What you need to know before you buy a sound card
Friday, May 04, 2007
By Stephane Brault
The sound card is the most important thing to consider when building a home studio. Most computers now have a sound card when you buy them but most of those devices are onboard and do not meet the requirements to build a proper recording studio.
Internal or external?
The first thing you should look for, unless you have a laptop, is a PCI-based sound card. Although there are some USB-based sound card, they do not provide enough transfer rate. However there are some USB sound cards that support the new USB 2.0 specification so they can probably handle the job. If you really need an external sound card, you might also consider a Firewire-based one. But best of all, stick with a PCI-based sound card as you won't have to deal with transfer speed issues.
Inputs and outputs
A typical sound card will provide you with a number of different inputs and outputs including line-in, microphone and speaker. Audio devices such as tape decks, radios or synthesizers can be recorded through a line-in input whereas a microphone needs to go through a pre-amplified input because of it's low volume output. Speakers also need an amplifier as the signal coming out of the sound card is not high enough. Some middle-range and high-end sound cards also offers digital inputs and outputs for better quality. These connectors need special devices, such as some CD players and digital audio tapes, that support digital data. Most sound card uses 1/8-inch jacks but higher-end sound cards uses 1/4-inch, RCA or XLR jacks. Connections can also be shielded against radio frequency interferences. Those are "balanced connections". Unbalanced connections do not provide interference protection.
If you need to record from more than one external source at a time, you will need a sound card with multiple inputs. Depending on the sound card quality, those inputs can be mixed down to a single stereo signal (cheaper cards) as well as being recorded into individual tracks (more expensive cards).
Another aspect is sound quality. Sound quality can be measured by four elements (at least) : sampling rate, bit resolution, signal-to-noise ratio and frequency response. The higher the sampling rate is, the better the sound quality is going to be. A typical audio CD uses a sampling rate of 44.1 kHz. All sound card support this but professional cards can hit 48 kHz or higher. The bit resolution is also a quality factor. The higher the bit resolution, the better. An audio CD has a resolution standard of 16 bits. Some cards can go up to 24 bits. As for the two other measurements, signal-to-noise and frequency response, the higher the better. As all electronic devices produces some amount of noise, the signal-to-noise ratio tells you how much higher is the sound signal compared to the internal noise generated by the sound card. A quieter card is better for recording. Frequency response is the audio range encompassed by the sound card based on human hearing. The human hearing si approximately 20 Hz to 20 kHz.
MIDI Interface and USB to MIDI converter
If you have an external MIDI device, such as a synthesizer, you might need a MIDI interface on your sound card. If you have multiple MIDI devices, you may need more than one MIDI port. You can also get a USB-based MIDI interface. MIDI does not take a lot of bandwidth therefore a USB-based MIDI interface will do the job. Another advantage of using a USB to MIDI converter is that you won't have to plug and unplug your MIDI devices from behind your computer which can be irritating if you have to do that often.
You also want to make sure that the sound card drivers are WDM (Windows Driver Model) or ASIO (Audio Stream Input Output) compatible. Sonar supports both these technologies and will give you much better performance in terms of audio latency. The latency is the communication delay between Sonar and your sound card.
Recording Software Requirements
And finally, you will probably need to consider your recording software requirements. Depending on which software you use, you may want to make sure that it meets the manufacturer's requirements. If you plan on using Cakewalk Sonar, you might want to read the Open Audio Hardware Guide from Cakewalk at http://www.cakewalk.com/Tips/audiohw.asp .