Alesis Microverb4 Signal Processor

The Alesis MicroVerb4 digital reverb is designed to provide a wide variety of great-sounding, easy-to-use effects for small studios, engineers and performing musicians. The key to MicroVerb 4’s power is in its simplicity.

Reverb Effects
Reverb is made up of a large number of distinct echoes, called reflections. In a natural acoustic space, each reflection’s amplitude and brightness decays over time. This decaying action is influenced by the room size, the location of the sound source in the room, the hardness of the walls, and many other factors. The MicroVerb 4 offers the following types of reverberation:

• Concert Hall (Programs 00-09, 100-109) This is a simulation of a large concert hall. Halls tend to be large rooms with lots of reflective surfaces, where sounds can swim around, changing timbre over time. This is a classic reverb which sounds good on just about anything. Try it on vocals, drums, acoustic, electric, or orchestral instruments.
• Real Room (Programs 10-19, 110-119) This algorithm gives you the sound of a medium size studio room. This algorithm uses a lot of processing power for a rich sound and smooth decay. It has a punchier, bigger sound than a Hall reverb, which makes it good for Rock and Dance music. The attack is also more reflective. It sounds good on drums, keyboards and guitars. This type also includes Nonlinear, Gated, and Reverse reverbs. for percussion and effects.
• Plate Reverb (Programs 20-29, 120-129) This is a simulation of a classic echo plate, a 4′ by 8′ suspended sheet of metal with transducers at either end used to produce reverb. Popular in the 1970’s, it still prized for its transparent sound, particularly on vocals and guitars. It works well for a lush lead vocal, piano, or guitar, especially when looking for a classic rock and roll sound.

Chorus/Flange Effects (Programs 30-49, 130-149)
The Chorus and Flange effects alter the pitch and delay of a signal in various ways to produce “layered” timbres that are more complex than the original signal. Although MicroVerb 4 Reference Manual 23Chapter 3 – Overview of Effects some of these effects can sound similar to one another depending on the parameter settings, each is achieved differently and can be quite dramatic under the right circumstances.

Pitch effects are achieved by splitting the signal into at least two parts, effecting the pitch of one of the parts, then mixing them back together. This eventual mixing is essential since the overall sound of the effect is achieved by the difference between the dry, uneffected signal and the effects signal. Therefore, when using Chorus or Flange, it’s best to keep the Mix control around 50%. Also included in this bank is Auto Pan, which pans a mono signal from Left to Right. This type of effect works best with the Mix control set 100% wet. The various types of Chorus and Flange are:

• Stereo Chorus The Chorus effect is achieved by splitting the signal into three parts with a dry signal and a separate Detuning section for both left and right channels. The detuning is further effected by being modulated by an LFO (low frequency oscillator) which causes the detuning to vary. Many variables are available in this scheme: the Predelay can be varied, the LFO depth can be varied, the LFO speed can be varied, and a portion of the detuned signal can be fed back to the input to increase the effect. Finally, the waveform shape of the LFO can be changed from a smooth sine wave, to a more abrupt squarewave to make the pitch detuning more pronounced. Some of the MicroVerb 4’s Choruses have individual LFOs controlling the Left and Right sides, set at different rates. These effects, called True Stereo Choruses, often have a wider stereo image than regular Stereo Chorus effects. When the Rate is changed on a True Stereo Chorus, the frequency difference between the Left and Right sides is maintained. Note: These Choruses process the Left and Right sides individually, so any stereo imaging will be maintained.
• Quad Chorus Quad Chorus modulates four delayed signals, each with its phase offset by 90∞ gives you twice as much modulation effect as the Stereo Chorus, so it’s great for really fattening up a sound.
• Chorus This is a less processor intensive version of the Stereo Chorus, used in Multi Effect configurations. The effect of Chorusing is achieved by splitting and slightly delaying one part of the signal, then varying the time delay with an LFO. The delayed signal is then mixed back with the original sound to produce a thicker, warmer sound.
• Stereo Flange First used in the 1960s, “flanging” was achieved by the use of two tape recorders that would record and play back the same program in synchronization. By slowing down one tape machine, and then letting it catch up with the other, different phase cancellations would occur at different frequencies. Since the slowing down of the tape machines was done by hand pressure against the flanges of the tape supply reels, the term “flanging” came into being. Flanging is similar to chorusing , but modulates the delayed signal over a much shorter delay range (typically 0-12 ms). This produces a “jet airplane”-like sound. The flange modulation sweep can be triggered by the audio input (either the left or right input, or both), in order to sync up with the rhythm of your playing. In the case of the Stereo Flange, the signal is split into four parts with a stereo dry signal and a separate Delay section for both left and right channels with one channel flanging up while the other channel flanges down. Once again, this causes the effect to become more pronounced and dramatic. True Stereo Flanges have individual LFOs controlling the Left and Right sides for a wider stereo image. Some of the Flange Programs reset their LFO every time the input level passes a set threshold. These are called Triggered Flanges, and are useful for sweeping effects that move in time with the music or part. If the flange is retriggered in the middle of its sweep, this may cause a thumping or popping effect. This is not a malfunction of the MicroVerb 4. If you set the input volume properly ( retriggering will occur when the input signal crosses -6dBv on the input meters), the flanger will only retrigger for attacks and produce a smooth, sweeping sound.
• Auto Pan The Auto Pan effect alternates the loudness of the signal in opposite channels at a definable rate. This effect may be triggered by the input signal (either the left or right input, or both). It can also be used for Tremolo effects, creating a fast panning effect for surf guitar. Edit A controls the speed of the panning effect and Edit B controls the width of the pan. When using the Auto Pan effect, the MicroVerb 4 should have its effects mix 100% wet with no direct signal mixed in to avoid phase problems.

Delay Effects (Programs 50-59, 150-159)
Delay is a discrete echo repeat, unlike the rapid wash of repeats that create reverb effects. It is useful for adding depth to a track or performance if a reverb is muddying up the mix. There are several types of Delay in the delay bank:

• Mono Delay This subtype provides a delay of up to 1270 ms. The delay time can be adjusted separately by 10 millisecond increments. Feedback is also available to increase the
• number of delay repeats.
• Stereo Delay This Single Configuration provides two separate delays. Typically, the Edit A knob controls one side, and the other changes in proportion. The delay time can be adjusted separately by 5 ms increments.
• Ping Pong Delay So called because the output bounces from left to right in stereo with the speed determined by the delay time. The delay can be adjusted in 5 ms increments, and feedback is adjustable from 0-99%.
• MultiTap Delay This is like having three delays at once. They are usually arranged in a rhythmic delay pattern. The Edit A knob scales all of the delay times so that you can make the delay rhythm fit the tempo of a song.

Pitch Shifter Effects (Programs 60-69, 160-169)
The Pitch shifter in the MicroVerb 4 takes the Pitch of the input signal and shifts it higher or lower by a fixed amount. Pitch shifters are useful for creating instant parallel harmonies and for creating subtle chorusing effects. The Pitch Shifters in the MicroVerb 4 include:

• Stereo Pitch Shifter The Pitch Shifter effect transposes the pitch of the incoming signal by a fixed amount. It is useful for creating parallel harmonies, detuning, chorusing, and special effects. The Semi (Edit A) parameter shifts the pitch in increments of one half step, with a range of up or down one octave. The Fine (Edit B) parameter detunes the signal in very fine increments, with a range of up or down one half step.
• Stereo Pitch Detuner The Pitch Detuner has a range of plus or minus one half step in increments on 1 cent. It is useful for a slight chorus effect or for Half step shifts. The Shift L (Edit A) and Shift R (Edit B) parameters control the shift of the Left or Right output.

Multi Effects (Programs 70-89, 170-189)
There are several Multieffect Programs in the MicroVerb 4. A multieffect can be simply described as 2 or three effects at once. This typically involves a pitch effect with reverb, such as Stereo Chorus into a Hall, or something more esoteric such as Lezlie into a room.

• Lezlie With the Lezlie effect , the pitch change block becomes a rotating speaker simulator. This effect was extremely popular during the 1960’s and was achieved by mechanically rotating the speakers to produce complex timbral changes. The Lezlie speaker system is most often used with tone-wheel organs, but is occasionally used for guitar amplification as well. When changing the speed between fast and slow, the effect will ramp rather than change abruptly, just as a true Lezlie speaker system would do.

Dual Send Effects (Programs 90-99, 190-199)
The Dual Send programs all have two different effects. These effects are each fed by one of the inputs so that they can be used independently. This is an ideal setup for someone using the MicroVerb 4 with a mixer. By hooking two of the Aux Sends into the Left and Right inputs of the MicroVerb 4, you can use it to provide two discrete effects. Some of the multi effects include:

• Reverb/Delay The Left Input of the MicroVerb 4 feeds a Room reverb and the Right Input feeds a Mono Delay. The Edit A knob controls Reverb Decay (displayed in seconds) and the Edit B knob controls Delay time (also in seconds).
• Reverb/Chorus The Left input again feeds a Room reverb, and the Right side feeds a Stereo Chorus. The Edit A knob controls Decay time (in seconds) and the Edit B knob controls Chorus Rate (in Hertz). This Dual send Chorus has two individual LFOs panned hard left and hard right for a wide sound, and when the rate is changed the difference between the two rates will stay constant.
• Reverb/Flange The Left input again feeds a Room reverb and the Right input feeds a Stereo Flanger. Edit A controls the Reverb Time (in seconds) and Edit B controls the Flanger Rate (in Hertz).