The fella in the post did the following.
I did some more investigating and there appears to be a grounding problem. If I use a power cord that does not ground the NHT to mains I get no noise (the amp comes with a cord that grounds it).The NHT is the only component in my rack that actually has the grounding pin in the IEC socket.
There might be some funky wiring inside the NHT, I even looked at the wiring diagrams for the icepower modules at http://www.icepower.bang-olufsen.com...000aspdata.pdf. It looks like they all have balanced inputs by design so the NHT must be wired with the Vi- and analog ground shorted. In any case I would be interested to see if this is just a problem with my unit or if I am doing something wrong. In any case this is the first power amp that has done this in my rack and I have had quite a few. |
Goldenear...you mean iec adaptor? Why would I need that? All my gear is standard iec except the hddvd player which is unplugged/not used right now and it's a 8 shaped female plug I think called an A7 type. Anywho, doesn't matter as it's not being used. |
There is a ground bar or spot in your breaker panel to connect your earth ground. If you do not understand please do not experiment. There is very high voltage in the breaker box which can kill you. Maybe if you get your bar in the ground which is the hard part you can get the power company to connect the ground strap to your breaker box. Slip the guy a twenty. Once you get a good earth ground things will be quieter. |
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03-14-08, 12:16 AM vulture |
http://www.avsforum.com/avs-vb/showthread.php?t=1006934
people had the same problem as you, return the psa harvester, you need the ICE adapter.
Hope this works. Audioadvisor has the adapters in stock by Pangea. |
Vicdamone...I'm comfortable with chkng the wall plugs myself...not a problem. I replaced a some with powerports. I'll investigate and see what happens. Thanks for the tip on 'lifting' the gnd...I can try that too. |
Yes, in even the most exotic systems you'll hear varying small amounts of hiss with your ear right up to the tweeter. Whining? No, that maybe an indication of another problem.
Plugging the system into a single power strip channels the systems ground into the power strips ground wire. Plug the power strip into your wall receptacle and listen for any change. Then, use a three prong into two prong adapter "cheater plug" at the end of the power strips plug. Plug that into the wall receptacle and listen for any change.
Physically checking all the wall receptacles within the circuit in question will be done with that circuit disabled at the breaker box. A receptacle could still pass current even with a loose connection, this is what happened to me. The loose connection created resistance and eventually caused intermittent noise and interruption. Yes, the receptacles need to be pulled out just far enough to check their connections. Over time and hot and cold the connection screws may need tightening. If your not experienced with working with AC wiring call in some favors or hire a professional.
After I repaired my loose receptacle I decided to have both the two channel and HT circuits completely rewired with more robust metal clad cable and 20 amp dedicated breakers. Total cost by a licensed electrician was $375. in 2001. |
Vic...you are saying that 'you should hear...' some hiss/whining noise? It does dissipate as you move away from twtr/mid. Can't hear it from a couple feet but the center channel seems to do it the most.
I understand plugging all gear being used into a pwr strip...like one used for offices/computers...but how do I 'lift' the gnd...not sure how to do this. Thanks.
Should I pull the receptacles out of wall here in living rm andchk for secure connections? I know they all work if I need to use them though only a couple are used for anything...the rest have nothing plugged in them. |
I haven't read all the responses so far. I had a similar affliction and it turned out to be a loose connection from the house wiring to an outlet that wasn't in use but on the same circuit leg.
Plug the entire system into a power strip and the strip into an outlet then try lifting the ground with a cheater plug. listen for any changes.
You should hear some hiss with your ear right next to the tweeter which should dissipate within one to three feet. |
I have a psa harvester on the way...we'll see if that helps. Accorcing to my Panamax which shows both volts and amperes the voltage is usually about 122-124 and amperes are 1.1-1.5 when rig is being used.
I have pwr co coming out later in the week...maybe something will be found...maybe not. |
I normally use an AVR for all my audio gear, i usually hear noises when there's low voltage. |
DC current can ride along on your ac lines and cause noise in the system. I had that problem. Channel islands audio makes an outlet that can eliminate this problem. |
Coxhaus...I'm thinking about what you suggest and it reminded me that the direct tv gnd lead from the dish/cables tie in to the main somehow outside near main breaker box and my ac repairman showed me it contains a main switch/brkr from the street and two more...one for the compressor and one for blower unit.
Explain a bit more if you would please what you mean by clamp to main brkr box...? Clamp to what part...there is 220v in that booger somewhere...yikes. Thanks. |
I would install an eight foot copper ground rod. Attach it with lightening ground wire and clamp to your main breaker box. This can be bought at Lowes or Home Depot for less than $50.00 bucks. Having a good earth ground helped me with a noise problem at my old home. I installed one when I moved into my current home. It is real easy just use a garden hose to soften the soil as you drive the rod into the ground. When you get the rod low you switch to a sledge hammer to finish. |
Visiting the thread has me wondering more now...I am going to unplug the cordless phones, microvave oven, and satlt boxes tomorrow and listen to what happens.
I unplugged the modem/router and it made no difference. Also tried the fridge and no difference. Just unplugged freezer in garage and no effect. That only leaves the phones, microwave, and satlt tuner/s. Better not mess with that now...wife is watching her shows and I need micro wav to warm up my java...hehe.
We do have a couple giant towers, cellular I guess, less than a mile as a crow flies. My sons rig has only the slightest bit of this noise and in order to hear it you must crank the volume up to refernce level or so without any souce playing. I put together a 5.1 system in his room a couple yrs back for his b-day and he does not have this issue using a little Denon 5.1 recvr/tv/xbox, etc. That little rig will blow you away in his 10x12 room.
Anywho...I'll continue troubleshooting tmrw while home alone and follow-up. Thanks again. |
Sop1...I understand however, noise is clearly audible though not loud-loud...but there nonetheless. If I were to cover my ears/plug them I don't hear anything hardly. Thanks.
Hifihvn...What I meant by 'amp alone' is just that...amp plugged in and powered on...nothing connected but power cord of course. When I then connect a spkr the noise is evident. The noise, whatever is causing it. has to be travelling through amp and then on to spkr/s. Center channel seems to do it most/loudest if you wanted to look at things comparatively. I had a Yamaha recvr(rxv2500) in rig a few yrs ago...hiss. Then got a BA 7120 recvr...hiss. Then bought a BA 7200 pwr amp...hiss. Now with Nht amp...hiss. So yes it's a problem with all the recvr's/amps I have had in the loop. I now have minimized setup to include:
prepro
pwr amp
oppo Br
panamax
dual a1 mono's/x2 combo bi-amping the mains lower end...
...and the svs beast.
The Panamax does help as I connected things without it...noise was more prominent...disturbing. So the Panamax is helping quite a bit.
I just purchased a PS Audio noise harvester...going to see if it helps. I just can't go spending lots right now to solve this. At the moment it's reasonable and clearly audible when within a a couple feet from mains/surrounds. The center channel seems to amplify it the most and if it's quiet in here, which it is most of time, I can hear the whining noise sitting on the couch 10 ft away. Thanks for the advice/help. I 'm going to call pwr co as I said I would...this week if I can remember to do so with everything else going on in my life at the moment. I appreciate the help/concern...much thanks. |
>>Btw...amp plugged in alone is dead quiet as I suppose it should be as it uses B&O ice power class D.<< Is this statement an error?The more you describe the noise the less
chances of it being A/C power hum or bad power connection is less likely.A lot of power utilities will check for a poor connection in your breaker box as a courtesy.If it is not anything in your gear causing it,it still sounds like something electronic causing the problem,especially different gear doing the same.A fan speed control,even in heat/ac system,microwave oven timer clock,and on and on.A lot of appliances always have something electronic running when you think they are totaly off.Even sprinkler system timers. |
I have reread your posts describing the noise and, I am not writing this to be funny or rude, but it sounds like it could be early tinnitus. Can you hear this sound in a completely quiet room or with unplugged noise canceling headphones on with no music? I have tinnitus which is exactly what you described... "Noise is definitely high freq pitch like a shortwave radio band when out of tune...a whining noise" , and it is very annoying. When there are other sounds I don't notice but when I am listening critically to quiet things or going to sleep it drives me nuts. |
%JJones...what would foil do or more important what would it prove? Again, excuse my ignorance, what would the plugging lamp into same plug/receptacle prove? What am I looking for during experiment/troubleshooting? %
The foil is hard for radio wave like stuff to penetrate, if it had an effect on the noise that would be a good clue. The lamp with a high wattage (low resistance) bulb gives you a drain path for grunge on the ac line, again it would be a good clue if this made any difference. Just looking for something that would effect the problem & narrow down the possibilities. Good luck. |
Mlsstl...I have unplugged/seperated all gear. It's lying all around the lvng rm. Wife is giving me weird stares while I promise a quick fix...sshhhhh.
Anywho, No tv as stated in initial post. Don't have a tv in rig...those are reserved for bedroom and son's room. I use a pj with no tv/sat connected...dvd/br only. I don't watch tv personally...occasional news/weather.
Noise is definitely high freq pitch like a shortwave radio band when out of tune...a whining noise. |
Unplugged modem/router and no difference.
I am going to contact the pwr co tmrw and have things looked at to chk if all is within spec. Our pwr, phone, cable lines are undergnd though we don't have cable tv and junction boxes are every few houses or so.
I am going to turn off all brkrs except one used for powering rig and see what happens. I'll post with a follow up.
|
An "AC buzz" is the 60 Hz noise one hears when a ground connection is bad or the AC cord is plugged in backwards. It sounds like your noise is much higher frequency.
Where is your equipment located? If you have your amp, preamp and source equipment located in the same rack as your TV or similar equipment, they may be the source. TV equipment in particular can emit a lot of EMI at higher frequencies. (Also remember the "off" switch on a lot of modern equipment doesn't actually shut off power to the piece of equipment. It just puts it in standby so the internal circuits are still live - and noisy.)
Try removing your amp from the equipment rack and powering up the speakers with the amp several feet from any other electronics. If that solves the problem, then add back the preamp and audio source(s). In lieu of moving equipment, you could also try physically unplugging the other items.
If the noise is still gone, that means your interference is coming from other equipment on the rack. You'll simply need to physically separate the audio equipment from your other stuff. Often just a couple of feet will do the trick. |
I did the cheater plug method and extension cord method and results are no fix. Seems like anywhere in the house yields this high freq pitch from mid/twtrs. It is audible from within a foot or two and if you pay close attention in a quiet setting, which I have, you can hear the whining noise from farther away. It is not audible over source playing though.
I think I'll contact the pwr co tmrw and see if they can get a tech out hear.
In the meantime I am going to unplug the router which is at opposite end of house in back spare room/office. House is ranch style and I am next to garage in living rm.
If after all possibilities are eliminated and I still have this are there some things I could do to lessen it like better shielded spkr wires or ic's. My bluejean cables are known for the ability to reject emi/rf noise due to shielding on the cable/s. I was thinking a Ps Audio conditioner or something. My Panamax 5500 is not a cheap piece by any margin but it does not eliminate the noise.
I appreciate the help folks. Just want rig to be more quiet. Concerned this high pitch will hurt my gear whether it be preamp/pwr/or spkrs.
Btw...amp plugged in alone is dead quiet as I suppose it should be as it uses B&O ice power class D. |
What about wireless interference? The speaker wires or components in the amps might be picking up something external in the air. I had a problem with my HDTV pixelating intermittently. Turns out it was a cellphone that was on a frequency that was a close frequency to particular channels and the cable box unit was picking it up. Perhaps some device in your house is not shielded enough, malfunctioning, or too close like microwave oven, cellphone, cordless phone system, a wireless router, satellite dish, near the path of a business microwave communication link.
Another idea is to have your electric main on the outside of the house checked by the electric company. I believe they will come out for free to check this as the core in the box is their equipment. These cores can go bad and if they see the specs are out of normal they will replace it. They will probably put a new one in anyway since they are there already. If they do their job correctly they will also check that you are getting two solid, clean 120 (x2 =240)connections to the house from the pole as part of the call. |
Detredwings...I have had this problem with all amps. I have current amp plugged in to wall, and using one spkr cable to test main L, C, main R. No preamp connected at this time...amp is solo. I still get the whine/hiss. I am basically bench testing so to speak.
Concerning cheater plug...can I use a 1 male to 3 female type plug which is used for plugging in and powering 3 things from 1 outlet? I have a couple of those around the house for desk lamp/phone charger/etc. It has ability to accept 3 prong plugs but only has 2 prongs to plug in receptacle. That would work for testing purposes would it not?
If I use headphones to test for noise I will have to connect prepro to amp of course which I can do in a moment as this thread is happening in real time almost and I appreciate all the help/advice. |
Mnnc have you always had this problem or is it something that just starting happening?
As far as the cheater plug. No it will not hurt it to just plug in your amp into it to check the noise. I would recommend just one amp plugged in with one set of speakers not all your components.
You can also try your surround speakers in the mains positions to verify a possible mismatch as Mlsstl has mentioned. But try only the two connected disconnect the surrounds.
One last thing if you have some headphones trying hooking them up via the same power outlet through your CD player or amp and see if you hear the noise. |
Well, I'm not sure if it's an ac buzz as I 'm not really sure what an ac buzz is. I am figuring that based on other users of the same gear report no noise/buzz/hiss. The noise is slightly audible from main listening position @ 11ft. in a moderately quiet room and clearly audible as you approach the spkrs closer. Particularly from middle channel which produces the most. The best way to describe the noise is it's a whining hiss...like you might have in a car audio system when alternator buzz is heard through the spkrs...just not as pronounced. The mains are 87 or 88db rating at nominal 6ohm. All spkrs are Nht Classic series. |
Try to define the problem a bit more. You indicate this is not an AC buzz, but rather a white noise hiss from the mids/tweeters.
Is this audible from the listening position or do you have to put your ear to the speaker?
All electronics produce white noise but it is usually very low in level and inaudible at the listening position.
Do you have an usually efficient set of speakers? This could have nothing to do with your home's AC power but rather a mismatch between the gain of the amp and the speakers. If it's not audible at your listening position, I personally wouldn't worry about it much. |
So a 'cheater' plug is one of those adaptors that has 3 female/2 male...? Basically eliminating use of the gnd pin being plugged in? Will this not hurt my gear? Not all the amps/recvr I have are being used at same time and a couple of them differ in design concerning having 2 prongs in their iec or 3 prongs. This is by the nature of the manufacturers design. All gear is US 120v. |
This may sound odd but I had this problem before.
I had AC riding on the ground. Try using one of
those cheater plugs. Three prongs to two prongs.
If you plug in the power cord into the cheater
plug and the problem goes away you can then look
into the grounding issue. It only takes a couple
minutes to try and costs nothing. Good luck |
Hifihvn...interesting ideas. I will try some of your sugg...however, the loose connections in brkr box...forget it unless I kill pwr from outside main and then what do I tighten? When I look inside brkr box all I see is brkrs sticking out and ON or OFF. Where are the connection screws? Our pwr feeds are underground type. I could call pwr provider and have them do a chk/service if it's at no charge to me...pardon the pun. Thanks.
JJones...what would foil do or more important what would it prove? Again, excuse my ignorance, what would the plugging lamp into same plug/receptacle prove? What am I looking for during experiment/troubleshooting? Thank you too. |
I had a weird similar problem (buzzing noise inside amp, everything else in house aok) that was fixed by tightening all connections in my breaker box. The manufacturer suggested that it was more than likely a neutral connection that was causing the problem.
Would be interesting to play with wrapping the receiver in aluminum foil to see if this had any effect on noise just to eliminate emi as a possible source.
Another thing is to carefully eliminate the ground connection (assuming there is one) to the receiver using a cheater plug.
Yet another thing is to plug in a high wattage light to the same outlet your receiver is plugged into & see if this changes the noise.
I liked the previous posters ideas also. |
I wonder if there is something you overlooked like an outdoor security light,etc.Try turning off all of the breakers except the one its on,and see if it changes.Another thing to try is a 50-100 foot extension cord,and try the system on outlets in different rooms.This should get you on the other phase leg powering your home,plus a different circuit.A bad breaker,loose connection in the breaker box could cause this too.Also,where your service ties to the feed/drop wire to your home,and the transformer(utility) could have a bad connection somewhere. |
