Discussion of USB mics in the FAQ

[Paul_Claessen]

At the end of the FAQ there is a LONG explanation of why one shouldn’t use USB based microphones.
It comes down to the evil of using different clocks for ADC and DAC.
But what is the alternative? An ‘analog’ mic, plugged into an audio interface? An audio interface being a very common device for working with a DAW, doesn’t it present the same problem then also? It too connects to a computer through USB (mostly), right?

And isn’t a LOT of sampled audio coming from a different device (clock!) than the playback device (thus: different clocks)?
Think for instance a DVD, or CD.

[tseaver]

@Paul_Claessen

But what is the alternative? An ‘analog’ mic, plugged into an audio interface? An audio interface being a very common device for working with a DAW, doesn’t it present the same problem then also? It too connects to a computer through USB (mostly), right?

USB isn’t the issue: the issue is that there needs to be only one device handing both the input and the output. A USB audio interface handles both encoding audio to digital samples (from microphones, line-in signals, etc.), on the way into the DAW (ADC), and it handles re-encoding them coming out of the DAW to analog audio (DAC), en route to your speakers or headphones.

And isn’t a LOT of sampled audio coming from a different device (clock!) than the playback device (thus: different clocks)?

Not so much: the case I can think of is having a set of one or more add-on microphone preamps/ADCs which route their digital samples into the USB interface: for instance, I have a Behringer Ultragain ADA800 connected like this via ADAT to my Focusrite Scarlett 18i10 audio interface (outputs go back out over ADAT as well, but I don’t have anything plugged into them). They stay in sync because there is a secondary “word clock” cable plugged between them, with the Ultragain configured to follow the “master” word-clock signal from the Scarlett.

[x42 (Robin Gareus)]

@Paul_Claessen

And isn’t a LOT of sampled audio coming from a different device (clock!) than the playback device (thus: different clocks)?
Think for instance a DVD, or CD.

Those are both playback devices, and they don’t need to be in sync.

When you record, all inputs (microphones, instruments) need to be in sync with each other, and also in sync with what you hear (metronome click, previously recorded tracks). So during production it does matter that the same clock is used for both capture and playback.

–

As the FAQ explains, when there are different clocks, the signal is resampled, which lowers the quality. In many cases this is of no big concern (e.g. casual podcasts, streamer/gaming), and you can also use it to record music.
Yet if you’re planning to get into music production best get a dedicated audio interface.