Big Subwoofer Thump When Changing Sources

When I change from my DVD (digital) source to my TV (analog) source, I get a huge thump through my subwoofer. It is really loud and actually rattles the walls. It doesn't happen when I change from the analog source to the digital one. Is there an easy explanation for this? How can I fix it?

First, unplug the subwoofer and try the switching again, to see if it is _only_ the subwoofer causing the noise. If the noise is still there, through the other speakers, it could be either your DVD player or the 950 causing the problem. If the noise _only_ happens in the subwoofer, there might be some problem with the 'standby' power circuit itnside it. Some subs power themselves down to 'sleep' mode in the absense of signal. When a signal is detected, they turn themselves back on, which should _not_ cause a big thump. If there is a switch on the sub to make it stay on continously, do that, and see if it still thumps when you switch the DVD and TV.

If the sub is not the problem, try switching from your DVD to some other input that is in 'analog' mode, even with nothing attached to that input. It the thump goes away, it is possibly the TV. Reverse the procedure, switching from the TV to a digital input with nothing connected to see if the DVD player might be causing the problem.

I would tend to thing the problem lies in the auto power switching in your sub woofer. One other thing, are your DVD and TVs power "on" _before_ you do the switching from DVD to TV? They should be. If you do isolate the cause, and it seems to be a defect, there is unfortunately nothing you can do yourself to repair the 950, your DVD or TV. That should be left to the manufacturer.

One final thought. Make sure that all your interconnects are in good shape, and not corroded: gold plated ones are the best in this regard, but you don't have to spend a lot of money to get ones that will work well. Good luck!

Wow, thanks for the quick response.

My subwoofer is an older Klipsch model and does not have any kind of standby mode. It's either on or off.

I'll try switching between different components tonight, and maybe try a different sub cable. So far I've only noticed it happenning with the TV when it's powered on.

I'll vote for it being an issue with the 950. This was one of the problems that led me to ultimately return the 950 I had (along with a second one, just in case the first was defective).

I got a loud pop, not limited to the subwoofer, whenever I changed from ANY digital input to ANY analog input. Switching from analog to digital was quiet, just as you described. I never found a solution for this, unfortunately. Too bad, because the 950 performance with a steady input source is really quite impressive!

-Gary

I'll definitely look more into this tonight when I get home. I was one of the earliest to buy the 950, but I haven't been able to use it until I finished building my equipment closet. The unit has been sitting in its box for months, and I just got it fired up last week. My love for home theater is rivaled only by my laziness.

I think you can pretty much eliminate the sub woofer if it doesn't have an 'auto turn-on' feature.

About the only thing left is that some IC in either the 950, the DVD, or your TV has a high DC offset voltage, which when switched in sends a burst of DC downstream. Bummer.

Gary - thats a bummer, yet FB and you are the only two who have reported this "issue". Hence, I'd say that something else possibly contributed this to your system. An issue woud likely be far more widespread.

Well, I played around with this last night. In case anyone's interested, here's what happened.
I unplugged the subwoofer and the thumping went away...there is no thump through any of the main speakers, just the sub.
I plugged the sub back in and the thump was back. As with Gary, it happened when switching from any digital source to any analog source, whether a component was connected or not. I did this with the TV both on and off.
While my sub is 5-6 years old, I have never had a problem like this with it initially plugged into a Yamaha DSP A-2070, and then a cheapo Sony Dolby Digital Receiver.
I guess I'll try a different sub cable (grasping at straws here) and if that fails contact Outlaw.
Could the setting of the main speakers to large have any effect on this? I wouldn't think so, but it would be easy enough to test.

From the looks of things, it appears the 950 might be the source of the thump. I really doubt the interconnect would be the culprit.

You might want to talk to Outlaw. Does seem unusual enough that there may be something wrong there. Mine doesn't do this either. And I can't see it being a sub or cable issue either.