Top 20 Sunfire True Sub MK II Subwoofer Questions & Answers

Start with the volume way down on the sub. Connect the line out of a source you know is working with cables you know work to the inputs of the sub. Try left and right. This will let you know if the problem is in the sub or the output you're trying to use.

Hi,
I had the same problem as this, the fix was quite simple and the hum never came back.

If you pull straight out on the sub amp's volume knob it will slide off, then to fix the hum, tighten the nut that is behind the knob on the potentiometer and your hum should go away. My hum went away and never came back after this fix. Hope this helps you.

check the box for air leaks, or rubber surround deterioraton.

Easy. Your home theatre amp will have a sub or LFE output ( RCA plug ). You simply connect this output to the input ( usually the left side, or use a Y splitter and use left and right inputs, or the LFE input if your sub has it ). Then, you must turn the sub on in your recievers setup menu, and your sub should work.

Check on ebay, I see em occasionally.

The passive radiators on those are notorious for coming apart inside and making a knocking noise. You can sometimes glue it back together but youll have to remove the driver from the cabinet.

passive radiator is likely separated internally.

The input jacks on the subwoofer panel are for connection of satellite speakers to it's crossover. The outputs are for the crossed over signal input to your receiver or amplifier, as there will be no amplification or channel processing from the subwoofer connection. It's only an optional crossover that may have a sonic advantage over the crossover in your receiver. What you also can do is connect the speakers directly to the 703 and set the crossover frequency on it.

How to isolate annoying background hum.

As long as the music or movie is playing, you can forget about it, at least until a quiet passage occurs, then there it is again: HUMMMMMMM! Be gone, bad hum, you think. But, like a bad odor at the back of the fridge, it takes some dogged persistence to track it down and eliminate it.

Hum is a constant low-frequency buzz, usually at about 60 Hz or 120 Hz, which results from voltage differences between true "ground" (what you'd get shoving a copper pipe into the ground) and the electrical "ground" of your receiver's chassis, the incoming cable-TV feed, or any video or audio components interconnected within your system, including powered subwoofers. When this voltage differential exists, it's called a "ground loop," and the hum it produces is darned annoying. You'll hear the hum mainly from the subwoofer because it's a low-frequency noise, but there will also be hum from your floorstanding front speakers or even compact bookshelf models.

First, try disconnecting your subwoofer from the coaxial sub cable from your AV receiver but leave the subwoofer turned on. Does the hum go away? If it does, then the ground loop is entering the system from your AV receiver and/or your cable-TV system set-top box (or satellite dish and decoder).

Disconnect the incoming TV-cable or satellite feed to a set-top box or to your TV and the A/V receiver. If the hum disappears (and you don't use a satellite dish) complain to the cable-TV company. They may know what you need and supply you with a ground-isolating transformer. If they don't know what you are talking about you'll need to order a video ground isolator and install it in-line with the TV cable before it enters your set-top cable-TV box. Axiom has special wide-band isolation transformers that will not interfere with any digital TV or HDTV signal. (N.B. You CANNOT use one of these with a satellite decoder box.)

Before you order one, you can try plugging your subwoofer into a different AC outlet in the room, ideally one that is not on the same circuit as your AV receiver and video equipment (TV, DVD player, sat or cable TV box, etc.) That may solve the problem. If it doesn't, see if the back panel of your sub has a "ground-lift screw". It will be labeled as such. Just remove it. That may remove the hum. If it doesn't and you have a standard cable-TV feed (not a dish), then order the ground-isolation transformer. (Axiom has special wide-band isolation transformers that will not interfere with any digital TV or HDTV signal.)
Axiom Audio Ground Isolator

If that still doesn't eliminate the hum, or if you use a satellite dish video feed, then you could try one of these from Radio Shack, which goes between the subwoofer and the coaxial cable from the receiver's subwoofer output.

With persistence, all ground-loop problems can be solved.

Hope it helped..

Have a nice day...

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

sounds like a grounding issue........Verify grounded properly

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.

use a ground loop isolator from radio shack, the device is hooked up to the rca plugs in, the other side has, (of course rca plugs), outs. solved My problem of feedback in the sub and into the processor.....

you can try to replace it with a similar potentiometer if your soldering skills are up to par. Otherwise I'd just glue it.

hello, the reason for the this is because theres a dead short in the unit someware i'd check the diodes first with a multimeter then the transistors then the resistors then the capacitors

regards
shaun

This sounds like a blown driver (speaker). I would open it up and first check that the speaker wire is securely connected to the driver.

Hope u fixed this by now but I had a hum also and tracked it down to the cable box as found a site which told me to unplug the coax cable from the setup box and see if the hum stopped and it did. However after trying their suggestions and was gonna get a transformer went to my receiver I had used a dig coax for sound from the mot box to my receiver, pulled that cable and the hum stopped, replaced it with a toslink cause I had one laying around and have the receiver inputs for it end of hum for good so one more thing to try if your connected that way but it was definitely cable related.

If you are looking at the sub from the back (side with the volume knob etc) then the passive speaker is on the right.