Is Your System's Noise Floor Low Enough? - Page 4 - Home Theater Forum and Systems - HomeTheaterShack.com

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post #31 of 60 Old 12-17-15, 10:02 AM
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Re: Is Your System's Noise Floor Low Enough?

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I completely agree. And the grounding system you describe sounds exemplary, and it is always better to keep noise low through using such practices, but I am also confident that very few listening or home theater rooms have a grounding system like the one you describe. Just like most rooms do not have ideal acoustical symmetry or ideal acoustical treatment. In the case of grounding, it promotes a quiet system while being safer than lifting grounds, another good reason to do it that way, but even so there are probably only a few who would go to the trouble.

It is a reality in our hobby that few users have the luxury of having ideal anything in their systems. Most start from a best they can do on a budget perspective and have to do some bandaid work from there. But your description of an ideal grounding system is much appreciated and is useful for all to keep in mind as the ideal and as a goal when the opportunity arises.



I would not say that UPS equipment only promotes, implying that there is only downside and no upside. UPS in my case is for my Windows desktop machines - I have two - and helps prevent operating and file system corruption in the event of power outage. A well-designed UPS can be fairly quiet in terms of HF noise generation. Mine is used only for those two computers, the rest of my audio equipment runs on the same outlets/circuit but not off of the UPS.

I readily agree that typical UPS equipment can be a source of noise, and might not even keep a computer from shutting down the way it is supposed to. Mine is designed to provide a pure, low-distortion sine wave output when the input power disappears, and I have tested it to be effective in running my systems safely.

Another point not yet mentioned, that I learned the hard way (a long, painful story) is that all of the equipment in an audio and/or computer system should run off of the same power phase. Most homes are supplied from a 240 V two-phase transformer. So there are two phases available in a house at its outlets. Without a voltmeter, one cannot tell if two sets of outlets, even in the same room, are on the same phase or on the opposing phases. I always check with a voltmeter. Measuring from hot to hot will show the 240 V value if the sets of outlets are on opposing phases. This can cause noise and even equipment damage where sensitive inputs in equipment on one phase are driven from outputs on the opposing phase. Some will argue that it should not be a problem, I can testify from first hand experience that it can be a cause of equipment damage.

Talley, I appreciate your post and your comments and perspectives, and I am not arguing with anything you have said, simply clarifying
Thank you and note that your comments are 100% accurate. I should retract my statement and say "Typical" UPS equipment so there are good equipment out there just research before you buy and I do agree that for a computer it's important. I have a APC UPS on my computer only to keep power flickers from turning the computer off.

I recently found out about the phasing myself.... not thinking about it previously. Good thing for me all I need to do is move a few breakers around to complete this.

Good point and forgot about that, literally read up on it a few days ago late one night. Haven't tried it yet but will do that TONIGHT. I'll report back if that very faint hiss that is on my system within 1/2" is completely removed. Not sure what will happen when I move everything to the same phase yet or not to my system.

EDIT: I actually commented on this on post #25 on this thread last night http://www.hometheatershack.com/foru...ml#post1350393

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post #32 of 60 Old 12-17-15, 10:22 AM Thread Starter
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Re: Is Your System's Noise Floor Low Enough?

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EDIT: I actually commented on this on post #25 on this thread last night http://www.hometheatershack.com/foru...ml#post1350393
So you did, and I missed that. Very few seem to know about that, or at least say so. Thanks again for your insights.
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post #33 of 60 Old 12-17-15, 07:43 PM
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Re: Is Your System's Noise Floor Low Enough?

Thanks for the tips guys. Just for clarity, my APC is not a ups(computer has one though). I will look up specs for its filtering capabilities. There is plenty of food for thought here, and I will start with something not yet mentioned. I am going to unbraid the snake pit behind my rack and organize, and check all my connections. This is free! I did look up the furman and the extra hundred bucks will definitely go to my kids Christmas fund first.
Side note, my AC isn't as dedicated as Talleys, but I did pull 4 home runs to where my rack is and separately grounded each one to earth. Talleys point of sharing bus bars makes sense but I don't know when I'll open the service panel up(in a hole). This system was silent as a stone before adding the Yamaha amp so I hope to find something when I start sorting cable. Thanks again. Best forum ever!


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post #34 of 60 Old 12-17-15, 08:14 PM
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Re: Is Your System's Noise Floor Low Enough?

I'm still learning and trying to grasp all the interconnect/shielding/grounding stuff now. I have to lean on alot of pro audio experts advice and use my personal electrical background and try to make sense of it all.

One thing is for sure.... without a doubt a ground issue can be the biggest pain to correct.

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post #35 of 60 Old 12-17-15, 08:29 PM
 
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Re: Is Your System's Noise Floor Low Enough?

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Thanks for the tips guys. Just for clarity, my APC is not a ups(computer has one though). I will look up specs for its filtering capabilities. There is plenty of food for thought here, and I will start with something not yet mentioned. I am going to unbraid the snake pit behind my rack and organize, and check all my connections. This is free! I did look up the furman and the extra hundred bucks will definitely go to my kids Christmas fund first.
Side note, my AC isn't as dedicated as Talleys, but I did pull 4 home runs to where my rack is and separately grounded each one to earth. Talleys point of sharing bus bars makes sense but I don't know when I'll open the service panel up(in a hole). This system was silent as a stone before adding the Yamaha amp so I hope to find something when I start sorting cable. Thanks again. Best forum ever!


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I have cleaned up rats nest of wiring in the past, and eliminated ground loops. That might be all you need.

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post #36 of 60 Old 12-17-15, 08:56 PM
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Re: Is Your System's Noise Floor Low Enough?

Fingers crossed! Wires uncrossed!


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post #37 of 60 Old 12-17-15, 09:18 PM
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Re: Is Your System's Noise Floor Low Enough?

I moved all my circuits to the same phase and it introduced a very slight buzz... mainly from midrange/tweeter but it's very very faint. I literally press my ear to the tweeter to hear it. it's definately a buzz where as before was a faint hiss and not detectable in the midrange.

i mean I have volume set to max... and my ear to the tweeter pressed against it. with a disc in the player on pause.

shoot me if it ever decided to play at that moment eeek.

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post #38 of 60 Old 12-17-15, 09:20 PM
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Re: Is Your System's Noise Floor Low Enough?

As everyone has mentioned, noise comes from many sources and for many reasons. If you can turn the amp up and down without an increase in noise volume then the point of the noise is before the amp. If you are using a computer or music server the noise could come from there and would most probably be a light buzz in the system. Sometimes cables make a difference, and by that I mean interconnects. I have been listening to some different interconnects recently and every now and then I would get a weird buzz. I took cables out of the system and replaced them with tried and true cables until I found the bad ones.

If anyone wants to try an experiment this one is cool. Much of the equipment we use does not have a ground plug but merely a double bump on one of the prongs of our power cable. A manufacturer once told me at an audio show in Chicago that when these electronics are manufactured, there is only a 50/50 chance that the line assemblers will get the negative portion of the power cord soldered to the right pin in the electronics. He went on to tell me how to check. You put a cheater plug ( And yes this works with 3 pronged plugs as well ) on the original make end of the chord and plug it into the wall. Then take your multi meter and set it low and take one end of the meter cable and touch the ground of the wall socket and the other end of the meter cable touch a metal component of your equipment. Write down the value. Now turn off the equipment and change the orientation of your cheater plug in the wall outlet and do the same thing with your multi meter and write down the values. Which ever of the 2 values that is lowest would indicate which way the negative side of the power cord should reside in the wall outlet.

By the way, It works.

Good Listening

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post #39 of 60 Old 12-18-15, 08:31 AM Thread Starter
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Re: Is Your System's Noise Floor Low Enough?

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ellisr63 wrote: View Post
I have cleaned up rats nest of wiring in the past, and eliminated ground loops. That might be all you need.
Agree, that is the best place to start.
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post #40 of 60 Old 12-18-15, 08:34 AM Thread Starter
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Re: Is Your System's Noise Floor Low Enough?

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Savjac wrote: View Post
If anyone wants to try an experiment this one is cool. Much of the equipment we use does not have a ground plug but merely a double bump on one of the prongs of our power cable. A manufacturer once told me at an audio show in Chicago that when these electronics are manufactured, there is only a 50/50 chance that the line assemblers will get the negative portion of the power cord soldered to the right pin in the electronics. He went on to tell me how to check. You put a cheater plug ( And yes this works with 3 pronged plugs as well ) on the original make end of the chord and plug it into the wall. Then take your multi meter and set it low and take one end of the meter cable and touch the ground of the wall socket and the other end of the meter cable touch a metal component of your equipment. Write down the value. Now turn off the equipment and change the orientation of your cheater plug in the wall outlet and do the same thing with your multi meter and write down the values. Which ever of the 2 values that is lowest would indicate which way the negative side of the power cord should reside in the wall outlet.

By the way, It works.
Good suggestion.
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