Behringer UB-Xa User Manual - Page 8

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UB-Xa User Manual

Switching on neither (both LEDs off) selects a Triangle waveform.

(26)

OSC 1+2 PULSE WIDTH

– sets the width of the pulse when the Pulse

wave is selected on either or both VCOs.

When fully to the left (CCW) a

square wave is produced where the up and down cycles are equal.

Turning

the control further to the right (CW) decreases the amount of the up cycle,

producing a thinner effect.

At all levels below the maximum Pulse Width

Modulation will vary the waveform.

Holding the Pulse button (25 or 31) for either Osc 1 or Osc 2 allows the

pulse width control 26 to affect each oscillator separately.

(27)

SYNC

– causes the wave of oscillator 2 to reset at the same time as that

of oscillator 1; giving a harmonically rich but sometimes glitchy effect,

particularly when used in conjunction with F-env.

(28)

F-ENV

– allows the filter envelope (see below) to change the pitch

of oscillator 2, producing a distinctive effect as oscillator 2 attempts

to synchronize with oscillator 1.

The depth is controlled by the Filter

Modulation control.

(29)

OSC 2 FREQUENCY

– sets the base frequency of oscillator 2 in semitone

steps over five octaves.

This allows oscillator 2 to be offset against

oscillator 1.

(30)

SAW

– switches on Sawtooth waveform for oscillator 2 (Saw LED on).

(31)

PULSE

– switches on Pulse waveform for oscillator 2 (Pulse LED on).

Switching on neither (both LEDs off) selects Triangle waveform.

Filter Section

The filter is the way that the UB-Xa shapes the sound produced by the VCOs to

control their timbre.

The UB-Xa has two switchable Low Pass Filters (LPF):

a

24 dB/octave 4-pole filter which gives a fuller sound, and a 12 dB/octave 2-pole

which gives a smoother sound.

(32)

FREQUENCY

– controls the amount of high frequencies that are allowed

through the filter.

When the control is fully to the left (CCW) no sound

will pass (subject to modulation – see below).

As the frequency control is

turned to the right (CW) an increasing amount of high frequency is passed,

until once the control is fully to the right (CW) there is no filtering at all;

and all frequencies can be heard.

(33)

RESONANCE

– also known as ‘Q’ or Emphasis, Resonance increases the

prominence of frequencies centered around the position of the Frequency

control.

In 2-pole mode the overall patch will get louder; in 4-pole mode

it will reduce in volume.

The filter will self-oscillate in either mode,

depending on the Atrophy settings in the Voice menu.

(34)

MODULATION

– controls the amount of modulation from the Filter

Envelope that is applied to the filter.

This control also controls the amount

of Filter Envelope that is applied to oscillator 2 when the F-Env button is

used.

(35)

NOISE

– allows the output of the Noise Generator to be routed to the filter.

When the control is fully to the left (CCW) no noise will be heard.

Turning

the control to the right (CW) increases the amount of noise heard until the

control is fully to the right (CW) where the noise is at its highest level.

(36)

OSC 1

– allows the signal from oscillator 1 to be routed to the filter at full

volume.

(37)

OSC2 Half

– allows the signal from oscillator 2 to be routed to the filter at

approximately half the level of oscillator 1 (- 6 dB).

(38)

OSC2 Full

– allows the signal from oscillator 2 to be routed to the filter at

the same level as that of oscillator 1.

(39)

4 POLE

– when this switch is on (LED lit) the filter is working in 4-pole

mode, as described above.

When it is off then 2-pole is used.

(40)

TRACK

– when this switch is on the keyboard voltage is applied to the

filter, resulting in higher notes sounding brighter, particularly if the

frequency control is set low.

Envelope Section

The UB-Xa has two envelope generators, which allow the patch of the filter

and the amplitude of the Voltage Controlled Amplifier to be contoured.

Both

Envelope Generators feature four stages of contouring.

Filter Envelope

The Filter Envelope controls the contour of the filter when in use.

Its effect will

be more obvious if the frequency control is set low.

There are four controls

associated with this Envelope Generator:

(41)

ATTACK

– controls the time taken for the envelope generator’s level to rise

from zero to maximum.

The UB-Xa’s attack is adjustable between 7ms and

13 seconds.

(42)

DECAY

– controls the time taken for the envelope generator’s level to fall

from maximum to the level set by the Sustain control (see below) once the

Attack stage has finished, and providing that keys are being held.

The time

is adjustable between a minimum of 9ms and a maximum of 16.5 seconds.

(43)

SUSTAIN

- controls the level at which the filter will be held once the Decay

cycle has completed and providing that keys are still being held.

There

is no time limit to Sustain.

It should be noted that a high Sustain setting

(above 50%) will cause the Decay stage to have little or no effect.

(44)

RELEASE

– controls the rate at which the envelope generator’s level drops

to zero once keys are released.

It should be noted that if Sustain is set to

minimum the Release control will have no effect if keys are held down; but

if keys are released during Attack or Decay then Release will still affect the

filter.

Release time can be adjusted between a minimum of 50ms and a

maximum of 20 seconds.

The Filter Envelope also affects the pitch of oscillator 2 when the OSC2

F-Env switch is active.

Loudness Envelope

The Loudness Envelope controls the level of the UB-Xa’s output (subject to the

position of the Volume control).

Like the Filter Envelope it has four controls:

(45)

ATTACK

– controls the time taken for the envelope generator’s level to rise

from zero to maximum.

The shorter the attack, the punchier the patch.

The UB-Xa’s attack is adjustable between 7ms and 13 seconds.

(46)

DECAY

– controls the time taken for the envelope generator’s level to fall

from maximum to the level set by the Sustain control (see below) once

the Attack stage has finished, and providing that keys are being held.

As

with Attack the shorter the decay, the punchier the patch.

The time is

adjustable between a minimum of 9ms and a maximum of 16.5 seconds.

(47)

SUSTAIN

– controls the level at which the VCA will be held once the Decay

Behringer UB-Xa User Manual - Page 8

Filter Envelope Filter Envelope, Loudness Envelope - release

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