of the same receptacle. I'll see what I can do about rearranging plugs to at least get them on the same strip or even the same receptacle.

I know everything that's on that circuit. It's all PC related equipment except for 3 lamps. They hum even with the lamps off, but I'll unplug them while the speakers are humming to see it makes any difference.

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#3
April 18, 2020 at 12:37:00
As is often the case with me, this is based more on
speculation than on a solid knowledge of electronics, but...
The speakers have built-in amplifiers, right? So when they
are turned on but not getting any signal from the computer
(including silence), they amplify the noise, right?

Do the instructions for the speakers say anything about
turning them off when not in use?

Oh, right! I thought this sounded familiar. I have a pair of
radio (pre-bluetooth) speakers that I haven't used in about
three years. They always made a horrible racket when the
transmitter wasn't turned on, or they weren't receiving the
transmitted signal. So they had to be turned off (or at least
the volume turned down) before turning the transmitter off.

-- Jeff, in Minneapolis


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Related Solutions

#4
April 18, 2020 at 13:35:39
Remember that in Canada/USA there are two live feeds running around the property; and they share (for want of a better term) the common neutral.

If the load on each live half of the "box" is equal there is no current in that shared neutral. But if there is an imbalance (even a small one) - i.e there is more current being drawn on one side of the box than the other - then there is a current in that shared neutral.

This gives rise to a situation which can be either:

When you touch the metal parts of anything drawing current from one side of the box (e.g. table lamps, appliances etc...) and they are "off" you may feel a slight tingle. Switch the item on and the tingle effect goes away. It can also be the other way around; not tingle effect when off but there when on...

(By tingle effect I mean a very mild electric shock sensation.)

Most people are't aware of it most of the time; as table lamps etc have non conducting switch controls; and appliances are usually likewise non conducting switch controls. But you could still feel the tingle if present regardless (of which condition exists as above) when touching the appliance etc..

Normally it isn't a concern... "unless" someone has a dodgy heart, or is using a pacemaker... At which point anything more than a "very" slight tingle (electric shock) effect might not be good news...

A side effect of this imbalance across the main fuse/cct. breaker box is that hum can arrive that way too. When I used to run power into an area where we would be shooting/recording a programme or whatever (using tv cameras usually - but sometimes film) that imbalance had to be monitored as we set up lighting - very carefully. This to avoid serious imbalances between the two phases. We usually used a Fluke clip around/ring meter to check the current in the neutral. If it was more than a trickle we shifted load from one half of the distribution breaker box (which was feed from the 3 phase bus bar for the area - usually...) to the other until we had a good a balance as possible...

The technical kit - cameras and audio - were invariably powered from that same breakout box...; so again that imbalance had to be kept to a minimum. And even then it was not "unknown"for the occasionally earth/ground to be lifted of a given bit of audio(rarely video) kit to lose a detected hum...

Switching lighting kit on/off might still cause imbalances - albeit minor and briefly if the light went on or off at any time thereafter... When possible technical kit - audio especially - was fitted with a hum bucker to (hopefully) minimise any possible hum that might arise... Usually it got rid of the lot.

So you need to check what's on each half of the main fuse box and see if you can spot anything that loads one side more than the other; a slight difference ought not to be an issue; but a significant one...?

Another option... If the speaker power has a two pin plug... turn it around (rotate 180 degrees) and re-insert into wall outlet; that sometimes resolves minor hum problems...

Another is to attach a ground wire from the speaker power unit chassis to the case or main chassis of the Dell. That too sometimes works. A lot of amplifiers have a ground/earth terminal post the back panel for such a purpose (often connected between a turntable and the amplifier). Sometimes it's needed and sometimes better without that connection; regardless of the fact that both bits of kit will also have their own ground/earth pin connection too..

Another approach - presuming your Dell tower has power outlets at the back - and my tres elderly '98 vintage Dell Dimension tower had at least one (possibly two) - plug the speaker power unit into one fo those outlets? This would ensure that both bits of kit have the same ground/earth cct.

If those outlets exist and are hot when the front on/off button on the tower is "off" fine; your speakers will still get power if needed... I have seen tower systems where there is also a true on/off switch at the back - and logically you would leave that "on".

Pre ATX boards and later... the on/off switch on any computer was a true "on/orff". When "off" there were no volts and no current running around in the system. Cometh ATX boards and that all changed. And Dell were one of the first to go that route. The front switch merely powers down parts of the system; and leave the psu still delivering power around parts of the system... (wake on LAN requirement to say the least) and you have to either use a rear panel (usually) on/off switch to kill power completely - or remove the power cord from the wall outlet or the computer.

Always remember that if you want to go inside any ATX - or later - system, first you totally remove incoming power; as otherwise you run serious risk of damaging chips which likely will still be"powered" (RAM especially)... And with laptops that means removing the battery too.

Sorry to digress a little; but trying to cover possible and known causes of hum between bits of electronics...

One other approach... and it's used on occasion... get a U-ground adapter which allows you effectively to not earth/ground either the speakers or the Dell; I'd go for the speakers.

It has a two pin plug (the adapters I've seen/used are usually grey...). The input/socket is three pins - live/neutral/earth (ground). The ground pin is not connected internally in the adapter - should you insert a three pin plug (live/neutral/ground). There is a flying lead (green usually) which is attached to the ground pin within the adapter and that (when a ground pin is required) is attached to one of the mains socket wall plate screws. I've seen them at Home Depot, Target, most supermarkets and so on; and as best I know they're still available. I have a couple in my travel kit for when I invade the USA - from the UK; or visit my adopted country north of the 39th Parallel/border.

Using one of these might well do all you need to do?


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#5
April 18, 2020 at 15:02:39
Thanks for all that info. Just so you know, I am pretty familiar with residential wiring, having pretty much rewired my own house (and others), installed generator inlets, generator interlock kits, etc. I even had, for reasons I've never understood, a single Edison circuit in my house. With about 20' of 14/2 cable they could have split the circuits at the panel, but for some reason they ran a 3 wire cable to a junction box and split the circuits off of that. I eliminated that soon after moving in.

As far as balancing the load on the panel buses, I already took care of that (as much as reasonably possible) when I installed the generator. Even though I don't need to run the entire house off of the generator, I rearranged the panel to even out the load as much as possible, concentrating on the most important circuits first (kitchen, bathrooms, freezer, furnace, etc.) and then filling in as necessary.

On the other hand, when is the load ever really balanced? When I power up the table saw and dust collection system, I'm not checking to make sure that there is enough load on the other bus to even it out. (I was careful enough to put the shop lights on their own circuit. Wouldn't want to get plunged into darkness if a machine trips a breaker.)

Back to the PC...

No power receptacles on the tower. However, the speakers don't have a grounded power cord, so the only ground is in the speaker cable. I'll see if I can rotate the plug as soon as I get a chance to crawl behind the hutch to reach the extension cord. No ground on the power cord also eliminates to need to try the grounding adapter on the speakers.

I'd prefer not to eliminate the equipment ground for the PC.

Running a dedicated ground between the speakers and the PC chassis is an option, although the speakers are on the opposite wall. Just means a long ground wire, that's all. Oh, yeah, the speaker case is plastic, so I'd have to open it up to find a suitable ground.

For some reason, I think I see Bluetooth speakers in my future. ;-)

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#6
April 19, 2020 at 08:53:15
I went across the load balancing issue more to ensure that "anyone" reading this post (later via whatever link) would be aware of "some" of the issues that might be involved.

Clearly olde DD is well aware of all of that...; and if into generators too then even more than many might be. There is specific category, specialisation for those running generators for outside broadcast (aka remotes in N. America); they have to be very aware of all manner of issues and load balancing is just one... I invariably left the chap with the generator to do what he knew best and took advice from him whenever detected more than a slight imbalance.

It is true that in most domestic situations there will inevitably a slight imbalance most of the time - and with the possible tingle effect too. But unless that tingle is more than barely there it's seldom an issue to be overly concerned with.

Back the speaker issue.

I was suggesting a single cable connection between the speaker amplifier chassis (if exists) and the PC tower chassis; not between the speakers and the PC tower. The speakers get their common return/ground (+ and -/ or red and black or whatever) connection from the amplifier; and that return is not always linked to the amplifier chassis - it can be totally isolated depending on the amplifier design. But in most domestic, and some pro kit, one side of the speaker feed is usually tied to the amplifier chassis.

It's unlikely the speaker cable run is picking up mains hum unless those wires/cables run very close too and alongside a live mains lead. Should that be situation then one has to move them further away from each other. If they have to cross each other, usually best at 90 degrees.

There are shielded cables around which sometimes solve the hum problem; but that approach requires that the speaker feeds are such that they are not in anyway directly tied to the ground/chassis of the amplifier. The speaker outputs being fully isolated (transformer or a suitable IC component); much as a balanced microphone is similarly screened. Balanced mics use a three pin connector; two for the mic and one for the shield. The mic's two wires connect to a transformer (or possibly an IC these days as well) in the amp/pre-amp and are thus the mic is isolated. The amplifier or pre-amplifier supplies the ground connection for the third wire/the shield on the cable. And on a serious rig audio out (the PA) will be screened/isolated feeds too; again using the same approach as for mics in...

If you start to hear cable noise (mechanical etc.) on a shielded mic cct... time to check that mic's cabling... as likely the grounded shield connection has failed.


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#7
April 19, 2020 at 11:26:40
(Edit: This was written and posted while trvlr was writing and posting his latest response. There is some overlap in the concepts discussed.)

I found the cause of the hum. It's not something that anyone trying to diagnose this from afar could have figured out. Ready?

It's my in-tank aquarium filter.

As noted earlier, the speakers are on the other side of the room from the PC, specifically they are behind me. Therefore, there is a long 3.5 mm aux cable that runs from the PC, along the side wall to the speakers on the back wall. I wanted to see if moving that cable around, perhaps away from the various AC cords, might help. Things were a bit tangled up under the desk, so I unplugged the aquarium filter from the power strip just to get the cord out of the way and the speaker hum stopped. I then plugged the filter back, hum came back on. OK, source found.

I then tried moving the speaker cable away from the filter, the AC cords, etc. Little to no change in the hum. Unplug the filter, hum gone.

Last test: grab an extension cord and plug the filter into another circuit. No help.

Then I discovered something really interesting. I unplugged the filter from the extension cord and the hum stopped, as expected. The extension cord is a heavy duty, outdoor 12 gauge cord with nice thick insulation. I held the 3.5 mm plug on the speaker cord between the fingers of my right hand and picked up the extension cord with my left, touching only the insulation. The extension cord was plugged into the wall, but nothing was plugged into it. The speakers were plugged into a different circuit, but the speaker cord was not plugged in. The speaker hum came back. Repeatable. Fun stuff.

My next step is to try either an in line ground loop isolator or a few of the clip-on type. I haven't decided yet.

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#8
April 19, 2020 at 14:17:32
How long is the cable to the speakers?

Is it relatively thin cable too?

If the ground pin interrupt doesn’t resolve the problem, then a pair of theses ought to?

https://www.amazon.co.uk/gp/product...

Set one to transmit, t’other to receive - via bluetooth.

I think they’re available in Canada/USA as well as the UK.


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#9
April 19, 2020 at 16:27:34
re: "How long is the cable to the speakers? Is it relatively thin cable too?"

Relative to what? ;-) Thick relative to a human hair, thin relative to my 20A generator cord.

To be specific, it's one of these, diameter is 4 mm:

https://www.radioshack.com/collecti...

Plus there's another 5' of cable that's owned by the master speaker of the pair. Relatively thin zip cord. ;-)

re: "If the ground pin interrupt doesn't work..."

What is your definition of a "ground pin interrupt"?

Googling that phrase returns not much more than Arduino, Arduino, Arduino, Arduino hits.

Are you referring to the ground loop isolator?

re: A pair of Inateck Bluetooth units (which don't appear to be available in the US)

The Win 10 system has it's own Bluetooth transmitter, so I might as well just try a single receiver, like this:

https://www.amazon.com/Anker-Sounds...

I like Anker products, so I think I'll order one of those and hope for the best.


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#10
April 19, 2020 at 17:38:09
In reverse order...

Like you I like Anker products, but have used this Avantree device as an excellent receiver:

https://www.amazon.com/gp/product/B...

The Inateks are dual function/switchable as rx or tx, which is why I like them. Gave a pair to a university professor (a friend) when he visited UK last fall. Allows him to connect his Mac and iPads into any sound system where he maybe lecturing. Easier than assorted cables trailing wherever.

A review of the Avantree was very favourable when I was researching such devices for elderly friends in SLC a couple of years ago. He has a “very” expensive hifi system... but this adapter was to allow their iPads to feed into his amp... I plugged into an adjacent mains outlet, ran a better quality mini jack cable from it to his amp - et voila... Amazon have a range of better quality mini jack cable - various brands. Ugreen, and Cable Matters are two who come to mind

Ground interrupt referred to the (grey?) 2 pin adapter with a fling ground lead, and which accepts standard U-ground 3pin plug but doesn’t allow the ground pin to make entry into a standard 3 pin mains socket.

Typical mini jack plug cables are no more than 5 mm in overall diameter; some maybe 10mm including outer sheath and the 3 inner insulated cores. Those latter often nor more than about 3mm each...

The signal loss over more than say 5-6 feet isn’t usually a problem, but the quality of an analogue signal depends on the diameter of each core, and nature of the actual metal in the conductors. The bigger (the diameter) of a conductor the less the signal loss and better the quality of the analogue signal when it gets to its destination. Cheap, thin twin cable is often bundled with less expensive audio systems; but any hifi techie will always advise heavier (larger cores) cable; and the better the cable... the more it costs.

The Radio Shack cable isn’t the best... and a 20 foot run of it, plus the 5ft “zip wire” added on is really not an ideal combination. Some RS mini jack plug cables are in effect shielded - the common ground/return for the left/right Stereo channels/speakers being the screening on that cable. Problem is the connectors are plastic-and not shielded. Metal plug/sockets are better as they are screened by being connected to the common ground/return.

When I was installing conference audio systems - recording, PA, and simultaneous interpretation systems too, we used metal mini jacks if possible. Main mics were always balanced (Canon XLR or equivalent) cabling and then a balanced to unbalanced adapter into an unbalanced (two conductor) mixer input, if no balanced input available.

Serious PA could be unbalanced from the amp via an unballanced to balanced adapter onto a balanced (three conductor) cable which used XLRs at both ends. The link to the speakers from the 3 conductor (balanced) cable was again an adapter to unbalanced - think typical stereo jack sockets. RS used to have their own brand, pretty decent XLR kit, often cheaper than say Canon, and a useful resource in emergencies. I still have (somewhere) my own standby emergency audio adapter kits; mostly top grade Canon, or Switchcraft(?), but some also from RS.

http://www.switchcraft.com/Category...

https://www.radioshack.com/search?q...

You could, if your proposed tests don’t resolve the hum, go for a balanced (XLR ends) cable for the 20ft run and then adapters at both ends to connect to the speakers and amp outputs?

But the bluetooth option would likely be more attractive, as it dispenses with the 20ft cable run (be it balance or not); and that would be my option if full hifi isn’t the final goal.

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#11
April 19, 2020 at 18:44:18
re: Ground interrupt referred to the (grey?) 2 pin adapter with a fling ground lead, and which accepts standard U-ground 3pin plug but doesn’t allow the ground pin to make entry into a standard 3 pin mains socket.

My adapters are orange. I might have a grey one someplace, but not sure. ;-)

I don't see how they would apply in this situation. As I mentioned in an earlier response, the powered speakers do not have a grounded plug.

In addition, the source of the hum - the aquarium filter - also does not have a grounded plug.

The only device in this equation with a grounded plug is the PC tower and I do not want to lose the equipment ground by using the adapter.

re: "amp outputs" and "any hifi techie will always advise heavier (larger cores) cable"

I should have mentioned long ago that there is no "amp" other than what is inside the master speaker of the pair. The speakers in question are an older pair of JUSTer computer speakers, which is all I need for this system. No need for 12 AWG speaker wire or 4 AWG power and ground cables. This isn't like the sound system in my minivan:

https://www.youtube.com/watch?v=lUW...

Kidding!

In any case, I just ordered the Avantree device. I'll let you know how it works out.

Thanks for all the info and the interesting conversation.

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#12
April 19, 2020 at 20:47:06
It might be easier to get a slightly better aquarium Filter set up that does not output interference.

You have to be a little bit crazy to keep you from going insane.


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#13
April 20, 2020 at 04:20:31
Easier than ordering a Bluetooth receiver?

How?

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#14
April 20, 2020 at 07:12:18
Blootoof receiver can of course be repurposed anon...

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#15
April 20, 2020 at 09:00:17
I take it that the "hum" comes from the AC power, and the
aquarium filter just acts as a transmitting antenna or some
kind of inducting element for the speakers to pick up and
amplify. Right?

You could further experiment both to find out what part of the
aquarium filter is transmitting and what part of the speaker is
picking up that signal.

I mentioned here just a few weeks ago that I once had a Sony
reel-to-reel tape recorder that eventually had the sound of a
local AM radio station coming out of the recording/playback
head. I don't remember identifying the station.

-- Jeff, in Minneapolis


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#16
April 20, 2020 at 10:05:58
"You could further experiment both to find out what part of the
aquarium filter is transmitting and what part of the speaker is
picking up that signal."

I just spoke to Occam. He said to try the BT receiver first. If it works, move on to more important things.

Then he gave me a KISS. ;-)

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#17
April 20, 2020 at 13:22:05
Incidentally the other reason - apart from good reviews - I chose the Inatek tx/rx system was that it doesn't have an external aerial/antenna. One appendage less to either lose or have "snapped "orf..." Plus the option to use a module in either role (tx or rx).

BT - ??? British Telecom is now in the USA? How dun that happen and does AT&T and the others know about it?


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#18
April 20, 2020 at 13:37:29
Chose the one that you feel is most appropriate for this thread:

BT BitTorrent
BT British Telecom
BT Bhutan
BT Bergens Tidende
BT Bacillus Thuringiensis
BT British Telecommunications
BT Bluetooth
BT Back Trace
BT Booker T (the R&B singer, not the WWE wrestler)
BT Basic Training
BT Black Tie

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#19
April 20, 2020 at 14:30:34
It was too good to resist...

Occam techie however did give you a good suggestion...


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#20
April 20, 2020 at 18:27:37
I stay away from characters wielding razors.

But I love to disassemble things. I'm sometimes able
to get them back together without breaking them, too.

-- Jeff, in Minneapolis


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