-i forgot to mention the problem doen't occur unless the cd and amp are connected
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It sounds like there is a short circuit somewhere, or something groundng in the signal chain that shouldn't be. Are any of the RCA connectors loose? Can they be turned in the chassis? Has the volume control pot rotated from it's normal (mounted) position so that one of the lugs is touching something? If you're comfortable with working inside the units, use a non-metal stick to gently touch items in the audio signal chain (not the AC circuitry) to see if you can locate the problem. Otherwise, take it to a technician.
check continuity between the outlet and the circuit breaker / fuse box in the basement.
in my 'built-in-the-1800s' apartment (former place. thank god) they had thankfully run a ground wire from the metal outlet box down the metal conduit to the metal breaker box... so i simply had to jumper the hospital-grade outlet i installed over to the conduit or box, and viola, i had a 'proper' ground.
this would seem to be the source of your problem (grounding) - assuming you don't have anything nasty like an airconditioner or computer etc. on the same circuit. the only thing that concerns me is the whole 'sometimes it's gone, but when i touch it...' thing - you could be dealing w/ failed / faulty equpment? best of luck!
Dweller-i have tried many of the recommendations found in the archives, as mentioned i have dealt with this problem in the past, in this apartment i not only do not have cable i do not a have a tv anywhere near my system, which is the first or second outlet from the fuse box, i have tried different interconnect, cheater plugs and several other things mentioned in other post, I will try grounding the cd player to the amp, i have checked both my ac plugs and interconnects, if i do not fix it soon i will take the amp to a tech
When experiencing hum or noise, you have to narrow down the field of possible culprits by performing a simple process of elimination. You do this by "reverse engineering" the system, component by component, cable by cable and AC connection by AC connection. If you don't have the tools mentioned here, you really should think about purchasing them. Believe me, once you get in the habit of using them, they will be VERY easy to operate and well worth the miniscule investment.
(1) First of all, disconnect all of your interconnects from each component and all of the power cords from the wall. You now have only the speakers and speaker cables connected to your amp with no other cabling connected anywhere else. Without connecting anything, plug in your AC Polarity & ground tester and verify that the outlets are wired correctly. As a side note, you can probably find this at a local hardware store cheaper than you can at Rat Shack.
Once you've done this and verified that the outlet is wired properly and grounded, you can move onto the next step. If the outlet(s) aren't wired properly, that is the first thing that you have to deal with as AC is the foundation for our electronic components.
(2) If everything checks out okay, plug the amp into the wall and turn it on. If all is quiet, move onto the next step. If it is noisy, something is funky with the amp, the AC or you're picking up RFI / EMI. Relocating or changing speaker cables and / or your power cord may help.
At this point in time, you should use your multimeter to take a voltage measurement. Set the multimeter to read AC voltage ( at least 200 volt scale if manual ranges ) and connect one of the test leads to the "third pin" or ground on the AC outlet and touch the other to the chassis of the component. Remember, you're working with lethal voltage and current here, so be careful and pay attention. As a side note, you can use any of the ground connections on that outlet so long as they are on the same circuit. The component should be turned on when doing this.
Once the meter stabilizes with a reading, write down the voltage. It should be VERY, VERY low if everyting is working correctly. This would be a good time to start an "audio log" and this could be your first entry. Title it "chassis voltage" and break it down by specific component. Turn the amp off.
(3) Paying close attention to what you are doing, plug the interconnects that you use into the amp, but leave them unattached at the other end. Make sure that they aren't going to touch anything else or move about. Turn the amp on and listen. If it is silent, you are good. If it is noisy, one or both of these interconnects has a problem. If only one channel is noisy, TURN THE AMP OFF and swap the cables from side to side. Once you've done that and made sure that the cables aren't going to short out or touch anything else, turn the amp back on. If the noise follows the cable, you know that the cable is bad. If the noise remains on the original channel, there is something going on with the amp / cable interphase there. This could have to do with one cable being exposed to a greater level of EMI or RFI due to proximity to AC lines, transformers, etc....
If everything is good here, move onto the next step. Otherwise experiment with various cabling that you have to find out if you can resolve this problem without having to buy new interconnects. It is quite possible that one cable may demonstrate a problem whereas there are no signs of it with a different make / model in the same place.
(4) If the amp and one set of interconnects are quiet, turn the amp off and plug your preamp into the AC outlet. If not running a preamp i.e. you have an integrated amp or receiver, substitute a source component for the preamp in this step. At this time, we are NOT connecting the interconnects. Turn the amp on and listen. If all is quiet, turn the preamp on and listen. If all is still good, measure the voltage from the AC ground to the preamp's chassis like you did with the power amp and write it down. It should be very similar to that of the power amp i.e. VERY low. If it is measurably higher and you can reverse the power plug i.e. non-polarized two prong plug, rotate the plug and then re-measure the voltage that way. One orientation will probably be lower than the other and in most cases, the lower reading is "better". Use whichever orientation reads the lowest and if you can, try and mark the plug so that you know which way it should be plugged in for future use. I always mark the side that should go in the bigger opening for sake of consistency. If everything is working okay here, turn both components off and move onto the next step.
If you have noise here and you can't get rid of it, one of the components is probably damaged. The only way that they are connected is via the AC line. In order for noise to be passed from one component to the next in this manner would be if the power supply in one of the components was not operating properly or VERY poorly designed. Not good news, but at least you've narrowed down your problem.
(5) With both components turned off, connect the preamp to the amp with the interconnects now. Turn on the preamp and then the power amp. If everything remains quiet, that's great. Slowly bring the gain up on the volume control with everything turned on and see what happens. If the system remains quiet, and it should, you can move onto the next step.
If you have noise and reversing the polarity on one of the AC plugs doesn't do the trick, you might want to try using a ground lift aka "cheater" plug on one of the devices and give it another shot. If the noise goes away, one of the components is oriented out of phase from the other in terms of AC polarity or has leaky coupling capacitors to ground. This should have shown up in the chassis voltage measurements that you previously took.
By lifting the ground, you minimize the difference in voltage potential between the chassis and AC ground. As a side note, some people lift all grounds, some folks leave everything grounded and some folks ground one specific component and lift all the others. If you are going to lift the ground on everything but one, leave the ground connected to either the preamp or amp. To me, the preamp would be the logical one to ground in this type of scenario, but some feel that the amp is the right answer. Their reasoning behind this is that the amp probably has the biggest power supply and possesses the most potential for AC hazard should something go wrong. While this is logical, my thoughts are that the preamp is centrally located between all of the components, making it the "center of the universe". On top of that, the amp pulls WAY more current. Do you want all of that current running through one of those cheesy plastic "cheater" plugs???
(6) Just like we did with the amp and then the preamp, we are going to connect a set of interconnects to the preamp and leave them disconnected at the other end. If running a phono system, start with this input. If your TT doesn't have removable interconnects, keep reading here but you'll be skipping the first part here. If you're not running a TT at all, skip to the next step.
Turn the system on and check for noise with the input selected to the phono stage and the interconnects hanging loose. If it's quiet, good. If it is noisy, swap the interconnects between channels ( turn the preamp and amp off first ) to see if it is a bad cable / connection or if this isn't a suitable place for those interconnects. If you hear no major noise and can advance the gain control on the preamp way up, we are good to go here. If you get audible / measurable noise with the gain cranked up, this is somewhat normal, but it shouldn't be excessive. Phono interconnects can make or break a vinyl set-up, so don't skimp here. Experiment with what you have in terms of interconnects until you can get it as quiet as possible.
(7) Phono systems are VERY touchy when it comes to proper grounding. Plug the TT into the wall, turn it on and then power up the preamp and amp in that order. Remember, the TT is NOT connected to the interconnects yet. Measure the chassis voltage between the AC ground at the outlet and the "ground" wire or ground connection on the TT. Since many TT's use a non-polarized AC plug, you really should check the chassis voltage both ways and see what gives the lowest reading. Write down this reading and mark the plug for future reference. If you don't have noise in the system, and a TT shouldn't feed a bunch of garbage back into the system, it's time to start making connections to the preamp.
(8) Turn the system off and first connect the ground connection of the TT to the chassis ground on the preamp. Fire up the TT, then preamp and then the amp. Hopefully, we are still silent. Shut the system down and then connect the interconnects from the preamp to the TT and fire things back up. Hopefully, we are still quiet, even with the gain turned up quite a bit. If not, kill the power to the system and try reversing the orientation on the AC plug for the TT. As mentioned before, the lowest chassis voltage is "typically" best, but not always. Once you've done that, fire the system back up and listen for noise. If it's good, and one AC orientation for the turntable WILL be better than the other, you're ready to move on.
(9) If running a transport & DAC, hook up the appropriate interconnects to the preamp and put the system through the paces in terms of checking for noise, if the cables are not appropriate for that input, if you have noise does it follow an individual cable, etc...
(10) After all of this is done, hook up the DAC to AC. Once again, we aren't connecting the DAC to the preamp interconnects, just testing to see if the DAC ( or other source ) is pumping high levels of "garbage" back into the AC system and other components or introducing RFI into the system via "spraying it around". Turn the DAC on, then the preamp and then the amp. If all is quiet, measure the voltage between AC ground and the chassis of the DAC and write it down. If you can play games with the orientation of the AC plug, do so and record that reading. Like we did above, we are typically looking for the lowest voltage reading. If everything is quiet here, move onto the next step.
If you've got noise here, the DAC is generating "digital nasties" and it is affecting the other components. Some type of AC filtering between the wall outlet and the DAC should be tried. Sometimes, something as simple as tying a "knot" in a very cheap and flimsy AC cord or attaching a ferrite bead around the power cord where it enters the DAC is all that you need. Other times, more advanced filtering is required. This is obviously something that you can experiment with to see what works best now that you know how to do this type of thing.
(11) If all of that is sorted out, turn everything off and connect the DAC to the preamp via the interconnects. Turn the DAC on first, then preamp and then the amp. If all is quiet, increase the gain via the volume control and give it a listen. It should still be quiet. If that is the case, move onto the next step.
If you've got noise, it is time to break out the cheater plug or reverse the AC plug orientation on the DAC. It is either that or you've got leaky caps inside the DAC, causing higher voltage to appear on the chassis. Did you remember to check this BEFORE hooking up the interconnects???
(12) Once you've got that sorted out, move onto connecting the next set of cables, either to the preamp for what would be another source or from the DAC to what would go to the transport. The cables are NOT connected to this source though and we follow the same procedures as listed above. Check cables for noise, verify which channel or cable the noise is in if there is any, etc...
(13) Plug the next source or the transport into the AC and measure the chassis voltage. Play with plug orientation if possible, record the voltages and select the orientation with the lowest voltage possible. Check for noise with the system fired up and take the appropriate steps. Don't forget to mark the plug if non-polarized and two pronged. Unplugging it once and not having it properly polarized when you plug it back in can throw all of this hard work right out the window.
Now that you've got the hang of it, you can walk through the whole system inch by inch and know what works and what causes problems. Remember, we aren't just checking to see if the problem is related to the audio output of a component, but also each set of interconnects and / or the power supply of each component. When everything is connected and working properly, you might want to measure the chassis voltage for each component again. If everything is "right", you should show the same voltage on each chassis for everything in the system. If a component varies from the others, and this is possible if it has a "floating chassis", it should read "0"
By using a scientific approach, taking measurements and recording data, we can eliminate specific combo's and / or minimize the variables as to what could be causing the problem. At the same time, we've also established a point of reference for each component individually and the system as a whole. We now have a reference that we can refer back to at a later date if something starts getting screwy or you experience major changes in performance for whatever reason.
Hopefully, this will help someone out or at least give some of you a better idea of how to track things down. While some might find the idea of an "audio journal" a little "silly", it really isn't. Those that swap components on a regular basis and / or start writing things down now before they experience a problem will probably have a different point of view. That's because they'll have all the info that they need to know at their fingertips should they ever need it. No need to guess as to why something happened, they'll have taken the first steps towards becoming "audio scientists". Obviously, white lab coats and pocket protectors are optional : ) Sean
My compliments - that is as thorough and helpful a post as I have seen in my 3 plus years on Audiogon. Truly, it is input and helpfulness such as this that will foster a true appreciation for a truly "under-appreciated" hobby/pastime such as ours.
No, I don't have a ground loop problem - I just wanted to commend you on your willingness to help. Nice work!
LOL...has this now turned into a forum on "Sean" responses...LOL...yet again a plethora of information...I almost feel that there is really no need to post a question in the forum...just email Sean personally...keep up the good work Sean, and invest in a parrafin wax hand bath...I have a feeling it would be a great investment for your audiophile lifestyle...or maybe allthe audiogoners who read your insightful posts should chip in and get you one...I'll send a buck for the cause.
I know a lot of homes(older) in the South did not use the regular three wire outlets with neutral, hot and ground. Instead they used the neutral as ground(there is no actual ground wire) I have run into problems actually grounding and/or installing stuff around here. Check the wire and see if it is 2 conductor Romex or if it has a metal shield on the outside going to your outlets. If it has the metal shield, you can use this as a ground.
Try(if you haven't already) rotating the plug 180 degrees on one component at a time and see if the hum will stop. I doubt you have the standard sockets with the large spade small spade opening unless they were upgraded at some point. You can use a cheater plug if need be. You may have a polarity problem with one piece of equipment.
Also, if you have any variable lighting---turn it off. It feeds back on the line in these homes.
thanks for all the help, especially the post from Sean, i'll probably have to look it up in the future. Thee problem truned out to be something wrong with the cd inputs, i did not detect this the first time i checked them as they do not repond to movement (it does not affect the problem when they are wiggled) and they occasionally work leading me to believe the problem was elsewhere, however upon trying another set of inputs for last night and this morining i have not had problems since, once again i appreciate the help for all and once again thank you Sean for your time.
Mkaes: Glad that you were able to solve your problem and that it was a LOT simpler than what i suggested. What i discussed is a LOT of time and labor and i'm glad that you didn't have to go through all of that without planning for it. Having said that, this is something that really should be done if striving for optimum results. Between doing this and cleaning all of the connections within the system, the difference in the noise floor, dynamic range and liquidity can be staggering.
Other than that, i appreciate the words of support posted here and received in e-mail. The main reason that i take the time to do things like this is that i think that it may help others. That and the fact that i think that you folks are worth it : )
Hopefully, having a step by step guide to walk one through such things like this will encourage those that are "hands off" type of people to give it a try. It is not nearly as tough as you think, but it does take time and a plan. Now that you've got a plan, try to make the time. Maybe it will take longer then expected, and you might be without a system for a day or two ( possibly longer depending on your schedule ), but in the long run, you'll come out WAY ahead. On top of that, this will not only benefit the entire system equally, you'll have learned a TON along the way AND done so without spending a small fortune.
Besides the benefits that can be achieved, you'll come to understand just how much "small" tweaks can add up into major improvements. Just bare in mind that the result of doing all of this isn't necessarily an "additive" tweak i.e. MORE of everything. This is more of a "subtactive" tweak. That is, it removes a lot of the grain, glare and noise that you never realized that was there. By reducing these effects, you do get "more" detail, resolution, clarity, liquidity, "ease of presentatin", etc.. but it is not an "in your face" change. Rather than sounding "BIG" and "DYNAMIC" and jumping out at you in a "hi-fi" sort of way, you find yourself being drawn into the music rather than the presentation. While listening to the music, you find yourself not only tapping your toe, but marveling at the small sonic details and subtle changes that were never to be found before. That's because a lot of the artifacts of the gear itself i.e. self-generated noise within the system is no longer interfering with the music and what we hear. Call it a removal of "inner-conflict". Not only does the system sound more confident due to casting out the inner demons, it is no longer afraid to reveal the inner beauty that it had all along.
Try it. I'm not joking about the results. And clean those contacts while you've got it all pulled apart. Sean
Here's one more "tip" that i overlooked. Agon member "Brick" posted this tip over in another thread about "dedicated AC lines". Kudo's to Brick for pointing out the obvious. It was so obvious, i didn't even mention it in this thread at all. I'm good like that sometimes : )
Before starting on anything else, take your multi-meter and turn it to AC voltage ( 200 volts if manual ). Measure your AC voltage and see what you have. It should be somewhere between 115 volts and 123 or so. Getting up much above that can cause problems with some gear, so it's not a bad thing to check this once in a while. Going below this can also cause problems, but this would be more of a sonic problem than one of potential damage.
For those that don't know how to do this, you simply insert one probe tip into the outlet on the wall and the other probe tip goes into the other slot. It does not matter what slot the red or black goes into as AC works differently than DC. Bare in mind that i'm talking about the "slots" here and not the "hole" for ground.
After measuring the AC voltage, pull the probe tips out of the outlet and adjust the multimeter to measure DC voltage ( also 200 volt range ). Insert the tips into the outlet just like you did before and see what the multimeter reads. Hopefully, it should be phenomenally low i.e. "0" or "0.01" etc... The higher the reading that you get, the more DC that you have on your line. While most gear can tolerate a small amount of DC on the AC line, other gear can buzz, hum or run very hot. As such, this would be one more thing to check if your system starts making noise out of the blue. Keeping track of data like this in your "audio log" might come in handy. Should you need specific dates for reference when trying to resolve a problem like this with your AC provider, you'll have all the information you need at your fingertips. Sean