DISCOVERING REAPER - 001 - Setting Up Audio

Setting up audio preferences is the next important topic tackled in the user guide. Having software and hardware agree with each other before you hit the "record" button will ensure the likelihood of a hassle-free home recording experience.

I clicked on Options>Preferences to bring up the Preferences dialog box. I also found that Ctrl+P does the same thing.

Following the user guide, I selected the Device sub-topic under Audio from the list of topics to the left of the dialog box.

In my case, ASIO is an available driver option for my Line 6 UX2 so I chose the following settings:

Audio System: ASIO
ASIO Driver: ASIO UX2
Enable Inputs: Checked, First Input: Send 1, Last Input: Send 2
Output Range: First: Output 1, Last: Output 2

Then I clicked on the ASIO configuration button and changed the Bit Depth to 24-bit. I left the rest at default settings.

What is ASIO?
ASIO (Audio Stream Input/Output), developed by Steinberg, is a cross-platform, multi-channel audio transfer protocol that is being adopted by many of the manufacturers of audio/MIDI sequencing applications. It allows software to have access to the multi-channel capabilities of a wide range of powerful sound cards.

The user guide recommends using ASIO for good reason. I found out that by using ASIO, Reaper is able to bypass the normal Windows O/S audio paths and connect directly to the UX2's sound card. What does that mean for me? Lower latency. Latency is the delay between an application sending audio information and it being reproduced by the sound card, or input signals from the sound card being available to the application.

The ASIO driver allows Reaper to "see" all of UX2's  inputs and outputs. This in turn allows me to assign these I/O ports independently as needed for recording or playback, and gives me the ability to record more tracks simultaneously as opposed to the limitations of my computer sound card which only provide two-channel (stereo) audio I/O.

Another advantage is higher audio fidelity since an unmixed ASIO output is "bit identical" or "bit transparent", that is, the bits sent to the sound card are identical to those of the original source. (Sources: ASIO Wikipedia, Search-CIO)


Notes On Sample Rate
Sample rate is the number of samples of audio carried per second, measured in Hz or kHz (one kHz being 1 000 Hz). For example, 44 100 samples per second can be expressed as either 44 100 Hz, or 44.1 kHz.

Bandwidth is the difference between the highest and lowest frequencies carried in an audio stream. The sample rate of playback or recording determines the maximum audio frequency that can be reproduced. 44kHz can reproduce a Maximum Frequency of 20kHz.

I left the default sample rate at 44.1 KHz since it is the sampling rate of audio CDs. It has a maximum frequency of 20kHz. The full range of human hearing is between 20 Hz and 20 kHz, making 44.1 kHz the logical choice for most audio material. (Sources: Sampling Rate Wiki, Audacity Team Wiki)


On Bit Depth
In digital audio, bit depth describes the number of bits of information recorded for each sample. Bit depth directly corresponds to the resolution of each sample in a set of digital audio data. Common examples of bit depth include CD quality audio, which is recorded at 16 bits, and DVD-Audio, which can support up to 24-bit audio.

UX2's ASIO configuration default bit depth is 16-bit which is actually fine. I changed it to 24-bit as a preference just to give me more room when it comes to editing, especially if there is a need to stretch audio. The higher resolution provides for the lowest probability of introducing artifacts and aliasing when manipulating recorded audio. The only downside is that it takes up more hard drive space and longer rendering time. (Source: Audio Bit Depth Wiki)


NEXT: DR 002 - Backing Up