7900s osc

7900s O S C an Amplitude Modulator

version 1.0
In this text, all parameters (sliders) and attributes are colored red.

1. Introduction, the standard AM part 2. Pulsewidth for pulse-shape 3. Modulation of frequency part 4. Modulation of amount part (least important feature) | 5. Stereo phase part 6. Attributes 7. Links and gossip

# 1. Introduction, the standard AM part

What is Amplitude Modulation ?
Straight forward, Amplitude Modulation means: Volume Variation.
A standard Amplitude Modulator has the following three features:
1. The variation speed can be controlled by asigning: the frequency (also called LFO frequency).
2. The variation can also be giving a certain shape, the way the volume is changed (also LFO shape), the shapes are:
100% dry (no shape, but this turns the AM off), saw, -saw, tri, pulse, sine.
3. Finally you can set the amount of which the volume is modulated.
Amount = 100% means the volume can change from 0 to 100 %
Amount = 60 % (for example) means the volume can change from 40% to 100%
Amount = 0 % means the volume keeps on 100% (same as 100% dry)

# 2. Pulsewidth

When the shape 'pulse' is chose, one so called period exists of
a part with 100% volume, and a part with (100 - amount) % volume.
When pulsewidth is set to bigger than 50%, then the part with 100% volume gets bigger and
when pulsewidth is set to less than 50%, then the part with 100% volume get smaller.

# 3. Modulation of frequency part

This part has 3 parameters (sliders).
It makes the main-frequency (mentioned above) go a bit slower and then back to the speed it is set on
(just like when you're moving the main-frequency slider yourself), with the value of main-frequency as the right-end.
1. With freq-of-freq you can alter the rate with which the main-frequency is modulated / changed.
2. With fof shape you can set the way this change manifests itself. Look at it as the way you would move the
main-frequency slider to the left and back, this is how the different shapes behave:
none turns off the modulation of the main-frequency
saw will act as if the slider quickly jumps to the left and then is drawn to the right (at constant speed).
-saw just the opposite of saw
tri (triangle) will act as if the slider is drawn to the left and back at a constant speed
pulse will let the main-frequency jump to the left and back
sine same as tri but smoother
3. With fof amplitude you can set the influence that this frequency-of-frequency (and shape) has on the main-frequency.
0 % means no influence, 100% means a lot influence.
Using these parameters with those mentioned in (4) will make the sound shitty, so it's not recommended.

# 4. Modulation of amount part (least important feature)

This part has 3 parameters (sliders): freq-of-amount, foa shape and foa amplitude.
It makes the main-AM-amount (mentioned above) more, or makes it less.
It works the same way as the parameters in (3), but now it doesnt change the main-frequency, but the main-AM-amount.
Using these parameters with those mentioned in (3) will make the sound shitty, so it's not recommended.

# 5. Stereo phase part

stereo phase, phase difference between left and right stereo channels.
Instead of doing the same with both stereo channel at the same time, it does the same but now on a other time.
Because this effect does AM, a channel has: a period of loud sound, and a period of soft sound.
When both channels are IN PHASE (at 0% or 100% of 2 PI) these periods are exactly on the same time. When you shift the phase, these periods happen
at another time. Maximum phase-difference (at 50% of 2 PI) means that the channels do the opposite.

6. Attributes

divider [slow down] frequency : Can be set in the attribute dialog (right click on machine), ranges from 500 to 5000 (default = 2000). It sets the frequency range of all three LFO's. The higher the value, the slower the LFO can go.

7. Links and gossip

This effect works with the soft-studio BUZZ www.jeskola.com , get other effects at www.BuzzMachines.com
You can send me some mail if you like at: jvdlubbe@kabelfoon.nl .
or some of your music on cd:
Jochem vd. Lubbe
Flothuisstraat 8
2692 CM
's-Gravenzande
The Netherlands
Thanx and greetz:
MvA, Zephod, Thev, Hymax, Apo, SurfSmurf, ofcourse Oskari for making Buzz
and all others at EFnet's #buzz and #buzzdev