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Thread: Common Ground

  1. #1

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    Default Common Ground

    So I was brainstorming this a bit with another polk member at my house the other day. I have two power conditioners that have a ground lug on them. All of my audio/video components all have, or have been changed to 3 prong power cables. All my components are plugged into the conditioners, I had to buy two as I had more components than inputs. I also ran a copper braided cable between the two power conditioners. So with this I would suggest that all of my components have the same common ground. So I would think that even if I had a non-common ground amp....and I plugged it into the conditioner, wouldn't it now be common grounded? Certainly electrically they would all have the same point of reference...

    Chime in....would be curious to what you think..

    scott

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    The 'common ground' issue is relevant to the internal design of the amp, and how the rails for each channel are grounded INSIDE the unit.

    It has nothing to do with how / what it is plugged into.

    Cheers,
    Russ
    Check your lips at the door woman. Shake your hips like battleships. Yeah, all the white girls trip when I sing at Sunday service.

  3. #3

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    Originally posted by RuSsMaN
    grounded INSIDE the unit.
    Cheers,
    Russ
    Thanks for chiming in. I understand that, but I have opened up many amps in my day, (happens to be part of my day job), and they are grounded to the chasis. Which is how I wired all my 2 plug equipment. I purchased three prong cables and used the third lead to ground to the chasis. So all components are grounded via chasis to the house ground I put in. There shouldn't be a difference in potential from one ground to the other.

    So I would say when they are grounded inside the unit, they are actually grounded to the chasis in the unit.....I have never opened up a non-common grounded amp, so I don't really have experience in this realm. But if I had such an amp, I would think that even if it had two power supplies they would be common chasis grounded.....


    edit: What brand and model amp is non-common grounded? I would like to go to an A/V store and buy it and then return it just to see how such an amp is wired....

    scott

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    "But if I had such an amp, I would think that even if it had two power supplies they would be common chasis grounded....."

    No


    "edit: What brand and model amp is non-common grounded? I would like to go to an A/V store and buy it and then return it just to see how such an amp is wired...."

    This should save you the trouble, because after you open it, they will not take it back.
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    Default Get your terms straight!

    Don't use the word "GROUND". It is confusing you as it has little to do with the grounding of the amps input power circuitry.

    Start thinking "Common Negative Speaker Terminals" as that is the "ground" in question. You are looking for negative speaker output leads that have the circuit in common, they come from the same circuit board and thus aren't "single ended" as F1's dual mono amp pictured would be.

    BTW, what monster amp is that you pictured, Jesse? Nice stuff!
    HT
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    BAT VK-500
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    Looks like Sid got into it with his bedliner!:D
    HT
    Optoma HD25 LV on 80" DIY Screen
    Anthem MRX 300 Receiver
    Pioneer Elite DV45A
    Polk CS350LS
    Polk SDA1C
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    Speaker-Raymond Cable

    2 Channel
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  8. #8

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    Originally posted by F1nut
    BAT VK-500
    That looks like an amp BATMAN would have in his 2-channel rig:)

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    All right, so I am back on this thread, a bit bored and I know I was asking about the common ground thing, now I am an owner of (3) sets of SDA's, the SDA-1A, the SDA-2A's and most recently the SRS 1.2's, so I was browsing through the owners manual of the SDA-2 and came across this bit of info, for those that have the manual it is stated under the "Amplifiers and the SDA-2A" paragraph.

    Here is the text.

    "When using separate monophonic amplifiers, it is a good idea to connect a wire between the two chassis to ensure a common-ground"

    F1/Gardner or someone, please fill me in on this. I can read and read many posts on common ground, as it keeps coming up. Thing is, I don't want to attempt this with my 1.2's if it is going to fry my amps or possibly damage my 1.2's, I am currenlty running a Parasound HCA 1500A and these speakers are begging for MORE.

    Has anyone tried this, running a wire between the chasis of monoblocks?

    The reason I am asking about this is that there aren't any, (that I know of), two channel stereo amps that are in the 600w or greater power range. There probably are some exotic one off 600 pound gorillas amp manufacturers out there that have some, but surely way out of my price range, but there are some mono's in my price range that I would be willing to try and buy (if I knew it would work). A pair of Bryston's or Krell's monoblocks would be in order. Or another HCA-1500 and running them in MONO would be the most cost efficient way.

    scott

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    Scott,

    If you want to run mono blocks or dual mono's with the 1.2's you should really get (very hard to find) or build a AI-1. You can connect a heavy gauge wire between the two negative output posts on some mono blocks, but you should check with the maker first. I do know that the Bryston 7B ST's can be run with the negative posts tied together, not sure about Krell's.

    Remember that the 1.2's are rated at 6 ohms nominal, so a amp rated at 300 wpc at 8 ohms and 600 wpc at 4 ohms is about 450 wpc at 6 ohms, but more important than watts is current (amps) and the more the better.
    'Political Correctness'.........defined

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    That is the plan then, but I'll check the continuity between the two amps and ensure that the terminals are at a common reference point before hooking the speakers up. I got the instructions for the AI-1, and will have one just in case, but I have a feeling that it wouldn't be needed in this instance..

    scott

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    IMO, if you plan on making a AI-1 you should use it.
    'Political Correctness'.........defined

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