Problem with Quad L-ite sub... hissing/static when connected to power only. Any ideas PLEASE?

[Richdog]

Hey guys. I have a serious issue with my Quad L-ite Subwoofer that I am hoping someone can recognise or diagnose. http://www.whathifi.com/review/quad-l-ite-sub

The problem is that when it is only plugged solely in to the power (no connection to amp or any speakers) it makes what can be best described as a hissing/static noise and seems to mlidly vibrate to the touch. This is consistently replicated when trying a different power cable, and when also trying different power sockets around the home where other AV and electrical equipment works fine, so potentially and very likely we are looking at some kind of fault.

The sub previously worked fine, and was in storage for 6 months (carefully and well-handled, it's my baby) before it was newly set up yesterday in a new apartment, and this issue seems to be new.

This is one of my prize possessions that I have had for around 6 years, and I now live outside of the UK (Quad have no hope of service outside of the UK), so I will be gutted if I have to scrap it without hope of a repair.

Does anyone have any ideas what it could be, or recognise the issue?

Thanks in advance, and really hoping someone could have some ideas on this...

Rich.

 

[lucid]

Let's start by trying to eliminate the simple stuff.

1) Does it make these sounds when connected to the amp?

If not, then do you think it's possible that it's picking up local RF interference when the input stage isn't grounded through the amp?


2) Is the mains supply earthed where you live?

There's a lot of countries where the power plugs are two pronged (Live & Neutral). This might not even be a practical solution depending on the type of property and the construction, but it may be possible to provide an earth via the cold water mains riser, or by putting an earthing rod in the ground. Consult a local electrician before going down either of these routes.


3) Is there a significant difference in ambient temperature or humidity where you now live compared to previously?

If so, then the sub might need time to acclimatise.


If there is a fault then it could be that in being powered down for so long that one or more of the capacitors have dried out. If you have eliminated all the simple stuff then this might be your first step for a repair.

 

[Richdog]

Hi lucid, thanks for the reply!

1) Do you think that there will be no risk to the amp etc by hooking it up to the sub to test? I was a bit scared of doing so in case a fault in the sub could cause damage to the amp.

2) I am pretty sure it is earthed... Swiss plugs are three-pronged.

3) Summer was roasting, but at the time of testing it is back to coolness so I don't think that is an issue.

Thanks!

Rich.

 

[lucid]

1) You can leave the AV amp in standby (i.e. plugged in, main switch on but soft switch off). It's just grounding of the input on the sub that we are interested in at this stage.

2) If it's three pronged then it will be earthed. You never said where you were though in the first post, so it was best guess on limited source info.

3) Again, because you never said where you had moved to I was just eliminating options. For all I know you might have moved somewhere really humid such as Florida. The container might have been on the quay side for weeks, then the sub gets moved to a nice air-con'd apartment so the outside is chilled but the inside still relatively moist and condensing out due to the chilling on the surfaces.

Anyway, try the grounding via the amp first. Let us know how you get on with that.

 

[Richdog]

1) You can leave the AV amp in standby (i.e. plugged in, main switch on but soft switch off). It's just grounding of the input on the sub that we are interested in at this stage.

2) If it's three pronged then it will be earthed. You never said where you were though in the first post, so it was best guess on limited source info.

3) Again, because you never said where you had moved to I was just eliminating options. For all I know you might have moved somewhere really humid such as Florida. The container might have been on the quay side for weeks, then the sub gets moved to a nice air-con'd apartment so the outside is chilled but the inside still relatively moist and condensing out due to the chilling on the surfaces.

Anyway, try the grounding via the amp first. Let us know how you get on with that.

No need to explain your questioning, it was all sensible! I live in CH and it does get very hot and humid in summer, so I didn't blink an eye at that.

Will try the amp and grounding tonight, cheers mate!

 

[EddScott]

I know it doesn't help but mine has had an intermittent but quiet hum since I've had it. It went back to the shop but they said they couldn't replicate the noise. I just ended up having to live with it.

 

[Richdog]

Well, tested it tonight but no joy... still makes the noise regardless when plugged into the amp. I am waiting to hear back from Quad email support on their opinon also, but I can't help but think that it is a fault.

I know it doesn't help but mine has had an intermittent but quiet hum since I've had it. It went back to the shop but they said they couldn't replicate the noise. I just ended up having to live with it.

This is more than a hum... its a louder static-esque noise.

 

[Oxide™]

Hey guys. I have a serious issue with my Quad L-ite Subwoofer that I am hoping someone can recognise or diagnose. http://www.whathifi.com/review/quad-l-ite-sub

The problem is that when it is only plugged solely in to the power (no connection to amp or any speakers) it makes what can be best described as a hissing/static noise and seems to mlidly vibrate to the touch. This is consistently replicated when trying a different power cable, and when also trying different power sockets around the home where other AV and electrical equipment works fine, so potentially and very likely we are looking at some kind of fault.

The sub previously worked fine, and was in storage for 6 months (carefully and well-handled, it's my baby) before it was newly set up yesterday in a new apartment, and this issue seems to be new.

This is one of my prize possessions that I have had for around 6 years, and I now live outside of the UK (Quad have no hope of service outside of the UK), so I will be gutted if I have to scrap it without hope of a repair.

Does anyone have any ideas what it could be, or recognise the issue?

Thanks in advance, and really hoping someone could have some ideas on this...

Rich.

My same speaker has just started doing the same thing.

Was on the pc next to my tv etc (everything turned off) then heard like a pop sound and then a random static noise coming out of the sub with no sources turned on.

Did you get your issue resolved? It's been working great for 10 years until now

 

[Richdog]

My same speaker has just started doing the same thing.

Was on the pc next to my tv etc (everything turned off) then heard like a pop sound and then a random static noise coming out of the sub with no sources turned on.

Did you get your issue resolved? It's been working great for 10 years until now

Sorry to hear you're having the same issue. My dad contacted Quad and they told him to send it to them and then then replaced some part of it and it now works good as new. Give them a shout and see what they say.

 

[Oxide™]

ok cheers, I'll see what Quad say