There seems to be a delay in the sound coming out of the computer.
Currently most, if not all, USB Audio devices seem to suffer a small amount of "latency," a delay from the time audio is input until the time audio is output from the computer. This delay is measured in milliseconds, and varies slightly depending on the configuration of your Mac. Generally, disabling Virtual Memory and File Sharing will shorten the delay significantly. But even with reduced latency, you may not be able to do real-time monitoring and recording. If you don't require real-time monitoring (recording from VCR, turntable, etc.), latency is of no concern.
Using iMic to record with minimum latency is possible through the use of an external mixer. The mixer doesn't have to be fancy, but it will need at least three, preferably four, outputs. Brand name mixers such as Midiman or Samson can be purchased for less than $125.
Here's how to handle latency:
- Plug the "Main Outs" of the mixer into your receiver or powered speakers.
- Plug your instrument (keyboard, guitar, microphone, etc.) into the mixer (i.e., "Input 1" or, if stereo, "Inputs 1 & 2") and route the signal to the main output of the mixer. You should be able to play and hear your instrument as you do when you're playing live.
- Plug iMic's "Audio Out" into the mixer. You might have to use an adapter on the cable to make this work. It's recommended that you buy a dedicated cable with the right connections, as adapters are prone to all sorts of problems.
- Assign the input(s) that your instrument is on to a "submaster(s)" (i.e., submaster 1 or 1&2). If your mixer doesn't have a submaster, you could use an "auxiliary send" such as the one you would use to send a signal to a reverb or delay unit. Any way that you can get out of your mixer WITHOUT using the "main outs" will work. Whatever output you choose, connect it using the appropriate cable to iMic's input.
- In the Sound control panel, set the input to "iMic USB Audio". Make sure you turn off the Sound Playthrough or Passthrough in your audio recording software. That way you won't hear your input as it comes out of the computer. You don't want to hear the sound from that source because it will be delayed and you'll be out of sync with your pre-recorded material. Instead, because you have assigned your instrument to play directly out of the mixer, you are playing in real time with the pre-recorded material. All tracks will be in sync on playback.