Have your say & ask the experts

Hi all - its been a while so g'day to members old and new ; )

Just wondering what everyone considered a minimum safe distance for positioning a subwoofer (I have a Velodyne CHT-12R) from sensitive kit like amps, cd/bluray/pvr etc and all the associated cabling - tv antenna cables etc?

I know they are all shielded and the advice will of course vary based on make / model but I'm looking for a general rule of thumb to potentially solve an interference problem which has been dogging me for months.

Hey Damien,

I wouldn't presume all subs are shielded - I know the n-Sub from Naim isn't for example.

Regardless of magnetic interference, I personally would keep a sub as far from the rest of my kit as possible, mostly due to physical resonance...much like I would keep the main speakers away from sensitive items such as pre-amps and transports.

What is the interference you have ? 

I've been getting an intermittent high pitched background noise when watching DTV - heavily variable - all channels -some more than others. Previously I had the sub sat flush up against my cabinet thus about 2" from the side of the amp and about 12" from the antenna point on the back wall. After 6 months of tossing around and checking just about everything that can be checked; a couple of weeks ago I moved the sub away giving it about 6" from the amp and about 18" from the antenna point and the problem has gone - for now.

That said, its disappeared for weeks on end before and then come back - and I cant remember if I had moved the sub during these periods and thought nothing of it. Either way, I'm currently shifting the sub away and then I'll just have to see how it goes over the next weeks.

Not sure what the best position is going to be - I can leave the sub inside the left front - this gives me about 6" to the amp etc - I can move the sub to the outside of the left front and bring the main speakers in a but - this will five me about 2 feet clearance but places the sub closer to the corner of the room. Another option is to move the sub to the left wall of the room firing to the side of the sofa - miles away from everything else though not sure how it will sound??? Its going to be trial and error I guess on all counts.

This was my initial post back in January:- http://community.whathifi.com/forums/post/188502.aspx

Since then I've ascertained that its not the other equipment at fault as I have a nextwave HD stb and the problem occurs with that as well as the DMR-BW500 - I also found that there's no interference over analogue connections between the source and amp - only HDMI/Coaxial/Optical. What I hadn't considered before was that perhaps the sub is inducing interference in the antenna connection at the wall - I tested the sub's field with a compass and its effective out to about 2ft - well within range of the antenna outlet. Another possibility is that the subs EM field is inducing EM interference in the amps DAC's etc - hence the lack of issue with analogue sources.

Its a curly one and driving me nuts to be honest as the LX90 is otherwise a dream machine.

Yep, that would all drive me nuts too !

My first suspicion would have been some sort of ground/earth loop issue - although in some ways you have effectively ruled that out...

Receivers these days have so many things plugged in & out of them it's a right breeding ground for interference...

Simple question at square one: Have you tried plugging in various sources, alone, one by one, until the buzz starts...? Unplug everything at the mains also as you do this, only having the LX90, a source, TV and speakers connected...

Yeah been through all that - its not a ground loop - there's no buzz or hum - its a high pitched whine - more or less like car brakes squealing to a halt or a badly tuned radio - and comes and goes depending on the material on screen - its bizarre No problems with DVD/BluRay or CD/iPod or Xbox - just dtv.

I've been through a full strip down and re-connect twice now - swapped cables, power board, antenna connections etc etc. Have moved the sub to the side of the room alongside the sofa - sounds ok so will see how it goes like that for a while. If nothing else I'll at least be able to rule it out as a source of interference but the more I think about the more likely it is to be the cause - a 12" sub has a pretty heavy EM field - dunno why it never occurred to me before - doh.