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Way to get quadrature oscillators sine and cos direct instead of signals multiplied by them and merged

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All the talk down below about frequency shifters and pitch shifders has got me thinking. BTW I don't think we can call the SingleSideBandRM a true frequency shifter because it doesn't user the Hibert transfer and the 90deg phase shifter inside doesn't shift all frequencies by 90Degs. It can be used if your not to worried about acurate results and if the ltency the Hilbert introduces is too much.

What I want to do is make a frequency shifter but back to front i.e. quadrature oscilator first and Hibert at the end.

Now why would I want to do it that way round? because I can have many different signals shifted by different amounts with there own quardriture oscilator and mixed together (as a real image pair) but have just one Hilbert at the end post mix.

I was thinking of my resosynth with generated string type sound (among others) but it always gave the harmonics in perfect tune to each other. Pianos and real world stringed instruments don't. So if I use a frequency shifter I can detune the harmonics after the event, but this puts the resosynth fundementals out of tune. So the solution is to make the Poly phonic resosynth out of tune in the opposite direction before hand. also if we doubled up the resosynth tone generators and mixed the As together and Bs together and pitch shifted then seperatly. also high noe would probably want a diferent amount of shift as low notes so they could be dynamicaly allocated through the approprate quadriture oscilator.

So on to the problem. The quadrature oscilator monos up the output and doesnt keep the sine mod and cos mod seperate (for feeding the Hilbert). There is a new complex multiply in the prototypes  which could do the multiplying part if I could get the sine and cos out of the quadrature oscilator seperatly. My solution in the past is to use two Quad oscilators and keep the controls identical and on one put constant one on the left input, and zero on the right and on the other put constant zero in the left and one on the right. This sort of teases out the sin and cos from the quadrature, but it's not very elegant and will need a lot of wires and doubling up of the controls to implement in a big system. Is there a way to get a sine and phase locked cos out of one module or may be two modules without doubling up on the cotrols to keep then in sync. Or is there a way to remove the monoing mixer insider the quad osc module?

I hope this makes sense

thanks Pete


asked Jun 23, 2018 in Sound Design by pete-johnston (Practitioner) (670 points)

1 Answer

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Hi Pete, If you look at the ComplexProduct prototype, the lower branch is a stereo signal with Cosine on the left and Sine on the right. That should give you the complex oscillator that you need.
answered Jun 24, 2018 by ssc (Savant) (120,590 points)
So does the complex product contain an oscilator aswell?