Ghetto rigging a ghetto PA system. Help me make it work.

Discussion in 'Beginners/FAQ' started by Mike, Feb 14, 2018.

  1. Mike

    Mike The Traveler Contributor

    Messages:
    2,512
    Likes Received:
    393
    Joined:
    May 18, 2013
    Location:
    OH
    Being the only person under 60 and capable of working electronic devices, I've been tasked with making some magic happen with a PA system at work for a presentation.

    Except it's not really a PA system...so here's where it gets tricky. My workplace uses this receiver:
    [​IMG]
    [​IMG]

    And runs this wireless mic into it for our current addressing needs:

    [​IMG]

    It somehow works because of a 1/4" to RCA adapter cable that runs from the wireless receiver for the mic to the audio in (red+white) on the back of the receiver.

    So you've already got a working mic, what's the problem you might ask? Well my workplace is having a presentation where we've invited a man with no arms to tell us about why it's a bad idea to cut off your arms and how you can't get work done if you do.

    He is bringing his own special setup that requires our system to have an XLR input. Not a problem with a normal PA system, but using a fuckin home stereo, it's an issue.

    I've already gone ahead an bought this cable to try to create an XLR input for the system to make it work:
    [​IMG]

    Using my SM58 and a mic cable I brought in, I went to test it, and it almost worked but with a big problem. Even maxed out in volume, any speaking into the mic is extremely quiet coming out of the speakers.

    My guess is the mic level signal is just not loud enough and not being amplified in anyway before it hits the receiver's audio input(s). Our current wireless setup is plenty loud so I'm thinking maybe the 1/4" out on it is outputting a line level signal possibly?

    Regardless though I need a way to get a working XLR input into this receiver that makes the output loud enough for the room to hear. Is there some kind of unit out there that has an xlr input that can then output in a manner similar to our wireless mic's receiver?

    Unfortunately I have little to no budget for this endeavor, so it probably needs to stay under $100.
     
  2. TedEH

    TedEH Cromulent

    Messages:
    4,192
    Likes Received:
    643
    Joined:
    Jun 8, 2007
    Location:
    Gatineau, Quebec
    IMO if this is a work thing, get a proper budget and rent something appropriate. $100 here could get me a small PA (some powered speakers, cables, and a mixer) and a mic or two for a full weekend.
     
  3. Mike

    Mike The Traveler Contributor

    Messages:
    2,512
    Likes Received:
    393
    Joined:
    May 18, 2013
    Location:
    OH
    Trust me I've pitched this idea. It'll probably be a last resort effort. The powers that be have some severe autism so once they get an idea in their head they have to make it work and can't see any other solution. So for the time being, I'm still being tasked with fitting the square peg into the circle hole.
     
  4. Ernesto

    Ernesto SS.org Regular

    Messages:
    211
    Likes Received:
    47
    Joined:
    Jun 18, 2008
    Location:
    Verde Valley, AZ
    If his system has a power source of some kind and has a volume control on it, that likely means that it has a preamp. Your mic was quiet because it needs a preamp to bring the output level up. If you can find out what he's using, we can figure out if you'll need a separate preamp or not.
     
    Mike likes this.
  5. Mike

    Mike The Traveler Contributor

    Messages:
    2,512
    Likes Received:
    393
    Joined:
    May 18, 2013
    Location:
    OH
    I contacted the guy's manager to see if he can give me the exact name/model of whatever headset/receiver the speaker will be using. That's what I'm hoping is that the guys system already has some kind of preamp of it's own.
     
  6. bostjan

    bostjan MicroMetal Contributor

    Messages:
    13,778
    Likes Received:
    1,829
    Joined:
    Dec 7, 2005
    Location:
    St. Johnsbury, VT USA
    The impedence of the microphone is wayyy off from what the input is expecting to see. You might get somewhere with an impedence matching transformer.

    If you have an LM386 audio amplifier, you could breadboard a preamp together to make this work, but the transformer might get you by without it.
     
  7. Mike

    Mike The Traveler Contributor

    Messages:
    2,512
    Likes Received:
    393
    Joined:
    May 18, 2013
    Location:
    OH
    Any specific suggestions for an impendence matching tranformer? I'm not really even sure what to look for in that department.
     
  8. bostjan

    bostjan MicroMetal Contributor

    Messages:
    13,778
    Likes Received:
    1,829
    Joined:
    Dec 7, 2005
    Location:
    St. Johnsbury, VT USA
  9. Malevolent_Croatian

    Malevolent_Croatian SS.org Regular

    Messages:
    813
    Likes Received:
    196
    Joined:
    Apr 30, 2012
    Location:
    Toronto
    Uhm....whut? o_O
     
    cmtd likes this.
  10. Mike

    Mike The Traveler Contributor

    Messages:
    2,512
    Likes Received:
    393
    Joined:
    May 18, 2013
    Location:
    OH
    Sorry, I'm a bit of a cynical dick. Basically it's one of those workplace safety talks where they're using the token example of what not to do to drive the point across that this is what happens if you don't take safety seriously.
     
  11. Malevolent_Croatian

    Malevolent_Croatian SS.org Regular

    Messages:
    813
    Likes Received:
    196
    Joined:
    Apr 30, 2012
    Location:
    Toronto
    Ah, I thought it was gonna be some kinda fetishist dude with regretful tastes and life choices.
     

Share This Page