[LAU] [Music] Sans titre - Without title

[Robert Edge]

Do whatever you want.  I can't explain it to you any more clearly.


On Mon, Jul 18, 2016 at 10:25 AM, Len Ovens <len at ovenwerks.net> wrote:

> On Sun, 17 Jul 2016, Robert Edge wrote:
>
> If you don't believe me, do this simple test:
>>
>> feed a 1kHz tone in to the input
>>
>> set 'analog volume' control in software to 0dB
>>
>> connect to ardour or your choice of recorder with decent metering.  set
>> meter
>> point to 'in'
>>
>> increase volume of test signal until you are getting 0dBFS.  no matter
>> how much
>> you increase the level of the test signal from here it will continue to
>> read
>> 0dbFS.  turn the signal generator up a good few dB so you are well in to
>> clipping.
>>
>> record a bit of this.  you will see a squared off wave.
>>
>> now turn down the 'analog volume' control until you are seeing a nice
>> comfortable
>> level.  do not change the level of the test signal generator.
>>
>> record again.
>>
>> the result will still be clipped.
>>
>> in fact it will be identical to the first signal you recorded, just
>> scaled down.
>>
>> I mean, you guys do whatever you want, but that is what is actually
>> happening in
>> your signal chain.
>>
>
> How do you know this is digital and not analog clipping? The result would
> look the same.
>
> signal path:
>
> AC -> resitor -> buffer -> digitally -> ADC
> in    pad on     amp       controlled
>       card                 analog gain
>
> if the input signal after the input pad has p-p higher than amp's power
> rails allow, the signal will be squared off, just as you are seeing. The
> gain stage would be a part of the ADC chip BTW. The buffer amp is probably
> not, but rather a gain stage added to allow the use of mic level inputs.
> (M-Audio advertise it as a Mic Pre)
>
> --
> Len Ovens
> www.ovenwerks.net
>
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