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Topic: USB signal or A/D sound card (Read 2927 times) previous topic - next topic
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USB signal or A/D sound card

I assume that the USB signal from the turntable is digital but how does it differ from the signal produced by sound card A/D conversion? How can the USB signal be saved as a 44.1, 48 or 96 kHz sampling rates if it is already digital?  What don’t I understand?

I am using a Numark TTUSB turntable with a Sure cartridge to move my vinyl LPs into MP3 files. I use the USB signal to via Nero Sound Trax to save a 16bit 96kHz file. I manually clean-up the visual clicks using Nero WaveEditor and save the individual tracks as constant bit rate “256 kbit, 48 kHz, sterio” MP3 files. (I very seldom use any noise reduction.) I then use foobar2000 to tag the tracks.

Maybe my old and abused ears are not working as they once did but I can seldom hear the difference between my old vinyl LPs played directly through the amp or the 16bit 96kHz Wave and the resulting 256bit 48kHz MP3 files of the same track played from the file via the sound card to the aux of the same amp. If anything, there seems to be a little “less fullness” in the sound. Btw - the Sure cartridge has a greater stereo separation than the Grado mounted on my old Sony direct drive turn table but the Grado seems to produce a slightly fuller warmer sound.

Thus, these are academic questions that I would very much like an answer to.

USB signal or A/D sound card

Reply #1 –
Your TT contains a soundcard, or at least the ADC part of a soundcard. The soundcard outputs from the ADC via USB to your computer. Some A to D converters are better quality than others, but the data it sends to your computer is not different than would be received if you were using a different kind of soundcard, whether it was external, with a firewire or USB connection, or was internal, such as built-in or PCI.

The recording application determines the sample rate. It tells the soundcard what it wants and the soundcard sets the sample rate accordingly. If you are recording at 96kHz, then the ADC in the TT is capable of running at that sample rate, almost certainly at 44.1kHz and 48kHz, and possibly others as well.

If your goal is 48kHz audio, you might as well record at 48kHz and avoid the resampling that is otherwise necessary. You cannot gain anything by recording at 96kHz unless the converters just happen to work better at 96kHz (not especially common, and differences are not often audible if there is any difference).

The audio quality of probably any professional soundcard is well beyond where one is able to hear differences from LP recordings, but that doesn't necessarily apply to built-in soundcards or gaming/multi-media cards such as Soundblasters and clones. If you are using such a card for playback, you may not be hearing the best sound your recordings are capable of producing.

There are some differences in the sound produced when using different cartridges. "Warmer" usually means ‘adds some distortion I have come to expect and feel more comfortable with' but if the goal is your enjoyment, you should do what achieves that goal.
 

USB signal or A/D sound card

Reply #2 –
AndyH-ha - Thank you.