Sound Quality Vs. Measurements

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We must be having one of those East coast-West coast things. We do a lot to try and eliminate ground loops. Best thing ever to hit a data center was fiber.

Your diagram looks exactly as I expect. Of course, neutral and ground are connected back at some point with all kinds of parastatic ugliness in between. I only see a problem if you were to tie signal ground to safety ground. 5 to 10 Ohms lift should fix that right up.
 
Your diagram looks exactly as I expect. Of course, neutral and ground are connected back at some point with all kinds of parastatic ugliness in between. I only see a problem if you were to tie signal ground to safety ground. 5 to 10 Ohms lift should fix that right up.

No need to fix problems if don't create them. Especially, when fixing does not eliminate the problem, rather attenuate it.
By the way, the diagram does not show the whole story: power lines are not balanced in respect to ground, so differential mode currents contaminate ground as well.
 
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Of course every transformer also has capacitance between primary (tied to hot and neutral) and secondary which is then tied to directly to signal ground somehow, usually through rectifiers in a bridge(!). There's also capacitance between each winding and the transformer chassis, which always (for good safety reasons!) connects to the equipment chassis.

The capacitors going to ground in that diagram (post #2162) are generally several orders of magnitude larger than between any transformer windings, so not nearly as much noise and crap goes through transformers and it's not nearly as much of a problem, but it can still inject "dirty currents" into safety and signal ground.

But also important is how equipment responds, which can vary greatly depending on design. This is a way to test various audio equipment for suceptibility to such problems:

TVTechnology: How to Test for the Pin-1 Problem

but also, I'd do the test on input grounds both with nothing connected and with some other equipment connected to the input, or a connector with a 1k resistor between signal and ground, thus testing the input under all conditions.
 
Exactly which part of "power line filter" is enigmatic?

I would have thought the description is self-explanatory. It's quite simply a filter which cleans up the incoming power, the device being placed between the wall outlet and whatever you wish to obtain filtered power from it.

Since the filter is of the floating type, it has no connection to the ground, except for the indicator LED (if it's shining, the filter is functional, if it's not shining, the filter has blown a fuse).

Ultimately, there's a photo of it a few pages back.

Once again, the filters installed in most equipment are to prevent noise contamination of the mains by the equipment.
Filters installed in so called surge arresters do filter incoming noise from the grid.
Are you implying that input and output of "the filter" can be swapped? And it would still work as intended?
That's why you have not answered the question...
 
Power lines are usually dirty. So, we use power line filters to clean up the power line. Many simple passive filters are designed to contain the RFI generated by other electronic equipment like faxes, computers, etc, and keep it out of the power line. These filters can be problematic with audio equipment. I generally avoid using them as such. I usually make my own.

"Dirty" is really being polite. They can be much more than just dirty.

While this is in a sense speaking against my own trade, I have maintained and will continue to do so that the biggest problem with power line filters, or in modern communist talk "conditioners" even if they are just passive filters, is that you NEVER know how they will or will not fit into the system. You never can, there are far too many variables on the electrical side, and just as many on the snake oil peddlers side of filter sellers.

Honestly, some of the ads I have seen regarding power filtering have quite literally made me physically sick. As bad as with cables, if not actually worse. At 58, I still marvel at what some people will publish to make a buck.

Over the years, I have compiled a small list of my own, using customer feedback, of equipment which will come alive as it never did before, but also of equipment which will degenrate with it; last month, I refused to sell a unit to a gentleman from Switzerland because he owns some equipment from my No.1 position on the "No-No" list. Saved him and myself some unnecessary hassle.

As an example, practice shows that Audio Research (11 cases) and Krell (3 cases) will react very well to my filters, but that Jadis (2 cases) will not. So, if someone owns Jadis equipment, I will not sell to him. I know he'd be unhappy, he'd send it back for sure, and I just don't need the costs incurred.


@Alexberg

I am not implying it, I am saying it outright. It has no A or B side as a filter, however, the production version does have input and output sides, as dictated by the necessity to have that indicator LED.

Aside from that, it filters equally both ways. Which is as it should be, because just as we don't want contamination in our devices, we equally don't want ourselves to sned our own much back into the grid.

In addition, this means that any device is perfectly isolated from all neighboring devices in all cases when a device has a dedicated to it alone filter unit working for it.


@Wavebourn

I thought your only question was related to whether I'm sure it was connected properly, which I did answer. But I may have missed a second one, I'll go back and recheck. If I've missed it, I apologize.
 
Hi,

While this is in a sense speaking against my own trade, I have maintained and will continue to do so that the biggest problem with power line filters, or in modern communist talk "conditioners" even if they are just passive filters, is that you NEVER know how they will or will not fit into the system. You never can, there are far too many variables on the electrical side, and just as many on the snake oil peddlers side of filter sellers.

The problem is that you have on side the consuming equipment which may be designed any number of ways and you have little control about the mains itself.

So any of these combinations of these with a simple LC filter may cause untold tank circuits that can make a bad situation worse, rather than better. Furthermore, few of the power line filters sold have any significant impact in the 30KHz - 300KHz range where all the crud injected by switched mode supplies for computers, electronic ballasts for cold cathode lamps and electronic transformers for halogen lights ends up and where HiFi gear is most easily upset.

At AMR we design the appropriate filtering into the device, into the mains transformers and additional components. We usually recommend to at least trying to use direct, unfiltered mains via a good quality distribution system, as most LC filters make things worse, not better.

Of course most customers ignore this advise and then complain to us and are upset when we must tell them that their very expensive mains conditioner (often more expensive than our gear) is degrading the performance of our gear.

To be honest, the only "valid" power conditioners I can accept are full analogue (class AB Amp) mains regenerators (preferably run at 100Hz or a little higher as well but not too high as losses go up too much) and balanced power systems with voltage regulation (e.g. Servo Driven Variacs, we use these in our factory), filters are just too much like shooting craps in the dark...

Ciao T
 
OK, strong opinions on power line filtering. We all agree the lines are poor. I suspect we agree the $8 all in one filter, suppression, fuse and power cord socket is not up to the job.

So to educate properly those of us who do not do this for a living, could some concrete examples of issues and even solutions to quality sound with respect to mains filtering of both high power amps and line level loads be offered? Possibly a reference where it is discussed more fully? We can start with a .01 across the mains, and one across the secondary as close as possible. Now what?

A reference to commercial products for good and bad would be welcome. I would love to see the difference in the residual noise across the spectrum of my little test amp, which has nothing but a big inefficient e-core transformer and two wire cord.
 
Hi,

We can start with a .01 across the mains, and one across the secondary as close as possible. Now what?

Now we have lowered the resonance frequency of the various resonant circuits and possibly made them more efficient.

I would love to see the difference in the residual noise across the spectrum of my little test amp, which has nothing but a big inefficient e-core transformer and two wire cord.

You may have to also send through a signal and do a bit more extended analysis. Solid State amp's usually hide such issues behind ton's of feedback.

This does not mean the noise is just eliminated, it will still intermodulate with signals, distortion products etc. and hence may cause audible differences even if in the FFT of the output there appears no difference.

Ciao T
 
Hi,

Your are not leading me to a "best practices" goal :D

Best practice is just another way of saying: "what everyone does".

So usually "best practice" is all but.

To me best practice derives from understanding the problems. Once you understand the problem, solutions are easy to find.

Of course, I could just tell "do this and do that".

I used to be inclined to that, however in the current intellectual climate here at diya this would only lead to various technocrates jumping in, demanding proof and arguing that there is no performance different between "common practice" and my more expensive solutions (on which I incidentally do not make a penny) and to be honest, I can do without that.

You could try Tina-Ti (it is easy to use) and try setting up a circuit that is a good representation of a real transformer (e.g. based on measured data from the one in your amp) and a real mains supply, plus rectifiers and capacitors (take not of the obvious parasitics). Then try various things and look at what they do...

Ciao T
 
Common practice is well established as often not the best practice. I believe that is your meaning and quite correct. I was not intending to get too far diverted from basics of amps to delve into the other half of an amp system, the PS. There are two topics here. Line filtering and "problems" doing it incorrectly may cause, but no hint so as to what incorrect or correct may be, and that of the rectifier. Fast or slow, snubbers or not.

Several comments have been made referring to matching or same die diodes. I am not aware for the problems this could potentially cause. The faster large diodes tend not to be in potted bridges and if they are, I suspect they are just 4 $.65 diodes in a box for $14. Easy to use.

You make a valid point that the amp PSRR has as much to do with a spectrogram of the residual noise as anything. I offer an argument that it is the result that matters. Direct measurement of the rails, measurement at the exists of CCS's etc would also be valuable. Better is....better. I grant you not complete, but better. The 8 to 13 dB measured I consider better.

Feel free to PM my your thoughts about which you do not wish to take heat. This forum can be a warm kitchen. Usually that means people are passionate about the subject.
 
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