Hi Paul. I am a subscriber of your youtube channel and also your daily post. I have benefitted from your sharing and your wisdom for a long time. I use a Chord hugo TT which is a great dac/preamp. When I add a preamp to the Chord hugo TT the music sounds worse - it is that transparent. I am changing out the hugo TT and am considering getting a dac/preamp from PS Audio. What would you recommend? I feel customers are at a disadvantage once we are not in the US (I am not) as all the show discounts, trade-ins, launch offers do not apply outside the US. But I have received so much from you that I think I should try one of your products. If you or your staff read this post do you mind giving me a recommendation. Thank you.
also what does a loose neutral at transformer do to sound. I had that with a window ac and its motor did weird crap. finally narrowed it down to loose neutral so power company fixed it at the top of the pole. never noticed if it affected my sound.
Hi Paul, Thankyou for this very informative channel. I get this problem with my Hegel H20 power amp, could I use a mains isolating transformer similar to those used on a building site as DC will not get through to the secondary output.
So two diode bridges in series huh? I didn't know that, got to try out something with a test circuit where I can inject some dc into a low voltage ac signal so I can hook up my oscilloscope and see what's actually happening, thanks for sharing this video you made my creative mind light up with it. 💡
Howdy. A powerful half wave rectifier may cause unsymmetry in the mains sine wave. I suppose this may be thought of as a sine wave riding upon a small DC. Loading one halfwave will decrease the voltage and surprisingly enough increase the unloaded halfwave if the grounding in the electrical panel is weak. Appliance transformers are usually designed to just go into borderline saturation when the sine wave is symmetrical. If one halfwave is stronger the core will saturate harder making it sing. One possibility is using a separation transformer to feed the amplifier. It should be designed to stay way below saturation. It should have more turns in the windings as normally. Say 10% more. The separation transformer will break the DC. Regards.
The video isn't about noise getting into the signal path. It's about the power transformer emitting audible humming directly into the air, which EMI doesn't cause. EMI can only cause noise in the audio output to the speakers.
How to use a rectifier bridge: Paul's description wasn't right. You only need a single bridge to get 1.2V drop. 1. *The bridge does NOT go across the AC mains!* Instead, connect *one* of the bridge AC terminals to the mains live side, disconnect the equipment power lead from the mains live side, and connect it to the other bridge AC terminal. That is, the bridge's AC terminals go *in series with* the transformer in your equipment. Make sure all of these connections are inside a safe enclosure and that all connections are well insulated. Also make sure the bridge has adequate heat sinking, if required by its design. 2. Put a shorting jumper across the bridge's + and - DC terminals to complete the current path. 3. If that's not enough voltage drop and you need more, you can use two bridges with their AC terminals in series, with a separate jumper across the DC terminals of each. Transformer Core Saturation - why DC is a problem: Transformers are provided with enough core steel to allow for the magnetic flux that occurs when it's connected to the AC line, plus a little margin. But cores have a limit on the amount of flux they can "conduct" (called the saturation flux) and if you try to exceed that, for example by connecting to a line voltage that's too high, then the primary current rises very fast. Electrically, we say that the effective inductance when the core saturates becomes very low. Because transformer primaries have very low copper resistance, the current rise can be tens of amps, even for a transformer that's only rated 500 VA. Even a small DC voltage can cause the transformer to draw many amps of DC current through its primary. If that DC current, on top of the normal AC current, exceeds the saturation level, it causes a large pulse of current to be drawn in every AC cycle. Often this produces an audible hum from the transformer. Note that low-frequency AC on the line, that is much lower than 50Hz or 60Hz, can cause the same problem as steady DC; it will just be intermittent. Such low frequencies can be caused by any heavy load that is varying with time, such as a motor starting up, a heater turning on, or a high-power audio system, and that could be in a neighboring home or building.
Hold up, if, I just want to get rid of the whistle from my sub, for example: Do I get one suitable rectifier after it's main power cord, connect FROM ac, and put another rectifier in series from what would be the DC out of the 1st rect, going into what would be the 2nd rectifiers AC in? What is "across the AC mains"? What about earthing?
@@donpayne1040 Normally, bridge rectifiers are connected with one AC terminal connected to the mains live side, and the other AC terminal connected to the mains neutral side. That's what I mean by "across the AC mains" but it's not the configuration you want for the application Paul was trying to describe. In normal use, a bridge puts out DC power, but here we just want to use it to cause a small voltage drop in the AC going to the transformer. So the mains neutral and earth connections are still wired directly to the equipment as before, with no change. We are only inserting the bridge in series with the mains live side. You don't have to use a bridge; it's just a convenience which reduces the number of connections you need to make. Instead, you can just use a pair of power diodes in parallel, facing opposite directions (cathode to anode), and insert that pair in series with the mains live lead. That gives you 0.6V drop. Add more diode pairs in series with that, if you need more voltage drop to solve the problem. However, if you are getting a whistle from your sub, it's probably another problem. The video was not discussing noise coming from speakers. It's about audible mechanical noise coming from the power transformers.
@@marianneoelund2940 True, yes transformer buzz, i've experienced that on a very "hhm let me plug this transformer in and see what it does...eww" level. Wow, you're well endowed with some great knowledge. Fair well.
@blackened 1 BUT, without this video I would not have just recognised the fault in my psu and it's reason for making the transformer buzz. Faulty diode, quick change, buzz reduced/gone. Without videos like this slightly electronics inclined audiophiles do very vey foolish things. Tough call.
I have replayed the beginning of this video 4 times and nowhere does it say that the hum is in the power transformer or the audio output .. he says "I have a pesky set of monoblocks that hum at certain times of the day"
@@bobross6802 I agree Paul should have clarified. You are not the only person confused about whether or not he is talking about hum from the speakers. However, DC on the mains - the central point of the discussion - certainly can cause power transformers to hum or groan audibly, so it's reasonable to assume this was the issue that George was reporting. It is the same sound you can get momentarily from any power transformer when it is turned on, if there was residual magnetism left in its core the last time it was turned off. I've done some experiments with a 500 V-A isolation transformer I have, and even without a load, it will draw current peaks higher than 40A for the first cycle or two. That's accompanied by a very audible "groaning" sound. DC coming from the mains can result in similar current peaks.
The best solution to the majority of AC mains issues as well as total elimination of ground loops is to use a balanced power isolation transformer to supply the power to all AV equipment. An example would be a Furman IT-1210.
Mike Eastridge I’ve lived in the UK for my entire life, so far! I’ve been a beer drinker for the major part of that life. There somethings that should not be put in the same sentence, ‘man and bag’ and ‘warm beer’!
Years ago I got a power conditioner, but it didn't seem to do anything to the sound from my system, this in a single family home, remote from neighbors. A dozen years ago I got a condo in a group of 24. The sound system I put in there didn't sound good at all, so I dug out the power conditioner, not expecting much, but what do you know, it made a great improvement to the sound. Perhaps a lot of noise from the neighbors, or an unbalanced supply, who knows? Meanwhile a lot of US beer tastes so disgusting (Bud, Miller, Coors, Pabst etc, etc) it is necessary to serve it very cold so you can't taste it. I notice that brew pubs here serve their beers much closer to cellar temp.
I suffer from terrible DC on the mains where I live. I built a DC blocker using a couple of capacitors and a bridge rectifier. Actually I built 3 housing them all in the same box, one for each of my mono blocks and one for the sub. The capacitors help by filtering out very low frequencies, like putting a capacitor in line with a tweeter. I call my little device the BUZZ KILL.
@@blanchbacker I live in rural England. I didn't measure my mains supply. When I moved into my current property my transformers started buzzing. I did a bit of research and found that dc was the most likely cause. Building the buzz kill eradicated the problem. Many people have found that putting any type of filter on the main supply can suck the life out of the music. (This is why the ps audio regeneration is so good as it doesn't filter the mains, it reconstructs it). Luckily my DC blocker doesn't seem to have had any detrimental effects on sound quality.
Probably yes. If you build a home that's very remote from neighboring buildings, then the power company may give you a dedicated transformer. Otherwise, it's likely very difficult to convince them to give you one. As an alternative to the diode-bridge method, you could use a nice heavy-duty isolation transformer installed near the electrical panel, but those aren't cheap, either.
@@marianneoelund2940 A power systems transformer is alot cheaper then a ps audio system, not very expensive for what it is, couple grand maybe,, used ones readily available due to building upgrades. But the labour will be huge. And they wont just come give you a dedicated line either. To get clean AC you would use your own generator or a UPS system designed to give you clean power.
If there is significant DC on the mains, transformers will overheat and burn out. Want to see how fast it can happen? Connect a small transformer to an old-fashioned light dimmer. It will take a few seconds at the most.
@@redleather100 Sounds great! Thanks for sharing. I used to work in a pub many years ago, here in the States. They had (iirc) over a hundred kinds of beer, ales, stouts, and lagers (collectively). They had the most interesting ale I've tried. Made by Trappist monks using the same brewing methods they developed in the Middle Ages. It was almost like a wine, and had a natural sediment.
What this country needs is a good 3 phase amplifier. And a real good 3 phase transistor and vacuum tube. And an efficient 3 phase speaker. That way the folks in Washington DC can hear when a voter in any state wants to be heard.
As so often, it's best to fix the root cause of the problem rather than add medicine to cover it up. You can cause a DC on the mains if you have a load that's not symmetrically loading on both halves of the sine wave e.g. if someone made a heater with a power level switch that works through a diode cutting the power in half.
Also, momentary asymmetrical loads occur any time a heavy load is changing its current draw, such as a motor starting up or a heater turning on. Lots of kitchen appliances are in that category. Or, more pertinent to the question discussed, high-power audio equipment in a neighboring building.
Your heater example is a good one, that could (in some circumstances) cause DC on the mains. In my garage, I have a pair of 3000W 240V overhead infrared heaters. To make a "low" power level I used half-wave diodes, which work great. Just to be careful, I called my local utility company and asked if this type of load would bother them. They said no.
@@kc9scott LOL, funny. I actually wondered if anyone dared to do this. But it will work, although it is one way to mess up the mains power sine wave. And it will not be cheap if your audio system ends up needing a power regenerator while you run your heater in your garage.
So generally speaking the colder the liquid the less time your tongue has to taste. Your nose also has a lot to do with taste. Some beer tastes better ice cold. It's also terrible beer 😋 Thanks for the details on the ac filter that's really interesting!
Mains voltage isn't that accurate. The voltage you actually receive could be anything from about 210V to about 250V depending on your location and current grid load.
Fair to say DC will also cause your transformers to saturate which also degrades their performance. So DC gives noise in the form of hum and a degraded musical performance if the power supply is sagging due to saturation.
@@kolinstallman3788 I believe it is not a flat voltage, but an imbalance. Instead of a sinusoidal swing from +120 to -120V there is +120.8 to -119.2V. The magnetic imbalance causes mechanical movement resulting in 60 Hz hum.
American homes are also 240v and you could get commercial equipment in your home if you really wanted it. But yea their single phase 230 is better in pretty much every way.
But simply, yes. A typical euro circuit is 230v 13 amps while US is 120v 15/20 amps. So they get roughly 500 more watts to play with vs our 20 amp 120v circuit. Then frequency comes into play.
I think the main reason mains gets unbalanced is that engineers have this nasty tendency to draw a schematic with the three incoming phases across the top and then pick the first one to drive the controls and other single phase loads. This means that the first phase always seems to be mistreated. It’s certainly what I’ve seen on a daily basis along with half wave rectifying a supply to 4KW infra-red paint dryers in two rows of 144! Oh and I don’t drink a beer warm unless it’s one made especially to drunk that way. Thanks, Drunk Dunk. Hic!
UK voltage is NOT 230V. The pesky EU made us say it is 230V...it is 240V. My local supply is usually hovering around 246 to 250V, depending on the time of day.
@Mike Eastridge I wish I had nexit too, mate. Worse thing is that our governmental retards gave up our own coin for that shitty euro. Now they end up giving our pensions to Southern countries like Italy so they don't have to pay tax and are able to keep their pensions. That is just the tip of the gripes I have with that institute. A different gripe is the lack of cultural diversity in Europe since the EU came about and borders were dropped. It's just one unity sausage of ground remains of what once was into a big heap of unrecognizable mush.
@Fat Rat Actually that is historical fact. Before and until shortly after WW2 you had the League Of Nations (the United Nations under its former name). Countries part of this League Of Nations were amongst others the United States of America (USA) and the Soviet Socialist Republic Union (CCCP). After WW2 ended in 1945 the involved countries went back to their isolationism as it is called. The League Of Nations came to the conclusion in the years after WW2 that Nationalism and national identity was the cause of ever reoccurring conflict in Europe but also the world at large. So they set out a long term plan that was to setup a New World Order in which Nationalism and national identity were to be obliterated by scratching them away slowly over time. Since the League Of Nations with a different agenda was at its end and over the years had a loss of face, they brought forth a plan to create a renewed concept of the same under a different name.... the United Nations with its common enemy being Nationalism. To do this it would be best to rip out the heart of nationalism in the place in the world where there were the most concentrated variety of cultures in the world, Europe, and as luck would have it this was now in turmoil from basically two bloody world wars. Sadly because all the countries went back to their isolationism the American laws didn't allow that military treaties could be signed outside of times of war, and they needed this in order to plant the seed of destruction called the ECSC or European Coal and Steel Community (the foundation for what is now the European Union). So the Soviets setup a very convenient blokkade in Berlin on the 24th of June 1948 after which on the 11th of July 1948 the treaty of Brussels was signed. Which lead to the Schumannplan and the creation go the ECSC and much later the EU as we know it today. Of course this created a cold war but because both are UN members at most they were doing was barking and no real biting. Also in east Germany there was this communist experiment on how to control a country of people and keep them under surveillance so they keep doing what you want them to do. Later as the Berlin wall fell and the EU was created, they basically retried this experiment on a larger scale in China. Which started with the student protests basically, of which we all still remember the man/student standing in front of the tank to stop it in its tracks. So yeah, it's just simply history that you can read up on if you fancy the time. All of these articles on Wikipedia are checked by the UN and EU for their correctness, as any big company does. But feel free to dive into books and documents if you must.
@Fat Rat Depends on which beer you talk about, besides export beers are different from beers you get in the country they originate from. There is even a difference between bottled and tap and export bottled and export tap. Hell, there is even a difference between what you can get in a bar or in the shop. Or worst of all during an event which often has less alcohol contents but more salt, so you drink more of it at premium prices. In the Netherlands you can nowadays get a big variety of good bears from big and small breweries in the supermarket. If you then go to a good liquor store you can get even more special beers. So yeah, it's a bit complex as to say if it is all horsepiss. But there is a lot of horsepiss out there. I myself can't handle Heineken in any way. My body just naturally protests to it and it simply says "return to sender, address unknown" and it comes right back out. Same with all that non-alcoholic and light crap. So when I was in the USA I simply order a Bud. The guy behind the counter said "A Bud Light?!"... at which point I kinda annoyed said "No, a Bud! " in a tone of 'I don't want horsepis'. Also we like our beer cold in the Netherlands as opposed to the luke warm crap over across the Nordsee puddle in the UK.
@Fat Rat No bears beers... Darn it. 🤣 Bloody autocorrect at 5am typing style. I better hit the hay. I am not much of a drinker though, but when I do I'd rather get something decent or try something new. There is this Belgium beer I like... La Chouffe. A nice blond beer but with a bit more alcohol then most. Fruity, spicy with coriander and a light hop taste. I don't know if you can get it there though.
The diode bridge part was very badly explained Paul ... do it again using a white board and explain it properly as some people might try experimenting with lethal results any way it's not as simple as just a diode bridge ... What Paul was referring to is the 3 phases that power comes from. Uneven loading causes the star neutral point to drift away from neutral .. in an ideal world this point would be clamped at 0 volts. Delta connections are a better way to go .. but not always feasible
To be more accurate, I wouldn't call it "warm" beer: it's at room temperature, which in the U.K. or Ireland (where I used to live) can actually be quite cool. I thought I'd add this because I didn't want someone from say, southern California, thinking that the Brits serve beer at 75 degrees F!
It’s not normally served at room temperature, cur cellar temperature, which is p below room temperature - but not as cold a a fridge, it’s certainly not warm.
It's also a different kind of beer: "bitter", or "ale"....Unlike lager, bitter has a different flavour that suits a slightly warmer temperature due to the different flavour and character coming from its fermentation process. Bitter is top fermented, whereas lager is bottom-fermented. In the UK, bitter is served at cellar temperature, whereas lager is (hopefully!) served cold, like anywhere else! As said above, if bitter is served ice cold like lager it really loses much of its characteristic flavours - it's much better consumed at cellar temperature.
you must install 2 separate 30 amp lines for your stereo and a separate ground otherwise dont even bother. youre better off with 3.2 beer and day time tv.
Beer should be below 32 degrees Fahrenheit. The little bit of alcohol can keep your beer liquid at 28F or so. That first sip should be brisk. As you sit and chat, or watch the telly, each drink after is still very refreshing but it gets a bit smoother.
@@Ian_Allen There are three in the range Ian. Old Crafty Hen, Old Speckled Hen and Old Special Hen. Old Special Hen is a little richer tasting and 6.5% if I recall correctly. I'm sure you would love it :).
@@donk1822 Old Crafty Hen is 6.5%, the other two in the range are Old Golden Hen and Old Hoppy Hen. I've never come across Old Special Hen. Gave up alcohol 14 years ago.
Which would cause a transformer to hum why? The distribution transformer maybe but I dont see how DC or an unbalanced load will make a transformer hum.... Thats just what they do naturally and is mitigated by a higher build quality.
What a bunch of nonsense. Those diode bridges might stop residual current near the zero crossings of the AC but would conduct otherwise and would not alter the AC + DC waveform, if that is something you truly believe is happening which I would seriously doubt given the total load impedance placed on the line transformer. I would suggest looking to see if the line/pole transformer (or even possibly substation) is being overloaded at those times of the day causing the AC to be less sinusoidal. And if that's the case your power provider should be required to address the distribution problem.
@G Guest Please explain how the "DC blocker" would prevent such a significant offset that it would cause an offset in the AC waveform. Also a DC offset won't add to the eddy currents but yes a laminated transformer will have less eddy currents. The problem isn't some phantom direct current.
I agree with Chris, and am skeptical about the diodes being able to solve such a problem. On a perfect 120V AC source, the sine-wave peaks will be ±169.7V. Now, envision an actual problem where the 120V AC line has just 1.0V of DC offset. The positive peak becomes +170.7V, and the negative peak becomes -168.7V. The wave shape will still look like a perfect sine, it's just shifted up a volt. Now put in the 1.2V dropping-diode assembly. With this, the positive peak will be +169.5V and the negative peak will be -167.5V. The 1.0V DC offset (pretty much *all* of it) is still getting through.
This is a good topic and often goes overlooked in the Audio world itseems. Aside from eliminating transformer hum I’ve also heard distinct sonic differences when using a DC blocker.
"What to do when there is DC on the mains?" You start by walking away from smiling audiophile ''engineers'' and start consulting/working together with constant frowning microsystems engineers, ones that know and understand high pass filters and RLC correlations to start with. On that note, while on the sensitive subject of AC coupling in removing DC component, beer, pregnant belly and other digressive nonsense has no place.
If your transformer is humming, give it the lyric sheet so it can sing instead! Waa Waa! Honestly, I've never heard of that phenomenon! So, you're saying if there is a big phase imbalance between L1 and L2, a DC voltage could be generated? Is there an instrument that can measure that? All I know, if I'm right, is that in a home, if one phase is heavily loaded, it could cause a voltage on the neutral leg. In severe cases, of if the neutral is not super well grounded, an additive voltage may appear on the less loaded leg and actually cause a voltage increase on that leg. But creating pure DC? Wow, that's a new one for me.
A few things. "... if there is a big phase imbalance between L1 and L2..." he didn't say this, or imply this. We might be using words differently though, so to be clear, "phase" is measured in degrees, not volts. It is a product of the AC generation itself, where each "phase" is 120 degrees apart (in 3 phase electricity). In Europe, the 3 phases are distributed evenly to each building(1 leg of each phase on 2 wires making 2 legs of single phase), in the US, the power is converted to split phase, and each building gets a 2 phase (180 degrees) power supply. I am not an expert on this, so someone might correct or clarify this. Commonly we use the word "leg" to talk about the actual wire that makes up each "phase." To get to the heart of the matter, DC on an AC circuit. AC goes from -120v to +120v for a total of 240v. Lets say you input +10v of DC electricity, now your AC will go from -110 to +130 for a total of 240V. Since 0 volts is a physical ground, it remains always 0 volts, and an imbalance exists between the high and low voltage. The iron frame of the transformer still "sees" the 10v DC, and act like an electromagnet, and resists the swing to -120v, the transformer will resonate causing hum.
@@joshua43214 Thanks for your constructive input! I am NOT an electrician, so my terminology may not be accurate. I only have a superficial understanding of phase angles and such. I know of wind generators that send their DC power into a syncronous (sp) inverter that "inserts" the DC voltage into the mains AC in a manner that it adds to the AC voltage at the voltage level supplied by the generator. Right? Anyhow, that's not here or there. What I can't figure out is how a DC voltage can be induced onto the mains to a big power transformer?
@@curtchase3730 it doesnt, its possible but ive never seen it anyways in my 10 years of herding electrons, ive induced it in lab class not but never seen it in the wild. This is way overthought. Its probably just an old transformer, thats what they do lol. But if you wanted to see it you would use an oscilloscope and measure the peaks. Remember a transformer is just a motor with a stationary rotor and some wires coming off of it. It naturally wants to move and will make noise. It take excessive build quality to silence them.
Years ago I had the problem of mechanical noise coming from most of the transformers in my hi fi chain of equipment. It drove me nuts. In the quest for perfect silence in my listening room I hooked up an oscilloscope to the mains. The sine wave was far from perfect with clearly visible distortions on the top and bottom curve. As a result I called in the utility company to investigate. They hooked up their equipment to the incoming side of my meter board and left it installed for a couple of weeks to record the quality of the incoming power over a set period. The conclusion was that I was correct in analysing DC on the mains, however the power quality was within the government’s guidelines and I would have to take it or leave it. I then got an huge isolation transformer installed which instantly cured the problem. At last I had a perfectly silent room but that was not the end. Immediately upon playing a reference track my heart sank. The life was sucked out of the music. The dynamics were just not what I was used to. The isolation transformer was promptly returned to the vendor for a refund as it was on trial. At that point I gave up the quest to tame the DC on my mains. A few years later the utility company replaced the large supply transformer feeding my property, which solved the problem of vibrating noisy transformers for good. Paul’s solution would possibly have solved my problem all those years ago!
