Why am I told an audio Interface is better than a soundcard for my guitar

Question

I plug in my electric guitar to the Line-IN port (No pre-amp) of my desktop PC’s HD soundcard. It's onboard soundcard by Realtek.

I use amp sim called Guitar Rig 5 (GR5) on Windows 10. It works. My guitar does not have active pickups and I am not using any pre-amp.

Everywhere on the internet and Youtube videos it’s said that it’s not a good idea to plug in electric guitar to PC soundcard Line-IN.

• However a basic audio interface supports 16 Bit 44.1 KHz but my soundcard supports even 24 bit 192KHz.
• Audio interface supports multiple instruments. I need to use just a guitar.
• If there’s any hissing from single coil, I can suppress it using Noise Reduction in GR5.
• I do not need to use any DAW

In what way an audio interface at 16 bit 44.1Khz better than my soundcard (Line-IN port) which is supporting 24bit 192Khz.

In what way I will get better sound quality and fidelity by using an Audio Interface at 16bit 44Khz?

Answer 1

The two primary issues with cheap built in sound cards is noise level and latency.

Noise in the recording path matters for recording audio – e.g. vocals or real instruments. If they are recorded with added noise, this will affect the quality of the recording. Note, that many techniques of processing music amplify the signal and thus the noise – e.g. compression or distortion effects, commonly used for electric guitars.

With 16 bit resolution the noise level can't be lower than -96dB. In practice, the input noise is often much higher, due to poor quality analog path. 24 bits allow for noise of -144 dB, in practice good interfaces are better than -110 dB noise.

As the others point out, line input is not suitable for connecting passive guitar due to impedance mismatch, and may result in loosing high frequencies from the signal.

The latency matters for live audio processing in the PC, that is playing virtual instruments using a MIDI controller (e.g. MIDI keyboard), or using effects – such as your Guitar Rig. With big latency, there will be perceivable time delay between playing the note and hearing it back, which may make recording impossible. Some workarounds are possible, but not necessarily convenient.

In what way I will get better sound quality and fidelity by using an Audio Interface at 16bit 44Khz?

First of all, I think nowadays all decent audio interfaces are 24 bit. Good quality 16bit would be still better than poor quality 16bit, due to quality of the analog path and the analog to digital converters (ADC).

The sampling frequency matters less. 44.1 kHz is a compact disc standard, 48 kHz is the most common in consumer digital to analog converters (DAC). In practice, a single conversion of the sampling frequency won't harm the sound quality much.

Higher sampling frequency are most likely waste of the disk space and CPU, unless you're making music for cats. While some processing effects may benefit from oversampling, as it helps to avoid aliasing artifacts, recording at higher frequencies means recording sounds that are inaudible for most humans anyway, and will likely be removed from the final recording anyway.

Answer 2

An external interface that only supports 16 bit, 44.1k samples/sec must be a really basic one. Even my cheap one will do 24 bit, 96k samples/sec.

More bits and more samples per second is good, up to the point where it becomes ridiculously high and you're just filling up disk space.

The main issues to consider are voltage and impedance. A magnetic guitar output will be medium to high impedance, at a reasonably high voltage (tens to hundreds of millivolts). The voltage is about right for a line input, but you may be losing signal level if the sound card's input impedance is too low. That could be the cause of the hiss - you're having to crank up the gain to make up for the lost signal.

An external sound interface will usually have a high impedance instrument input, and you will lose less voltage. This may result in better sound quality.

Answer 3

If you plug in a guitar with no pre-amplification, it's going to be extremely quiet. That means you're going to be increasing the volume digitally. I read recently that amplifying a quiet input signal has similar effects as reducing the audio resolution. Maybe it's like how if you zoom in on a low resolution image, you don't see more detail. For the best sound quality, you want the signal to be as loud as it can be earlier in the chain. An interface will ensure your guitar is at an audible volume before it reaches your computer, to increase the signal/noise ratio. Maybe you don't need high quality audio if you're just practicing, but I hope this helps explain why you'll definitely get better sound quality if you get an interface.