Agh! I can't get rid of speaker feedback!!

hagmanm2

Ok, I've done as much as I know how to do and still can't figure out why I'm getting very noticeable feedback and moderate levels (and substantially worse at higher dBs). I don't even know if that's the right terminology for my issue: by feedback/noise I mean a high pitched buzzing that increases as the dBs increase. If anyone has any suggestions beyond what I've already tried please please help, it's starting to bug the bejeebus out of me!

This may also be of importance. The feedback is *less* noticeable when only the AVR or only the AMP is on. That being said, the AVR produces much more noise than the AMP when on by itself. The AMP's feedback seeems almost acceptable, but I still think it's rather noisy. Regardless, when both are on the feedback is much louder.

1st. I checked all speaker wires (bi amping to the 500s) to make sure they weren't running along power cables (which they weren't). I re-bridged the terminals and tried the cabling from *just* the AVR then from *just* the AMP and still heard the noise with no noticeable reduction.

2nd. I checked the interconnects between the AVR and the source: I checked the TV, TT, CD player, and the PC. I'm using throw away RCAs but I've ruled them out as the issue since the feedback occurs between all sources (unless I just need to get decent interconnects for all my connections).

3rd. I don't have a power conditioner but my roommate has a Monster HTS2600 so I moved that to my setup and plugged everything in. Still noisy!

Agh! What else could it be? The components are on a 3 shelf A/V rack and have a plenty of room to breathe... if it was just the AVR then why would more noise be produced when both the AVR and AMP are turned on? As I'm not very experienced with A/V equipment I'm kind of at a loss as where to go next... Any thought would be most appreciated. Thanks guys!

danger boy

first off, i would say you need better interconnects.. that's a no brainer. it may not solve your problem, but I would start there.

could also be a problem with the receiver or amp. i would disconnect the Yamaha amp, replace the jumpers and run the speakers off your Denon and see if the buzz is still there.

it could also be something inside the receiver or amp that is going out and causing the buzz.

unplug everything but one source. say the CD player and hook that up to the receiver, then add the amp... still with only the CD player, then add one component at a time and see if any of those are what's introducing the buzz.

your problem is not feedback though.. that's the wrong term.. i would just call it a buzzing sound. most all lower to mid fi components will have some kind of static or buzz, especially if they are older units.

billbillw

Feedback is not the correct term. Feedback is when you have something that is microphonic (like your turntable cartridge) picking up sound from the speakers (usually bass) and re-amplifying it which causes big problems.

I can almost certainly say that interconnect cables are not the problem. Sorry Dangerboy, but that is bad advice. Unless there is physical damage to the cables (bad ground connection or loose signal wire), cables will not cause that type of problem unless he was using the $hitty thin cables that come prepacked with AV equipment, which he is not. His sig shows Audioquest cables, which like them or not, they are certainly good quality.

Sounds to me like you either have ground loop hum or you have a component going bad. For ground loop, here are some things to look at:
Mixing components with grounded plugs and non-grounded plugs can cause this, especially if you have a cable box, satellite dish, or antenna hooked to the system.
Try unhooking the cable/satellite/antenna feed from your system and see if there is any difference. If that is it, you can get a ground loop breakers from RadioShack.

Just to make sure, you are using the ground cable on your turntable? If so, you could try unhooking the turntable altogether and see if that makes a difference.

Usually, if you have a component going bad, the problem will be there even when nothing is hooked to the device; ie: the amp hooked to the speakers with no other connections. Same with the AVR. You just need to trial and error things.

Chances are, its a ground loop. I've had it come up several times.

joeparaski

If the noise gets louder as you increase the volume, then the problem is BEFORE the AVR. Unplug ALL your sources, then try each source individually....report back for further instructions once you've done this.

Joe

danger boy

billbillw, did you miss this quote from the OP? "I'm using throw away RCAs" exactly the type you say.. thin throw away cables.

yeah it may not be the problem.. but they may contribute to the increase in buzzing sound he is getting. replacing them may, key word, May decrease some of that buzzing level.

billbillw

danger boy wrote: »

billbillw, did you miss this quote from the OP? "I'm using throw away RCAs" exactly the type you say.. thin throw away cables.

yeah it may not be the problem.. but they may contribute to the increase in buzzing sound he is getting. replacing them may, key word, May decrease some of that buzzing level.

Sorry, missed that. OK, Throw away connectors need to go, but also check the ground loop issues I mentioned.

hagmanm2

Thanks for the advice guys, I think we've narrowed it down!

danger boy wrote: »

"I'm using throw away RCAs"

yeah it may not be the problem.. but they may contribute to the increase in buzzing sound he is getting. replacing them may, key word, May decrease some of that buzzing level.

I apologize for the *slightly* misleading wording, they're not exactly the thin junk cables that come with components. Instead, they're radioshack cables which have thicker cabling and 'gold-platted' connectors. Still they were very cheap and I'm sure no where near the build quality I should be using (I'm upgrading cables incrementally as funds allow).

Anyways, the 1/8th to RCA from the computer was the biggest culprit causing the most noise. I had the PC and TT right next to each other on the back of the AVR and also noticed a *small* amount of noise jumping across, so I spaced the cables apart.
Also, I need better cables. What splitter cable would you guys recommend? AudioQuest, BlueJeans, etc? The computer is the device most listened to on my system. I have over 1TB of multimedia on there, so I want to make sure I don't cheap out on this cable.

billbillw wrote: »

Feedback is not the correct term.

Sounds to me like you either have ground loop hum or you have a component going bad.

Thanks for correcting me bill.

The ground loop also caused some of the hum. This is how I had it setup, please tell me if this is wrong. First off, I no longer have the ground cable that my technics TT uses, so I made a ground out of some left over speaker wire. Can that cause any problems? I didn't think it would since it's just grounding my component but it can't hurt to double check.

The Yammie AMP also has ground and the manual says, "If hum or noise occurs, try grounding the amplifier or connecting this terminal to the control amps ground terminal." This is how I had it setup: a spare speaker cable coming from the AMP and TT and meeting at the Denon's Ground Terminal. The TT didn't seem to make a difference in noise when disconnected, but the AMP did (though the hum is very very low). I thought it was supposed to be the other way around... When I remove the Amp's ground from the AVR there's no more hum! So can I run the external Amp without grounding it to the AVR? Sounds like I can but, once again, I want to be sure.

Once again, thanks so much for all the advice and sorry for the rather lengthy post. You guys saved me from clawing my hair out. :cool:

billbillw

Sounds like you have narrowed it down pretty well. You hadn't mentioned that you had your PC hooked up. That is a common source of ground noise as well as source noise (from inside the PC). What type of sound card are you using? Does it have an optical digital output that you might use? If so, that would eliminate any potential for the computer to contribute to noise. Optical cable from the PC to one of the Denon's optical inputs would be a great improvement. Any cheap sound card with an optical output would do since the DAC portion would be handled by the Denon.

You didn't really specify what you need a splitter cable for. Please explain.

In general, I wouldn't recommend using a splitter unless there is a very good reason (like to split a mono signal into two stereo outputs or to drive two amps from a single source).

BTW, the type of grounding wire is not critical, as long as it is connected in the right spots. On the Turntable, it should be connected to the tonearm ground (this is usually an internal connection which is not visible). Where do you have it connected?

As for the Amp grounding to the AVR, it is not necessary. If you get no hum without it, don't use it.

hagmanm2

Sorry for the confusion, the splitter cable is a 3.5mm to RCA, the current method of connecting my PC to my AVR... which is a story in itself.

I had the PC hooked up to the AVR through Digital Coax cable for the same reason you mentioned, to let the Denon do all the processing. However, for some reason it refused to send a 5.1 signal. Thankfully, I am very familiar PCs and although I don't know why, the problem is the digital out was only sending a stereo signal to the AVR, so the other channels weren't receiving any signal to play. Honestly, I just chalked it up to the cheapo audio driver the mobo probably is carrying. So I'm not using a nice audio card, just the mobo's optical out (but once again, didn't think it would matter if I used it or a nicer Creative card since it was keeping the signal digital and letting the Denon act as the DAC... is that correct?..). I may be reconsidering...

So I switched back to the 3.5mm headphone output to RCA. Oddly enough, when I switched back to the 3.5mm to RCA I left the digital coax connected and when I removed it (during the trouble shooting) I noticed the cable was carrying a good bit noise to the AVR. Well, I thought it was weird anyways. :O I would have preferred to use optical audio cable, but couldn't find a 15ft and the coax cable was ridiculously cheap. Do you think there'd be a difference between the optical and the digi coax cables?

billbillw

hagmanm2 wrote: »

I would have preferred to use optical audio cable, but couldn't find a 15ft and the coax cable was ridiculously cheap. Do you think there'd be a difference between the optical and the digi coax cables?

Yes. Digital Coax can carry ground noise. Optical cannot. Check monoprice for long optical cables. They are pretty cheap and shipping is reasonable.

http://www.monoprice.com/products/product.asp?c_id=102&cp_id=10229&cs_id=1022901&p_id=2766&seq=1&format=2


As far as getting 5.1 from your computer, that will depend on the source and of course, the drivers. That's another story though. For feeding stereo music, you just want stereo anyway, so I think that's the route you need to go.

hagmanm2

word. Thanks billbillw for the help!

danger boy

you never mentioned you were using a PC in your system. that opens up more possibilities for introducing noise into a system.

adam2434

+1 on using optical and ditching the mobo headphone output.

Regarding 5.1, have you checked the supported formats in the sound settings area in the Windows control panel?

hagmanm2

yeah I did check that: it supports DTS Audio, Dolby Digital, and Microsoft WMA Pro Audio. I also checked the drivers (completely up to date). The really funny thing is when I locate 'sound' in my control panel it wouldn't let me 'configure' my digital audio after selecting it (something it should let me do). I was even able to right click the icon - go to properties and test the output. Turns out it was capable of sending signal to the center channel, the **** just didn't want to. I even played an HD movie with VLC and set the 'audio - audio device' to 5.1 and nothing.

Seriously, it became more hassle than it was worth after that (especially considering the noise coming through the cable). I'm going to try optical and if I'm still having an issue I'm going to stick with my 3.5 to RCA cable while giving serious consideration to