[chuck-users] Filters blowing up: any news?

Kurt Kotheimer sobrilliant at gmail.com
Thu Apr 1 20:07:25 EDT 2010


I found a great way to blow up RezonZ today.  Give it a freq value  
beyond the sample rate.
Noise n => Resonz z => dac;
1.0 => z.Q;
Std.mtof(440) => z.freq;//whoops!!! -- gave mtof a cps value instead  
of a midi value.
This gets REALLY loud on a Mac.
Hope this gets looked at.  In the meantime watch your ears.
Later.
Kurt
........................................................
http://www.kurtKotheimer.com
.......................................................






On Mar 1, 2010, at 4:48 PM, Tomasz Kaye's brain wrote:

> Hi Robert. Thanks for the pointer, that's very useful.
>
> I'd stayed away from RezonZ until now because I thought it would be  
> wisest to begin by using filter types I already knew (or thought i  
> knew) from other environments: LPF BPF and HPF.
>
> I saw that RezonZ doesn't have the runaway tendency of the other  
> three when plugged into the test patch (and now I think I understand  
> the significance of the line in the RezonZ ugen documentation:  
> "keeps gain under control independent of frequency").
>
> I'll have a try at getting RezonZ act as a rough approximation of  
> the other three filter types (any further pointers anyone can offer  
> in this direction would be great), and try again to do some reading  
> around musical applications of biquad filters, though filter-related  
> writing tends to make my head hurt :)
>
> On Mon, Mar 1, 2010 at 9:00 PM, Robert Poor <rdpoor at gmail.com> wrote:
> Tomasz:
>
> I use SndBuf => ResonZ => Envelope => DAC frequently in live
> performances.  Even though the center frequency and Q of the ResonZ
> are controlled by pitch bend and modulation wheel (respectively), I've
> never had any problems with stability.  Am I missing something?  :)
>
> - Rob
>
> 2010/3/1 Tomasz Kaye's brain <tomasz.brain at gmail.com>:
> > About the filter problem: does it mean that currently no one is  
> using chuck
> > for classic sutractive synthesis patches like:
> >
> > Oscillators -> Filters (cuttof driven by an ADSR) -> Amplifier  
> (Level driven
> > by an ADSR) ?
> >
> > Are people just not doing this kind of routing in ChucK yet, or  
> are there
> > workarounds that avoid the filters going unstable when modulated  
> in this
> > way?
> >
> > (Sorry to keep on about this, but I'm really keen to keep using  
> ChucK if at
> > all possible)
> >
> > 2010/2/17 mike clemow <michaelclemow at gmail.com>
> >>
> >> OT:
> >>
> >> 2010/2/16 Andrew C. Smith <andrewchristophersmith at gmail.com>
> >>>
> >>> Seems that ChucK can crash brains, not just computers!
> >>
> >> Chuck's filter code is actually written in Sumerian.  The Goddess  
> Asherah
> >> created Chuck to erase peoples' minds and make them worship her.   
> The sound
> >> is actually a nam-shub and if you hear it, you will lose your  
> wits and start
> >> mumbling Sumerian syllables...
> >>
> >> (sorry, i couldn't help this outburst.  i finished the book just  
> a few
> >> short weeks ago.  ;)
> >>
> >> -Mike
> >>
> >>
> >>
> >>
> >>>
> >>> Actually, my other solution was to run the audio through Jack  
> and into
> >>> Logic, where I can do a much better job of controlling the  
> volume. This
> >>> actually doesn't distort (since the distortion comes at the dac  
> level), and
> >>> changes the sound entirely. Anyway, just an option.
> >>> -Andrew
> >>> On Feb 16, 2010, at 5:03 PM, Kassen wrote:
> >>>
> >>>
> >>> 2010/2/16 Stefan Blixt <stefan.blixt at gmail.com>
> >>>>
> >>>> If you do SinOsc s=> dac and the 100.0 => s.gain, are you then  
> able to
> >>>> blow a speaker on a Mac laptop even if it's main volume is  
> turned down?
> >>>> That's the curious thing to me, how the filter messes up so  
> badly it makes
> >>>> my MacBook's speaker scream even though the volume is almost  
> down to zero.
> >>>>
> >>>
> >>> 100? Try something like this value for a output; 242210436022272.0
> >>> That's a actual recorded output of .last(). I'm not sure what  
> would
> >>> happen if something of that volume would be played back on real  
> speakers;
> >>> there is probably a UN convention against that kind of thing ;-).
> >>>
> >>> From what I understand of the situation you wouldn't blow the  
> speaker. If
> >>> Apple was smart they put in a pre-amp that's slightly smaller  
> than the
> >>> maximum load of the speaker yet slightly over-speced for the  
> output of the
> >>> dac to keep repairs down. But yes; apparently you will can get a  
> very high
> >>> volume even though the (software) fader is down.
> >>> This is what we know.
> >>> Then from that I speculated (and unless something more credible  
> comes by
> >>> I think it's a good theory) that Apple is doing everything in  
> float (with
> >>> virtually unlimited headroom for practical applications),  
> setting the master
> >>> volume with a floating point multiplication, and handing the  
> resultant value
> >>> to the dac where inevitably it will be turned into a plain  
> integer. In this
> >>> case that integer will be the highest volume the poor little dac  
> can take.
> >>> If that's not it I can't imagine why +/- some 15 digit number  
> would have a
> >>> higher amplitude than +/-1, as a final output, post master fader.
> >>> This is cheap compared to tweaking the voltage on the final  
> hardware amp
> >>> (which would always preserve the full bit-range) and probably  
> sounds a lot
> >>> better than going integer and throwing away a lot of bits at low  
> volume, but
> >>> it fails to take into account that we may not just turn the  
> volume down for
> >>> a more pleasant listen but also to protect our ears. Combine  
> that with with
> >>> potentially very sensitive studio or DJ headphones and you have  
> a situation
> >>> that may lead to hearing damage. I know that my own pro DJ  
> headphones will
> >>> output a lot more volume than my mid-range earbuds at the same  
> volume
> >>> setting for a headphone jack.
> >>>
> >>> IMHO this would be a oversight by Apple and I'm a bit surprised  
> there
> >>> hasn't been a storm of practical joke mails aimed at OSX users  
> featuring
> >>> videoclips embedding floating-point audio. I'd offer at least a  
> optional
> >>> output limiter like what has been proposed for mp3 players. I  
> don't believe
> >>> in those for protecting children's ears through mandatory  
> regulation because
> >>> of the differences in headphone output volume, but for user-set  
> protection
> >>> it might be a good idea. Of course ChucK is a bit more likely to  
> cause this
> >>> sort of issue than the average off-the-shelf audio player.
> >>> Here is the original topic if you'd like to try to reproduce the  
> findings
> >>> so far; http://electro-music.com/forum/viewtopic.php?t=37921
> >>> Yours,
> >>> Kas.
> >>> _______________________________________________
> >>> chuck-users mailing list
> >>> chuck-users at lists.cs.princeton.edu
> >>> https://lists.cs.princeton.edu/mailman/listinfo/chuck-users
> >>>
> >>>
> >>> _______________________________________________
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> >>>
> >>
> >>
> >>
> >> --
> >> http://michaelclemow.com
> >> http://semiotech.org
> >>
> >>
> >> _______________________________________________
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> >>
> >
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