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Question for Vince or other PC recording gurus

Discussion in 'Computers' started by Mike LS, Feb 2, 2004.

  1. Mike LS

    Mike LS Well-Known Member

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    I built a PC to integrate into my church sound system a while back, and am now getting around to trying to patch in and use for recording services.

    Problem is that any way that I try to get an input into it, I get a horrible ground problem (I'm guessing that what it is...speakers buzz and all connected video devices have interferance)

    Granted, I'm just working with the integrated sound card and I know I'll need a more professional card to do things right, but I would like to connect things as is just to try to figure things out.

    I've tried coming directly off my mixer with a 1/4 out. Buzz. I've put a direct box in the same line and lifted the ground. Buzz. I've even run RCA outs from a connected tape deck (that has no buzz) and run that to the PC. Buzz. Any way I connect it I get the same result.

    Is there anything else I can try before I put the $$ down on a different sound card?

    Also, should I get an internal PCI card, or would a USB card make more sense? I don't need anything fancy, but any suggestions on that would be great too.
     
  2. Sam Greco

    Sam Greco New Member

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    The problem is definitely in the PC itself. My guess is a cheap sound card, but it could be as simple as moving the sound card to a different slot.
     
  3. Mike LS

    Mike LS Well-Known Member

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    I simply need an input. I have no problem getting clean output into the system.

    My best option is to go from an auxillary send via 1/4 and have a sound card that has a 1/4 input, or convert to RCA and input that way.
     
  4. Mike LS

    Mike LS Well-Known Member

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    I'm not just after the signal from a single mic. I need to get an entire system feed. That's why I'm going to use an auxillary or bus output.

    I'm also not using the mic input on the soundcard. I've always had better results using the aux input on the PC. Granted, I have no luck with either in this case.

    The mono-stereo idea sounds good, but I don't think that's the issue either. I've got a cassette deck connected to the mixer for recording now, so I hooked up a set of RCA cables to the outputs of that recording deck and tried to pass a signal with the deck recording as well (it only passes the signal to the outputs when the deck is in record mode). I used an RCA Y cable to merge the two feeds together into a 1/8" plug and still got the buzz.

    It's got to be a grounding problems since I get the buzz whether there's actually a source signal coming through the line or not. It starts buzzing as soon as the plug touches the jack.
     
  5. John_Berger

    John_Berger Well-Known Member

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    Yeah, that pretty much clinches it as improper grounding.
     
  6. Mike LS

    Mike LS Well-Known Member

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    So in that case, is there anything that can be done? Where is the bad ground? Is it the computer or other part of the system? Would some sort of external sound card...like a USB card give any different results, or is there any way to tell without some trial and error? Not that I mind that, I just don't have a bunch of cash to throw at this right now.
     
  7. John_Berger

    John_Berger Well-Known Member

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    No. This is purely a case of electromagnetic principles. You are using electrical equipment that is likely not grounded yet a ground needs to be available. I have run into this numerous times before. For example, I can have a device plugged into an outlet with no grounding abilities and I'll get the grounding buzz; yet if I switch to batteries, there is no buzz because I am not plugged into any electrical system and therefore am not getting grounding problems.

    An external sound card will make no difference in this scenario. The problem is improper or non-existant grounding between your source and your PC.

    My best suggestion right now (and also an inexpensive one) is do try what I said earlier. Get an all-metal coupler and another cable of the same type as though you intend to get a few extra feet out of it. MAKE SURE it's an all-metal coupler, not a plastic-covered coupler. Expose a few inches of speaker wire and tie or wrap it around the exterior of the metal coupler. Then, connect the other end of the wire to a direct, grounded source, preferably the screw of a fully-grounded outlet. If you try to take an easy way out and connect it to the grounding of an electrical device, like a computer case, you will likely not have any effect.

    This very inexpensive method has worked beautifully for me for over 10 years of videography where my external microphones are directly connected to my camcorder.

    I have to stress again that really severe grounding issues can only be reduced by this method. They cannot be eliminated. However, you can hopefully get it down to a level where the audio can be run through a graphic equalizer to reduce the frequency range of the grounding buzz.

    I must also stress again that you confirm that you are not experiencing a scenario where a ground is accidentally coming over what should be an audio channel. I've run into this as well, almost always when electrical tape was not used to cover the connectors and a wire decides to move around. The only solution in this case is to fix the wiring problem, making sure that the ground never comes in contact with one of the audio channels. Makes sure also that your wires are not crossed where the channel that you think is the audio is actually the ground. I've done that before, too. Nasty. To be honest, based on what you said in your first post I would not be surprised if this is the issue.

    This scenario is where you will benefit from making your own cables without soldering or crimping. Unscrew the plug and confirm that everything is connected properly. Crimping and soldering could be a nightmare, especially if you're on-site and don't have access to the necessary tools to fix a problem.

    The short of it is that there is no silver bullet here because the culprit could be a couple of different things. Fortunately, none of them should be too expensive to fix - IF they can be fixed.
     
  8. John_Berger

    John_Berger Well-Known Member

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    Also, if the problem is indeed a mono-to-stereo issue like I describe in my second post, Radio Shack does sell mono-to-stereo adapters to prevent the grounding from directly connecting to the "middle" audio section of the plug.
     
  9. Mike LS

    Mike LS Well-Known Member

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    I'll have to hunt around for a metal coupler and try that method.
    I'd be willing to bet that's the problem. I've had grounding problems in the system at other times, and I believe the buildings electrical wiring is the mostly likely culprit. The place is rather old and the electrical system has been added to and expanded over the years....who knows if the people doing the work knew what they were doing.
    Of course, that goes for the audio system too. Nothing is really done right because at the time, it would be too expensive. It gets left for some poor schmuck (me) to deal with down the road somewhere.

    I think it would be more obvious if the problem were an individual channel grounding problem since I'd have the buzz whenever that channel were open. I've got 22 channels running most every time I use the board, and there's only been 2 times I can remember when I got a buzz because of a specific channel (wound up being a bad cable in both instances). I've not had that problem for a good while. But if this keeps up, I'll unplug every wire from the board and rewire it until the buzz comes back and I can localize the problem.
     
  10. John_Berger

    John_Berger Well-Known Member

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    I'm not sure how you define "rather old", but you might be out of luck. Many "old" buildings (even as young as 30 years old) did not incorporate three-wire electrical connections. The hot and neutral are present for you to get the electricty, but the ground wire is not present. So, it is very possible to have a three-prong outlet, yet the ground prong and thus the screw are actually not grounded at all.
     
  11. Mike LS

    Mike LS Well-Known Member

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    That's possible. I'll have to check into that. I believe the building was built in the 70's.
     
  12. Sam Greco

    Sam Greco New Member

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    I was gone for 2 days and I come back to this. If I'm wrong, I'm sorry. But now I remember why I don't visit this forum often.

    Thanks for the kind welcome...

    I'll not be back.
     
  13. John_Berger

    John_Berger Well-Known Member

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    Why bother? The problem is definitely in the PC itself! ([​IMG] Sorry. I had to.)

    If you have an electrician's store in your area, there should be devices out there to determine if an outlet is grounded or not. I doubt these will be cheap, but I would hope that your church would pay for it. Otherwise, just hook up your equipment and try it out.

    IANAE (I am not an electrician [​IMG]), but I believe that they used grounding back in the 1970s. That doesn't mean that your particular electircal system has it since it all depends on the construction, but it's certainly more hopeful than a building that was built - say - 50 years ago.
     

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