mart360

Was playing arounf with the system this evening, (now the wifes gone to bed)

I was running some thx frequency sweeps, and have noticed when i switch the sub on i get a mains hum... not noticeable when in use but when no audio or music, its audible.

any ideas on how i cure it...

i,m guessing its the p supply in the sub itself..

its an early pioneer shell style, im loath to get rid, becuuse it fits the house and the system well

Mart

4x4chris

bad earth i guess...
nowt much you could do about it i think...
not worth worrying about unless it is really getting to you.
could try a 'cleaner' PSU....

ru'

First off I'd decide if it was noticeable from my listening position (i.e. not when you have you head stuck in front of the thing).


If it was then it's probably worth investigating further. If not, then why bother?

Things to try (assuming it's a sub with a built-in amp):

Does it do it when the input cable is disconnected? If it doesn't, it suggests the noise is coming from upstream, or getting picked up by the cable. Try re-routing the cable away from mains wiring.

If it still does it, then its the sub unit. Check the mains wiring in the plug for earth, other than that not much you can do unless you really get your hands dirty...

Assuming its the sub, does the noise get worse when you raise the sub level on the unit? If it does, you could try raising the sub line output of your AV amp, and turning the actual sub down.

ALi-B

iTrader: (1)

Very often it is a bad connection/cable issue. Do as above and disconnect all audio inputs to the sub.

It also should be noted that If the source to the sub is switched off but still connected, it is quite possible to get a hum - that is usually normal on some equipment.

NorthDave

Have look and see if it is the connection where the line input goes in to the sub. The outer ring connects to the circuit board inside and can get damaged very easily. You may be able to position the cable to ensure a good connection or take it apart and put a blob of solder on. You should be able to tell by gently wiggling lead.

Always seems to be this when i've seen it in the past.

mart360

soldering iron job cool...


thanks for the pointers guys, i.ll have a look when mrs Mart goes to work on monday

Mart

David_Wallis

try plugging everything into the same socket and see if it goes away, ie get a 4way adaptor just to test with, let us know if this clears it.

chrisowe

Mine used to do the same, fixed it by running a length of speaker wire from a screw on the sub to the amp.