I have a humm in my system, need help troubleshooting

[Mike82]

I have a Sunfire Theater Grand 2 pre amp, Parasound HCA-855A Amp and I am using my PC as a audio player. I am coming out of my PC's motherboard optical output as of now. I get the Humm when I have the pre-amp and amp turned all the way up and nothing is playing.

What I have Tried
-Tried different RCA cable(Humm still there)
-Unhooking the optical cable from the pre-amp(Humm still there)
-Trying all the 5 channels on the amp(Humm still there)
-Shutting off the Pre-Amp and keeping the power amp on(Humm Gone)
-Hooking up different Amp and keeping pre-amp on(Humm Gone)
(This is obvious but the second amp is a audio source amp and seems to idle power when no input is being sent to it)
-Hooking optical cable back to pre-amp with new amp and playing a song and muting it with power all the way up.(Humm still there)
(I think that I get noise from my PC to start with, which I also am trying to figure out. But cant figure out why I get Humm with no PC connection?)

It seems it is the pre-amp but is there anyway for sure to test it? I am stumped.

 

[Mike82]

I found some analog drivers for my sound cards optical output. Now when I am hooked up to the PC with the pre amp and amp turned all the way up the Humm or I should say crackle is much quieter. You have to have your ear within a foot to here it. Is this normal I am new at this?

Edit:
After playing one song and trying it again, it is back to what it was much louder.

 

[Joeteck]

check your ground at the outlet,and on your other components that don't use 3 prongs..

I think the outlet is your problem. Your ground and neutral are swapped. Or ground and hot...

Try a totally different outlet and see if it goes away..

 

[walter duque]

check your ground at the outlet,and on your other components that don't use 3 prongs..

I think the outlet is your problem. Your ground and neutral are swapped. Or ground and hot...

Try a totally different outlet and see if it goes away..

That's what it seems to me to. Plug your components into a a different outlet or just change them around and see what happens. When I unplug my processor I get a hum in my powertowers, plug processor back in and it's gone.

 

[Mike82]

I think you might be right I have been having problems with power issues. I checked the plug for the pre amp which has a 3 plug. But on the back of the pre amp there is only 2 plugs but the plug going into it only has 3. I checked to see if it was broke off but it does not seem to be. Is that normal, its seems to me that the pre amp should have a 3 plug.

 

[walter duque]

I think you might be right I have been having problems with power issues. I checked the plug for the pre amp which has a 3 plug. But on the back of the pre amp there is only 2 plugs but the plug going into it only has 3. I checked to see if it was broke off but it does not seem to be. Is that normal, its seems to me that the pre amp should have a 3 plug.

You could have a bad walloutlet that's tied to the same breaker. Outlets do go bad since most of them only cost 99 cents.

 

[Mike82]

I just ran a brand new curcuit from the box on its own 20amp breaker. All I have on it is my amp pre amp and monitor. Its still there, I am going to try to swap out surge protectors next.

Edit:
I put a 3way on the end of the extension cord instead of a surge protector and plugged in just amp and pre amp and its still there. The extension cord is a 20ft 3 prong if that makes a difference. The humm or crackle it makes is much louder when the optical is unplugged from the pre amp for some reason. Also I tried in the mean time trying different optical inputs on the pre amp which made no difference.

 

[walter duque]

I just ran a brand new curcuit from the box on its own 20amp breaker. All I have on it is my amp pre amp and monitor. Its still there, I am going to try to swap out surge protectors next.

Edit:
I put a 3way on the end of the extension cord instead of a surge protector and plugged in just amp and pre amp and its still there. The extension cord is a 20ft 3 prong if that makes a difference. The humm or crackle it makes is much louder when the optical is unplugged from the pre amp for some reason. Also I tried in the mean time trying different optical inputs on the pre amp which made no difference.

Do you have a cheater plug handy. Thats goes from 3 prong to 2 prong. I have to use that on one of my poweramps. I also have an electrical mess where I live.
http://www.instawares.com/three-prong-grounded-plug.fel99480.0.7.htm

 

[Joeteck]

I just thought of something... I bet a set of your RCA wires went south... Disconnect everything, and then start adding them and see when you start hearing the hum. When you do, could be the wire or the device its connected to.

 

[walter duque]

I just thought of something... I bet a set of your RCA wires went south... Disconnect everything, and then start adding them and see when you start hearing the hum. When you do, could be the wire or the device its connected to.

Very good possibility.

 

[Mike82]

I tried swapping out RCA cables already and even hooking them up to different outputs on the preamp to see if that was it. I had no such luck though.

 

[Mike82]

Do you have a cheater plug handy. Thats goes from 3 prong to 2 prong. I have to use that on one of my poweramps. I also have an electrical mess where I live.
http://www.instawares.com/three-prong-grounded-plug.fel99480.0.7.htm

I just tried the cheater plug you recommended but the humm is still there. I just got off the phone with my dad, which is also a audioholic. He said that even in his system when he cranks the his pre amp and amps on wide open he will get some noise. He said it is amplifying little to nothing so much that in the end there is a little when turned wide open. At my highest power level I listen to I have to be about 6in away from the speaker to hear it. When wide open I have to have my ear 1 ft away or closer to hear it. He said I was being to idealistic. I am guessing the rca cables I am using make a little noise and when amplified that much it shows. I dont really have high dollar RCA cables.

 

[TLS Guy]

I tried swapping out RCA cables already and even hooking them up to different outputs on the preamp to see if that was it. I had no such luck though.

This is a classic ground loop. This issue comes up again and again and again.

A ground loop is a potential between grounds. The potential causes current to flow through cable interconnects and induces hum.

This is not a power issue, a cable issue or faulty equipment.

The likely culprit, and it usually is, is the potential between your cable and or phone grounds and you mains ground.

A good system should have one ground only. Make sure you have one ground and disconnect any cable, satellite or phone systems from your rig. If that stops the hum we will tell you how to proceed. You could also research the volumes of postings in this forum on this most frequent of problems.

 

[Mike82]

The only cables I have hooked up to my audio system in 2 RCA cables going to my amp from my pre amp and a optical going from my PC to my pre amp. Thats it. I also just tried putting in a cheaper plug which as far as I understand eliminates the ground issues. Also how do I make my system have only one ground?

 

[scooterp7]

The humm is still there.

I was always under the impression that the humming was because it didn't know the lyrics.

 

[BillP2R]

the Humm or I should say crackle

Well which is it?

While the responses are all focused on the potential causes for a classic 60Hz hum, if your problem is really a hiss or crackle it's not a classic 60Hz hum.

------------------- Bill

 

[sawzalot]

Well which is it?

While the responses are all focused on the potential causes for a classic 60Hz hum, if your problem is really a hiss or crackle it's not a classic 60Hz hum.

------------------- Bill

Definitely true while I never experienced the true groundloop hum I did have a distinct hum from the cable line at the digital recvr and I fixed that by changing the ground outside and a cylinder filter inside I also had the hiss crackling noise especially when using the master volume that turned out to be a short in the dcx 2496 now all is deadly silent.So there are different Hums, crackling and pops.

 

[Mike82]

It is more of a hiss crackle than a humm, sorry for miss leading anyone.

 

[sparky77]

Is this only at full volume? What does it sound like if you stop the music when your listening at your usual level?

 

[Mike82]

From my sitting area it is dead silence. At my highest listening lvl I have to be about 6in away from the speaker to hear it. When the amp and preamp are maxed out in my sitter area it is still dead silent, I then have to be about a foot away to hear it.