Speaker interference - advice please

[BlueStringPudding]

I would love some advice please on how to get rid of interference noise coming from some speakers.

 

The previous owner of my boat must have been really into his music because there are 12v speakers built-in all over the place. Two large speakers are wall mounted behind where I now have my tele, so I decided to try and make use of them. I bought a 12v amplifier and got advice from the makers of the tele to connect it to the tele via its headphone socket.

 

The tele, amplifier, booster aerial and satellite receiver box are all connected to a new switch panel and the negatives all run through the same bus bar.

 

When I initially tested the set-up using the original and rather knackered speaker wiring, although I got good sound from the speakers, there is also noticeable interference - a humming tone which is very annoying.

 

So I thought it best to replace the speaker wiring and give them new spade connectors. When the tele and amplifier are both on, the humming sound is still there. It goes away when I pull out the power plug from the tele even though the amplifier is still on and connected to the speakers. The power plug to the television is immediately next to its headphone socket, if that's relevant.

 

The humming sound doesn't go away when other close-by electrical items such as the 12v booster aerial, the satellite receiver box or the nearby bilge pump switch is disconnected. 

 

The only other electrical item in the area - and it's about 20" away on the opposite wall of the cupboard in which the electrics are sited - is the MPPT controller for the solar panels. Whether it's daylight or dark outside, the humming sound is still present whenever the amplifier and television are both switched on. So I doubt anything from the solar panels is causing the interference.

 

Any suggestions please as to what exactly is causing the interference noise and why, and how to stop it?

Thanks. 

[GUMPY]

Its caused by a ground loop.

You need something like this

 

https://www.djanddiscostuff.com/consumables-cables-c92/accessories-tools-c198/ground-loop-isolator-rca-plugs-rca-sockets-p4896/s5167?utm_source=google&utm_medium=cpc&utm_term=av-link-ground-loop-isolator-rca-plugs-rca-sockets&utm_campaign=product%2Blisting%2Bads&gclid=Cj0KCQiAwc7jBRD8ARIsAKSUBHKcccHzi38pk2TPr-SHYGo3pcvxUf_sAQtqkeKym_hfCdkdvyYMhbMaAq_CEALw_wcB

 

Between the TV and the amp.

 

It's basically an isolating transformer between the two

 

I may have one in my junk box at the cottage what connectors are on the TV and amp?

Edited February 25, 2019 by Loddon

[WotEver]

It certainly sounds like a ground loop to me. 

[BlueStringPudding]

44 minutes ago, Loddon said:

Its caused by a ground loop.

You need something like this

 

https://www.djanddiscostuff.com/consumables-cables-c92/accessories-tools-c198/ground-loop-isolator-rca-plugs-rca-sockets-p4896/s5167?utm_source=google&utm_medium=cpc&utm_term=av-link-ground-loop-isolator-rca-plugs-rca-sockets&utm_campaign=product%2Blisting%2Bads&gclid=Cj0KCQiAwc7jBRD8ARIsAKSUBHKcccHzi38pk2TPr-SHYGo3pcvxUf_sAQtqkeKym_hfCdkdvyYMhbMaAq_CEALw_wcB

 

Between the TV and the amp.

 

It's basically an isolating transformer between the two

 

I may have one in my junk box at the cottage what connectors are on the TV and amp?

The television has a headphone jack socket, SCART socket (although that would be in use if the satellite receiver box was connected, it's not currently being used but I'd rather not block use of that socket), a PC Audio In jack type socket, a blue VGA socket and a HDMI socket. There's also a USB socket but the maker didn't suggest using it for audio, I suspect it's for input only but I'm not sure.

The amplifier has a headphone jack input socket (I've bought a cable that has a headphone jack plug at both ends to connect the amplifier to the tele as Cello, the maker of the tele advised). The amplifier also has input sockets for red and white audio type plugs but the tele doesn't seem to have these.

[BlueStringPudding]

Would this sort of thing work connected to the headphone jack cable that I've already bought? 

 

https://www.amazon.co.uk/Besign-Ground-Isolator-Stereo-System/dp/B06XQYN77L/ref=mp_s_a_1_1?ie=UTF8&qid=1551131605&sr=8-1-spons&pi=AC_SX236_SY340_FMwebp_QL65&keywords=ground+loop+isolator&psc=1

 

Edited February 25, 2019 by BlueStringPudding

[stegra]

When I read the thread title, I immediately thought of the solar controller. I had problems with interference on my campervan. I never managed to cure it, just had to make do without the ancillary speakers. Perhaps you can check it by disconnecting the controller from the batteries. Do it when it's dark or cover the panels. The controller won't like being connected to the panels alone. 

[GUMPY]

8 hours ago, BlueStringPudding said:

Would this sort of thing work connected to the headphone jack cable that I've already bought? 

 

https://www.amazon.co.uk/Besign-Ground-Isolator-Stereo-System/dp/B06XQYN77L/ref=mp_s_a_1_1?ie=UTF8&qid=1551131605&sr=8-1-spons&pi=AC_SX236_SY340_FMwebp_QL65&keywords=ground+loop+isolator&psc=1

 

Looks the sort of thing that will sort it.

Cheap enough to try it.

[Chewbacka]

Have you tried turning the tv up very loud and the speaker amplifier set fairly low that would improve the signal to noise ratio going into the amp.

Also are you using screened cable between the tv and amplifier? if not that might help.

[Jess--]

I found that my tv (also cello) had a low level buzz (not a hum, more like the low throb of an engine running somewhere) on it's audio at all times which seemed to be caused by the backlight, I didn't get to the bottom of whether it was actually in the audio directly or was being induced onto the audio ground line.

I ruled out ground loops by temporarily running the audio amp from batteries, which made the audio ground the only link anywhere between the amp and any other equipment.

 

for me the simplest solution was to switch my audio feed from the tv to the computer since the computer was already handling everything, I have usb tv tuners setup allowing the computer to run as a full pvr system capable of recording & playing multiple channels at the same time so never actually use the tuner in the tv

Edited February 26, 2019 by Jess--

[Tony Brooks]

11 hours ago, stegra said:

When I read the thread title, I immediately thought of the solar controller. I had problems with interference on my campervan. I never managed to cure it, just had to make do without the ancillary speakers. Perhaps you can check it by disconnecting the controller from the batteries. Do it when it's dark or cover the panels. The controller won't like being connected to the panels alone. 

No, No, and NO again. Unless the controller manual specifically says you can do this DO NOT. The basic rule is NEVER have the panels connected to the controller without the batteries. Connect the batteries first, then the controller.

 

So by all means disconnect the panels (one wire will probably do) and then the batteries and replace battery cable first then controller but never just disconnect the panels. If you do you may find the controller decides that you are running a 24 volt system and then 12V batteries will get very upset.

[WotEver]

11 hours ago, BlueStringPudding said:

Would this sort of thing work connected to the headphone jack cable that I've already bought? 

Yep. 

[BlueStringPudding]

34 minutes ago, WotEver said:

Yep. 

Thanks 

[BlueStringPudding]

1 hour ago, Chewbacka said:

Have you tried turning the tv up very loud and the speaker amplifier set fairly low that would improve the signal to noise ratio going into the amp.

Also are you using screened cable between the tv and amplifier? if not that might help.

Fascinating about the volume thing - thanks -  that does indeed reduce the interference noise but not completely. However, if I want even 30% volume from the amp and speakers, the interference noise can still be heard clearly.

 

I'm using the only cable on Amazon I could find that I could tell had the correct plugs and that can be delivered to my local Amazon locker, since I can't receive post on the boat (that massively reduces choice of sellers).  I don't know exactly what screened cable is but I doubt that what I have is screened, I expect it would have said on the packaging. 

 

 

[BlueStringPudding]

12 hours ago, stegra said:

When I read the thread title, I immediately thought of the solar controller. I had problems with interference on my campervan. I never managed to cure it, just had to make do without the ancillary speakers. Perhaps you can check it by disconnecting the controller from the batteries. Do it when it's dark or cover the panels. The controller won't like being connected to the panels alone. 

Thanks. If I disconnect the panels and find that was contributing to the interference, then doesn't that leave me with the quandary of having to choose between using the amp and having solar power? I would rather simply be able to turn the amp on and use it, than have to empty the cupboard to get to the solar controller, and get a screwdriver to disconnect solar panels every time I want to play music or watch a film with decent sound.

Apart from being a faff that I've not got the energy or inclination to go through repeatedly, wouldn't it damage the cable ends and MPPT connectors eventually? I think wherever the interference is coming from (and the tele seems the most likely culprit at the moment) I need some sort of permanent solution ideally. I don't know what that would be if the solar panels/controller is the cause. 

[WotEver]

4 minutes ago, BlueStringPudding said:

If I disconnect the panels and find that was contributing to the interference...

You won’t. The dead giveaway was when you said that simply unplugging the TV mains lead removed the hum. In other words as soon as the earth connection was removed so was the hum. That’s why I asked if you had a rewireable 13A plug on the TV - there’s a simple test you could do to confirm it 100% before you spent a fiver. 

[Tony Brooks]

4 minutes ago, BlueStringPudding said:

Thanks. If I disconnect the panels and find that was contributing to the interference, then doesn't that leave me with the quandary of having to choose between using the amp and having solar power? I would rather simply be able to turn the amp on and use it, than have to empty the cupboard to get to the solar controller, and get a screwdriver to disconnect solar panels every time I want to play music or watch a film with decent sound.

Apart from being a faff that I've not got the energy or inclination to go through repeatedly, wouldn't it damage the cable ends and MPPT connectors eventually? I think wherever the interference is coming from (and the tele seems the most likely culprit at the moment) I need some sort of permanent solution ideally. I don't know what that would be if the solar panels/controller is the cause. 

Please read my reply to your quoted post. If you do not understand please come back and tell us what you do not understand.

 

If you get interference at night (dark) then its almost certainly not the solar controller because it will have nothing to control..

 

I agree with the earth loop theory on the present information but LED bulbs are also known to create interference.

 

 

[Chewbacka]

11 hours ago, BlueStringPudding said:

Fascinating about the volume thing - thanks -  that does indeed reduce the interference noise but not completely. However, if I want even 30% volume from the amp and speakers, the interference noise can still be heard clearly.

 

I'm using the only cable on Amazon I could find that I could tell had the correct plugs and that can be delivered to my local Amazon locker, since I can't receive post on the boat (that massively reduces choice of sellers).  I don't know exactly what screened cable is but I doubt that what I have is screened, I expect it would have said on the packaging. 

 

 

Can you take the audio lead out of your tv and plug it in to a phone or portable radio and play music from the phone or radio through your amp.  Whatever you use (phone or radio) should be powered by it’s own internal batteries, then let us know if the hum is better or worse.

[BlueStringPudding]

With the audio lead plugged into my phone there's very little interference noise. A faint high pitched buzz when the volume is turned up on the amp, but it's a very different sound to when the tele is on. Not too irritating and totally different to the tele interference hum, but it's still an interference noise of sorts.

 

However when I switched the tele on, with the audio cable still between my phone and the amplifier, as soon as the tele changed from standby to on, the original interference hum returned. So the annoying hum is there even when if the amp is not plugged into the tele, as long as the tele and amp are both switched on!  The hum may have been slightly fainter than when the audio cable was plugged directly into the tele but it's still very noticeable.

 

What if anything does that suggest the solution is? Still a ground loop gizmo when connecting the amp to the tele or something else?

[BlueStringPudding]

13 hours ago, Tony Brooks said:

Please read my reply to your quoted post. If you do not understand please come back and tell us what you do not understand.

 

If you get interference at night (dark) then its almost certainly not the solar controller because it will have nothing to control..

 

I agree with the earth loop theory on the present information but LED bulbs are also known to create interference.

 

 

I don't understand what I don't understand, Tony! But thank you  I've not disconnected anything from the MPPT controller because I can't see it leading to a workable solution even if it was causing the problem. And since the interference noise is there at quarter to midnight, that suggests the solar controller isn't part of the problem anyway.

 

I have LED bulbs and fluorescent bulbs in that cabin. So far it's made no difference to the interference noise as to which lights are on or off, or in the daytime when no lights are on. 

Edited February 26, 2019 by BlueStringPudding

[BlueStringPudding]

13 hours ago, WotEver said:

You won’t. The dead giveaway was when you said that simply unplugging the TV mains lead removed the hum. In other words as soon as the earth connection was removed so was the hum. That’s why I asked if you had a rewireable 13A plug on the TV - there’s a simple test you could do to confirm it 100% before you spent a fiver. 

No plug, I'm afraid. The first day of testing the tele was plugged into a 12v cigar socket on different circuit to the one that powers the amp.

On the evening of the second test the tele was plugged into a cigar socket on the same circuit as the amp.

Now the tv is securely hard wired into the switch panel on the same circuit as the amp.

All three scenarios have the same interference hum when both the tele and amp are switched on. 

[Boater Sam]

Modern electronics run on switched mode power supplies which create lots of interference. Try disconnecting one thing at a time. If it is the power box for the TV you will be stumped. Try running the TV on the inverter at mains setting, but then you may well get interference off the inverter!   

 

 

ITS the switched mode power supply in the telly!

[BlueStringPudding]

4 hours ago, Boater Sam said:

Modern electronics run on switched mode power supplies which create lots of interference. Try disconnecting one thing at a time. If it is the power box for the TV you will be stumped. Try running the TV on the inverter at mains setting, but then you may well get interference off the inverter!   

 

 

ITS the switched mode power supply in the telly!

I don't use an inverter. I have a 12v system here.  I have disconnected one thing at a time and listed in my first post the results of that.

 

I don't know "switched mode in the tele"  means (do you mean alternating current?) nor what the solution to that causing interference would be if it's not the initial suggestion above to buy a ground loop isolator. 

 

 

 

Edited February 27, 2019 by BlueStringPudding

[Tony Brooks]

1 hour ago, BlueStringPudding said:

I don't use an inverter. I have a 12v system here.  I have disconnected one thing at a time and listed in my first post the results of that.

 

I don't know "switched mode in the tele"  means (do you mean alternating current?) nor what the solution to that causing interference would be if it's not the initial suggestion above to buy a ground loop isolator. 

 

 

May electrical items need a different voltage or even voltages to the voltage they are supplied with to run. The thing that converts the voltage is called a powder supply. This could be a fat plug in a wall socket or a block in the lead for many mains powered appliances but may be built into an appliance. There are a number of different types of power supply circuits but a very common one nowadays is termed switched mode. The important thing about fixed mode power supplies is they accept a wide range of input voltages and they are small and cheap to make. They also tend to produce a horrendous amount of interference that needs dealing with - often not totally satisfactorily. So Sam is suggesting that you have one of these in your TV and it is that causing your interference.

 

I am not so sure as you say you are running it from 12V but it may have a buck boost voltage stabiliser built in that may also cause interference.

 

Try moving a radio or phone close to a phone that is on charge and see how much interference is picked up. If your amplifier and TV are close together try moving them further apart (several feet would be good) and also try to feed them from a different 12V circuit with lots of wiring that electrically separates the TV and amp. For example if you have different circuits for left and right hand 12V sockets try running one form the left and one from the right.

 

My concern about the solar controller is that one of your replies seemed to show that you may disconnect the panels from the controller and lave the batteries connected - exactly what I advised against and explained why in a previous post but a s you say you have discounted the controller it does not matter.

 

AS you are feeding the TV and I assume the amp from 12V via a 2 core 12V lead I am having doubts about it being an earth loop porblem.

 

If it is interference from some sort of stabiliser or power supply then it becomes more difficult to cure. I am no expert in suppression but it may involve putting the amplifier in a metal box that is connected to the boat's negative or hanging ferrite beads on the amp's or TV's 12V lead. You may even have to put a choke suppression item in one of the power leads. Hopefully others will advise on this but after a certain point trying to cure interference becomes very difficult

 

Edited February 27, 2019 by Tony Brooks

[Chewbacka]

How close is the amp to the tv?   if less than a foot try to separate them by a couple of feet and then using the phone see if the hum is still there with the tv on.  This will give an indication if the interference is going through the air to the amp or if it is going via the dc supply wires.  Also thinking about it if either of the speaker wires passes close to the tv that could also be part of the problem, if so move that speaker and it’s wire away from the tv.

 

added - if the interference is travelling through the air from the tv or its supply box to the amp, the interference needs a bit of wire connected to the amp to act as a receiving antenna, this could be a supply cable or even a speaker wire.

 

added - if the speaker wires are longer than you need don’t coil them up all nice and neat but lay them out on the floor away from the tv for the test.

 

added - interference will pass through wood panelling, so if either speaker wire passes behind the panel the tv is mounted on, use another cable for the test

Edited February 27, 2019 by Chewbacka

[WotEver]

2 hours ago, BlueStringPudding said:

I don't use an inverter. I have a 12v system here.

Then it’s not an earth loop. 

 

Try the suggestions above, and good luck