STF 2 Thumping Sound When Changing Modes on Receiver, On / Off, etc.

[Bob_B]

I e-mailed this question to tech support early this week, but I still haven't heard back so I figured I would see if I could find some help here.

I recently purchased the Ventriloquist / STF 2 package and I have it set up in my home theater system. When I have the subwoofer on, I hear a thumping sound when I change modes on my receiver (e.g. CD->DVD->TV) or when I turn the receiver off and on (Note: I've detached the cable TV connection from the system and I know it's not causing the problem.). When I turn the subwoofer off, no problems!!!

The troubleshooting section of the manual for the STF 2 says to turn the subwoofer on last and off first, but I don't think this is an acceptable answer (e.g. when I have the TV on and using full surround sound the thumping occurs as I change the cable channels!!!!).

Based upon what I’ve researched so far, it appears that I have a "ground loop" problem between my subwoofer and my receiver. The plug for the STF 2 has two prongs, so I don’t think a “cheater plug” would work. The only other option I have come across is getting an audio line isolation transformer (supposed to break ground loops between components and allow the audio signal to pass).

There have been some references in other posts to the possibility of faulty “muting circuits” in receivers causing this, but in my case it doesn’t seem to occur in the other speakers when I have the subwoofer off.

Any thoughts / recommendations on this would be greatly appreciated? Thanks in advance for your help.

[tdekany]

can you try a different cable? Just in case?

[Bob_B]

Thanks for the idea. The cable is new and came with the STF 2 subwoofer from HSU. I thought the cable would be suspect if I heard other background noise on the subwoofer (e.g. cracks, pops, etc. from the cable not being properly shielded). However, the only time I hear any form of background noise is when I turn the receiver on / off, mode change, etc.

[cschang]

What kind of receiver is it? It should not be sending anything to the sub when changing sources.

[Bob_B]

Pioneer VSX-D912K

[cschang]

Definitely should not be sending any signal to the sub or speakers when changing modes. Are the sub and receiver plugged into the same circuit?

[Bob_B]

They're plugged in to separate outlets, but I believe they're on the same circuit.

[cschang]

I'd would try them on a different circuit.

[cschang]

You can also isolate if it is coming from the power cable or the RCA input by disconnecting the RCA input and switching modes.

[Bob_B]

Thanks for all of your help on this Curtis (and tdekany of course).

I tried plugging the subwoofer into a different circuit, but it didn't help.

In terms of the RCA cable, I did unplug it and was able to switch modes with no noise. However, I'm not sure what this tells me (i.e. Is it the RCA connection on the subwoofer itself that's the problem or is it other noise upstream?)? I was going to try installing an audio line isolation transformer (I had thought the problem was probably other noise upstream), but let me know if you would recommend something different?

Thanks again.

[tdekany]

I really don't know thechnical stuff, but try a different cable. So untill someone with brains responds I'd do that - if another cable doest make the issue go away, then I'd either ""exchange""? the receiver or try hooking up another sub with the Hsu cable and see what happens.

BTW, I have the same setup as you down to the Hsu cable. I have another setup (same) with the STF3 and that works perfect as well.
Keep us posted.

[tafguy]

I recently purchased the Ventriloquist / STF 2 package and I have it set up in my home theater system. When I have the subwoofer on, I hear a thumping sound when I change modes on my receiver (e.g. CD->DVD->TV) or when I turn the receiver off and on (Note: I've detached the cable TV connection from the system and I know it's not causing the problem.). When I turn the subwoofer off, no problems!!!
How do connect your receiver to your subwoofer? I know it is different but you need to work the problem by elimination.

Have you tried to see if you get the same problem with speaker line level? Does this problem happens using your receiver's subwoofer output?

I have a different pioneer receiver (VSX 509), an old one, which accept 5.1 inputs from other source but has a lot of configuration for size, length of your speakers but I haven't tried using the subwoofer output from the receiver.

The pioneer receiver, mine, has a lot of configurations and their meanings. You should check the pioneer manual on how to config this with the remote control first correctly.

But I did not encounter any sort of thumping sound like using only speaker line-level on my VTF-2 Mk2.

[Bob_B]

I have the subwoofer hooked up to the subwoofer output on my receiver.

It's good to hear that others out there have similar setups to mine with no problems.

Maybe I'll try swapping out the sub cable or going with the speaker hookups instead?

[tafguy]

It's good to hear that others out there have similar setups to mine with no problems.

Maybe I'll try swapping out the sub cable or going with the speaker hookups instead?

Give it a try. You will not solve the problem with the subwoofer output from the receiver. But it will let you know with this configuration whether or not the problem persists on switching input (DVD/CD/VCR,etc). Turned off Tape Monitor .

If you don't have the problem, something must be wrong with the subwoofer's output and it is definitely come from the receiver.

If you do, double check these smoke tests first in Stereo mode

1. Check the subwoofer's connection: Must be subwoofer's L/R low levels inputs using Y adaptor to if using receiver's subwoofer output
2. Check line speakers level connection, one pair from Front L/R output to L/R speakers input and one pair from subwoofer's speakers L/R output to your ventriloquist Front speakers
3. Double check speakers wire connections of the Ventriloquist for any wrong speaker connection to the receiver
4. Check manual of your pioneer model for correctly configuration, you must configuration the sub to be ON
5. Get back to us what you find to us for more help


Using receiver's subwoofer output, you may also want to try not to connect any speakers at all (Ventriloquist speakers) except the sub to see whether or not you still have thumbing sound on input selection on your receiver.
Make sure to check your subwoofer input correctly.

These problems seem at first to be complexe, but most of them will come up in the end to bad configuration .

Good luck!

[Bob_B]

Thanks

The odd thing in this case is that the troubleshooting section of the manual for the STF 2 refers to this thumping problem and just says that it originates from noise upstream in the system (presumably receiver, etc.) -> and recommends to turn the subwoofer on last and off first. I've been through the configuration / settings on the receiver already (including the automatic calibration process, subwoofer on, etc.) and the subwoofer (aside from the intermittent thumping) works great otherwise, so I'm not sure what's left to configure on the receiver.

I may just try the audio line isolation transformer and (if that doesn't work) either try using the speaker connections, swap the sub cable, etc.

During the interim, maybe there is someone out there that's specifically had this problem and knows the "cure"?

[tafguy]

I remembered reading one the threads, see link below, discussing on a different problem. You may want to read it to see if it could help you solve it

http://hsuresearch.com/forum/archive/index.php/t-571.html

In that post, Sasha_G mentioned ground loop problem. Could that be the same problem?

Keep us posted of your findings. I don't have STF-2 sub but a lot of people with their STF-2 in the HSU forum will sureley come to your rescue.

[wid]

Is there a way to try use another reciever (borrow one from a freind) and see if the problem still exist.Sounds like an internal switching problem on the reciever.

I doubt it is a ground loop problem or you would have a 60hz humming at all times.

[Bob_B]

Thanks Wid

I think you're right.

I did some (more) testing / troubleshooting this morning. I have a pair of speakers hooked up to the "B" bank on the receiver. When I switched the "A" bank off and only listened through "B", I could still hear the popping but obviously at a much fainter level. It appears that it may have been there all along, but I obviously didn't notice it without the sub.

Not sure if it is a switching problem or a problem with the "muting circuit". Actually, from what I've read, I'm not sure if the Pioneer VSX-D912K has a muting circuit at all - which could be the source of the problem. Based upon the fact that tdekany's set up appears to be working fine, it must be a problem with my receiver? In any event, I'll need to call Pioneer to confirm if the Pioneer VSX-D912K has a "muting circuit". If it does, I'll need to bring the receiver in for service. If it doesn't, I guess I'm screwed???

Thanks again to everyone for bearing with me on this one.

[wid]

I see your reciever has pre outs.Try and connect the sub through the pre outs and see if the problem still exist.

[Bob_B]

When I look at the manual for the pre-out connections, it says to attach the subwoofer to the same subwoofer output I already have it connected to (i.e. there appears to be no separate pre-out for the subwoofer -> assume this makes sense because the assumption is that it's a powered subwoofer)? There is an option for connecting the subwoofer passively (i.e. non-powered) to the surround back channel, but this seems like such a waste.

[Bob_B]

PROBLEM SOLVED!!!!

I did a bit more searching on the web and came across the following link:

http://hdtv.forsandiego.com/messages/3/1827.html?1094096014

I had my receiver set to "Auto" for the input signal on some of my components (even though some of them only had the digital output connected) and apparently this must have caused a delay in the receiver leading to the thumping / popping on the subwoofer / speakers. I changed the input to "Digital" and the problem went away. Apparently, I won't be needing that audio line isolation transformer after all!!!!

Thanks again for everyone's help.

[tdekany]

don't you feel a million times better?

I am glad for you.

[Bob_B]

Thanks man

Hopefully this thread will help someone else out???

[wid]

Congrats on finding the fix.

[Bob_B]

At least I won't get those death stares from the wife anymore when either of us changed inputs on the receiver (or cable channels for that matter) and got those deafening thumps on the subwoofer!!!!!! However, I'm sure she'll find other reasons. . . .

[tafguy]

I'm glad you made it after a stressful week-end!

That was quick!

Did I tell ya in the end, it will come back to receiver setup which is in your case the digital input that causes all this? A pretty lucky guess!

[Bob_B]

Probably a bit of luck and experience combined on your part.

I still feel on some level that this is a minor design flaw in an otherwise great receiver. It wasn't as if I had the input on Analog, DVD 7.1, etc. when it should have been on Digital??? I would have expected that with the input on "AUTO" the receiver would have been able to sense the input without emitting noise? However, it is what it is. I'm just happy I don't need to drag the bad boy in for service.

Actually, after I made the changes last night I did still hear a slight pop - barely audible - on the front speakers when I switched the mode to CD (an analog source in my setup), but it didn't seem to set off the loud thumping I was getting before (and it didn't happen when switching modes within the digital inputs -> DVD, TV, etc.). Assume this must be modest residual noise in the receiver from "normal" switching (i.e. just switching modes from digital to analog and not trying to "auto sense" the input type)? However, as long as I'm not hearing the thumping anymore - I'M HAPPY!!!!!!!!

[gjritter]

PROBLEM SOLVED!!!!

I had my receiver set to "Auto" for the input signal on some of my components (even though some of them only had the digital output connected) and apparently this must have caused a delay in the receiver leading to the thumping / popping on the subwoofer / speakers. I changed the input to "Digital" and the problem went away. Apparently, I won't be needing that audio line isolation transformer after all!!!!

Thanks again for everyone's help.

I have a similar problem on my system, which also uses a VSX-D912K. Whenever I switch inputs, I hear the loud thump from the subwoofer, as well as when I change channels on my HD cable box. It also happens when the cable box loses the audio signal on an HD channel, which seems to happen quite often with my cable company, so I hear a lot of thumping in the middle of shows.

I tried doing what you described above, but it hasn't changed the problem at all. What I did is go to each of the inputs on the receiver, and press the input select button on the receiver to select either analog or digital as appropriate for the input, so that none of them are in auto mode. However, I'm still hearing the thump when I change between any two inputs, regardless of whether they are analog or digital.

Am I going about this correctly, or did I misunderstand the solution that worked for you?

TIA,

Greg

[tdekany]

I have the same receiver is two different houses and have no issues. I hope you can solve the problem soon.

[brijvad]

I am also having this problem whenever I change modes or sources on my receiver. I am using a Pioneer 1014tx receiver which is basically a de-badged Pioneer Elite 52tx. Everything else works just fine but it is extremely annoying everytime I change modes and, no to mention, it always scares my 1YO daughter with the thump of the sub.

Any further ideas would be greatly appreciated.

Thanks,

[octalon7]

I get a loud thump when I switch my preamp off, I'm still hunting down the problem. It does it most of the time, but sometimes after I let it all sit idle and then shut it off I won't get the thump...other times I do. I'd hate to have to reach where my sub is to turn it off and on all the time.

[tdekany]

If the unit is not defective it has to be connection/setup issue. I'd unplug everything, and reread the instruction and follow the manual when reconnecting, selectingoptions.

[octalon7]

It's all connected right, no mistake there.

[tdekany]

It's all connected right, no mistake there.
And you selected digital and/or analog where applicable etc???

[octalon7]

Yeah, no need to worry about that, I don't have a fancy DTS/Dolby or anything of the such preamp. I run a tube pre, with the most basic of settings. Even if I cut the volume out on the pre I still get the thump, so I'm still curious.

[brijvad]

I had the subwoofer thump problem with my Pioneer 1014 receiver when I would change inputs, power the unit on/off and even when changing radio stations...

I tried just about every idea I could find on the net but none worked. I ended up returning the Pioneer and got a Yamaha 5760. It solved the problem. Must have been a problem with the receiver. Just thought I would post my comments.

[Bob_B]

I've been away for a while. However, to answer one of the subsequent questions that were posted after I left (I think it was "gjritter") on what I did with the Pioneer VSX-D912K, it was just setting each of the digital / analog inputs manually based on the type of input instead of having the receiver "auto sense" the input. Seemed to solve the problem in my case (aside from a barely perceptible noise when switching from a digital to an analog input), but I'm not sure what "gjritter"'s setup is like (e.g. both digital and analog connections on certain pieces of equipment, other settings, etc.). I know that I only have digital OR analog connections for each piece of equipment, so I'm not sure if this makes a difference in solving the problem (e.g. receiver may still have problems handling simultaneous digital and analog connections -even if you're trying to force it one way???)?

Overall, it seems that there are others out there that continue to have this thumping problem with Pioneer and other types of receivers. Some of the research I had done suggested that this problem was possibly caused by the lack of a "muting circuit" in the receiver itself. I'm not an electrical engineer by trade (obviously), but, as the name suggests, the muting circuit would presumably prevent extraneous noise in the receiver (e.g. from switching inputs, powering on, etc.) from being emitted downstream in the speakers. Not sure if the Pioneer's have a "muting circuit" or not, but I would guess no based upon my experience.

Don't think I can offer much more in the way of help on this, but I certainly appreciate the help I've gotten on this board.

Thanks,

Bob

[blakelock]

hi all,

I recently had the same problem. I have a Hsu ventriloquist speaker system with an STF-2 subwoofer. I had used the sytem for ~6months with no problem but then I rearranged the setup and started hearing a loud thump every time I switched modes on my pioneer 1014 reciever.

I tried plugging the sub into a different outlet, I made sure that all inputs were selected as digital or normal as appropriate. I even tried removing all inputs to the reciever to eliminate noise . None of this worked. Finally, I tried a new (and better) sub woofer cable. That fixed it! Apparently the new arrangement must have placed the cable closer to some EM noise sources that weren't previously close enough to cause a problem.

good luck,
blakelock