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Discussion Starter #1
Built a house in a new area and are having some problems with power. Both my Barco 1208/2 and my Mitsubishi CRT RPTV have electrical noise in the picture (NOT video noise) noticable from the seating positions. This electrical noise can be seen with very clean sources like computers and component splash screens. In the theater, the plug for the components and the plug in the ceiling for PJ are on the same circuit and are the only things on that circuit per my spec.


Had the electrician out to check the ground connections and he found no issues. He says he has been to most of the houses on my side of the street and the houses immediately behind us for power problems such as subwoofer hum (which I also have) and appliance brown outs, etc. He even talked to the electric company about it and they claim that it will be better when the whole neighborhood gets build out.


So, other that waiting, it seems like I have the option of power conditioning. I've always viewed power conditioners as snake oil, but have not really tried isolating transformers or power regeneration. Wanted to see if anyone has experience with this and if it helped. As I understand, I've got three options:


1) Power Conditioning - just regulates the voltage and supposedly cleans up the power, though no objective test I've seen measured any difference in the power. These range for $100 or so for commercial ones to over $1000 for HT ones with switched and unswitched outlets.


2) Isolating Transformers - will balance the power and regulate the voltage. These run about $700+.


3) Power Regeneration - converts AC to DC then back to AC for no hum, perfect sine wave, balanced and voltage regulated power. These run $1500+


Any experiences or knowlege anyone could share?


Thanks,

Dave
 

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I get a momentary brown out every time my AC cuts on. The only electrical devices in my house that DON'T suffer from this are my computers and PJ.


Try lifting the ground on your sub. That eliminates the hum in mine.
 

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Do you have any kind of connection from the cable company coming into your system? If you do, try an isolation transformer on the cable connection.
 

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You'd be surprised how cheap a 2000 watt isolation transformer can be had on the surplus market. Or a big UPS, for that matter. Only the batteries will usually need changing. I have both, and swear by the extra safety for my equipment. We have had a main transformer burn out on our block. Before it completely died, however, the voltage went up to nearly 200 volts. The entire house smelled of hot wires. Thanks to the isolation and UPS backup, NOTHING was damaged. Most of my neighbors lost tv's, microwaves, etc, etc.


So.... I paid on average $100 for a 2500 watt sine wave UPS. I have 6. I paid $40 for my 2000 watt isolation transformer that I use in my shop. It weighs a TON, though. All surplus.

Look around. Universities are often a good place for such things.


Marc
 

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I purchased a Richard Gray Substation. This is 75 pound block with four outlets. My thoughts were to give the stack and Faroudja the cleanest power I could as a means of improving stability of the set up. I will say that I can see absolutely no difference in pq running some very high quality HD at 1080p 60Hz with it in the chain or not. Just my take to date.


Art
 

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a richard gray substation is a most excellent solution.. alot of audiophiles use this to fight ground loop in their systems... my audio used balanced xlr's between my amp and preamp and its very sensitive to ground loop.. the best way to fight this is to keep everything on the same circuit and isolate sat, cable inputs.
 

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Discussion Starter #7
Quote:
Originally Posted by Art Sonneborn
I purchased a Richard Gray Substation. This is 75 pound block with four outlets. My thoughts were to give the stack and Faroudja the cleanest power I could as a means of improving stability of the set up. I will say that I can see absolutely no difference in pq running some very high quality HD at 1080p 60Hz with it in the chain or not. Just my take to date.


Art
This is why I wonder if any will do anything. All the "reasonable" guys seem to say that they do nothing. Its usually the audio guys that claim to hear a difference, but that is so subjective it is not measurable. Then again, there are those that claim they only help if you have a problem. I have a problem, you may not have. This is why this is a difficult issue. I would think that I need to handle the problem in the PJ if it were not for the same issue with my CRT RPTV--of course both could be having power supply issues I guess.

Quote:
Originally Posted by Wireless
Do you have any kind of connection from the cable company coming into your system? If you do, try an isolation transformer on the cable connection.
Nope. I'm one of the mass of people who hate the cable company. :)
 

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One test you may try, is in your car radio on am, see if there is any static comming in with a strong station. some times this can be inductive interferance.
 

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Quote:
Originally Posted by Tinman
So.... I paid on average $100 for a 2500 watt sine wave UPS. I have 6. I paid $40 for my 2000 watt isolation transformer that I use in my shop. It weighs a TON, though. All surplus.


Marc
A suggestion: Move to Kansas. All that extra weight will keep the house in place when the next tornado hits.


:)
 

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Quote:
Originally Posted by Curt Palme
A suggestion: Move to Kansas. All that extra weight will keep the house in place when the next tornado hits.


:)
Yeah Curt, you got that right. I think the House settled about an inch into the ground so far.


Honestly, I also can not see ANY difference in PQ with running filtered power. A well designed powersupply should isolate the video chain from the AC line in the first place. I suppose that some items could benefit from line conditioning, but I have not seen any compelling evidence of this. "I" use isolation and UPS backup only to protect my electronics from events that fall outside NORMAL parameters.

It's nice to sit through a movie only to find out later we had a 10 minute power outage, etc.


Marc
 

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Rather than blow money on an 'audiophile' power conditioner, get a 'pure sine wave' or 'online' UPS.


It will give you pure sine wave power on the outputs, and has the added advantage of protecting your gear from a sudden power outage which can damage a CRT. Some of them come with free insurance as well (probably worthless, but can't hurt.)


I put one in as our washing machine caused a hum in the audio and a moving line down the picture whnever it was running- best thing I ever did - no more problems and the power has gone of twice since I got the unit, and I was able to do a nice controlled close down of my equipment.


If you have clean power already, it won't do a thing or make a stick of difference, but if you have dirty power, you get the cleanup as well as protection from blackouts/brownouts., Money well spent in my book.
 

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Hi Marc,

Quote:
Originally Posted by Tinman
I have both, and swear by the extra safety for my equipment. We have had a main transformer burn out on our block. Before it completely died, however, the voltage went up to nearly 200 volts. The entire house smelled of hot wires. Thanks to the isolation and UPS backup, NOTHING was damaged. Most of my neighbors lost tv's, microwaves, etc, etc.

Marc
I may be a bit thick, but you'll need to explain that :D How will an isolation

xformer save your equipment during a power blast? An isolation xformer is

nothing but a 1:1 ratio winding setup (well maybe it has some fixed taps to

get an exacter voltage, but this doesn't change the basic problem). If I input

200V from a malfunction pole pig, I'll also get 200V out of the secondary of my

isolation xformer. The only thing an isolation xformer will do is to cut out AC

ground hum.


The real purpose of an isolation xformer is to isolate the voltage potential to

ground. I.e: if you touch one of the wires on your mains outlet, you have a 50%

chance of getting a shock (at least). If you touch N (basically ground), nothing

happens as no (or only low) current flows. If you touch L, you get shocked as

this is the "hot" side and current will flow from L through you (at whatever

effective resistance your body and the surrounding conditions present) to

ground.


Touch any of the two wires of a 1:1 isolation xformer and nothing happens,

since this voltage is no longer referenced to ground. Of course this only

holds true if the isolation breakdown voltage of the tranny is high enough :D


An online UPS MIGHT save your equipment, but ONLY if it cuts out during an

overvoltage condition. Not all UPS do that (some only look for too low voltage).

Depending on the rise time of the peak voltage, the UPS might not be fast

enough (e.g. lightning strike) to save the equipment.


Regards,

Reinhard
 

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Quote:
Originally Posted by Tinman
A well designed powersupply should isolate the video chain from the AC line in the first place.
And regulate the power, which was the point I was trying to make. Someone long ago posted that the power supplies in out PJs were well equipped to handle all kinds of power problems. His post went completely ignored--apparently by everyone but me. I'm no tech, but from my everyday experiences, what he said seems to be true.


AC hum is as old as AC. It's not a new phenomenon that requires an expensive power conditioner to eliminate it. Lifting grounds and/or running short ground wires (that's what those ground posts on the back of you A/V gear is for) will eliminate ground loops.
 

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Reinhard,


You are correct in your explanation. I do have a ferro-resonant isolation transformer that can tolerate a window of 80-150 volts, or so. But my UPS's DO indeed switch over on high voltage as well. So while not ideal, it's better than no protection at all.


Phil,


I also read those posts and remember them well. :D


Marc
 

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Don't mess around with the cheap stuff, IMHO. And don't waste money on supposedly high-end stuff with funny names. You can get a full-blown APC Matrix 5000 XR UPS on ePlay, which currently retails for $4800, for less than $1500 with new batteries, and down to $500 or so with used batteries. It locks the voltage down to a range, never too high and never too low, has enough iron in its transformer to iron out any impulse spikes you are likely to see, and has the best sine wave and cut-in times I have ever seen in a non-online unit. It is big enought to put every single piece of your electronics gear behind, and your power quaity problems are gone forever. It is simple insurance against getting your expensive gear zapped, and unlike the MOV varistor-protected power strips and cheapie UPS, which blow out like a fuse the first time they pass a joule or two spike, this unit keeps on ticking nearly forever without a complaint.


I have never installed a HT without one. Just my 2 cents.
 

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Quote:
Originally Posted by Phil Smith
I get a momentary brown out every time my AC cuts on. The only electrical devices in my house that DON'T suffer from this are my computers and PJ.


Try lifting the ground on your sub. That eliminates the hum in mine.
Phil, that IS a ground loop problem. You should check all your outlets to see if there is any voltage from neutral to gound (which is bad news).
 

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Hi Marc,

Quote:
Originally Posted by Tinman
Reinhard,

You are correct in your explanation. I do have a ferro-resonant isolation transformer that can tolerate a window of 80-150 volts, or so.

Marc
Okay, a CVT is something different :D :D of course. Now I see why you said

they are heavy. What does yours weigh? Somewhere around 75-80 lbs I

would guess.


Regards,

Reinhard
 

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Quote:
Originally Posted by techman707
Phil, that IS a ground loop problem. You should check all your outlets to see if there is any voltage from neutral to gound (which is bad news).
Bruce,


Other than my PJ and my computers, my ENTIRE house browns out. If I have a ground problem, it's a really bad one.


I'll check it when I get time. Which socket is neutral? The wide one or the narrow one?
 

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Quote:
Originally Posted by Tinman
Phil,


I also read those posts and remember them well. :D


Marc
Marc,


Do you remember that post? Was it you? :)
 

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Quote:
Originally Posted by Phil Smith
Marc,


Do you remember that post? Was it you? :)
No, not me.... but I did make some comments at some point.


Marc
 
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