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From: MooseFET on 29 Mar 2010 09:57 On Mar 28, 11:27 am, Jan Panteltje <pNaonStpealm...(a)yahoo.com> wrote: > On a sunny day (Sun, 28 Mar 2010 19:05:29 +0100) it happened "markp" > <map.nos...(a)f2s.com> wrote in <819jqmFpt...(a)mid.individual.net>: > > >I think the best solution would be to do what another poster suggested, use > >an A2D on a processor, sample into a buffer and play the buffer back through > >a D2A at twice the sampled rate. This would of cource last 1/2 the time, so > >you would need to 'repeat' sections. To get the distortion down you'd choose > >zero crossing points in the waveform and repeat small sections. It's going > >to add some distortion but that's the best I can come up with. > > >Mark. > > I think: > audio -> ADC -> n byte audio sample -> fft -> modify spectral components -> reverse fft -> DAC -> audio > > A bit like I do here for video: > http://panteltje.com/panteltje/subtitles/lowpass.html I just had an interesting idea. Since we are trying to double the frequencies, the Walsh waveforms would also work. Basically, this makes all the constants in the FFT -1 or +1 no sin() and cos() are needed. You also need to avoid jumps where one FFT ends and the next starts.
From: JosephKK on 30 Mar 2010 21:53 On Sat, 27 Mar 2010 10:00:39 -0700 (PDT), «Leo» <leo2100(a)gmail.com> wrote: >On 26 mar, 12:23, «Leo» <leo2...(a)gmail.com> wrote: >> I want to make a circuit that takes a guitar input signal, and then >> outputs a signal with fundamental and 2nd order harmonic with the same >> level (or arbitrary levels, I want to amplify the two components at >> will). >> >> I figured that there are various ways to do this, but I'm trying to do >> it all analog if possible (since it usually produces more pleasant >> sounds). Plus there are already commercial digital octave doublers, >> and the ones that are analog come as ring modulators (they add more >> components to the signal). The frequency range is 20hz-20khz at worst, >> the available DC source is 9V. >> >> I'm trying to get the 2nd order harmonic by taking the input signal >> through a emitter follower stage, biased so the amplification is >> sufficiently non-linear to produce 2nd order harmonic distortion (and >> a little 3rd). Then to isolate the 2nd harmonic, I thought of >> inverting the input through another signal path and then adding the >> two signals, and hope that the fundamental frequency cancels out. >> While trying to do this in spice, I realized that I'm going to have to >> have some kind of AGC so the two signals hace the same component of >> the fundamental. Designing the AGC has been rather complicated so far. >> So the idea that i had is getting a little bit complicated. >> >> Any help or new ideas would be appreciated. > >In response to all: > >Thanks for the ideas. Some of them are much too complicated or >expensive for the scope I was aiming at. > >The simple techniques with spurious frequencys are already >implemented, and the circuits are available on the web, so I don't >think I would try reinventing the wheel. > >I was just trying to implement my original idea, but it doesn't seem >to be an easy task and I don't think it would be reliable in the end. > >So, could I arrive to the conclusion that getting a 2nd order harmonic >from an audio source is not a trivial task (with as little distortion >as possible)? I have an idea that is all analog and just reachable for DIY. I need to set up a simulation and see if i can get it to do what i think it will. If it works the way i think it might, it will do a real neat octave trick. I'll be back when i get my SPICE simulation done.
From: Jim Thompson on 30 Mar 2010 21:59 On Tue, 30 Mar 2010 18:53:42 -0700, "JosephKK"<quiettechblue(a)yahoo.com> wrote: >On Sat, 27 Mar 2010 10:00:39 -0700 (PDT), �Leo� <leo2100(a)gmail.com> wrote: > >>On 26 mar, 12:23, �Leo� <leo2...(a)gmail.com> wrote: >>> I want to make a circuit that takes a guitar input signal, and then >>> outputs a signal with fundamental and 2nd order harmonic with the same >>> level (or arbitrary levels, I want to amplify the two components at >>> will). >>> >>> I figured that there are various ways to do this, but I'm trying to do >>> it all analog if possible (since it usually produces more pleasant >>> sounds). Plus there are already commercial digital octave doublers, >>> and the ones that are analog come as ring modulators (they add more >>> components to the signal). The frequency range is 20hz-20khz at worst, >>> the available DC source is 9V. >>> >>> I'm trying to get the 2nd order harmonic by taking the input signal >>> through a emitter follower stage, biased so the amplification is >>> sufficiently non-linear to produce 2nd order harmonic distortion (and >>> a little 3rd). Then to isolate the 2nd harmonic, I thought of >>> inverting the input through another signal path and then adding the >>> two signals, and hope that the fundamental frequency cancels out. >>> While trying to do this in spice, I realized that I'm going to have to >>> have some kind of AGC so the two signals hace the same component of >>> the fundamental. Designing the AGC has been rather complicated so far. >>> So the idea that i had is getting a little bit complicated. >>> >>> Any help or new ideas would be appreciated. >> >>In response to all: >> >>Thanks for the ideas. Some of them are much too complicated or >>expensive for the scope I was aiming at. >> >>The simple techniques with spurious frequencys are already >>implemented, and the circuits are available on the web, so I don't >>think I would try reinventing the wheel. >> >>I was just trying to implement my original idea, but it doesn't seem >>to be an easy task and I don't think it would be reliable in the end. >> >>So, could I arrive to the conclusion that getting a 2nd order harmonic >>from an audio source is not a trivial task (with as little distortion >>as possible)? > >I have an idea that is all analog and just reachable for DIY. I need to >set up a simulation and see if i can get it to do what i think it will. >If it works the way i think it might, it will do a real neat octave trick. >I'll be back when i get my SPICE simulation done. You can certainly double the frequency of a single sinusoid with a multiplier, but you'll get a real mess with music and its chords. ...Jim Thompson -- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | The only thing bipartisan in this country is hypocrisy
From: JosephKK on 30 Mar 2010 22:22 On Tue, 30 Mar 2010 18:59:41 -0700, Jim Thompson <To-Email-Use-The-Envelope-Icon(a)On-My-Web-Site.com> wrote: >On Tue, 30 Mar 2010 18:53:42 -0700, >"JosephKK"<quiettechblue(a)yahoo.com> wrote: > >>On Sat, 27 Mar 2010 10:00:39 -0700 (PDT), «Leo» <leo2100(a)gmail.com> wrote: >> >>>On 26 mar, 12:23, «Leo» <leo2...(a)gmail.com> wrote: >>>> I want to make a circuit that takes a guitar input signal, and then >>>> outputs a signal with fundamental and 2nd order harmonic with the same >>>> level (or arbitrary levels, I want to amplify the two components at >>>> will). >>>> >>>> I figured that there are various ways to do this, but I'm trying to do >>>> it all analog if possible (since it usually produces more pleasant >>>> sounds). Plus there are already commercial digital octave doublers, >>>> and the ones that are analog come as ring modulators (they add more >>>> components to the signal). The frequency range is 20hz-20khz at worst, >>>> the available DC source is 9V. >>>> >>>> I'm trying to get the 2nd order harmonic by taking the input signal >>>> through a emitter follower stage, biased so the amplification is >>>> sufficiently non-linear to produce 2nd order harmonic distortion (and >>>> a little 3rd). Then to isolate the 2nd harmonic, I thought of >>>> inverting the input through another signal path and then adding the >>>> two signals, and hope that the fundamental frequency cancels out. >>>> While trying to do this in spice, I realized that I'm going to have to >>>> have some kind of AGC so the two signals hace the same component of >>>> the fundamental. Designing the AGC has been rather complicated so far. >>>> So the idea that i had is getting a little bit complicated. >>>> >>>> Any help or new ideas would be appreciated. >>> >>>In response to all: >>> >>>Thanks for the ideas. Some of them are much too complicated or >>>expensive for the scope I was aiming at. >>> >>>The simple techniques with spurious frequencys are already >>>implemented, and the circuits are available on the web, so I don't >>>think I would try reinventing the wheel. >>> >>>I was just trying to implement my original idea, but it doesn't seem >>>to be an easy task and I don't think it would be reliable in the end. >>> >>>So, could I arrive to the conclusion that getting a 2nd order harmonic >>>from an audio source is not a trivial task (with as little distortion >>>as possible)? >> >>I have an idea that is all analog and just reachable for DIY. I need to >>set up a simulation and see if i can get it to do what i think it will. >>If it works the way i think it might, it will do a real neat octave trick. >>I'll be back when i get my SPICE simulation done. > >You can certainly double the frequency of a single sinusoid with a >multiplier, but you'll get a real mess with music and its chords. > > ...Jim Thompson I have something rather different in mind. I need (multiply tuned) tank circuits in the megahertz region and other kinds of circuits.
From: Jim Thompson on 30 Mar 2010 22:26
On Tue, 30 Mar 2010 19:22:40 -0700, "JosephKK"<quiettechblue(a)yahoo.com> wrote: >On Tue, 30 Mar 2010 18:59:41 -0700, Jim Thompson <To-Email-Use-The-Envelope-Icon(a)On-My-Web-Site.com> wrote: > >>On Tue, 30 Mar 2010 18:53:42 -0700, >>"JosephKK"<quiettechblue(a)yahoo.com> wrote: >> >>>On Sat, 27 Mar 2010 10:00:39 -0700 (PDT), �Leo� <leo2100(a)gmail.com> wrote: >>> >>>>On 26 mar, 12:23, �Leo� <leo2...(a)gmail.com> wrote: >>>>> I want to make a circuit that takes a guitar input signal, and then >>>>> outputs a signal with fundamental and 2nd order harmonic with the same >>>>> level (or arbitrary levels, I want to amplify the two components at >>>>> will). >>>>> >>>>> I figured that there are various ways to do this, but I'm trying to do >>>>> it all analog if possible (since it usually produces more pleasant >>>>> sounds). Plus there are already commercial digital octave doublers, >>>>> and the ones that are analog come as ring modulators (they add more >>>>> components to the signal). The frequency range is 20hz-20khz at worst, >>>>> the available DC source is 9V. >>>>> >>>>> I'm trying to get the 2nd order harmonic by taking the input signal >>>>> through a emitter follower stage, biased so the amplification is >>>>> sufficiently non-linear to produce 2nd order harmonic distortion (and >>>>> a little 3rd). Then to isolate the 2nd harmonic, I thought of >>>>> inverting the input through another signal path and then adding the >>>>> two signals, and hope that the fundamental frequency cancels out. >>>>> While trying to do this in spice, I realized that I'm going to have to >>>>> have some kind of AGC so the two signals hace the same component of >>>>> the fundamental. Designing the AGC has been rather complicated so far. >>>>> So the idea that i had is getting a little bit complicated. >>>>> >>>>> Any help or new ideas would be appreciated. >>>> >>>>In response to all: >>>> >>>>Thanks for the ideas. Some of them are much too complicated or >>>>expensive for the scope I was aiming at. >>>> >>>>The simple techniques with spurious frequencys are already >>>>implemented, and the circuits are available on the web, so I don't >>>>think I would try reinventing the wheel. >>>> >>>>I was just trying to implement my original idea, but it doesn't seem >>>>to be an easy task and I don't think it would be reliable in the end. >>>> >>>>So, could I arrive to the conclusion that getting a 2nd order harmonic >>>>from an audio source is not a trivial task (with as little distortion >>>>as possible)? >>> >>>I have an idea that is all analog and just reachable for DIY. I need to >>>set up a simulation and see if i can get it to do what i think it will. >>>If it works the way i think it might, it will do a real neat octave trick. >>>I'll be back when i get my SPICE simulation done. >> >>You can certainly double the frequency of a single sinusoid with a >>multiplier, but you'll get a real mess with music and its chords. >> >> ...Jim Thompson > >I have something rather different in mind. I need (multiply tuned) tank >circuits in the megahertz region and other kinds of circuits. OK :-) I've done sub-bass stuff for boom boxes, by using 1/2 octave filters at the low end, digital DIV2, then reconstruct the envelope. Sounds good even on Souza, and classical stuff, particularly Beethoven :-) If you've ever done Bobby McGee's in Phoenix, that's my stuff.) ...Jim Thompson -- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | The only thing bipartisan in this country is hypocrisy |