Sample and Hold? Sample and Gate?

[daffy]

Hi

Does anyone know what the S+H in the LFO section does? Does it stand for Sample and Hold? It appears that on each cycle of the LFO, a "snap shot" of another signal is taken. However cannot seem to figure out what is being sampled in the sample and hold cycle.

Also the same question for the S+G in the LFO section?

[Onkel Dunkel]

S&H means "sample and hold". The LFO will shift between random values in steps with the speed of the rate setting making a random stepping of whatever parameter the LFO is controlling.

S&G means "sample and glide" and is the same as S&H except that instead of shifting between the values in steps it glides between them making random smooth shifts of the parameter controlled.

I?m not sure what they mean by "sample". Perhaps it?s because it samples a random value and either holds it (S&H) or glides to it from the previous value (S&H)

[daffy]

Hi Onkel Dunkel

Thanks for the reply.

I guess this provides a similar function to the "Random" in the Matrix section.

Re Sample and Hold, on some old analog Control Voltage synths it is possible to set up a patch as follows:

The first LFO has CV and Gate outputs. The Gate output of the first LFO drives the gate input of a sample and hold module. A slow moving

waveform such as that from a second LFO is fed to the signal input of the Sample and Hold module. The output of the Sample and Hold module

drives the CV (Pitch) input of an oscillator. This oscillator's audio output then goes out through a typical ADSR section to the output mixer. The

gate signal of the first LFO is also used to trigger the ADSR envelope. This creates a simple sequence of notes which have a more interesting

musical form than purely random notes. Putting Portmento between the Sample and Hold and the oscillator CV input gives glide. Quantinzing it

to the standard one volt per octave gives a chromatic scale. The sequencing possibilities are endless.
It would be nice if it was possible to have some control over the signal that is being sample and held by the LFO in the Virus TI or be able to

sample and hold an exteranl signal. Not sure if this is possible on the Virus.

Regards Daffy

[Onkel Dunkel]

Originally Posted by daffy

Hi Onkel Dunkel

Thanks for the reply.

I guess this provides a similar function to the "Random" in the Matrix section.

Re Sample and Hold, on some old analog Control Voltage synths it is possible to set up a patch as follows:

The first LFO has CV and Gate outputs. The Gate output of the first LFO drives the gate input of a sample and hold module. A slow moving

waveform such as that from a second LFO is fed to the signal input of the Sample and Hold module. The output of the Sample and Hold module

drives the CV (Pitch) input of an oscillator. This oscillator's audio output then goes out through a typical ADSR section to the output mixer. The

gate signal of the first LFO is also used to trigger the ADSR envelope. This creates a simple sequence of notes which have a more interesting

musical form than purely random notes. Putting Portmento between the Sample and Hold and the oscillator CV input gives glide. Quantinzing it

to the standard one volt per octave gives a chromatic scale. The sequencing possibilities are endless.
It would be nice if it was possible to have some control over the signal that is being sample and held by the LFO in the Virus TI or be able to

sample and hold an exteranl signal. Not sure if this is possible on the Virus.

Regards Daffy

I think random in the MOD section means that the source is picked random from the possible sourches. At least it doesn?t act the same way as S&H. I tried routing a random source to the LFO1 rate and it seems that it only changes value when a note on is registrered. The manual dosn?t seem to explain this at all

I have no idea how it works on old analog gear but this is snatched from the Virus C manual:

Originally Posted by Virus C manual

- S&H (Sample and Hold) is a structured random modulation. Here random modulation are generated. The value is held until the next beat impulse, then it abrutly jumps to a new random value.

- S&G (Sample and Glide) is a continual random modulation. Here the random values glide seamlessly into one another, the rate of which is determined by random modulation of the rate value.

I don?t know if you can sample and hold and external signal like you say its possible on analog gear. I actually doubt it very much since analog gear works with CV signals and the Virus with MIDI values from 0 to 127. If you have a CV to MIDI converter you might be able to do something similar by converting the CV to a controller value that was used as a source in the mod matrix. Then you would of course have to use a CV signal and not an audio signal