Sub Thump Need Help!

[stidrvr]

I recently started having a problem with my sub. Every time I change chapters or the Menu screen on the dvd player repeats, I get a thump through the sub. I switched cables and removed everything and rewired it and I still get it. Im using coax digital from the dvd player to the receiver. I didn't change anything in the system and this started happening all of a sudden. A friend of mine had a similar problem on his H/K receiver with an optical cable from his PS2. Anyone have any ideas? Thanks in advance.

[dyazdani]

That's an odd one...does it happen on all DVDs or only some? What kind of sub is it and does it have an auto-sensing power supply?

[fauzigarib]

I recently started having a problem with my sub. Every time I change chapters or the Menu screen on the dvd player repeats, I get a thump through the sub. I switched cables and removed everything and rewired it and I still get it. Im using coax digital from the dvd player to the receiver. I didn't change anything in the system and this started happening all of a sudden. A friend of mine had a similar problem on his H/K receiver with an optical cable from his PS2. Anyone have any ideas? Thanks in advance.

Hey there,

I have a feeling that this is a receiver / DVD interface issue. As chapters and menus change, most receivers have a constant "eye" on the signal coming into their digital inputs, and then automatically adjust sound modes / volumes, etc, accordingly.

Just to try to narrow it down, switch from optical cable to regual analog RCA's from the DVD to the Receiver. Does this help?

Also, a couple of questions:
- Which receiver / processor is it?
- Which sub?
- Which DVD player?
- Do you have the sub levels set *significantly* higher than the other speakers in your surround system?

Let's try to get this fixed!

Fauzi

[stidrvr]

Well I did a little testing this morning. I think it might be the receiver. I used just and RCA cable from the sub out on the 5.1 channel output on the DVD player, even though no sound is coming through, I still getting the thump. Not only that but when I change sources on the receiver from DVD, to Video 3, to Tuner etc. I still get the thumping.

Receiver is a Kenwood VR-7070 6.1
Sub is a Kenwood SW-X1 (Passive) With a PE 240w plate amp
DVD Player is a Sony DVP-S560D

Not sure what else to do. Keep in mind that this sub was purchased for use as a computer sub, the receiver was purchased just to get me by, and the DVD player was the first DVD player we've ever had. Its not even progressive scan. I am in the planning stages of a dedicated room in the basement and all components will be replaced. So I'm not dead set on any of them. Just trying to figure out whats wrong so that it will stop annoying me.

[peterS]

turn on pop
only experienced it with car audio, and in the cheaper amps

i would suggest its the pe plate amps pre amp that is to blame

[stidrvr]

Yeah but why does it do it when its powered up. I can see if it does it on power up, but all the time.

[peterS]

i believe it is still the same issue
when you switch inputs the preamp stops recieving a ground reference then does again
for what ever reason it sends that through the amp as an input
.... some type of ground issue
not surprising since the plate amp is on the sub box or near it i assume, causing a solder to loosen over time

[stidrvr]

OK I ran some tests today trying to rule some things out. First thing I did was move the sub out into the garage and hooked it up to my system out there. Its a Sony rack system that has in integrated sub that also acts as the lower stand. Anyway the stereo has Left Right and Sub out that goes to the amplifier and powers the sub and the tower speakers. I hooked up my sub to the line out and played many Cd's switched sources turned the stereo on and off and turn the sub amp on and off. Mind you I'm still using the plate amp. No noise or pops whats so ever.

No fully convinced I bought it back into the house and hooked it up to my computer using ad SB Live 5.1 card. I enabled 5.1 speakers and hooked it up to the sub out. I played some of the demo Dvds and ran all sorts of tests. No popping there either.

So now I have ruled out the plate amp as the culprit. Next I moved every component downstairs in preparation for my dedicated room. I hooked everything up and still get the popping sound. I switched video inputs, and switched cables. Still does it.

I thought that it might be the Sony DVD Player, so I hooked up my XBox360 and using an optical cable this time. It still pops.

So now the only thing that I haven't ruled out is the receiver which I'm beginning to think is what the problem is. The last thing that I could try was with my Receiver. Its a 6.1 Receiver and one of the options that it has is for the surround back for the sixth channel. The receiver allows me to select if I want to use the sixth channel for surround back or for sub woofer. I set it to sub woofer, and since my sub was original a passive sub I hooked it up and got NO popping.

So from all my tests, I pretty sure that its something in the preamp of the receiver. Any Thought?

[Arneson]

My system popped when I fed the output of my monitor back into the AV receiver.
As I switched inputs between DVD to TV the system went crazy.
I had some kind of loop going on.