input is passed directly to the application without modification. To reduce the level of the digital audio signal at inputs A and B, you will need to reduce the output level of your digital source.
Note about levels and gain structure here. The TRIM controls directly affect the input level at the A/D converters on the US-224, so it’s advisable to use the SIGNAL and OVER LEDs to help set your levels. Unlike analog tape, when recording digital audio, it’s important to keep your input level close to 0dB, but never to exceed it. If the input level is too high, the audio signal will clip - not a desirable sound. If the input level is too low, then the dynamic range that the US- 224’s A/D’s are capable of is not being used, and the signal will be closer to the noise floor than it needs to be. In either case, this can not be fixed after the tracks have been recorded, so it’s important to make this adjustment carefully.
Illustration 4.02 - Input trims and level indicator LED’s
4.2 Hooking up MIDI
The MIDI in and out jacks give you 16 channels of MIDI I/O. Simply connect the MIDI out of your keyboard or other device to a MIDI in jack on the US-224, and vice versa. If you’ve got a MIDI sync box, you
can use the MIDI I/O’s to send and receive MTC (MIDI Time Code). This allows you to sync tracks from your MTC-capable Portastudio, DTRS multitrack, or any other machine that accepts time code with your digital audio software, for transferring tracks back and forth for editing and processing.
4.3 Using the Input Monitoring
In digital audio, the amount of time it takes for the input signal to pass through the circuitry of the unit and the software processing and arrive at the outputs will sometimes result in an audible delay. (This is commonly referred to as “audio latency”.) This added delay can be confusing when, for example, you’re trying to overdub to previously recorded tracks.
The INPUT MONITOR mixer built into the US-224 eliminates this problem by providing a way to listen to the signals you’re recording directly, without any computer processing delay. When the INPUT MONITOR button is depressed, the first two channel faders control the input levels of inputs A and B to the US-224’s internal mixer. Changes in these levels affect the monitor and headphones outputs, but have no effect on the audio levels seen by the audio software application. The first two MUTE buttons also affect the inputs, and PAN is also available in this mode; the inputs come up panned to center, but can be SELected and PANned anywhere within the stereo field.
NOTE: In INPUT MONITOR mode faders 3- 4 are inactive.
NOTE: All the controls mentioned here are also accessible via the ASIO control panel, which displays the current status of the INPUT MONITOR section.
