Sunfire Mk II hum (different from greekboy post)

eBay...


Price = variable $256 and up, final cost up to the skilled bidder.

http://desc.shop.ebay.com/i.html?_nkw=Sunfire+True+Subwoofer&_sacat=0&_odkw=Sunfire+True+Sub+MK+II+Subwoofer&_osacat=0&_trksid=p3286.c0.m270.l1313&LH_TitleDesc=1

guy gevais

you have a ground loop issue you could purchase a ground loop isolator, jensen makes them for about 40 bucks.I have discovered that if you have cable tv, unplug the incoming cable in your cable box and see if hum disappears.

Check your cabling to make sure you dont have a ground fault. if you still have humming, buy a "groundless" adapter for your power plug (takes the ground away) and plug it back into the power outlet and I bet your humming will be gone

It sounds like you are describing an earth loop problem. I won't go into detail in this post, but try an isolation test first. disconnect everything from the reciever except the sub and try connecting say a BATTERY powered mp3 player or cd player to minimise connections to the electrical mains earth. you could also isolate things by taking your sub to a friend's house and trying it on their system.
If it is an earth loop use a process of elimination to find out which two pieces of equipment causes the earth loop. then apply filtering.
you can buy earth loop isolation transformers for about AU$26 and I've used one on my sub myself. Theyhave RCA (phono)plugs on each end and they connect inline with the signal cable to the sub amp.

as for the thumping sound it might be the speaker protection circuitry cutting off the amp to protect the subwoofer speaker from damaged. This might be triggered if the earth loop sound is causing the sub amp to overload and clip.

Failing this there might be a dried out overheated electro capacitor in the amp circuit causing the hum. Hav a chat to your local electronics person, who should be able to spot it!
Hope this puts you on the right track
Happy Hunting!

had the same problem, so I installed a radio shack ground loop isolator and fixed the problem, it has 2 rca plug inputs and 2 rca outputs, goes in-between the sub and the input cables of your system to the sub...that's if your using the rca inputs..

Rita's Vintage Audio Repair is a Bob Carver Company & can repairs & updates Subs at a reasonable cost try calling them.

If you remove the volume knob, and tighten the nut below, it should take care of the popping noise, as well as any input noise issues. Based on my experiences with my MKII

A few more questions-
Does the sub hum without anything plugged into it except for power? If it makes a real loud hum almost a squeal then I think the rca cable between the receiver and the sub is dead shorted and needs to be replaced. If it's more of a low level hum, then it's a ground hum caused by many things, ie........the receiver and the sub being on different power circuits in the house.......sometimes diconnecting the cable tv feed as it enters the room while the sub is connected and humming to see if it stops........the easy fix sometimes is using a 3 to 2 prong ac adapter but lifting the ground on such a powerful amp could be a fire hazard.

you must change light switch now with a new one-and grounding is very very important.