Okay, understood. A fuse won't blow instantaneously. What would you use to resolve the problem?
EDIT: BTW, that type of circuit passes regulatory muster for consumer products in most worldwide jurisdictions... Remember, we are only isolating audio circuit ground from chassis ground. The latter is still directly bonded to AC line ground.
EDIT: BTW, that type of circuit passes regulatory muster for consumer products in most worldwide jurisdictions... Remember, we are only isolating audio circuit ground from chassis ground. The latter is still directly bonded to AC line ground.
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So far, I've had quite a lot of success by controlling the ground loop of the power cords. I consistently ran 100 foot unbalanced line level runs and experienced zero hum and noise. And in a 15 KW pre-standards SCR type dimmers environment (and no, not saturable core reactors, silicon with no snubbing).
It's only when the system consistently draws over 2 kilowatts (20 amp breaker) that I start to consider drastic measures, like balanced runs or (OMG) a DI break.
Once you have to split the loads into separate breakers off the service panel, you've no idea where the wires are going.
John
It's only when the system consistently draws over 2 kilowatts (20 amp breaker) that I start to consider drastic measures, like balanced runs or (OMG) a DI break.
Once you have to split the loads into separate breakers off the service panel, you've no idea where the wires are going.
John
I believe you. However, was this is for a very high resolution audio system? I ask because what shows up, say, on an oscilloscope, and what the human ear/brain system can potentially resolve are not necessarily the same. So, depends on how one measures, detection methodology, detector sensitivity, etc.
It doesn't matter how high a "resolution" the system is. I use the same techniques to fix equipment setups that are picking up nanovolt and picovolt noise signals. It's not rocket science.
Proper ground loop design does not need a ground loop isolator that may not be good enough to protect human life.
I would NEVER ever consider using an object in a safety position that was incapable of providing adequate safety. One of my work roles, electrical safety inspections, is to prevent such stupidity from happening.
John
ps. I do recommend not trying to bamboozle me with "very high resolution" yada yada. I kinda understand this stuff.
Proper ground loop design does not need a ground loop isolator that may not be good enough to protect human life.
I would NEVER ever consider using an object in a safety position that was incapable of providing adequate safety. One of my work roles, electrical safety inspections, is to prevent such stupidity from happening.
John
ps. I do recommend not trying to bamboozle me with "very high resolution" yada yada. I kinda understand this stuff.
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Snake oil keeps creating new and new threads. It is a classic ! 😀
This for the safety ground within an amplifier or whatever, right? It's impossible to argue with your reasoning there, nor would I want to.
How about for the circuit "ground"? By that, I mean stuff connected to the secondary side of the power transformer. Suggestions?
BTW, I've studiously followed your well explained current loop recommendations over the years with great success. Not just for minimizing hum, but other undesired currents, too. Works every time. Physically smaller loops always are better.
May I ask how you are currently measuring 'signal-correlated noise' in audio systems? (noise that is audio signal correlated, either closely or else less strongly correlated)
Thanks!
We made them here 40 years ago, I participated in the marketing process. It was a failure, the market is small and very few wanted to spend their money on these "special" cables.
I still have them in use in my main speakers, since they weren't OFC, they look rusty through the PVC cover.
I bought a few meters of a similar cable new recently - I think they are Chinese, they are sold by the meter - I have not noticed any audible difference, neither before nor now, I have used them for subwoofers.
CG : I hope this answers your question.
I still have them in use in my main speakers, since they weren't OFC, they look rusty through the PVC cover.
I bought a few meters of a similar cable new recently - I think they are Chinese, they are sold by the meter - I have not noticed any audible difference, neither before nor now, I have used them for subwoofers.
CG : I hope this answers your question.
Attachments
I'll not speak for him, but since he is a modest guy, I'll just throw this in. In his day job, he has to measure signals that are very tiny - like picovolts - in the presence of very high voltages and scarily high currents. Not audio, but a similar idea on a much bigger scale.
It still comes down to basic physics. (there's a joke in there, too)
CG, if you want to use the translator, read my post ( I used another nick, yes ) from Jul 01, 2020. That may clarify even more which part of the snake oil I mean, luckily I found the photo there. I can send you a photo of the gold-plated terminals, if you want. They were special for pressure terminals. I suppose it is another important point in sound quality, for a reason many technicians currently replace the original pressure terminals of the amplifiers and place Binding Post terminals... which I cannot guarantee if they do it at the request of the clients or On their advice, I imagine there will be a bit of everything.
https://audiovintage.foroactivo.com/t6514-revistas-de-audio
https://audiovintage.foroactivo.com/t6514-revistas-de-audio
I know. Do you think he is the only guy who has ever had to do anything like that for living? Okay, what I did was for experimental neutron Radiation Oncology, not high energy physics research, but I have seen a reasonable share of problems with low level signals and noise. IME audio is a different type of thing. When measurements numbers are small and below the threshold of audibility for 50% of the population, some people like to believe only large numbers are plausible. Whatever it is the particular person can hear, possibly on their particular system or on various systems. Know what I mean?
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When you have one piece of equipment, it's a simple thing to verify the grounding impedance. If it's good, all is well.
Once you go into two or more pieces of equipment, grounding can become problematic. Most equipment will bond chassis to safety ground (3 prong), so then the problem becomes...what is the reference point for the signal at the input to the power amplifier? If any piece of equipment loses the safety ground, can the other pieces trip the breaker in the event one has a problem? The previously shown ground isolator is not a safe entity should it be called upon to protect people. Heck, just switching to an aluminum case 25 amp bridge where the internal silicon is perpendicular to the case walls is a far better choice, as there will not be a containment breach and the dice will fail shorted. The bridge previously selected uses the 2851 epoxy for support, which does no good in a fault condition.
Rule #1. MEET code. While NEC is not perfect, it is still good and there to protect you.
Rule #2. When you follow code, remember that code does not care about your signal integrity.
Rule #3. Figure out where the currents are going. That is the entire crux of EMI/EMC teachings. THAT is how you eliminate grounding influences.
If that specific circuit with that bridge passes regulatory "muster", then the regulatory agency needs schooling. As a test and application engineer at the largest manufacturer of diodes on the planet (back in the day), I am quite familiar with the bridges being discussed.. and what they do when they fail.
If the audio is isolated from the individual chassis grounds, what does the consumer do when the chassis potentials are different due to EM noise in the environment?
I on occasion have a chance to see how amp PC boards traces are laid out. It's amazing to see amazingly well designed circuits executed poorly at the PC level. Even how the dual supply rails are laid out wiring wise. And, putting positive and negative pass elements far apart, and expecting zero radiated EM fields.
As I recall, John Curl would use a really good guy to layout his work. As I also recall, JC seemed to have a good name for himself. I wonder... correlation, or causation?
jn
You claim PTs generate noise?
Wow!!!!
And which would be the noise generation mechanism?
So it was a "Letter to the Editor" or similar?
Not exactly a full fledged article, huh?
FWIW lots of people write Letters to the Editor at, say, WSJ, NY Times, etc., some of them signed "Concerned Citizen", "Taxpayer", etc., they even get printed (there is a section for that), that doesn´t make them "Political Analysts", "Economy Advisors", etc.
Indeed.
However, I would like to think a little more about an audio circuit that runs on +-15v or maybe +-24v and that has a ground loop buster circuit between audio circuit ground and chassis ground, and where chassis ground is solidly bonded to AC line earth. Yes, there are some potential failure modes that could be hazardous, no matter the probability of one occurring. True.
Also true the life is not without risk. Tackle football and downhill skiing are both legally classified as assumption of risk activities. Likely working on tube circuits is one as well.
Not only that, but its true that vaccines are not without risk, just as the diseases they protect against are not without risk.
There are always people who put risk aversion above all else. Some people argue we are trying to protect our children too much today at the risk of not preparing them for later life on their own. Also, there is some evidence even that letting babies sit in the backyard and eat dirt helps develop the immune system, albeit at some potential risk.
Anyway getting back to audio, what if we have ground loop buster in a circuit where a primary to secondary short occurs in a audio circuit power transformer protected with, say, dunno, a 1A fuse. Maybe in a fault condition the fuse will fail to blow, and maybe a diode bridge will explode before a fault is detected and an upstream breaker is tripped. Could happen. Maybe more risk around a bathtub? Maybe tube circuits should be outlawed?
I don't claim to have all the answers. However I like my audio clean, while reasonably risk free. Think its doable.
EDIT: Looks like we may have been typing at the same time. Will try to catch up tomorrow. Thanks.
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I've tossed equipment because I could hear voltage dependent noise being generated by internal circuit resistors.
I've modified equipment because I could hear power dependent noise being generated by line cord haversine currents as the line tries to recharge the supply caps. Note, the noise is odd harmonic on the line cord side, even harmonic on the secondary side. Sometimes due to external equipment grounds, sometimes due to inside the chassis currents. One big problem at the design level I've seen is how the feedback run to the input pair is positioned, and how the ground of that input pair is laid out.
One can spend all day playing games with odd components slapped together to "solve" a problem in a random fashion like that isolator, or one can understand the coupling mechanism and engineer a solution to the coupling.
Alas, if you engineer a proper solution, then what do you have left to play with?? Taint broken... don't fix it..
Me, I just setup my stuff and go mingle. No hum, no noise, just social engagement.. I haven't had a ground loop noise or distortion problem in 20 years. But who knows, it might just be luck, no?
At work, I just point out where they have not controlled currents and loops, give solutions, watch them fix it and become happy, and move on.
Two benefits.. One, I look like I understand stuff. Two, those scientist guys do x-ray crystallography stuff on their covid protein crystal samples and figure out how to help all of us stay alive, or in situ battery x ray microscopy to keep us driving longer...
On my career glidepath, my flaps are down, the landing gear out, and the landing lights showing, I don't even care about the first benefit, I'm just getting my hobbies in line for retirement. Right now, I joke with my boss that I need the job to pay for my hobbies.
John
Please...life goes on... just giving me a pair of scissors falls under the assumption of "risk activities"..
I'll never forget my doctor telling me (who was concerned about a flu shot). ""Nobody ever died from a flu shot"".. well, the argument might be PPM level stuff, but it was a rather convincing argument.
Markw4 said:
NEC deals with the entire continent and experience gained over many decades. They are not perfect, seeing as it is updated every three years. But totally disregarding safety bonding with random widgits...code specifies bonding impedance levels for a reason. (course, why they decided in article 392 in 2023 that tie wraps holding cables in trays now have to be listed...WHAT?? REALLY???)
Given the choice between NEC and some internet stuff...hmmm, gotta think about that...
Just had a discussion with another engineer, I was explaining the freezout scenarios with off eutectic solders and the tie line method of determining alloy concentrations. Found a great link, sent it to the guy, but couldn't shake this feeling that something was amiss in the explanation, something was just off.
Hit the textbook, and sure enough, only half the explanation was good. Remaining liquid above eutectic temp was great, but the freezeout constituents were misinterpreted.
I generally look at online stuff with a critical eye, this one looked really good, and they almost got by me..
Electrical safety....yah, I'll remain wary on internet provided stuff.
John
The haversine currents on the primary during high power delivery to the speakers will generate lots of harmonics, a cap could help dull those out a bit.
Also, some diodes do tend to switch off in weird ways. Some turn off soft, some very hard. Even within a single product line, different diffusion runs can exhibit different behaviour.
Also, during diode conduction to recharge caps, HF audio currents can work back into the transformer. It acts like a gating mechanism. If the caps are small, large droop gives longer gating times. Larger caps give higher haversine currents but less droop.
Ya can't win, I tell ya!!
jn
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