The actual noise floor of a DAC output for instance w and w/o. Pretty easy to do, I would ask for THD but that would probably violate first principles (just kidding).
On a related point I bought a non-contact live circuit detector today because I wanted to put in some lights without turning off the breakers and just wanted to be safe. If I put the thing anywhere near my computer even the mouse it lights up like crazy even though the threshold is stated as 50V AC.
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It is amazing some of the electronics widgets and gadgets and gizmo's that are now in the home. Home automation and auto- this and that. WiFi et al.. Plenty of DM and CM noise on the ac now.
Though it is there in abundance - not so much from the utility company but from the electronics in the home plugged into the utility power. Its all locally generated in your home for the most part.
Now it depends on the quality of the A-V components to reject it. There-in lays the rub... has CE industry kept up and what about older gear at a time when so much noise/interference did not exist.
I cant do the DAC THD now because I am leaving in 2 days. But I am sure someone can do it. The test of RFI passing thru the power supply -- simulated and demonstrated by signal injection while reading THD and seeing it increase is probably the issue … And, not noise on the output per se.
I will look for that published test. Ben Duncan, D.Self? Cant recall now who wrote it but I wont forget the result of increased distortion on test signals fed to amp.
Whether or not it is very scientific - a listening session may be more important than any static residual noise numbers. If you hear nothing change, then all is good for you.
It seems the problem or potential for problem of egress thru PS/ac line is that PS regulator do not have psrr that is effective at HF. Same with PA. It can be done but is it being done/looked at? So far many people hear change with ac line filtering. So, my guess is No it isnt being sufficiently addressed by many companies. Or by anyone?
THx-RNMarsh
Though it is there in abundance - not so much from the utility company but from the electronics in the home plugged into the utility power. Its all locally generated in your home for the most part.
Now it depends on the quality of the A-V components to reject it. There-in lays the rub... has CE industry kept up and what about older gear at a time when so much noise/interference did not exist.
I cant do the DAC THD now because I am leaving in 2 days. But I am sure someone can do it. The test of RFI passing thru the power supply -- simulated and demonstrated by signal injection while reading THD and seeing it increase is probably the issue … And, not noise on the output per se.
I will look for that published test. Ben Duncan, D.Self? Cant recall now who wrote it but I wont forget the result of increased distortion on test signals fed to amp.
Whether or not it is very scientific - a listening session may be more important than any static residual noise numbers. If you hear nothing change, then all is good for you.
It seems the problem or potential for problem of egress thru PS/ac line is that PS regulator do not have psrr that is effective at HF. Same with PA. It can be done but is it being done/looked at? So far many people hear change with ac line filtering. So, my guess is No it isnt being sufficiently addressed by many companies. Or by anyone?
THx-RNMarsh
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Hi Richard,
From what I have seen in the field, any attempt at keeping noise out of the unit starts and stops with a corcom filtered IEC power inlet. There isn't often any other measures taken to keep the internal power clean after that. Not always true, but in the majority of cases, that is all there is.
-Chris
From what I have seen in the field, any attempt at keeping noise out of the unit starts and stops with a corcom filtered IEC power inlet. There isn't often any other measures taken to keep the internal power clean after that. Not always true, but in the majority of cases, that is all there is.
-Chris
It's well known that most regulators have dismal rejection past say 1 MHz for the best IC LDOs. There are thousands of models of passive components for filtering HF noise available from Murata, TDK, Wurth, etc. Maybe they are not common in boutique audio but they are commonly used in industries where products actually have to pass compliance testing.
"So far many people hear change with ac line filtering."
Anecdotal evidence with ridiculously small sample size.
Hi Chris,
You're being far too kind. For the common regulators seen in audio equipment, they don't do well at 100 KHz. Even 10 KHz can present a real problem for the original three terminal regulators such as the 78xx and 79xx series. If anyone is interested, just look up the data sheet for these regulators and look at the graphs.
-Chris
You're being far too kind. For the common regulators seen in audio equipment, they don't do well at 100 KHz. Even 10 KHz can present a real problem for the original three terminal regulators such as the 78xx and 79xx series. If anyone is interested, just look up the data sheet for these regulators and look at the graphs.
-Chris
Hi Chris,
Yes, but not generally used in audio equipment. Especially not the low volume manufacture of "high end" audio equipment.
-Chris
Yes, but not generally used in audio equipment. Especially not the low volume manufacture of "high end" audio equipment.
-Chris
Line filters-two separate issues, first do they work? How do you verify in measurements that they reduce interference/alter audio performance? Second, are those measured changes audible? If the measured changes are not demonstrably audible what is the point? However if there are no measured changes but there are demonstrable audible changes then what do you look for?
It turns out I do have all the equipment to do the audio frequency interference testing outlined in the Solar app note. However I'm not too inclined to do it all solo. Is there anyone reasonably local who wants to participate?
It turns out I do have all the equipment to do the audio frequency interference testing outlined in the Solar app note. However I'm not too inclined to do it all solo. Is there anyone reasonably local who wants to participate?
I have found that common RFI filters, like Corcom, can create problems as well as fix them. I tend to avoid them today, but 35 years ago, I was eager to use them, and I did!
Hi Demian,
I am not far away. But I will be, soon. Maybe when I get back... or might do it in Bangkok.... my spect/network analyzer is there. And AP et al.
What do you want to do?
It is easy to measure before and after filter. Thats been done long ago. I could do it again for the entertainment of people here.
Besides any noise reduction in DUT changes, I will also be interested in an amplifier's distortion changing with and without.
Then there is the noise source to consider. And how to apply it.
-Richard
I am not far away. But I will be, soon. Maybe when I get back... or might do it in Bangkok.... my spect/network analyzer is there. And AP et al.
What do you want to do?
It is easy to measure before and after filter. Thats been done long ago. I could do it again for the entertainment of people here.
Besides any noise reduction in DUT changes, I will also be interested in an amplifier's distortion changing with and without.
Then there is the noise source to consider. And how to apply it.
-Richard
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Scott and others make another assumption that only a small number of people have heard improvement/change in sound when a line conditioner is used. Monster distributed and sold a huge number of units for years. A lot of feedback came in that customers hear an improvement. Many of them just bought the unit for its protection of their A-V investment with any sound improvement would be just a bonus.
Lots of feed back exists. None used a rigorous DBLT. But the numbers are so large it might fall into metadata fall out.
THx-RNMarsh
Lots of feed back exists. None used a rigorous DBLT. But the numbers are so large it might fall into metadata fall out.
THx-RNMarsh
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Hi Richard, did you get to hear of any dissatisfied customers....ie those who claimed no subjective benefit on their system.
If the kinds of systems for this group were known, some data could be drawn perhaps.
Dan.
The problem with these hearing tests 😉 is the bias caused by spending lots of money, also how do they know the change was an improvement?
Same thing for the PSRR of amplifiers.
For a typical amplifier (VFA) with 85dB rejection at 100Hz, it falls to 31dB at 1MHz.
All good points, Demian.
1- I believe a HD (And IM) comparison with/without the filter should be enough. The main problem is from the AC line itself. You'll have to re-create a polluted enough one to enlighten the expected improvement.
You'll have to ensure the measured amp is in an average situation too, in regard to grounds currents, connecting to it several sources, including some digital ones with SMPS to mimic a hifi system in situation.
And the generator itself will have to be powered with/ without a filter in the same time.
Not so easy, a real study that highly depend of the environnement, the amp quality itself etc.
2- Only a blind test session with a high enough number of contributors, used to discriminate audio reproduction defects, should have an undeniable value. Forget if you don't have a large capital of sympathies and shares or obligations with a beer manufacturer. ;-)
The most simple, OMHO, was what Richard proposed: It is so easy for everybody to figure out for himself if he can ear an improvement or not with a cheap simple double trasfo filter connected to the source in his own hifi system. And, if he is not interested or if he does not want to get his fingers out of his a... to talk about something else. ;-)
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This discussion started by Richard is a very useful for me, the back to back transformers are easy try, build. I measured RF pollution coming from a nearby TV tower inside in a CDP with a 200MHz scope and I had a significant reduction of RF just using a ferrite ring on the AC cable.
What is the need to ensure that what you perceive is real or not, when all the purpose of this hifi game is to increase your pleasure ?
It has been established, under a medical EEG, with a sample of people who were asked to compare two identical cups of wine, one supposed to come from a very prestigious and expensive bottle, and the other from an ordinary one, that the zone of their brains dedicated to the pleasure was more excited by the first one.
They *really* enjoyed more this cup.
So what ? If you pay for something that will increase your pleasure, and you got this extra pleasure, you have what you paid for.
If this pure unobtainium cable insulated with Himalayan silk thread and placed on rare wooden pyramids has improved the quality of the hi-fi system that I am so proud of, how does it bother you?
Would you be jealous of this nice scammer who sold it to me?
Now, if you are an audio designer (are-you one ?) you will be interested with things that will increase the pleasure of your customers because your success will depend of it. Nice looking measurement numbers are just a part of it.
If you are a sound engineer (are-you one ?), you will be more interested to produce an album that will sound impressive at first listening, than closer to any "reality". Because this album will be more successful.
Some people here are better to consider all this with a little hindsight.
So, if hifi is more psychology than circuitry as you say (and it's a perfectly fair point), and budgets are not infinite, the best thing to do would be to learn how *not* to hear the differences between systems, and how to hear the music despite the system. Then, you can maximise pleasure and minimise cost - a perfect result surely? And then you have mode budget to spend on the music, instead of spending on gear or snake oil...
We should write a how-to book!
We should write a how-to book!
Nice looking box is a bigger part of it. I'm just a poor music consumer and as such I object to the snobbery surrounding "hi-end" audio, I don't care if people want to waste their money on it, but I do care when they say if sounds better than a piece of true hi-fi equipment the function of which is to reproduce the recording, whatever it may be, accurately. Because I prefer to listen to the music rather than the system an accurate (hi-fi) one is important to me because I don't want it to dictate what it will play well (I listen to all kinds of shyte)
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