[PD] what happens when you send signals between 0..1 instead -1..1 to dac?

[Christof Ressi]

Hi,

software like Pd or jack doesn't care because it's not forbidden to send 
only positive or even constant values. You might use your DAC to send 
control voltages for a modular synthesizer, for example. Most audio 
interfaces, however, apply some kind of highpass filter to the outputs 
to get rid of very low frequencies, but there are some "DC coupled" 
audio interfaces which pass the output unchanged. If you use such an 
interface with speakers, you have to be careful :-) But then again, you 
speakers might actually have a highpass filter...

Personally, I like to play it safe and add a [hip~ 5] as a DC filter 
before my [dac~] :-)

Christof

On 02.03.2020 00:24, ffdd cchh wrote:
> Hi everyone,
>
> I just found out that I have sent signals between 0..1 instead of 
> -1..1 to [dac]  (!!!), and I am wondering... what happens in that case?
>
> Does Pd take care of that in any way?
> Or, Is that the job of portaudio/asio/jack?
> Or, Is that the job of the audio interface?
> Or, nothing happens and you just send non-negative values to a speaker?
>
> I attach a minimal noise test patch to show this (I only hear a 
> difference in loudness on macos using portaudio and a motu...)
>
> Thanks in advance,
>
> f
>
>
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