Analog audio to digital USB without converter? How?

[babadoctor]

How is this possible without an analog to digital converter?

 

can I use something like this with a raspberry pi and an analog mic?

 

[AnonymousGuy]

They probably just molded the ADC into the USB connector.

[mariushm]

The USB "sound card"  or ADC/DAC  (analogue to digital / digital to analogue converter) is hidden inside the USB connector, basically where that "Audio2USB" text is printed. 

 

All you need is a audio codec chip and a bunch of ceramic capacitors and a tiny circuit board. The chip probably supports more stuff, but they just edited the parameters of the chip (a few bytes of memory inside the chip, or external to the chip) to make the chip report itself to the operating system as only "microphone array" (adc only).

 

For example, see the pictures in this teardown of a basic 3$ usb sound card : https://getgui.com/blog/desktop-pc-repairs/on-board-audio-not-working-bypass-it-with-usb-sound-card-or-dac/

 

Picture that circuit board WITHOUT the mic and headphone jacks and usb connector and hidden in the usb connector.

[Psittac]

I didn't click any of the links myself

 

But why would you go analogue to digital?

 

Your PC is capable of both analogue and digital output so why convert?

[mariushm]

1 minute ago, Psittac said:

I didn't click any of the links myself

 

But why would you go analogue to digital?

 

Your PC is capable of both analogue and digital output so why convert?

All kinds of reasons ... for example, let's say you have some old cassette tapes or old turntable discs and you want to convert them to audio files to listen on your phone / music player.

The product is aimed at people who want to transfer their recordings to PC.  Some computers / laptops don't have "line in" / "aux in" input jacks so this product gets around that by sending the uncompressed audio through usb to the operating system.

[Psittac]

27 minutes ago, mariushm said:

All kinds of reasons ... for example, let's say you have some old cassette tapes or old turntable discs and you want to convert them to audio files to listen on your phone / music player.

The product is aimed at people who want to transfer their recordings to PC.  Some computers / laptops don't have "line in" / "aux in" input jacks so this product gets around that by sending the uncompressed audio through usb to the operating system.

ohhhhh ok so this isn't an output thing.  I guess you answered my next question which would be why not take analogue input

[artuc]

5 hours ago, Psittac said:

ohhhhh ok so this isn't an output thing.  I guess you answered my next question which would be why not take analogue input

Audio on a computer is all digital

 

ADC and DAC are used either on the computer itself or on another device, ultimately drivers/speakers and microphones are analogue devices. So unless in the case that the signal chain is kept completely analogue there will be conversion going on somewhere either to or from digital.