DC Offset Blocker/Killer - where to buy in the USA
What about trying a 3000 microfarad 200v non polar cap in series with your line to block dc if there is any. Also if the line cord is flipped over (left prong on the right) shouldn’t the buzz move to the other transformer? Otherwise I’d think you should be able to see the offset at the box with a VOM. IMO you have a faulty unit that Mcintosh should replace. |
tomiiv30 OP21 posts01-05-2019 12:47pm It is an amp that is 14,000 watts so it is sensitive to DC being present in the lines.I think you meant 1400 watts. He said it has to either be the electrical coming from the pole or something within your house that is introducing DC in the AC of the lines ie. Faulty/poorly designed dimmer switch or something similar. So it is certainly not the amp or us, it is something going on at his specific home. It could be something as little as 1 volt of DC that can cause this issue." No,.... there’s nothing wrong with the AC power in your home. You measured for DC offset on the AC mains using your DMM and measured 0.9mv. You measured for DC offset exactly as McIntosh told you to do it. Exactly! tomiiv30 OP21 posts01-05-2019 10:40amChuck is the man, he should know. He is McIntosh’s expert on the subject. You followed his instructions to the letter. Can’t get any simpler than that. There is nothing wrong with the AC power in your home. The power transformer in the amp is defective. Period! . |
erik_squires4,643 posts01-06-2019 11:54am erik, keep this just between the two of us. Chuck is just plain ignorant when it comes to how to measure for DC offset on the AC mains. Jim |
After some serious thinking I will just return this unit for a full refund, I shouldn’t be the one obligated to do all those things since everything else works perfect in my house I know that I don’t have problem with my power and it has been checked so many times, I don’t have to invest anymore time and money in any kind of aftermarket equipment to silence the buzz, I would try with the DC blocker like the Emotiva CMX-2 that was shipped to me by a forum member but that’s that, it will just mask the problem and nothing else. Yes taking it to the dealer and having no buzz there means that they use all kinds of power conditioners and dc blockers and what not would not prove anything to me, this unit does not work at my place and at my friend’s, I have taken this unit to two others and still buzzed. If McIntosh does not want to invest in a proper circuitry that will fix this problem that they are having and they do have this problem for a long time I can see that since there were many people on forums saying the same thing that I am saying and we as consumers should not be held accountable for it. There are some threads that I red about the MC462 being dead on arrival which is another thing that tells me that quality check is lacking, since I am also having issues with loose parts on mine. McIntosh you better get your sh$t together otherwise you would start losing some serious sales or maybe you already have. |
It's a story as old as the hills. A company spends decades establishing a really good name. A conglomerate swoops in and buys it up--and they're buying the name much more than the factory or the know-how. They proceed to try and squeeze every last drop of profit out of it--and then they'll throw away the dry husk when they're done. The attitude you've gotten--it's your problem, we really don't want to take it back (=we've already made our profit off of you)--is a classic demonstration of this. |
@twoleftears , Exactly. I bought a 2016 TTS that has a B&O sound system. It sounds like crap. My previous TTS had a Bose system that sounded leaps and bounds above the B&O-and that is saying something. B&O had some really interesting gear in the day, but now that they have been acquired by another company, they are just resting on the name recognition. Too bad for me, Audi trusted them- but, hey, it all comes down to money. B |
Food for thought. Quote from an Audio Circle audio forum thread about DC offset on the AC mains. HALhttps://www.audiocircle.com/index.php?topic=47973.0 . |
https://www.diyaudio.com/forums/solid-state/2080-dc-filter-6.html#post331815https://www.diyaudio.com/forums/solid-state/2080-dc-filter-6.html#post331815 . 22nd May 2004, 05:20 PM #71 Eva diyAudio Member . |
gdnrbob2,190 posts01-07-2019 1:21pm No, I wouldn’t. There is not any need for a blocker unless you have DC offset on the AC mains. If you have a piece of equipment with a torid transformer that is buzzing loudly then it may be being caused by DC on the mains. The best way to find out is to measure for it. Measure for it the correct way. I am surprised there is not someone building a low-pass filter device to use on the AC mains to measure for DC on the mains using a regular DMM. For a DIY project it would be pretty simple to make one. All you need is, 1 - male plug (to plug into the wall outlet) 1 - 100K 1 watt resistor 1 - 22uF non-polar capacitor 2 - alligator clips for the probes of the DMM Maybe a short piece of 2 wire zip cord Soldering Iron Solder You could even install the resistor and cap in a small PVC plastic box with cover. Connect a short 2 wire power cord and male plug. Install a couple of recessed insulated female jacks for inserting of the probes of a DMM. Jim . |
@jea48 I wish there was a video or some kind of a drawing of how to make this simple low-pass filter device but yet too complicated for me and some others. I am a graphics designer by trade and not an electrician but I am willing to give a go to make one I am no afraid but only if I see it how it is made. I do have a soldering Iron and solder plus those alligator clips so I am half way there. I went to fry's electronics and the only item they were out of all the milion items they sell were the 100K 1 watt resistor and the capacitor. How unlucky I am that I drove like about 45 each way to get to the store. |
I wish there was a video or some kind of a drawing of how to make this simple low-pass filter device but yet too complicated for me and some others. Google, first hit: https://www.stereo.net.au/forums/topic/75460-diy-main-dc-blocker/ |
@ tomiiv30 OP and @ gdnrbob I ordered the resistor and capacitor over the internet yesterday to build the simple low-pass filter. Hopefully I will have them in about a week. 100K 1 watt resistor https://www.ebay.com/itm/5-pack-1-watt-5-carbon-film-resistors-100k-ohm/160460118738?hash=item255c2b... 22uf non polarized capacitor. https://www.amazon.com/22mfd-Non-Polarized-Grade-Mylar-Capacitor/dp/B00B4DVXJE Eva (DIY Forum member) didn’t give the voltage rating for the 22uf non polarized capacitor so to be on the safe side I ordered 250V. I’ll post back with the testing results on how it works. Here is a link of a wiring diagram that shows the wiring, configuration, of a low-pass filter. (Disregard the white paper for the use in the paper). It’s the best I could find for a wiring diagram of the simple circuit. https://www.electronics-tutorials.ws/filter/filter_2.html You need to redraw the simple circuit and add some wordage. ** ELIMINATE THE EARTH GROUND CONNECTION AS SHOWN ON THE BOTTOM LINE OF THE DRAWING. (This line will be the AC neutral.) Note on the left side of the drawing the two Vin AC (sine wave) line inputs. You will connect these to the 120Vac male plug. I would suggest the top line (resistor) connect to the Hot blade screw terminal of the plug. The bottom Line (other end of the capacitor) to the neutral blade screw terminal of the 120Vac plug. The right side of the drawing where it says (Vout) is where the DMM probes connect to. Edit: Another wiring diagram showing the Low-Pass Filter. In the last post by atmasphere in the link he provided there is a post with this link showing an Intergator Low-Pass filter. http://www.animations.physics.unsw.edu.au//jw/RCfilters.html#low Low-Pass Filter scroll down the page to, "Integrator" . Note the diagram is the same as the first diagram for a Low-Pass filter. You don’t need an electrician to build, assemble, this low-pass filter to measure for DC offset on the AC mains. All you need to find is an electronic service tech. Or anyone with any experience in wiring a simple resistor capacitor circuit together. Jim . |
Jim (Jea48), good posts as always. My only comment on your low pass filter project is that with the 22 uf and 100K values it will take around 10 or 15 seconds after the AC is applied for the cap to fully charge up to whatever amount of DC may be present. Which is fine, of course, but it’s just something to be aware of when the measurement is made. Best regards, -- Al |
Al, (almarg) Thanks! 10 to 15 seconds..... I would have missed that for sure. What do you think about using a 22uF value for the capacitor? I chose the 22uF cap because that is what Eva (DIY member) said to use in her post. Elliott Sound Products recommends using a 100K ohm resistor in series with a 10µF non-polarized capacitor. What are your thoughts on the value of the capacitor used? Jim |
Hi Jim, They both appear to be reasonable values for this purpose. The 10 uF/100K combination will charge up to the final value about twice as fast as the 22 uF/100K combination, which isn't important, but it won't be down quite as far at 60 Hz as the latter. That difference probably isn't important either, although I can't say that with certainty as I'm not familiar with the internal design of modern digital multimeters. Specifically, the 3 db bandwidth of the low pass filter (i.e., the frequency at which 3 db of rolloff will have occurred) = 1/(2 x pi x R x C). Let's refer to that as "bw" (bandwidth). For 10 uF/100K, bw = 0.16 Hz For 22 uF/100K, bw = 0.07 Hz The rolloff at 60 Hz will be 1/(square root(1 + ((60/bw)squared))), converted into db based on 20 x logarithm of the resulting numerical value. (That looks more complicated than it really is; it could be illustrated more simply if it didn't have to be shown as text. Some people depict "squared" as "^2" and "square root" as "^(1/2)", but I'm not sure if for most people that would make the equation more clear or less clear). For 10 uF/100K that calculates to -52 db at 60 Hz, which would reduce 120 volts to about 0.3 volts. For 22 uF/100K that calculates to -59 db at 60 Hz, which would reduce 120 volts to about 0.14 volts. Also, the time to charge to very close to the full value of the DC that is present will be approximately RC x 5, which is how I derived the 10 or 15 second figure for the 22 uF/100K combination. Best regards, -- Al |
P.S. to my previous post: I didn’t mention the units that should be used for R and C in the various calculations. If R is expressed in ohms and C is expressed in Farads, the calculation described in my last paragraph will provide an answer expressed in seconds, and the calculation of bandwidth that is described earlier in the post will provide an answer expressed in Hz. Best, -- Al |
Here is the update and it’s a surprising one: Went to the dealer today with the MC8207 and right away I was taken upstairs to their tech department where they plugged this amp and the result was a dead quite none buzzing transformer and I mean dead quite not even a small buzz. Now I don’t know if their outlets have been treated since this is the tech department and not any other place in the store, it was the only place that we tested it. I was very surprised and happy at the same time knowing that this amp can be quite so I guess it leads me back to my house or the outside power. I am in a search of somebody that really knows how to measure DC offset in the AC lines, I did what McIntosh told me to do and it returned 0.9mV which is nothing to make the transformer buzz but it could've been a wrong measurement. As for the LED Lights that were not illuminating equal Left Side to Center to Right, there was a slight shift of an inside part that the tech had to open the front and fix it to make it all Illuminate the same, bear in mind this is a brand new amp and it needed to be open to be fixed. I have already spoken to my electrician who is coming back to the house to do an extensive checking and we would be unplugging everything from the outlets and I mean everything, and will be turning off all the breakers off except the one for the amp and see if we can finally find the problem and if that doesn’t help than it would be the right time to call the electric company to do their part, because otherwise it would be very hard to convince them to come out just because I have a buzz. I am a person that do not give up and would like to find a solution to fix this problem no matter what it takes as long as it is fixable. And if anyone from here ever had to deal with their electric company would you be kind to share the steps taken to convince them to come out. |
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. |
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@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. |
@ 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 . |
@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). |
@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. |
@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 |
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 . |
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? |
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 |
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 . |
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 |
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 |
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. |
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 |
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 |
