Mackie 8 Bus noise - help

Discussion in 'Mixing' started by jimkarl, Oct 1, 2015.

Tags:
  1. jimkarl

    jimkarl Active Member

    Joined:
    Oct 1, 2015
    Location:
    Baltimore MD
    Have an older mackie analog 8 Bus 8x2x2 board that has random computer noise occurring. Little 1/2 to 3 seconds of random frequencies, very low volume, but showing up on 1-2 LED segments across all 8 channel meters and the L/R as well. Definitely something internal to the board or external power supply. Not coming from any specific channel or inputs (have muted/disconnected everything. Any known problems like this? Sent a support email to Mackie through their website but says right up front they don't support this model anymore (wasn't even a choice for the support request) so I don't expect to get an answer - other than take it to a service center. I have the tools and am qualified to do repairs, even at the component level, but need some guidance as to the cause - if already known. Or if not, a contact that could help. Thanks!
     
  2. bouldersound

    bouldersound Real guitars are for old people. Well-Known Member

    Joined:
    Jan 23, 2010
    Location:
    Boulder, Colorado
    You're not setting your phone on the console, are you?
     
  3. jimkarl

    jimkarl Active Member

    Joined:
    Oct 1, 2015
    Location:
    Baltimore MD
    LOL no.
     
  4. Boswell

    Boswell Moderator Distinguished Member

    Joined:
    Apr 19, 2006
    Location:
    UK
    Home Page:
    The last time I had one of those Mackies in for repair I had to replace many of the bulk smoothing capacitors on the internal power rails (not the external PSU). The problem was showing up as strange noises on all outputs - not quite as you describe it, but sufficiently similar to make it worth investigating that area.

    I would open up the mixer and go round the power rails with a scope (a.c. coupled). It should soon be apparent from the waveforms if any of the caps have gone. If you don't have a scope, you can get some idea by using a DI box as an audio probe feeding into a separate interface or mixer. Put a 100nF capacitor of at least 63V rating in the line from your probe and a pair of reverse-connected silicon signal diodes to ground as limiters at the DI input. Connect the DI box input ground to the mixer ground.
     
  5. simman

    simman Active Member

    Joined:
    Feb 20, 2012
    Location:
    New Jersey
    Does the board produce this noise with nothing connected to the inputs? I've not owned this mixer but I seem to recall that noise on the 8 group buses was a major knock on the board.

    The other thing which can cause this problem and is a pain to find, is/are a ground loop.
     
Similar Threads
  1. jeronimo
    Replies:
    0
    Views:
    499
  2. heybluez
    Replies:
    1
    Views:
    654
  3. supercharry
    Replies:
    4
    Views:
    2,117
  4. JamesG
    Replies:
    9
    Views:
    1,697
  5. JEYMACHINE
    Replies:
    9
    Views:
    2,614
Loading...

Share This Page