Tips for Using SONAR and 24-bit Audio Projects

When first installed, SONAR is set by default to create projects containing 16-bit audio sampled at 44.1khz.  Almost all soundcards available today support this kind of audio data (at least in mono if not in stereo, and at least in half-duplex if not full-duplex mode.)  Many professional soundcards offer the capability to record/play audio at a higher bit-depth (more bits per sample), and possibly also at a higher sampling rate. SONAR software can take advantage of this enhanced capability, allowing you to produce very high-quality, professional-caliber audio projects. However, to get the best results when working at these higher levels, you need to keep the following points in mind: 

Set the desired bit-depth and sampling rate before recording any audio:

You should specify the desired bit rate and sampling rate for your project before starting to record or insert any audio into the project, i.e., when the project is newly created and still “empty”. (It is possible to change a project’s bit-depth after audio has already been recorded into it, using Tools | Change Audio Format, but doing so can degrade the quality of the existing audio data. It is not possible in SONAR to change the sampling rate of a project after audio has been recorded; other sound editing applications can be used for this purpose, but the sample-rate conversion may also degrade the quality of existing audio.)

Specifying the desired bit rate and sampling rate is accomplished in the Options | Audio dialog box, on the General tab. The section of the dialog labeled Default Settings for New Projects allows you to specify the sampling rate and the sample size (bit-depth) of audio data that will subsequently be stored into your new project.

Make sure that you do not choose a sampling rate that your soundcard doesn’t actually support. (For example, don’t select 48000 Hz if your soundcard can only go up to 41100 Hz; SONAR will not display an error message if you select a sampling rate that is not supported by your card, but the software will fail to record your audio data in this case.)

Choose a File Bit Depth of 24 if you intend to use your soundcard at 18-, 20-, or 24-bit depth:

You may choose a File Bit Depth of either 16- or 24-bits. If your soundcard supports 18-, 20-, or 24-bit operation and you want to take advantage of that capability, you must select 24 in the File Bit Depth list, or else the data received from your soundcard will be truncated and stored in your project file as 16-bit samples, defeating the benefits of your card’s higher-bit-depth capability.

Try to use the soundcard driver at 24-bits even if your soundcard only operates at 20- or 18-bits:

Having established the default settings for new files, you must also specify at what bit-depth you want your soundcard to operate.  In the same Options | Audio dialog box, set the Audio Driver Bit Depth to the desired value. Even if you soundcard’s highest bit-depth is only 18- or 20-bits, you should try selecting an Audio Driver Bit Depth of 24 first. If you receive an error message when doing so, try selecting 20.  If this also produces an error message, try selecting 18. In other words, if you want SONAR to operate your soundcard at any bit-depth greater than 16-bits, try selecting the highest value possible in the Audio Driver Bit Depth setting, and work downward from there if you have to.

(If your soundcard’s maximum bit-depth is 20-bits and you specify an Audio Driver Bit Depth of 24 as advised above,  audio data will still be sampled by your soundcard in 20-bit samples, but each sample will automatically be padded with extra 0’s to produce a 24-bit sample, which will be stored at full 24-bit resolution in your project file (assuming you have set the File Bit Depth to 24 as advised above.) The advantage of this is that any subsequent processing performed by SONAR on that audio—such as applying off-line or real-time audio effects—will be performed and stored at full 24-bit resolution, ensuring maximum quality and signal-to-noise ratio for your audio.

Using 24-bit depth and/or high sampling rate can be costly:

While using 24-bit audio can improve the sound quality of your recordings, there are some important drawbacks to keep in mind. Projects stored at 24-bit depth will require 50% more disk space than those stored at 16-bits; if you have a large number of audio tracks (and keep in mind that stereo tracks require twice as much data as mono tracks!), your audio project file can grow very large and use up lots of disk space. Also note that recording, playing, and processing 24-bit data utilizes more CPU resources than working with 16-bit data. This means that for a given computer configuration, you will be able to record/play/process a smaller number of total simultaneous tracks, and use a smaller number of simultaneous real-time effects, in a 24-bit project than you would be able to in a 16-bit project. This is also true when working at higher sampling rates (i.e., a 24-bit/96khz project requires substantially more computing resources than a corresponding 16-bit/44.1khz project). Depending on the size of your project and the configuration of your computer (CPU, RAM, disk), you may need to reconsider whether working at the higher bit-depth/sampling rate is justified or even possible.

It’s also worth noting that not all audio projects benefit equally from the use of higher bit-depth/sampling rates. Most professional sound engineers will tell you that 24-bit, higher-sampling-rate audio is most beneficial when working with music that focuses on natural acoustic instruments and/or vocals recorded with very high-quality microphones. The benefits of 24-bit/high-sampling-rate recording are less audible when working with highly synthetic or highly compressed program material, often found in contemporary popular music. You must make your own judgment about whether the benefits of higher-capacity audio justify the extra demands it places on your computer.

Note: Red Book Audio CDs are still 16-bit (44.1 sampling rate), so if your goal is to burn a CD, you will have to mix down to 16-bit.

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