On 2014-06-10, Douglas Beeson <c.difficile@gmail.com> wrote:> Hello all, > > I'm back again with an audio zero-cross detection circuit that I > have designed based on valuable feedback from some of you (notably Jim > Thompson and John Fields). I am trying to gate an audio signal while > avoiding clicks as it switches on and off.zero crossing detection won't get you there. interrupting the signal at its steepest slope wont give good results. -- umop apisdn --- news://freenews.netfront.net/ - complaints: news@netfront.net ---
Zero Cross Detection circuit for review
Started by ●June 10, 2014
Reply by ●June 13, 20142014-06-13
Reply by ●June 13, 20142014-06-13
On 13 Jun 2014 12:24:31 GMT Jasen Betts <jasen@xnet.co.nz> wrote:> On 2014-06-10, Douglas Beeson <c.difficile@gmail.com> wrote: > > Hello all, > > > > I'm back again with an audio zero-cross detection circuit that I > > have designed based on valuable feedback from some of you (notably Jim > > Thompson and John Fields). I am trying to gate an audio signal while > > avoiding clicks as it switches on and off. > > zero crossing detection won't get you there. > interrupting the signal at its steepest slope wont give good results.I can imagine that switching on voltage zeroes might lead to current surges from the voice coil. I could try detecting current zero crosses. Do you have another suggestion? d> > > -- > umop apisdn > > > --- news://freenews.netfront.net/ - complaints: news@netfront.net ----- Douglas Beeson <c.difficile@gmail.com>
Reply by ●June 13, 20142014-06-13
On Fri, 13 Jun 2014 11:13:44 -0400, Douglas Beeson <c.difficile@gmail.com> wrote:>On 13 Jun 2014 12:24:31 GMT >Jasen Betts <jasen@xnet.co.nz> wrote: > >> On 2014-06-10, Douglas Beeson <c.difficile@gmail.com> wrote: >> > Hello all, >> > >> > I'm back again with an audio zero-cross detection circuit that I >> > have designed based on valuable feedback from some of you (notably Jim >> > Thompson and John Fields). I am trying to gate an audio signal while >> > avoiding clicks as it switches on and off. >> >> zero crossing detection won't get you there. >> interrupting the signal at its steepest slope wont give good results. > >I can imagine that switching on voltage zeroes might lead to current surges from the voice coil. I could try detecting current zero crosses. Do you have another suggestion? > >d > >> >> >> -- >> umop apisdn >> >> >> --- news://freenews.netfront.net/ - complaints: news@netfront.net ---In the audio biz they "fade" from one source to another. ...Jim Thompson -- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85142 Skype: skypeanalog | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.
Reply by ●June 13, 20142014-06-13
On Fri, 13 Jun 2014 08:18:15 -0700, Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:>On Fri, 13 Jun 2014 11:13:44 -0400, Douglas Beeson ><c.difficile@gmail.com> wrote: > >>On 13 Jun 2014 12:24:31 GMT >>Jasen Betts <jasen@xnet.co.nz> wrote: >> >>> On 2014-06-10, Douglas Beeson <c.difficile@gmail.com> wrote: >>> > Hello all, >>> > >>> > I'm back again with an audio zero-cross detection circuit that I >>> > have designed based on valuable feedback from some of you (notably Jim >>> > Thompson and John Fields). I am trying to gate an audio signal while >>> > avoiding clicks as it switches on and off. >>> >>> zero crossing detection won't get you there. >>> interrupting the signal at its steepest slope wont give good results. >> >>I can imagine that switching on voltage zeroes might lead to current surges from the voice coil. I could try detecting current zero crosses. Do you have another suggestion? >> >>d >> >>> >>> >>> -- >>> umop apisdn >>> >>> >>> --- news://freenews.netfront.net/ - complaints: news@netfront.net --- > >In the audio biz they "fade" from one source to another.This fading is what you want to eliminate clicks, not a sudden switch. Grant.> > ...Jim Thompson
Reply by ●June 13, 20142014-06-13
In article <20140613111344.71d43c28685c2ce51289fd1d@gmail.com>, c.difficile@gmail.com says...> > On 13 Jun 2014 12:24:31 GMT > Jasen Betts <jasen@xnet.co.nz> wrote: > > > On 2014-06-10, Douglas Beeson <c.difficile@gmail.com> wrote: > > > Hello all, > > > > > > I'm back again with an audio zero-cross detection circuit that I > > > have designed based on valuable feedback from some of you (notably Jim > > > Thompson and John Fields). I am trying to gate an audio signal while > > > avoiding clicks as it switches on and off. > > > > zero crossing detection won't get you there. > > interrupting the signal at its steepest slope wont give good results. > > I can imagine that switching on voltage zeroes might lead to current surges from the voice coil. I could try detecting current zero crosses. Do you have another suggestion? >You would need the circuit monitoring both inputs and waiting for both to appear at zero at the same time before performing the switch. The change of that happening is going to cause delay in your switch depending on how low of level you are sensing. Even if you did that, you're still going to have issues due to higher freqs on top of the lower ones. You'll get a zero sense for a moment and do the switch while there is still content in the lower freq spectrum on the new input, which still leads to noise. I guess if you are dealing with single tones you would not need to worry, but I don't think that is the case here. The standard method is to slowly reduce gain on input going away while increasing the gain coming in. This can take place is a very short time. Jamie
Reply by ●June 14, 20142014-06-14
Jim Thompson wrote:> > On Fri, 13 Jun 2014 11:13:44 -0400, Douglas Beeson > <c.difficile@gmail.com> wrote: > > >On 13 Jun 2014 12:24:31 GMT > >Jasen Betts <jasen@xnet.co.nz> wrote: > > > >> On 2014-06-10, Douglas Beeson <c.difficile@gmail.com> wrote: > >> > Hello all, > >> > > >> > I'm back again with an audio zero-cross detection circuit that I > >> > have designed based on valuable feedback from some of you (notably Jim > >> > Thompson and John Fields). I am trying to gate an audio signal while > >> > avoiding clicks as it switches on and off. > >> > >> zero crossing detection won't get you there. > >> interrupting the signal at its steepest slope wont give good results. > > > >I can imagine that switching on voltage zeroes might lead to current surges from the voice coil. I could try detecting current zero crosses. Do you have another suggestion? > > > >d > > > >> > >> > >> -- > >> umop apisdn > >> > >> > >> --- news://freenews.netfront.net/ - complaints: news@netfront.net --- > > In the audio biz they "fade" from one source to another.The attenuators on the consoles I maintained were speced to - 80 dB when turned all the way down. -- Anyone wanting to run for any political office in the US should have to have a DD214, and a honorable discharge. --- This email is free from viruses and malware because avast! Antivirus protection is active. http://www.avast.com
Reply by ●June 14, 20142014-06-14
On 13 Jun 2014 12:24:31 GMT, Jasen Betts <jasen@xnet.co.nz> wrote:>On 2014-06-10, Douglas Beeson <c.difficile@gmail.com> wrote: >> Hello all, >> >> I'm back again with an audio zero-cross detection circuit that I >> have designed based on valuable feedback from some of you (notably Jim >> Thompson and John Fields). I am trying to gate an audio signal while >> avoiding clicks as it switches on and off. > >zero crossing detection won't get you there. >interrupting the signal at its steepest slope wont give good results.--- Sounds like nonsense to me; have you tried it? If not, note that the sim generates a .wav file which you can play and listen for clicks. I did, and heard nothing go awry. Since the voice coil, cone, surround, and all those other loudspeaker moving parts have mass, switching the audio ON at a zero crossing will start the mass moving gradually from its resting point in the magnetic field, - thereby approximating a fast fade-in - and going open-circuit OFF at a zero crossing will allow the mass a short period of self-damped oscillation before it coasts to a stop, again gradually. John Fields
Reply by ●June 14, 20142014-06-14
On Sat, 14 Jun 2014 09:34:44 +1000, Grant <omg@grrr.id.au> wrote:>On Fri, 13 Jun 2014 08:18:15 -0700, Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote: > >>On Fri, 13 Jun 2014 11:13:44 -0400, Douglas Beeson >><c.difficile@gmail.com> wrote: >> >>>On 13 Jun 2014 12:24:31 GMT >>>Jasen Betts <jasen@xnet.co.nz> wrote: >>> >>>> On 2014-06-10, Douglas Beeson <c.difficile@gmail.com> wrote: >>>> > Hello all, >>>> > >>>> > I'm back again with an audio zero-cross detection circuit that I >>>> > have designed based on valuable feedback from some of you (notably Jim >>>> > Thompson and John Fields). I am trying to gate an audio signal while >>>> > avoiding clicks as it switches on and off. >>>> >>>> zero crossing detection won't get you there. >>>> interrupting the signal at its steepest slope wont give good results. >>> >>>I can imagine that switching on voltage zeroes might lead to current surges from the voice coil. I could try detecting current zero crosses. Do you have another suggestion? >>> >>>d >>> >>>> >>>> >>>> -- >>>> umop apisdn >>>> >>>> >>>> --- news://freenews.netfront.net/ - complaints: news@netfront.net --- >> >>In the audio biz they "fade" from one source to another. > >This fading is what you want to eliminate clicks, not a sudden switch. > >Grant.--- Since what's being controlled is a mass, a sudden switch at the proper time will do the fading automatically. John Fields
Reply by ●June 14, 20142014-06-14
On Fri, 13 Jun 2014 21:11:45 -0400, "Maynard A. Philbrook Jr." <jamie_ka1lpa@charter.net> wrote:>In article <20140613111344.71d43c28685c2ce51289fd1d@gmail.com>, >c.difficile@gmail.com says... >> >> On 13 Jun 2014 12:24:31 GMT >> Jasen Betts <jasen@xnet.co.nz> wrote: >> >> > On 2014-06-10, Douglas Beeson <c.difficile@gmail.com> wrote: >> > > Hello all, >> > > >> > > I'm back again with an audio zero-cross detection circuit that I >> > > have designed based on valuable feedback from some of you (notably Jim >> > > Thompson and John Fields). I am trying to gate an audio signal while >> > > avoiding clicks as it switches on and off. >> > >> > zero crossing detection won't get you there. >> > interrupting the signal at its steepest slope wont give good results. >> >> I can imagine that switching on voltage zeroes might lead to current surges from the voice coil. I could try detecting current zero crosses. Do you have another suggestion? >> > You would need the circuit monitoring both inputs and waiting for both >to appear at zero at the same time before performing the switch.--- Since a voice coil isn't resistive, good luck with that. ---> The change of that happening is going to cause delay in your switch >depending on how low of level you are sensing. > Even if you did that, you're still going to have issues due to higher >freqs on top of the lower ones.--- No. In a linear system like an audio amplifier, the output will simply be the algebraic sum of the inputs as a function of time. --->You'll get a zero sense for a moment and >do the switch while there is still content in the lower freq spectrum on >the new input, which still leads to noise. I guess if you are dealing >with single tones you would not need to worry, but I don't think that is >the case here.--- The case here (Douglas Beeson's application) is that zero crossings be detected regardless of the speed or direction of the crossing, and that switching occur either on, or very close to, the zero crossing regardless of frequency in the band of interest. ---> The standard method is to slowly reduce gain on input going away while >increasing the gain coming in. This can take place is a very short time. > >Jamie--- If you switch at just the right time and let the mass and viscoelasticity of the loudspeaker's moving parts do the damping, then the attack and decay will be taken care of automatically. Not that it would matter much, but have you taken a look at my circuit? John Fields
Reply by ●June 14, 20142014-06-14
In article <k8eop99lptp74e14q22sfuoeht672vsjjn@4ax.com>, jfields@austininstruments.com says...> --- > The case here (Douglas Beeson's application) is that zero crossings > be detected regardless of the speed or direction of the crossing, > and that switching occur either on, or very close to, the zero > crossing regardless of frequency in the band of interest. > --- > > > The standard method is to slowly reduce gain on input going away while > >increasing the gain coming in. This can take place is a very short time. > > > >Jamie > > --- > If you switch at just the right time and let the mass and > viscoelasticity of the loudspeaker's moving parts do the damping, > then the attack and decay will be taken care of automatically. > > Not that it would matter much, but have you taken a look at my > circuit? > > John Fields > >Yes, I looked it. Jamie
