I know, it’s been covered many times and I didn’t think I had a problem, so I didn’t read the posts.

The other day I was re-routing some cables and noticed that the EP600 would “thump” every time I connected / disconnected one of my components. My video processor (DVDO VP50Pro) uses a 120V AC – 6V DC power converter. Whenever I plug / unplug this, the sub thumps. It does not ever thump unless I plug / unplug this particular component. I’m not sure what’s causing this or why. The VP is downstream from my receiver and the only thing that is plugged into it is the HDMI output from the receiver and the SDI output from my Oppo 981. The 981’ s audio goes directly to the receiver via Coax.

I asked this question at the master VP50Pro thread at AVS, and one guy told me it is a ground problem and I should remove the 120V AC ground prong that is on the sub's plug. That doesn’t sound like a very elegant solution, if it is a ground problem.

This could be totally off, but would removing the ground screw on the back of the 600 help?

That doesn't sound like a ground problem Mike. As a matter of fact I believe that would be normal. If I unplug my power center before shutting down the sub it too will make a thumping sound. Don't worry about it.

I leave my subs on all the time and never hear any noise/thump when turning off my equipment. Now, when I unplug my preouts from my receiver when everything is powered on, I sometimes hear a thump from my 80's that are hooked up to my Odyssey amps.

But do you hear it if you UNPLUG your processor while the sub is on?

Not sure I've ever had a need to do that....hold on.....ok, I just tried it and unplugged my Denon, no noise or thump.

Mine does.

When I unplug my Hsu directly I get a series of diminishing thumps like the amplifier is getting rid of stored energy. I don't think I've ever had it happen while unplugging something else, but then I usually turn the power off on all components when I switching stuff around.

It's odd. If the VP50Pro is turned off, it makes no difference. The sub will still thump when I plug / unplug it. It isn't the 120V wall jack either, only at the 6V DC side.

If I unplug my 600, I do get a little thump as Sean mentioned.

If I unplug the sub cable from my denon when everything is on my ep500 thumps

'We are spirits in the material world....'


I've heard 'em in the past and really didn't think much of it, about like hearing the same thud whenever a microphone is plugged or unplugged during a stage performance.

Pretty sure this is normal behavior. You want to, at the very least, turn the the volume down on your receiver/amplifier, before unplugging or plugging in, and turning off the receiver/amplifier is preferred. I used to run live sound for a band, and I was taught to never plug or unplug anything with the amplifiers on.

They had amplifiers back then Jack?

Jack,

What makes this thumping even weirder, is the reciever was powered off. Everything was powered off, but the sub.

I think the sub amp has a reserve of power--maybe for those dynamic peaks. The light on my sub amp takes a while to dim after I turn the power off.

Well, with the sub's amp on, I can understand plugging in, or unplugging, a component upstream in the connection chain having an affect on the subwoofer driver. But, it is a little weird that unplugging a video processor, which (I'm assuming) isn't even directly connected to the subwoofer, would have that affect. I'm at a loss.

Unplug the sub cable at the sub. If it still thumps, the spirits are coming in from the AC plug that your sub is plugged into. When you plug/unplug it, it's creating a low frequency disturbance on the AC line that is getting through the sub's surge protection circuitry (which is designed for high frequency disturbances only - like lightning).

If it doesn't thump, then your cable is picking up a signal when you plug/unplug your VP50pro.

The solution is to stop messing with your VP50pro's power plug .

LOL!

Ya, I figured as much... Do not mess with the plug.

I think the root is, I just want to figure out why this is happening. It's driving me nuts, which usually inspires me to figure it out.

Let us know what you find out from my suggestions above.

Ajax is correct, and so is Mojo. Unplugging the video processor power with the sub on creates a low-frequency transient on the AC house wiring, which the EP600 reproduces.

I'd also suspect the filtering on those wall-wart power supplies, which typically are poorly filtered or shielded.

Of course we all get lazy about turning components off before we connect or disconnect any part of a system. But Jack's lesson learned many years ago is excellent. Turn everything off first.

Regards,
Alan

The only thing you can do about a low frequency disturbance is use an active power centre which I think is an absolute waste of money for a problem like this.

I use a Belkin Power conditioner for all the rack components, including the Video Processor.



I’m in the middle of a project and will do some more testing later and report back.

Middle of a project = sipping beer.

Hey Mike nice rack!

Mikey does have a nice rack

That remote is so hot, it has an aura.

Speaking of making sure things are disconnected first. Last week I was putting a new collar on my dog's invisible fencing collar (a must so he doesn't sicken himself at his sea side buffet on the shore.)

I told my wife I was just going to go crank the signal gain on the transmitter later to test it because I was too lazy to go out in the cold. She thought it would be funnier if she did it right away while I was still working on screwing in the leads through the collar material.

Lesson learned = remove the battery next time. She must have really cranked it up because it totally skipped the warning beep that occurs when he gets close to the perimeter.

Now I can sip a beer. I was building a cabinet for my wine coolers.

Mike, can you please adopt me ?

I call shotgun.

Yes, Mike apparently will need help with all that wine.

I don't know about wine or beer but can I come anyway?

Wow! Nice cabinet!

test

I just wanted to add myself to this weird phenomenon. My EP500 was thumping all by its lonesome self downstairs. Reciever was off, no signal at all going to the sub. A simple on/off reboot fixed the problem...

The ground loop was being caused by the Video Processor after all. It must have something to do with the AC/DC converter the VP uses. I used a ground isolation adapter on the VP and the thump went away. The humming I was getting with the addition of an amp went away too.

Rob, quite a few of us have done what you did. It’s the mystery thump. I know of at least two others besides myself, and now you, that have had to cycle the power to kill the thumping ghost. This last situation that I have been fighting is different.