Acoustic B20/Line-In

Discussion in 'Amps and Cabs [BG]' started by Nicole, Jun 26, 2008.

  1. Nicole


    Jun 23, 2008
    So, I just bought an Acoustic B20 (which I love, by the way). It has the line-in feature so I thought I'd give it a try. It's my first time using it so I asked the associate at the music store how to go about connecting the amp to whatever device. She gave me adapters (both 35mm).
    The thing is, when I plug it in there are a lot of pops and crackles which worries me a bit. I tried plugging it into both my imac and my mp3 player (both in the headphone jack). The .. smoothest (?) connection I had was when I left the adapter off of one end and plugged it into the 2nd bass input jack, but that doesn't seem like the right way to do it.
    Is it because I'm using headphones on my amp? I tried it once without and there was a loud ominous sound so I didn't even mess around with that.
    I guess I'm asking if there's a certain way to do this or are the crackles normal? For the record, the mp3 player and the amp are both on low volume.
  2. Stacknobuser


    Nov 11, 2007
    Hi Nicole,

    The situation you describe may have a few different causes.

    I am not sure what you mean by "trying the headphone jack". These actually need to be plugged into the "Aux In" jack even though both are 1/8" size jacks, which is the current standard. Assuming that you are doing this correctly, here are some suggestions.

    First, when you plug anything into the Aux In on the B20 it is going directly into the power amp, so you need to control the volume with your mp3 player or other device. Since this signal is going directly into the power amp, you want to make sure that the end plugged into the mp3 is plugged in first and that the volume is down, then increase to your need.

    Second, the crackling sound may be due to a bad cable, or the cable being non-sheilded. It would be possible to pick up noise this way. If it is an inexpensive cable, sometimes moving the cable around or shaking it will produce noise also. Or if you plug the cable into the amp first instead of the mp3 you might get some noise as you plug it in.

    On plugging into your computer the same thing with the level holds true, plus you could get a "ground loop" meaning that there could be a "hum" from the amp and the computer both being plugged in to AC power. The way to test for this is to unplug your computer (if it is a laptop and will operate on battery power) from the wall and see it the noise goes away.

    Lastly, when you plug the mp3 into the second bass input (nothing wrong with this, by the way), you will have the benefit of being able to add EQ to your programmed music. In addition, there may seem to be less noise since you have the volume control of the B20 now controlling your mp3 also instead or running directly into the power amp full blast.

    Hope this helps. :bassist: