Amplifier buzz is a thing to fix- but it really shouldn't have anything to do with the electrical system.
DC Offset Blocker/Killer - where to buy in the USA
I have McIntosh MC8207, the first unit I bought from an authorized dealer came with a loud buzzing coming from the left transformer, and was replaced with a new unit which came with even a louder buzzing. The buzzing can be heard from 8 feet away. Then I was told to have install new 20 amp outlet that has its own isolated grounding.
That was done professionally by an electrician who installed two isolated 20 amp outlets, two 20 amp circuit breakers, two copper polls for grounding for each outlet, each outlet has its own neutral and power line. After all this done the buzzing sound was still there.
I was then told to buy a power conditioner which I did (Audio Quest Niagara) which was like $4000 and that did not help. Called back McIntosh and was told that I might have DC offset in my AC line and was told by McIntosh that I would need a DC Offset Blocker/Killer to which when I asked them where to buy one they told me to go on the internet and search to find one, to which I cannot find one.
This bothers me a little bit, if you as a company think that I have dc in my ac and i need a dc blocker wouldn't you need to sell one as well. I brought this amp to my friends house and it was the same no improvement, so my guess is that he has dc in the ac line as well.
So If anyone of you knows where to buy a DC Offset Blocker/killer please let me know, but even if this helps kill the buzzing wouldn't you guys think that this expensive somewhat hifi amp/brand should be silent from the factory. I mean this is two units in a row all purchased brand new.
My house is 5 years old, everything is brand new, the whole neighborhood is about 8-9 years old, my electrician says that I have perfect power coming to the house and everything looks fine.
Thank You
That was done professionally by an electrician who installed two isolated 20 amp outlets, two 20 amp circuit breakers, two copper polls for grounding for each outlet, each outlet has its own neutral and power line. After all this done the buzzing sound was still there.
I was then told to buy a power conditioner which I did (Audio Quest Niagara) which was like $4000 and that did not help. Called back McIntosh and was told that I might have DC offset in my AC line and was told by McIntosh that I would need a DC Offset Blocker/Killer to which when I asked them where to buy one they told me to go on the internet and search to find one, to which I cannot find one.
This bothers me a little bit, if you as a company think that I have dc in my ac and i need a dc blocker wouldn't you need to sell one as well. I brought this amp to my friends house and it was the same no improvement, so my guess is that he has dc in the ac line as well.
So If anyone of you knows where to buy a DC Offset Blocker/killer please let me know, but even if this helps kill the buzzing wouldn't you guys think that this expensive somewhat hifi amp/brand should be silent from the factory. I mean this is two units in a row all purchased brand new.
My house is 5 years old, everything is brand new, the whole neighborhood is about 8-9 years old, my electrician says that I have perfect power coming to the house and everything looks fine.
Thank You
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Trying to fix the problem for this amplifier's buzz it made a mess of my house electrical. I shouldn't have done anything but just enjoy my new equipment, now we went totally different direction about fixing something that was not broken in the first place. When I hire someone to do work I expect them to do all the necessary things, if they needed a permit they should've got one, and like I said everything was working just fine before I started adding outlets, even now everything works just fine and maybe everything is correct but I just don't know that what I am saying is correct, maybe I am wording myself wrong. This problem cost me so much time and money and nerves that is giving me nightmares at night. |
jea48 Chicago? I didn’t think the city of Chicago AHJ allowed NM sheathed cable ...If this guy lives in Chicago, then the work he described would require an electrical construction permit from the city. It would also require that an electrical inspector approve the work before the circuit could be energized. While the permit may cost a few $$$, it would be cheap insurance against the sort of hazardous connections described here. |
@ tomiiv30 OP Chicago? I didn’t think the city of Chicago AHJ allowed NM sheathed cable, (Romex is a manufacturer’s Trade Name for NM), in residential occupancies. My understanding all branch circuit wiring has to be installed in EMT conduit. Did the electrician install Romex? Is your house wired with Romex? Do you actually live within the city limits of Chicago? Jim . |
stereo52,661 posts01-21-2019 6:16pm I will bet you the AHJ in Chicago does not allow the equipment grounding conductor of an IG receptacle to be connected to an isolated earthed ground rod as the OP described the electrician did it. OP said: The other 20 amp outlet is grounded directly from the outlet to the outside rod with a clamp that is attached to the rod itself, I saw that with my own eyes. It is a straight wire that goes from the outlet to the outside and has nothing to do with the inside panel or anything else in the house. OP said: What is the difference between the ground wire that is connected to the panel itself and the one that goes to the outside, it still goes thru the panel but it is not attached to the panel itself it just goes thru the pipe that goes outside where the meter is and from there it is attached to the rod. // 2014 NEC® section 250.146 Connecting Receptacle Grounding Terminal to Boxhttp://www.cooperindustries.com/content/dam/public/wiringdevices/BuyersGuides/AHBG/I/AHBG-I-09.pdf Wording is word for word right out of 2014 NEC, page 70-133. Nothing said about connecting the equipment grounding conductor to a ground rod. I see no NEC exception given for the OP’s electrician. I also doubt the Chicago AHJ would approve what the guy did either. It’s dangerous! Surely you would agree? AS for the OP getting another electrician out to house I agree he should. First thing he should do is land the IG equipment grounding conductor on the ground bar in the service electrical panel where it should have been landed in the first place. Then the OP should have the electrician inspect the rest of the work the other guy did. . |
@stereo5 I still have the amp, a member of another forum sent me his two Emotiva CMX2 DC blockers and told me to put them in series and after doing so there is still buzz in the amp but quieter than without the dc blockers. Couldn't return it because I was over my returning period. The sales man could do so much, management would not even bother look into my matter, McIntosh is nowhere to be found. It was an expensive learning experience for me and was a first one for me. |
I don’t believe anyone commenting here is a licensed electrician for your area nor knows your areas electrical codes. I would trust your licensed electrician before any of us. While everyone is trying to be helpful, we are merely speculating at best. If everyone got to you and you are truly worried, have a different licensed electrician come by to look at everything for a second opinion. It will be money well spent for your piece of mind. Do do you still have the Mac amp or did you take the refund? |
You guys are scaring me big time now, this is Chicago and we got some of the most f’ed up people here that say they are something to later find out that they are nothing. These are guys that have been recommended to me by friends and family. What the heck is this world coming to. And I paid them top dollar and never asked for any discounts or anything, whatever they asked I paid. The last guy that I used the one that has more than 30 years experience, he showed me his license and works for the union and is a foreman.(It could be a big lie). Maybe he is older and stubborn and don’t want to upgrade himself to the newer standards or he is in for the quick money. Just like a mechanic if he tells me to replace the engine I would do it because I trust his word and this is how it should be. The question now is how do I find an electrician that I can trust? |
tomiiv30 OP33 posts01-21-2019 2:31pm What is the difference between the ground wire that is connected to the panel itself and the one that goes to the outside, it still goes thru the panel but it is not attached to the panel itself it just goes thru the pipe that goes outside where the meter is and from there it is attached to the rod.@ tomiiv30 OP Like cleeds said that is an NEC violation. It is also not the correct way to connect the IG (Isolated Ground) ground conductor to ground. It can pass through a sub panel to the main panel the sub panel is fed from but it must connect to the ground bar in the electrical panel. Period! The problem with what you have now the earth is not considered a low resistive path for ground fault current to travel back to the source. In the event of a hot to chassis ground fault the chassis could/would be HOT with respect to any other piece of grounded equipment that is properly grounded within arms length. Heck, you would be better off just using a ground cheater at the outlet to plug the equipment into. At least then you know the outlet is not grounded. I am by no means an electrician and I am trying the understand as much as possible how everything should work.If the grounding is wired as you said, the guy is not an electrician either. He just passes himself off as an electrician....... Not all electricians are created equal. . |
@OP, I would find another electrician. From what you have described, I would be wary of what the original electrician did-especially with his nasty attitude, and concerned that this setup is according to code. Perhaps the whole problem with the Mac was a blessing in disguise. You might have uncovered a problem that could have become a Big Problem, if a lightning storm struck. Bob |
tomiiv30 What is the difference between the ground wire that is connected to the panel itself and the one that goes to the outside, it still goes thru the panel but it is not attached to the panel itself it just goes thru the pipe that goes outside where the meter is and from there it is attached to the rod.All grounds must be bonded together along with the neutral at the service panel. Your separate ground creates a chance that a fault to ground won't trip a breaker. That's the biggest problem with the arrangement and why its an NEC violation. The guy that came to my house and did this has been in business for over 30 years and I trust them thinking they know what they doIt's likely that your town requires a permit for this work. Did you check into that? |
tomiiv30 OP32 posts01-21-2019 2:05pm The other 20 amp outlet is grounded directly from the outlet to the outside rod with a clamp that is attached to the rod itself, I saw that with my own eyes. It is a straight wire that goes from the outlet to the outside and has nothing to do with the inside panel or anything else in the house. YOU are going to have to find out exactly what the guy did! Do you feel comfortable pulling the wall duplex outlet from the wall box for a look to see exactly what the guy did? IF yes. Turn off the breaker at the electrical panel that feeds the outlet. Plug a lamp into the outlet to make sure 100% the power is off. 100%! To verify the lamp is turned on and the bulb is good plug it into a live outlet. Lamp bulb should light. Pull off the outlet cover plate. Remove the two 6/32 screws that hold the outlet to the wall box. Pull the receptacle outlet straight out from the box far enough to look at the wires that are connected to the receptacle as well as those that enter the box. Is the box metal or plastic? As for the branch circuit wiring that enters the box, I believe you said in an earlier post it is Romex. You should see a black insulated wire (Hot), a white insulated wire (Neutral), and a bare copper wire, the safety equipment grounding conductor.WHERE IS THE BARE WIRE CONNECTED TO??? *****Examples: 1) ** IS THE BARE WIRE connected to the ground wire that comes in from the outside isolated ground rod along with a short wire, pigtail, that connects to the green equipment ground screw on the isolated grounding type receptacle outlet? IF the box is metal the box must also be bonded, connected, to the ground wires connection with another pigtail. All connections should be under one wire connector, example a wire nut. IF this is what you have then the guy wired the grounding per NEC Code as an Auxiliary Grounding Electrode. Lightning loves Auxiliary Grounding Electrodes! NOT NEC compliant! 2) ** IF a metal wall box was used the Romex cable bare copper safety equipment grounding conductor is bonded, connected, to the metal box ONLY. Period.... IF the box is plastic the Romex Cable bare equipment ground wire is not connected to anything. It is just pushed back inside the box. The ground wire that enters the wall box from the outside isolated ground rod connects to the green color ground screw on the isolated grounding type receptacle ONLY. Period.... If this is the way the guy wired the grounding it is dangerous and could cause an electrical shock hazard or worse possible electrocution in the event of a hot to chassis ground fault event. Also note you do not have a low resistance path for ground fault current to return to the source, the electrical service neutral conductor, in the event of a hot to chassis fault. This would also include anything plugged into the wall outlet. That includes the power cord feeding any equipment. Cut to the case, the breaker in the electrical panel that protects the branch circuit wiring will never trip open in the event of a ground fault event. // As for your power quality problem there is always a solution. It may require you hiring a certified credited power quality testing company. In my area they charge around $125 an hour. In your case the tech would be there about an hour or so..... He/she will have the test equipment needed to find your power quality problem. If it is coming in from outside your home the testing company will provide you with the necessary test reports to show to your utility power company. If it is inside your home the power quality company will identify the problem. If it is structure electrical wiring or fixed electrical equipment a licensed electrician will be required to make the repairs. In most cases the power quality company will recommend an electrical contractor company they use. Jim . |
@cleeds What is the difference between the ground wire that is connected to the panel itself and the one that goes to the outside, it still goes thru the panel but it is not attached to the panel itself it just goes thru the pipe that goes outside where the meter is and from there it is attached to the rod. I am by no means an electrician and I am trying the understand as much as possible how everything should work. The guy that came to my house and did this has been in business for over 30 years and I trust them thinking they know what they do. |
tomiiv30
The other 20 amp outlet is grounded directly from the outlet to the outside rod with a clamp that is attached to the rod itself, I saw that with my own eyes. It is a straight wire that goes from the outlet to the outside and has nothing to do with the inside panel or anything else in the house.If you're in the U.S., that's a violation of the NEC and is potentially hazardous. It also creates a potential ground loop, which can only exacerbate your problems. |
It is one rod that he installed in the ground that is few feet away from the outside meter/box, the other rod was installed form the electrical company, it was already there, that's why I thought he did 2. One of the 20 amp outlet is grounded to the inside of the panel. The other 20 amp outlet is grounded directly from the outlet to the outside rod with a clamp that is attached to the rod itself, I saw that with my own eyes. It is a straight wire that goes from the outlet to the outside and has nothing to do with the inside panel or anything else in the house. Both these outlets are on it's own there are not shared with any other outlets in the house. He did measure few different things he would not let me tell him anything he just said everything measures fine. I know I saw him measuring on the panel where he got 240 volts and said one is 120 and the other is 120 something in those lines. He measured the outlets too, I don't know what he was doing but after he was done he said that to him everything looks good and he said good like convincing the electrical company to come out. That's all I have. And I am not planning to spend any more time nor money to call other electricians or whatnot. |
Yeah he came to the house checked everything again and he said not to call him any more, he thinks that I am bulls^&#g with him, and that's why I did not write anything about it.What did you find out about how the electrician wired the two ground rods to the two new wall outlets for the two new dedicated branch circuits you had him install? |
Yeah he came to the house checked everything again and he said not to call him any more, he thinks that I am bulls^&#g with him, and that's why I did not write anything about it. I feel like I have been let down, like I said this were the worse $30K spent in my life. Talking to the electrical company is like talking to my 5 year old. I just don't have the nerves and time anymore and would just live with it, I got so tired of this whole situation that I gave up. |
@ tomiiv30 OP How about an update on your electrical. Did the electrician come out and check for possible electrical problems in your home? Possibly loose and or corroded wire connections in the electrical service panel? Have you spoken to any one yet from your utility power company? Jim |
Here is everything that went wrong from day one: Purchased demo unit MC452 and came to me broken, right side was running way hotter than left side, had to return it and got refund back. Purchased brand new MC8207, MC462: First MC8207 had a buzz and was replaced with a second that had even louder buzz to where you can hear it the other room. MC462 had loose parts from the get go and it was replace by a second unit that had all parts intact but very bad quality check, the chassis itself has very bed edge to where you can cut yourself, but since I can't take it anymore I just decided to keep the second unit and live with it. As you can see lately their quality check sucks big time. It's not just one thing but there is plenty other things happening. The only thing that came perfect was the Marantz AV8805 that I purchased brand new as well when I bought the MC8207 |
Would you guys be surprised if I told you nothing happen out of this situation. I get to keep this amp the way it is, it’s been over their return policy period and nobody cares to even take a look or find a solution to a problem that not just me but others are having and it is very common within McIntosh amps. I can tell you that nobody gives a flying f$%k about the consumer anymore, they just want your money and that’s that. Once you pay you are alone and that’s how I feel. The salesman could do just so much, he is there just like a middleman without having any authority over anything except to sell and make management happy. Even he admit it that this place sucks balls so what would you expect from place like that. Learnt from my own mistakes but I ain’t getting screwed again after this kind of treatment that I got from Manufacturer and Dealer. $30K in the hole and not one phone call to me. I was better treated when I bought a $200 item and was make sure I was happy with my purchase. |
jea48 ... why would you still want to buy a McIntosh product after hearing the way they have treated the OP?Because we don’t know how McIntosh treated the OP - it’s just hearsay from an anonymous poster. On the other hand, I have years of first-hand experience with Mac. Charlie Randall (top USA dog now) is already starting to make ARC equipment look like McIntoshARC doesn’t look at all like Mac - ARC has rack width; choice of silver or black finish; no blue meters or logo in a Gothic font ... |
@ nyev See page #17. It appears the power transformer is an EI type. EI type power transformers as a rule are not affected by DC offset on the AC mains https://www.manualslib.com/manual/1460643/Mcintosh-Mc462.html?page=17#manual Question is why would you still want to buy a McIntosh product after hearing the way they have treated the OP? Ron ( McIntosh representative) said maybe 5 complaints a year about torid buzzing power transformers. You want to beat the number of complaints is actually higher than 5? How much would it have cost for McIntosh to incorporated a DC blocker in the MC8207 amp? I would be willing to bet the design engineer first designed the amp with a DC blocker. No doubt the design engineer new that a large torid power transformer would vibrate/buzz if there was DC offset on a customer’s AC mains. How much you think them pretty covers cost that cover the transformer and DC power supply inside the MC8207? Or them big pretty blue front meters? They sure look pretty though don’t they? Charlie Randall (top USA dog now) is already starting to make ARC equipment look like McIntosh. . |
The DC issues are two different things. DC on your power (110VAC or 220VAC) causes mechanical vibration in the transformer, and otherwise rarely has ill effects. DC on the input terminals (RCA or XLR) is different. Ideally there is none, or very little (millivolts). Amplifiers which are "DC coupled" can pass DC from the inputs to the speakers, which could be over 100V DC. More than enough to fry parts. They use a servo to adjust and stop this. And this works within range, but after a while the DC offset in the signal from the source (CD player for instance) is too great and the amp instead disconnects. It sounds like this input DC is what's happening, instead of DC on the power. Best, E |
After reading this thread, I am second guessing a similar issue I’m having with an old Arcam P85 where I’ve noticed it buzzing, and the corresponding A85 integrated which has been switching off intermittently with a message that reads “DC Offset - Check Connections”. The connections are all fine. @nyev That’s probably a different issue. This sounds like you might have a bad source. Disconnect all your sources, and try adding them one at a time. Best, E |
After reading this thread, I am second guessing a similar issue I’m having with an old Arcam P85 where I’ve noticed it buzzing, and the corresponding A85 integrated which has been switching off intermittently with a message that reads “DC Offset - Check Connections”. The connections are all fine. Figured the P85 was just old and was toast, but now I will try taking it somewhere else and plugging it in. I’m concerned as I am considering an amplifier upgrade with a McIntosh MC462 as a candidate. Also, this problem only started after we moved into a house we fully renovated, including a full replacement of the electrical. Of note, there is no buzzing from the A85. |
Thanks Al, (almarg) for the response. The additional difference of 1.577 - 1.41 = 0.167 VDC is probably accounted for by a combination of the resistances of the connections to the several intervening outlets in the room with the 1.577, and imprecision in the estimates of the run lengths. I don’t think so. All in and out wire connections along with the pigtail extended for the receptacle connection are twisted together and then made mechanically tight using Electrical Spring Connectors. The live wire steel spring inside the connector is designed to expand and contract with the copper conductors. Varying loads placed on the circuit conductors can cause the copper conductor to expand from heat and contract from cooling as load falls off. The connector’s wire spring always keeps the connection tight. Jim |
That all seems perfectly consistent with the explanation I proposed in my previous post, Jim. The hairdryer draws considerably different amounts of current in the positive half-cycle than in the negative half-cycle. The resulting DC offset corresponds to that difference in current x the resistance of the wiring that current is drawn through, **for wiring that is in the path between the outdoor AC wiring and the measurement location.** For example: I then plugged the Low pass filter into the first outlet. (Outlet closest to electrical panel. First outlet on home run feed.) At that measurement location the DC offset resulting from the current differential between the two half-cycles will not reflect the resistance of the wiring between the first outlet and the last outlet of that branch. Regarding the 1.577 vs. 0.734 difference, note that 12-2 has about 60% more resistance per unit length than 10-2, and the length of the 12-2 was about 20% greater than the length of the 10-2. 0.734 VDC x 1.6 x 1.2 = 1.41 VDC. The additional difference of 1.577 - 1.41 = 0.167 VDC is probably accounted for by a combination of the resistances of the connections to the several intervening outlets in the room with the 1.577, and imprecision in the estimates of the run lengths. Best, -- Al |
almarg8,581 posts01-15-2019 6:12pmIf Al is still following this thread I am sure he will have a better technical answer. Al, Ah, that’s nothing.... In another room there are also several 120V convenience wall outlets that are fed with a 20 amp separate circuit. Wire is #12-2 with ground Romex. Home run feed to first outlet, closet to electrical panel. Branch circuit Romex is run around the perimeter of the room to outlet boxes in an in and out configuration. Up and down, and all around. The length of the Romex from the first outlet to the elecrical panel is approx 45ft. The length of the Romex from the first outlet to the farthest, last, outlet in the room is approx 50ft. Approx 90ft total from the last outlet to the electrical panel. The test. I first plugged the hair dryer into the farthest duplex receptacle outlet. (High heat, low blower speed). Mains voltage unloaded, 120.8Vac. Hair dryer on, loaded, 115.8Vac. 5Vac VD. Plugged in the low pass filter in the same duplex outlet. Fluke measured 1.577Vdc . . ??? Higher than my previous post test of 0.734Vdc. What are the differences between the two branch circuits? Length of the branch circuit wire and the AWG wire gauge size. (0.734Vdc 75ft, 10-2. Mains loaded VD approx 2.5Vac) (1.577Vdc 90ft 12-2. Mains loaded VD 5Vac) I then plugged the Low pass filter into the first outlet. (Outlet closest to electrical panel. First outlet on home run feed.) Hair dryer left in farthest outlet. Fluke measured 0.578Vdc....... (Note DC offset is decreasing) I then plugged the low pass filter in the outlet just below the electrical panel. (Basically connecting the low pass filter to the electrical panel itself. The branch circuit source) Turned on the hair dryer. (High heat, low blower speed). Fluke measured 0.106Vdc (106.3mVdc) meter then set to mV. Note the harmonics, DC offset, decays the closer its gets to the source the electrical panel. Or does the source have anything to do with it? Final test. I plugged the hair dryer into the outlet directly below the electrical panel. Plugged the low pass filter into the first outlet closest to the electrical panel. Fluke measured 0.115Vdc, it then settled down to 0.114Vdc I then plugged the filter into the farthest outlet on the branch circuit. The Fluke measured 0.115Vdc. Same thing here it settled down to 0.114Vdc Both measurements were taken without a connected load on the branch circuit. For a load I plugged in a quartz construction work light in the farthest outlet. I think it’s a 500 watt but can’t remember for sure. I’d have to check it. I then measured the DC offset again. This time it measured 0.112Vdc. Jim . |
If Al is still following this thread I am sure he will have a better technical answer. Not necessarily, Jim :-) Your finding that having the hairdryer plugged into the outlet where the measurement was taken resulted in a DC offset of around 730 mv, while measuring at the same outlet but with the hairdryer plugged into various other circuit branches on the same leg resulted in around 115 mv, is indeed a bit of a headscratcher. But not being familiar with the design of hairdryers I did a little research and found this interesting paper: http://www.idc-online.com/technical_references/pdfs/electrical_engineering/MEASURING_ACOUSTIC_NOISE_EMITTED_BY_POWER.pdf As stated on pages 4 and 5 and as depicted in Figure 13, at least when hairdryers are operated "at lower power" they place a half-wave rectifier diode in series with the load they place on the AC, or at least a substantial part of the load. So DC offset results from the difference between the amount of current that is drawn during the positive half-cycle of the AC waveform and the amount of current that is drawn during the negative half-cycle, and the differing voltage drops that occur in the resistance of the AC wiring between the two half-cycles as a result of that current difference. In tests 2, 3, and 4 essentially zero current was being drawn through the dedicated wiring between the service panel and the outlet where the measurement was taken, so no voltage drop would have been occurring in that wiring. And the DC offset that was measured would have resulted essentially from the voltage drop differential between half-cycles that was occurring in the panel and in the outside wiring, since the additional voltage drop in the wiring between the panel and the outlets where the hairdryer was plugged in would not have been in the path to the outlet where the measurement was being taken. And presumably the outside wiring is considerably heavier gauge than the 10 gauge Romex used for the dedicated line, and therefore it would present a lower source resistance (per unit length, at least) for DC offset to develop across as a result of the asymmetrical current draw. Whereas in test 1 that asymmetrical current was being drawn through an additional resistance in the path to where the measurement was taken, corresponding to the sum of the resistances of the dedicated line’s two 75 foot 10 gauge conductors, which amounts to about 0.15 ohms. Looking at it quantitatively, if my theory is correct the difference in the amount of current drawn by the hairdryer between the positive and negative half-cycles would be: (730 mv - 115 mv)/0.15 ohms = 4.1 amps. In the context of the large current draw of an 1875 watt hairdryer, and one that is placing a diode in series with much of the load it presents, I suppose that is consistent with your findings. Best, -- Al |
jea482,863 posts01-15-2019 12:14pm They are all connected to breakers that are on the same Line. Line 1, leg. What are the odds? |
Here are the DC offset measurements using a low pass filter. (DMM probes across capacitor leads) I used a 1875 watt hair dryer to create the DC offset on the AC mains. Test # 1 Dedicated Audio room. Low pass filter plugged into dedicated audio outlet. 120V, 20 amp branch circuit. Branch circuit wire is #10-2 with ground Romex. Length of Romex from wall outlet box to electrical panel is approx 75ft. Low pass filter plugged into wall duplex outlet. No other loads connected to the outlet. AC mains voltage at outlet, no load, measures 122.3Vac (DMM, Fluke 87 True RMS) **EDIT: (I just checked mains unloaded voltage again so I could check for the hair dryer loaded voltage drop. Unloaded mains voltage at the outlet now measured 121.5Vac. Loaded, hair dryer turned on, high heat, low blower, measured 119Vac). DC offset voltage measured across the low pass filter cap measured 1.6 mVdc, avg reading. (Fluke set on Dc mV scale). I also used a Radio Shack DMM. Meter set on DC volt auto scale. It also read 1.6 mV avg. With the hair dryer plugged in, heat on high, blower on low. (This combo setting gave the highest DC measurements). Fluke measured 0.734Vdc (meter set on auto DC volts. Dc mv meter setting is for 400mV max.) Radio Shack measured 0.726Vdc. 0.734Vdc (734 mVdc) is more than enough to saturate the core of a moderately sized torid and cause it to buzz loudly. From what I have read 50mVdc will cause a torid to buzz. Just for the heck of it I ran a few more tests. Test #2 Low pass filter plugged into same audio dedicated wall outlet. Hair dryer plugged into a wall convenience outlet in the same room. Branch circuit is separate 20 amp, #12 Romex, for several conv outlets in the room. Approx length of the romex from the wall outlet, the hair dryer is plugged into, to the electrical panel 80 + ft. Hair dryer turned on. High heat, low blower. Fluke measured 112.6 mVdc - 113.3 mVdc (Meter set first to DC auto, then moved to mV setting) Radio shack measured pretty much the same, 112.3 mVdc - 113.6 mVdc. Here is where, hopefully, Al (almarg) chimes in. With the hair dryer plugged into the same outlet as the low pass filter the Fluke measured 734 mVdc. With the hair dryer plugged into a different outlet fed from a different branch circuit the Fluke measured 113.3 mVdc. Just a guess on my part, two things are at play. Both involve the total combined length of the two Romex cable branch circuits, (Approx 75ft + 80ft). One is the inductance of the cable and the other the resistance of the cable. Inductive reactance? One other thought to consider is the utility power transformer. Just going from memory harmonics will travel back on the neutral conductor to the source. Some of the harmonics are dissipated by the secondary winding in the form of heat. If Al is still following this thread I am sure he will have a better technical answer. Test #3 Hair dryer plugged into wall outlet in dinning room. Wire is Romex, #12 , 20 amp circuit. Approx length? Just a guess 80ft or so. (Up, down, and all around). Low pass filter, still plugged into the dedicated audio wall outlet circuit, audio room. Hair dryer on, high heat, low blower. Fluke measured 106.7 mVdc. Radio shack 105.8 mVdc. Voltage at wall outlet unloaded measured 122.3Vac. With the hair dryer turned on voltage dropped to 116.2Vac. Test #4 Hair dryer plugged into an outlet directly below the electrical panel.Fluke measured 115.6 mVdc Radio Shack measured 115.4 mVdc. Note, here only the audio dedicated 20 amp branch circuit wiring length is at play. Approx 75ft, #10awg wire. One other thing...... I will have to go back this afternoon, maybe tomorrow morning, and Check for the Line, Leg, (in the electrical panel) that each of the branch circuits are fed from. (For tests 2, 3, and 4). There in, Line 1 or Line 2. I believe that would have some relevance. There’s a 50/50 chance, LOL, some are on the same Line as the audio room dedicated audio outlet circuit that the low pass filter was plugged into for all the tests. Jim . |
@OP, I think you have done everything you possibly could have to resolve the problem. I'm glad the dealer is refunding your money, but I think they should have been more active in resolving the issue. Especially having you install wiring, though a good thing in the end, should not have been something you had to do. Hopefully, you can find another amp to your liking. Bob |
@twoleftears It could be the electricity coming to the house form the outside, I've done everything I was told to do and more and nothing helped. The only thing left to do is convincing the electricity company to come out and maybe put a power analyzer on the entrance meter and record if there are any anomalies. The store has been pretty good with me as far as exchanges and getting new units to me but even I told them that I do not want them to get me new units but find a solution to the problem I am having, it just that they should've know more about the product they are selling or they should have been trained from McIntosh of how to address this kind of problems. |
@tomiiv30I I went through something similar with an amp. I tried dozens of fixes, from cheater plugs, extension cords, turning off all the breakers, different outlets, inexpensive filters, expensive filters, ground loop eliminators, DC blockser, power conditioners, power regenerators, isolation transformers, you name it. Nothing worked. Ultimately, sometimes it comes down to the electricity coming into your house and how it interacts with the component. I hope you have an experienced electrician, because most don't measure/don't know how to measure/don't believe are important, the kind of things, to vanishing small levels, that can be causing the problem. And if he does identify it, good luck getting your local electricity company to address it. I'm also here to tell you that if you buy a similar priced amp from a different company, there's every likelihood that it won't hum. As much as we like solving a problem once it's been identified, sometimes the expedient thing is the best route (i.e. I hope you haven't exhausted the store's return/refund policy). |
@ tomiiv30 OP I decided to deleted my previous post because I didn’t think it was right for me to instruct/dictate how the electrician, you hired, should go about trouble shooting for possible problems on the electrical service and or wiring of your home. I did save the first part of my post about the two ground rods that were installed for the equipment grounding of the two new dedicated circuits. I would appreciate it though if you would note and post back what the Line 1, leg, to Line 2, leg, voltages are as well as Line 1 to neutral and Line 2 to neutral voltages are at the electrical service panel. To high of an over voltage above the voltage rating of the torid transformer in the amp could also add to the cause for the transformer to buzz louder than it normally would. // @ tomiiv30 OP Make sure you ask the electrician exactly what he did with the equipment grounding conductors for the new dedicated branch circuits he installed. TAKE NOTES! A picture is worth a 1000 words. Have him physically show you exactly what he did. It is possible the electrician wired the new ground rods per NEC 250.54 ...... I’ll give the guy the benefit of the doubt. If he did wire the 2 ground rods per NEC 250.54 "Auxiliary Grounding Electrodes", then the equipment grounding conductors for each IG receptacle are connected to the branch circuit wiring equipment grounding conductor and the equipment grounding conductor of the branch circuit is connected to the equipment ground bar in the electrical panel the branch circuits are fed from. Per NEC 250.54 a ground wire is installed from the ground rod and is connected to the branch circuit equipment grounding conductor. He can use any any size wire he wants to use from the ground rod to the branch circuit equipment grounding conductor. Hell, it can be 20 gauge. Does an Auxiliary Grounding Electrode really do anything to improve the sound of an audio system? It can act as an antenna and add noise. It also provides another path for a lightning high voltage transient to enter your home. Lightning loves aux grounding electrodes. Jim . |
@jea48 Thanks for the detailed explanation I very much appreciated it. All the suggestions from all the other members of this forum are very welcome and like I said I will try to do whatever it takes to find the problem and fix it, it may take some time but I will do it. I will make sure I take notes and maybe record if he is ok with it and will snap few photos. But for now I think I need to relax and listen to some music because my head is gonna explode, I have to enjoy my stereo system little bit. Will be back with some more info when I get some. |
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I wanted to upgrade my service from 100 amps to 200 amps. Was told by electrician I had to contact the electric company to have the wire from the pole to my house upgraded that will carry 200 amps. The electric company came out to evaluate. I got a letter a few days later saying that I could safely go up to 150 amps but they won’t change the drop wire as there isn’t enough “electricity” for 200 amps. I took a picture of the pole across from my house where the hook up goes and lo and behold there is a big transformer on the pole. After i appealed the letter and they realized there was a transformer there, I got my way. I went through hell and this took 6 months for the permit to be issued. |
