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Author Strange's multiply
ketem13
 In his book Electronic music at page 114 in figure 8.7 the eg is multiply by it self then send to a carrier fm input. I was thinking that a multiple is taking a cv and output it for two signals In the patch it seems that the multiple is taking two different voltage and output the multiple voltage of the two. Is that correct? Can someone explain it to me more in details? If I multiple 5 v and 5v so the output is 25v? This is not sound correct for me.. Thanks
JohnLRice
 I don't have Mr. Strange's book but multiples should mainly be used for patching copies of one signal to multiple destinations. Passive multiples are simply several jacks all wired directly together, like a simple "Y" cord only on a panel. If you need to combine several audio or CV signals into one you should use an active mixer or a logic combiner for gate signals. If you did try to patch two 5v lines into a passive multiple the output would still be 5v.
chamomileshark
 I'm not sure it's talking about a multiple, it says a multiplier and suggests using a balanced modulator. Basically it's talking about ways of not getting a pitch shift when you create an FM patch. Today I think that would be overcome by simply using a linear FM input which many oscillators now have? At least my Blacet and Wiard ones do.
starthief
 He's probably referring to a four-quadrant mulitplier, aka balanced multiplier or ring modulator. Think of it as a range from -1 to 1, where 1 is the maximum voltage of the system (so it's -12V to 12V in Eurorack). The results of multiplying a sine wave by itself in that way would be: (only smoother because I only plotted every 15 degrees)
JohnLRice
 Ahhhh Thanks chamomileshark and starthief!
ketem13
 thanks you all
KSS
 ketem13 wrote: If I multiply 5 v and 5v so the output is 25v? This is not sound correct for me..

Balanced modulators and analog multipliers usually include attenuation to keep the signal output within reasonable limits. There is not only multiplication but also division being performed. A typical value is 5, where the 25V you correctly arrived at is then divided by 5 to become again 5V.

Mixers often do a similar attenuation for the same reason. This is an important design difference between various mixers and multipliers.

For the rest, what chamomileshark said.
AndreasD
 Multiplying (ringmod) a linear envelope with itself results in an exponential envelope. A keyboard cv is linear, multiplied with itself is exponential cv. I guess if you have exp. FM cv input and drive it with an inverted exp. envelope you get linear FM. As chamomileshark said.
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