Why I Rail Against Power Conditioners - Page 4 - AVS Forum
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post #91 of 100 Old 01-06-2007, 07:45 PM
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Originally Posted by MauneyM View Post

Ummm......this is just not true. Ask any lawyer, judge, cop, or psychologist. It has been proven time and time again that human eyewitnesses are among the LEAST reliable sources of information available. Why? Because people have an innate tendency to color the information they perceive based on perception.

One objective, repeatable test is worth a thousand expert opinions.

Human eyewitnesses are exposed to the sound only once. With the audio system you listen every day for years...

Truth always wins in the end.

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post #92 of 100 Old 01-06-2007, 09:07 PM
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While I don't spend a lot (OK, ANY!) time listening to esoteric stereos, the most realistic grand piano I ever heard through a sound system was an LP run through a tube preamp/amp, through some custom built home speakers with some massively complex crossover to take care of phasing problems.

(sorry, this was over 20 years ago, and I did a service call on a console TV at the guy's place. All I know is that they were vintage JBL 15s and a JBL driver on a wooden custom built horn.)

Why post this? 'Cause I've had two coolers on an empty stomach, and I still think me posting semi intoxicated makes more sense than Valhalla fully sober.

And yes, I'm a puss when it comes to drinking...

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post #93 of 100 Old 01-07-2007, 05:48 AM
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Originally Posted by AV Doogie View Post

It is clear that you are not trying to help here. I am trying to explain the basic principles behind a switching supply and point out how it can be possibly affected. Your modern incarnation simply adds additional information to an already confusing situation. And 'virutually' all SMPS supplies does not mean 'All of them'. I find it interesting that you know what type of switching power supply each manufacturer is using in each piece of equipment. If you want to help someone understand the situation...great. Otherwise, bugger off.

When looking for line noise and analyzing power quality, what kind of equipment do you use?

You are simply wrong about how modern SMPS operate. I work on many different brands and types of displays and none operate the way that you described. Early switching designs might have, but I can't recall any consumer goods that would likely be used today that do. Check up on a few. You will find that all of them rectify before conversion.

When I have tried to identify noise passing from the a.c. line to the secondary of power supplies, I have used my 200mHz scope, observed the noise on the primary side, then searched the secondary side for that noise or harmonics of it. I have seen noise filtered by line conditioners, infact I use an old Adcom filter on my bench. It is not very sophisticated compared to regeneration technology, but it cleans up some noise generated by other equipment. Regardless, I have never seen the effect of that noise when not using it. It simply does not get past the power supplies in the displays. So regardless of how effective the filtering might be, if it never gets past the convertor, why will it make a difference?

You incorrect characterization of how SMPS operate is what causes confusion and is not helpful. There is one case that I can think of that might be affected by noise at the transition point, however, and this may be what you are thinking of or what has confused your understanding. Some units use a zero crossing detector to minimize the effects of inrush surges at startup, and IIRC some use it for power factor correction, but I have never heard of a case where an a.c. line caused problems with these. Poorly generated a.c. from a cheap UPS might, but we never use these, anyway.

I do wonder about the possibility of common mode noise and ground problems affecting display operation, but I have not experienced it directly. I suspect there may be some merit to balanced systems in this regard but they have their own potential ground implications.

Yes, calibration is important...every user should be calibrated.

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post #94 of 100 Old 01-07-2007, 05:52 AM
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Originally Posted by Curt Palme View Post

Why post this? 'Cause I've had two coolers on an empty stomach, and I still think me posting semi intoxicated makes more sense than Valhalla fully sober.
And yes, I'm a puss when it comes to drinking...

It is nearly as entertaining, but I doubt that you could keep it up to compete with the volume of his posting.

Yes, calibration is important...every user should be calibrated.

Need electronics repair? A great place to start looking for a shop in your area: http://www.tvrepairpros.com/
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post #95 of 100 Old 01-07-2007, 05:57 AM
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Quote:
Originally Posted by AV Doogie View Post

A tip we give customers:
Check the voltage level from the return (neutral) to the ground at the outlet location to see what kind of variance you get. We typically find that if this volage level is in excess of 0.5vrms you may have a bonding or ground loop issue. Most power conditioners will not deal with this issue.
Good luck

This is very good advice and one should also check the grounding on cable, sat, and antenna installations. Faulty or missing grounds on these are the source of many problems in the real world.

Yes, calibration is important...every user should be calibrated.

Need electronics repair? A great place to start looking for a shop in your area: http://www.tvrepairpros.com/
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post #96 of 100 Old 01-07-2007, 05:58 AM
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Originally Posted by lcaillo View Post

It is nearly as entertaining, but I doubt that you could keep it up to compete with the volume of his posting.


Actually I read what I typed last night, and no, I'm still a boring geek even when drunk.

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post #97 of 100 Old 01-07-2007, 06:06 AM
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Originally Posted by FrantzM View Post

HI
I also beg to differ... WIthout going through the whole theory of it, I have personally observed the effect of bad power quality in my own Telecom/ISP business. I had a basic in line UPS of relative quality, line voltage was stable but waveform was horrendous.... Server and other PC would often freeze, moreover some PCs would not even turn on when the power was badly distorted , we invested in Dual conwersion Telecom UPS, Lorain to be precise big ugly Ferroresonant but stable and work forever ( I have the same type feeding my Audio and HT. They are in a soundproof concrete room outside the house)...
Power quality is a serious issue and its lack affect both performance and reliability of equipments. I have heard the differences on my Audio system, I have not bothered to verify this on video but I would assume that this could be the case as well. The effect on power quality on the sound are not necessarily subtle, they can be quite obvious... Modified sine-wave Inverters to take an extreme example induces audible buzz in the speakers Signal to noise ratio is severely affected.. not your audiophile "gritty" sound, often loud buzzing..
In my country the most popular form of power back-up is the DC/AC inverter (often with an automatic battery charger built-in, the contraption is called Inverter). The most common inverter is the one that provided "modified" sine wave a kind of staircase waveform trying to approximate a sine... SOme inexpensive UPS do not recognize these as an AC and would not charge their batteries when connected, some computers do not even turn on and all electrical motor buzz and have their lifespan severely curtailed. Switching to a true sine wave inverter eliminate most if not all of these problems.

Franz, I am not saying that there are no benefits to cleaning up power. What I am saying is that I cannot understand how low level line noise is going to get past a SMPS. There are certainly spikes and transients that can affect systems, and as I said elsewhere, grounds may not be adequate and there may be problems associated with common mode noise. My issue is with those that claim better video from adding a line conditioner. I want to see some actual evidence or even a good argument for how this sustained and pervasive improvement can occur.

If you want to differ, read the entire post for context. I can't see much in your post that I differ with, other than I would be skeptical of grounding and or other installation issues in a system with sustained problems.

Yes, calibration is important...every user should be calibrated.

Need electronics repair? A great place to start looking for a shop in your area: http://www.tvrepairpros.com/
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post #98 of 100 Old 01-11-2007, 07:15 AM
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Quote:
Originally Posted by Art Sonneborn View Post

Yes ,but without science where does that deep end start Steve ?


Good answer. Without finding the difference in double blind test and science, we can agree it's Placebo.

Funny, I wonder if the same people that believe in this "things" and say science cannot tell us everything, say the same if they get cancer and need a cure. Do they go with the doctor that have scientific metods or do they go to the village voodoo priest?

Sound and video is not magic, it is pure physics. Physics that can be magical
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post #99 of 100 Old 09-03-2007, 06:39 AM
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I'm not going to boast about whether or not the picture/sound quality differs with a power conditioner. What I can tell you is that in my house when the Central air kicks in and the lights all dim and the microwave fan struggles to whirr for a second, it scares the **** out of me.

At least I am doing SOMETHING to protect my stuff.
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post #100 of 100 Old 09-03-2007, 01:07 PM
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OK, Here we have a case where a power design issue in the house is overcome with a power widget box. A voltage regulator would likely be fine, but that is another discussion altogether.

In reality, a better solution for you is to go back to the panel and look at how it is all laid out. perhaps add an additional service to lighten the overall load. perhaps look at the grounding scheme.

but if the box fixes the brown out, then that is fine.

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