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

Robert Poor rdpoor at gmail.com
Thu Apr 1 20:12:24 EDT 2010


Kurt:

Has nobody told you that a synthesis system that won't produce  
occasional bleeding eardrums is a BORING synthesis system?

:)

Best,

- r

On 2010Apr01, at 17:07, Kurt Kotheimer wrote:

> 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.
>> >>> _______________________________________________
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>> >>>
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>> >>
>> >>
>> >>
>> >> --
>> >> http://michaelclemow.com
>> >> http://semiotech.org
>> >>
>> >>
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