Kurzweil:x Amp
From Sonikmatter
The x Amp block is essentially a Ring Modulator that is hardwired to the AmpEnv. This block multiplies the signal on the upper wire, by that on the lower wire, all in the time domain.
For pure single frequency samples (ie Sine waves), this creates sidebands at frequency's of A+B and B-A where A and B are the frequency's of the two input signals. The original frequency's of the inputs do not emerge at the outputs, only the sidebands.
This is the effect used to create the Dalek Voices in Dr Who, which should give you some idea of what this effect will do to input samples.
If either of the inputs is silence, then the output will be silence, and similarly if one of the inputs is a DC signal (ie constant non-zero signal) then this block will act in a similar way to the Gain block.
If one of the signals is very low frequency, then this block can be used as a Tremelo effect, with one of the audio waves essentially being an LFO
Care needs to be taken when using this block as the VAST singal path is susceptible to aliasing at high frequency's, and as this block produces frequency sums, it's quite easy to get into aliasing territory.
For a better quality Ring Modulator, try the KDFX:Ring Modulator, which has less aliasing artifacts.
The most musical results are obtained from the x Amp block when harmonically related signals are fed in. Ie if m x B = n x A, where m and n are integers. Bear in mind, however that with Equal Temperament that harmonically related notes such as perfect 4ths and perfect 5ths do not adhere to the rule above, exactly. A perfect forth has a ratio of 1.334840, whereas Ring Modulation works best with 4/3 (or 1.3333333). Similarly the Perfect fifth has a ratio of 1.498307 but works best with 3/2 (or 1.500000).
Fine tuning with the Hz controller on the Pitch page will work well in these cases, or alternatively a different Intonation Table can be used.
At slight deviations from perfect integer relationships (such as a perfect 4th or perfect 5th in Equal Temperament) will result in a Beat Frequency which may, or may not be desired.
At inharmonic or unrelated frequency's of the upper and lower wire, the results from the x Amp and similar blocks will not be pretty. This could be perfect for something like Industrial music.
A popular technique in noise genres and other difficult listening genres is to keep the frequency of one of the inputs of the ring modulator constant and vary the other. This will cause the output to go in and out of harmonic output and can cause some extreme frequency results.
The Puppeteer 02:58, 12 September 2006 (EDT)
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