[sdiy] some observations : audibility of phase distortion

[Czech Martin]

no no, it is not about static harmonics.
It is about transient response and if it is audible
if transient response distortions are longer than some
10 ms.


m.c.

> -----Original Message-----
> From: owner-synth-diy at dropmix.xs4all.nl
> [mailto:owner-synth-diy at dropmix.xs4all.nl]On Behalf Of ChristianH
> Sent: Montag, 12. Januar 2004 12:47
> To: synth-diy at dropmix.xs4all.nl
> Subject: Re: [sdiy] some observations : audibility of phase distortion
> 
> 
> That's what I remember having read some 20 years ago. 
> 
> IIRC, it was about additve synthesis, and it was stated that you can't
> hear static phase differences, i.e. you don't have to worry 
> about phase
> relations between each single harmonic you add. Of course, 
> the waveform
> will be different, but it will sound the same.
> 
> And of course, dynamically changing phase relationships over 
> time is way
> different. That's something you _can_ hear...
> 
> Christian
> 
> 
> 
> On Fri, 09 Jan 2004 23:24:45 -0500 harrybissell wrote:
> 
> > My Hex Fuzz Guitar has all the outputs run through an 
> allpass filter...
> > it is for vibrato generation.  I do not bypass the filter when the
> > vibrato
> > is stopped... I just stop modulating it.
> > 
> > I cannot hear any difference between  the original (pre 
> filter) sound
> > and the
> > post filter sound... but by looking at the scope you cannot even
> > recognize
> > the same waveforms.
> > 
> > Phase insensitive (I say)
> > 
> > H^) harry
> > 
> > Czech Martin wrote:
> > 
> > > During the vacations I made some experiments.
> > > Unit pulses and a short drum sample were filtered
> > > with a discrete all pass filter. I checked that the amplitude
> > > of that filter was flat, but phase was very nonlinar.
> > > The nonlinearities where arround 100-400 Hz.
> > > I tried 2nd , 4th and 6th order.
> > >
> > > The signals were visibly distorted, but:
> > >
> > > I couldn't hear a difference, even if the original sample
> > > follows imediatly after the processed with less then
> > > 1s distance. Looping serveral times and using good headphones
> > > did not help.
> > >
> > > What is wrong with my experiment?
> > > I think that the time domain effect is still occlused (SP?),
> > > i.e. the filter response is too short  to be heard.
> > > That would mean higher order and / or higher filter "Q",
> > > i.e. poles closer to unit circle.
> > > E.g. if two pulses follow too close to each other you will
> > > hear only one, with perhaps some coloring. The ear has some
> > > time limitation.
> > >
> > > m.c.
> 
>