Hum FAQ - Page 5

unfortunately I don't believe M-Audio can help. The reason is because if I bypass the M-Audio interface, and plug the cord directly into the computer (1/8" to RCA cable) the same buzzing sound still occurs. Only when I unplug the computer power cord does the sound go away.

Also I have tried different wires including monster cable.

I have 2 400w 4 channel amps when both are on - there is no hum once I turn on the receiver all speakers hum pretty loud. I have moved power around, different breakers,outlets,power protecters etc. I am using radioshack RCA to trimmed wires.

Anyone have any suggestions receiver in question is onkyo 805

Thanks

Have you tried this with just the amp and the receiver? In other words, are any other components hooked up including your TV?

No nothing else is hooked up just pre amp and amp

I recently unearthed an old, old Sony receiver (circa 1991) to hook up a new pair of Athena floor speakers to. You guessed it, I'm getting a nice hum that I can't get rid of (though it's more high-pitched, really). At first I thought it was a ground loop problem. So far I have:

-Unhooked every source from the receiver. Hum.

-Unplugged every device but the receiver in the entire living room, including lamps. Hum.

-Plugged in the receiver in a different room elsewhere in the apartment. Hum.

-Hooked a different pair of small computer speakers to the receiver with no sources connected. Hum.

-Hooked the Athenas up to the computer speaker sub to test them separately from the receiver. The computer sub was plugged into the same wall outlet as the receiver was originally. No hum (but nice music reproduction from my iPod).

I feel like all this points to a faulty component rather than a solvable ground loop issue. Given the extreme age of the receiver, I guess that's not too surprising. Does that sound like the logical conclusion to any of y'all (who are definitely more educated about this stuff than I am)?

If anyone concurs that the receiver is just going bad, I'll start shopping for a new one. Thanks!

rudds
You did a nice job troubleshooting.
Shop till you drop.

sfitzger

Sorry, but I'm not sure what that means!

In most building/electrical codes, the Neutral and Ground buss are tied together at the entry box. Separate N and Gnd wires go to each outlet, and there you can have a problem, with the way house wiring is "daisy-chained" one ground can get dropped, now you have not only a floating ground, but a shock hazard in addition to HUMMMM

You can purchase a ground tester. http://www.homedepot.com/webapp/wcs/...0&ddkey=Search

However, there's a way to ground the ground wire to the neutral wire on the wall socket. Just loop a small green wire from the ground hookup to the neutral hookup. This will create a grounded connection, but it's definitely not up to code and not advisable unless you must cheat.

Be sure to keep power cords away from interconnects.

The other night while listening to a SACD (5.1) very loud (-5 dBto -3 dB on the relative scale) I detected a low level hum between tracks( I would describe it as 60 cycle) . I have had this equpment for 9 months and hadn't heard this before. I don't think I had listened at that volume level before After investigating I found that I can start to detect the hum at volume set at -10 dB (very faint), it starts to get annoying at 0 dB. I have an Onyko 705, Panny PX75U Plasma, Oppo 981, Motorola Cable Box/DVR and Panny BD30 all connected via HDMI. I read this furum and did some research on ground loops. I replaced my power outlet with a three prong and checked it with a ground checker. It is fine. My cable is grounded outside with a seperate wire like I have read it should be. If I set my Onyko to direct, bypassing the preamp section there is no hum. I then began to troubleshoot.I disconnected all 4 HDMI cables (3 in and 1 out), there was no hum. I then started to plug in the HDMI cables one at a time. The Onkyo volume at max. With 1 cable in the hum returned but lower in intensity, with 2 in the hum got louder, with 3 in still louder, the 4th the hum stayed the same. I then disconected the cable (coax) from the cable box and unplugged the power cords of all the components, the hum was sill there. It doesn't matter what order I plug the HDMI cables in the hum is there and presents in the same way. Since it is only SACDs that seem to have a lower volume output, which would make me push the Onyko for extreme volume listening seesions, I increased the preset levels on the Oppo by +5 dB. This sort of solves the issue since I don't need to put the volume up above -10 dB to achieve extreme levels. But you know how it is, knowing the hum is there bothers me. Does anyone have any ideas or suggestions? Are there isolators for HDMI cables. I would greatly appreciate any responces. Thank you.

That's a first I haven't heard of humming type like this before? I mean sure with separates linking off an AVR, but not when increasing the volume on the AVR I gather your using the internal power amplification stage on the AVR.

Try this quick simple method of taking a short or any length of cable, wire attach it to the screw fitting on the AVR then go around each item attaching it to the screw head once you have isolated the humming issue screw the wire to that item and lets hope you don't get anymore humming issues

I am using the internal power. I will give the seperate wire technique a shot.

Well I hope it grounds the issue because I've used this technique many times.

A friend who is an Electrical Eng suggested I leave the HDMI cables plugged into the AVR and disconnect them from the various components. This will check to see if the HDMI cables are the problem. He doesn't think it's a ground loop. I'll try both and report back tomorrow.

Question is does the HDMI make your life better and wholesome if not junk them and use the other route to get around the issue or maybe one of the leads is broken or just keep working the problem. One time I had ground loop that took 24 hours around the clock to solve I got the bags under the eyes to prove it LOL.

I believe the noise or hum I'm getting at max volume is RF induced. Using an SPL meter near a speaker and plugging in each of the HDMI cables I am using, one at a time, I measured as much as a 4 dB differance in hum/noise between cables, which I could hear, but it was nice to quantify. It turns out the cable producing the least noise was the no name cable that came with my Oppo 971. The differance between this cable and the others is it has RF chokes at the ends. I ordered up 3 cables with chokes and some add on chokes from Monoprice. All for under $20.00. The noisiest cables were 2 from Bluejean Cables about 4 dB higher than the no name. The other was an expensive Monster Cable at about 3 dB higher. I'll let you know what happens when I get the new cables. Do you think a power conditioner will help?

I noticed a hum in my system when I install 2 subs. I had a different one before and used a ground lead over to the pre/pro and it took care of the problem. With the new subs (JL Audio F112's) connected with balanced interconnects it hummed. Grounding didn't work, lifting the ground on the power cord didn't work. I bought one of the Ebtech hum eliminators and it worked pretty good but I still had some hum. Finally figured it was coming from my cable TV cable and played with the ground at the outside box. Still couldn't get it quiet. So I bought one of the Mondial M.A.G.I.C. Cable TV Isolators used on Audiogon. What a great product. Absolutely no hum and I removed the Ebtech hum eliminator and everything is dead quiet. The hum was embedded in my cable signal. So if your in a similar situation, I would recommend checking out the Mondial device.

I have a sunfire cinema grand 5 x 200 watts. All channels hum. I have:

1) removed all inputs
2) turned off all other components
3) tested different speakers
4) tested all outputs
5) tried shorting input during test
6) moved amp away from all other electrical components


In all cases, I cannot get rid of the hum. With just one speaker connected, I can hear it from 10 feet away. with L/C/R speakers connected, it's very obvious!

It looks like fixing this amp is a $700 flat fee from Sunfire. Is there anything else I can do to fix this? Should I use one of the line "conditioners" like Belken PF60 (would it be a good idea to have one of these anyway?)? As a last resort, could I put some passive crossovers on each of the outputs to cut out the 60Hz hum?

I definitely have this ground loop issue on my TV.

My concern is as follows- while I am figuring out how to solve this issue, can I in any way damage my Plasma if I use it? Generally, can a ground loop damage the component it is affecting?

I've had two systems with ground loops. Both were caused by comcast cable lines. I resolved this by using a grounding block just before the the TV. My surge suppressor has a grounding lug. I grounded each component and made sure they were all connected to the same circuit. Obviously everyone's case is different, but you can try to see if you get anywhere with that method.

My Panasonic Plasma has had this problem for four years, but don't worry you will not hurt your TV.

I bought the Viewsonics ground loop isolator and it removed about 85% of the problem and cleaned up the picture a bit. For $25 it is a simple solution and took about 5 min to install. Give it a try.

I recently redid my AV system to use pretty much all HDMI cables and removed some obsolete components. The result was a very annoying hum.

After some isolation, I determined it was originating in the Comcast cable feed and being distributed by the HDMI cables. Putting in a 3 to 2 prong plug to lift the ground from TV (the only component with a 3 prong plug) helped but didn't fix the problem, plus running completely without a ground worried me.

So I got a Jensen Transformers VRD-1FF on ebay, plugged it in, and POOF! the hum completely went away, even at high volume and no input. This has had no impact on the quality of the cable video including the HD channels. I don't use view on demand or any of the premium channels so I can't comment on those.

Worked for me.

NB - Read and follow the directions that come with it!

#2 says "see number 2". I can't get out of this thread!

Note:
I posted this response in the "Subwoofers, Bass, and Transducers" forum, http://www.avsforum.com/avs-vb/showt...9#post17154999
but it should be part of this sticky as knowledge base info.





I had same problem, the cable people did a crappy job with grounding using cheap clamp, it had I think a bi-metallic corrosion going also as well. (wiggly clamp)

Before showing cable install job:


I took the clamp off, went to HD, bought 6' copper wire, attached to inside home copper pipe, actually next to where the 200A main also had a ground wire attached.
Copper wire going into basement shown:


To make matters a little more complicated, my outside faucets are "isolated" and not really connected to my inside pipes, due to my whole home EcoSmarte system, which uses various plastic/assy stuf for flowmeters, electrodes, etc.
So I connected a jumper wire from my inside pipes to my outside pipes, just to have them on the same ground plane.
This pict shows my whole home H20 system, kinda complicated but great H20 for whole home.


I also made sure the OTA antenna ground plane was same datum.
Here is in construction phase showing the home 2 ground rods.


Here is the OTA antenna being correctly grounded to the red circled one, it is visible just past hot tub cement pad.


Showing OTA copper wire on LH going around the corner under deck, while the antenna lighting rod is grounded next to the elect meters.


So, when solving ground loop issues you have to totally trace/follow your elect system and cable/sat/OTA/etc ground points.

For me, no more ground loop issue.
Maybe $12 max.

NICE post. In the truest sense of the word.

I've got a pretty vanilla 2-channel setup that I have setup.

- Sony XBR3 40" LCD (4 yrs old?)
- Oppo DV-981HD
- Yamaha V665
- HD TiVo
- MacMini
- NHTPro A10 monitor speakers (powered by it's own amp)
- Everything is connected the same circuit
- I don't get cable, I have OTA signal non amplified

I'm using the Yamaha just as a preamp for the signal to the speakers.

I can be watching for hours, and then I starting hearing a hum, which goes away if I turn off the Sony LCD, the audio from all the components will be hum-free

Any thoughts on that? I've considered trying the test by cutting out the NHT Amp,and powering the monitors through the Yamaha, but I don't suspect any improvement. Could it be that the age of the TV?

Thanks in advance . . .

It most like caused due to transformer interference from the Inverter Board of your Sony LCD. Call up Sony and see if they have a fix.

Maybe someone can shed some light on an issue I have. I already sent this message to PSB, but haven't heard from them yet.

I have an odd issue with a "PSB Alpha SubZero i" that I picked up. It is apparently never used, just long stored.

Setup:
PSB Image B25 Bookshelves
PSB Alpha SubZero i
Marantz PM5003 Integrated Amp

The B25s are connected to the A terminals on the Marantz, and the SubZero is connected from the B terminals to the high level inputs on the sub.

When the subwoofer is powered on, and absolutely nothing is connected to it, it is silent. Once I connect the speaker cables to the Marantz (powered off), the subwoofer begins to hum (and the hum is dependant on the volume control). Once I turn on the Marantz, the hum goes away completely. If I turn off the B terminals, the hum returns, turn the B terminals back on, hum is removed.

I've already tried changing the speaker cables, changing the power cable, plugging the power in to a different surge protector and UPS, getting power directly from the amplifier, connecting the sub to the A terminals, but I can't remove the hum when it's not receiving a signal from the receiver. I even tried to short the low-level input terminals with some RCA cables cut and the ground->signal wires twisted together.

Thank you for any help you can offer.

I've been mostly a 2-channel guy until recently when I bought a receiver to set up a home theater in the basement. I have 3 dedicated circuits that I use for my home theater gear. There have been no humming problems when I use just the receiver or when I use just my 2-channel gear (ie. 2-channel amp, pre-amp, CD player). However, as soon as I connect an external 5-channel amp to the pre-outs of my receiver, I'm getting loud humming noise through the speakers and even the subwoofer.

At first, I thought it was a problem with my 5-channel amp. So I swapped it out for my 2-channel amp to power just the front left and right speakers through the receiver's pre-outs. Now, this 2-channel amp has a ground lift toggle switch. When I toggle it on, the hum disappears and I have bliss. When it's off, the hum comes back.

Is it a simple solution to buy a 5-channel amp with a ground lift switch? Or is it better to attack the heart of the problem and figure out if I have a ground loop problem? I could just use the internal amps of the receiver, but I notice a better sound if I use the receiver's pre-outs and add an external amp to the set-up.

Thanks for your help!