[mdlug] Vinyl to digital

[Aaron Kulkis]

Ingles, Raymond wrote:
>> From: Paul
> 
>> 	Ratshack used to sell a phono pre-amp for not much, if you
>> really dont have a home amplifier with a phono pre-amp. Recording
>> such a low signal would I imagine, reduce the real dynamic range
>> of the signal, (eg. if you are sampling at 16 bits but your highest
>> sample never gets above 8 bits, you are essentially recording in
>> 8 bit quality) and then dramaticly amplify the floor of whatever
>> noise exists in the path thru the card.
> 
>  I would have thought so, too, but the resultant files have sound
> about as good as those records ever sounded. Sometime in the next few
> days I'm going to do some experimenting and see if things get any
> better. I'm not expecting miracles from source material that's over
> 20 years old in some cases. :->
>

Brand new vinyl typically has 72 dB Signal to Noise Ratio.
Digital is 6 dB SNR per bit, which means

8 bits => 48 dB SNR
12 bits => 72 dB SNR
16 bits => 96 dB SNR

Therefore, your ideal sampling size is 12 bits at >= 2 x f(hi)
where f(hi)is the highest frequency which is both reproduced
on your recording and hearable by the human ear.
(this is referred to as "the Nyquist frequency")


Typical human hearing cuts off at 20 kHz, which is why 44 kHz
is chosen for the Nyquist Frequency for CD's.. it gives f(hi)
of 22 kHz, which is comfortably above the 20 kHz upper limit
of human hearing.




>> 	Btw. AFAIK libsamplerate aka Secret Rabbit Code is the best
>> thing for resampling out there. Ive heard that sox uses more primative
>> techniques. (maybe that has changed)
> 
>  Well, I used the highest-quality SOX resampler for my tests with
> Gramofile. I'll play with libsamplerate next time, too.
> 
>  Sincerely,
> 
>  Ray Ingles                                             (313) 227-2317
> 
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