SV: Re: [sdiy] Good 16 bits A/D choice for mono audio recording

[Eric Brombaugh]

Karl,

That's true. the ADUC824 has a 24-bit Sigma-Delta ADC on-chip, along 
with an 8051 core and a 12-bit DAC. Unfortunately, the sample rate of 
the ADC is only about 20Hz at higher resolutions. Useful for precision 
instrumentation measurements, but not nearly fast enough for J-P's audio 
digitizing application.

Eric

karl dalen wrote:
> Ad has the Aduc series of MCU's some have 24bit sigma-
> delta AD but can these 24 bits in practice be realized? 
> 
> KD
> 
> --- Eric Brombaugh <ebrombaugh at earthlink.net> skrev:
> 
>> J-P,
>>
>> There are lots of decent SPI ADCs out there that would work just fine 
>> for 44kHz, 16-bit sampling. Linear Tech, ADI and TI make a wide variety 
>> of them. 16-bit parts are a bit harder to find than 12-bit parts though.
>>
>> The on-chip 12-bit ADCs in the PIC series parts will typically exhibit 
>> rather poor INL (Integral Nonlinearity) which reduces the ENOB 
>> (effective number of bits). They also tend to be pretty sensitive to 
>> noise in the VDD & Vref lines. This means that the 12-bit ADC will have 
>> an SNR that's closer to that of a 10-bit converter. If you can live with 
>> 60dB of SNR in your audio then you're probably OK. Otherwise you'd be 
>> wise to choose a converter that can guarantee better quantization noise.
>>
>> Eric
>>
>> jean-pierre.desrochers at ville.quebec.qc.ca wrote:
>>> It's good to see someone is still
>>> there to help...
>>> I'm looking for SPI for less pin count
>>> on the PIC cpu that will do the readings.
>>> I saw PIC18's with 12bits A/D but I fear some
>>> A/D noise from it since this is audio I read.
>>> If I go 12bits would the PIC18 be a good choice anyway?
>>> I think external 16bits A/D would do better..?
>>> J-P Desrochers
>>>
>>> -----Message d'origine-----
>>> De : Eric Brombaugh [mailto:ebrombaugh at earthlink.net]
>>> Envoyé : 25 mai 2007 11:33
>>> À : synth-diy at dropmix.xs4all.nl
>>> Objet : Re: [sdiy] Good 16 bits A/D choice for mono audio recording
>>>
>>>
>>> jean-pierre.desrochers at ville.quebec.qc.ca wrote:
>>>
>>>> I need to pick a good A/D converter for sampling
>>>> the surrounding audio. I found the Analog Devices AD7684.
>>>> It shows a suitable S/N ratio and is single supply
>>>> like I need.
>>> What sort of interface are you looking for?
>>>
>>> * Parallel
>>> * SPI
>>> * I2S
>>> * other?
>>>
>>> Eric
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> 
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