What Is The Audio Interface?
Audio Interface is intermediate device helps connecting between audio devices such as microphone, monitor, headphone to computer. If helps you change signals from these devices into digital signal for computer to process.
Audio Interface has many kinds and many ports connection to computer such as usb, firewire 1394, pci, pci express. After digital signals from audio interface is processed, they are carried back through those ports to audio interface. In this place, the signals is changed back into analog and delivered through monitor speakers or headphone.
So what’s the difference between Audio Interface and AD converter or independent DA converter? Absolutely not, these converters are important parts and they’re integrated in audio interface. But using audio interface is much more convenient than using external converters.
Most audio interface has analog input and analog output, microphone preamp and may be some digital ports like spdif, adap, midi.
Why Audio Interface Is Important?
Although Audio Interface doesn’t directly join your audio signal process when you record or mix with DAW software in the computer. But It affects the quality of audio when you record and the trueness of sound when deliver through speakers.
This mean Audio Interface affects recording process directly and mixing process indirectly. So it’s worth your time to choose the good Audio Interface.
Understanding The Technical Specification of A Quality Audio Interface
Now, I’ll introduce you to the technical specification of Audio Interface. You look at these figures to assess an audio interface quality.
1#: Zero Latency Monitoring
You should understand this as function, not number. The latency monitoring is one of important functions you need to consider when buying an audio interface.
First, we will talk about latency definition (delay). Latency in recording process results from what?
When you record analog audio signal to audio interface, it has to passed through many digital signal changing steps. Computer receives digital signals and processes in it, then send back to audio interface and audio interface continue to change this digital signal to analog and transmit through speakers. All those steps above take time. This amount of time calls latency, the lower latency is, the higher cost of audio interface.
Image credit: ask.audio
Therefore, when you use a bad quality audio interface, in recording process, you’ll hear your voice through headphone somehow slower than your real voice. You’ll feel discomfort even it’s a bit or much and when you’re annoyed, how can you sing your best, right?!
Some audio interface has checking latency function. The common method is to use the direct connection without converter, or without process through computer, just process directly on audio interface.
Zero Latency Monitoring is very important because when you record singing especially drum sound, if you hear the sound after 1/10 seconds from your real voice or playing, it’s easily affect you emotion and feeling of the beat.
This is important function, if you’re considering between two audio interfaces with the same good quality functions but different from each other in this function, you’ve already known which to choose!
2#: Signal To Noise Ratio (SNR or S/N)
Used to measure the strength of audio signal compare to level of the noise inside that audio signal. The noise can be hiss, humming or parasitic noise in which is in any digital equipment.
You should remember, no matter how good your audio interface is, when it has electric current run through, it’ll produce noise even though very small. The better audio interface, the less noise.
Unit of signal to noise is decibel and the value is high means better. If SNR is 100 decibel means strength of audio signal higher 100 times to level of noise. Therefore, one audio interface with 100dB is better than audio interface with SNR 90dB.
However, when assessing an audio equipment, SNR is not the only element even though it’s very important.
3#: Total Harmonic Distortion (THD)
THD helps us know the difference of harmonic sound produced when audio signal runs through equipment by comparing input signal and output signal. Simple to say, THD let us know this device keeps the originality of the signal when it comes till it goes or not.
If THD has the value of 0.004%, it means the level of changing harmonic sound is 0.004% to output signal. Therefore, the lower value of THD, the better.
The nowadays professional audio equipment all is with high quality with very low THD even can’t be recognized with human ears. With some high-grade device, THS is so low that’s hard to measure.
4#: Bit Depth & Sample Rate
Receiving and delivering sound of bit depth and sample rate affects so much on quality of the audio. However, till now, with these two numbers, I think it’s less important than the others I talked above. Because most of current audio interface all receives and delivers sound at 24bit and 96khz. Moreover, bit depth and sample rate can’t tell the quality of audio interface.
You should know, one $200 audio interface can receive and deliver sound at sample rate 192khz but quality of audio is far as well as one $1000 audio interface at 44.100hz.
Reading and understanding values of audio interface helps you determine which audio interface suits for your preferences. In the next topic, I’ll help you know more about ports which connect audio interface to computer.