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Run Into a problem with the Alesis I02

Discussion in 'Recording' started by kdc, Jun 11, 2011.

  1. kdc

    kdc Member

    Jun 11, 2011
    I just bought the Alesis I02 Recording interface and Sterling Audio ST51 Microphone. I am using a Dell PC running Windows XP. I use Mixcraft 3 to record (old, I know).

    When I hooked everything up the way the little instructions said, i started recording, and, at first, there was no noise. After downloading the ASIO4ALL v2 driver off of the Alesis website, I noticed that if i flipped the "+48 v" switch to 'on', I could barely hear my vocals, though they were very crackly. If anybody could help out, it would be greatly appreciated. Thanks!
  2. Boswell

    Boswell Distinguished Moderator Resource Member

    Apr 19, 2006
    Home Page:
    Surely you are not saying that you could hear your vocals clearly with the Phantom Power ("+48V") switched off?

    Try borrowing a dynamic mic such as a Shure SM57 or SM58 with its own XLR cable and try that with your interface. Professional dynamic mics do not require phantom power (PP) to operate, but they are happy to work with phantom power present provided the cabling and connectors are correctly wired and fault free. If the interface works with a dynamic mic, I think it is likely you have either a leaky coupling capacitor in the Sterling mic or the interface, or else there is a poor connection or cable. Is the problem the same on both channels of the IO2?

    To find out more, you need to do a bit of investigation with a multimeter. With no cable attached and the PP switched on, measure the voltage at pin2 of the XLR input connector relative to pin 1. You should see around +48V on pin 2, which should decay slowly to zero when you turn the PP off. If it does not, then check that after momentarily shorting the pins together the voltage does not leap back up to many volts. Repeat for pin 3 relative to pin 1. Now plug your XLR cable in and repeat the tests for both pins 2 and 3 on the free end of the cable. If all these tests are OK, and the interface works with a dynamic mic, the fault is likely to be in the Sterling ST51.

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