Kemper KPA Effects

Contents

Mono vs. Stereo

Although Stomps A-D, X, and Mod can all load the same effect types, some of them will function differently depending on placement. The Stomps section is limited to mono effects. Their stereo nature would have to be mixed down to mono to get processed by the Stack section anyway. For such effects, you may notice an extra Stereo Separation parameter when using them in the X or Mod slots. These use various techniques to "widen" their sound. Many effects, such as the Air Chorus and Stereo Widener, will not sound correct unless used as stereo effects.

Delay and Reverb

The KPA's Delay and Reverb blocks are special in that they can only load those types of effects. This is for good reason - the KPA's design treats them special. The wet portion of the combined Delay and Reverb blocks is accessible through the "Delay/Reverb Wet" output option that can be assigned to the Main or SPDIF outputs. Additionally, the Reverb block has a Del./Reverb Balance parameter that greatly simplifies what would otherwise require a complicated routing and mixing setup.

The Delay block outputs a wet (delay trails) and dry (unaffected by Delay) signal to the Reverb block. The Del/Reverb Balance setting chooses the proportion at which the reverb applies to each of these signals. At full left, the reverb applies only to the dry signal, not to the delay trails. At full right, the reverb only affects the delay trails, not the dry signal. At other settings, the reverb applies to both but at different amounts.

This is a powerful control - when used in combination with a 100% wet reverb, you can set it fully right so that the delay trails are washed into a reverb

Tone Controls

Both the Delay and Reverb blocks feature Frequency and Bandwidth settings that affect the frequency response of the blocks. The Bandwidth control is essentially a Q control, narrowing the range of frequencies allowed to pass through as you turn it higher and higher. At 0, it is doing nothing. At max, it is only allowing a very, very narrow range of frequencies through.

These controls function slightly differently in the Delay block vs. the Reverb block. Reverb's can be considered a filter on the wet part of the block's output after all processing. When set to 100% mix, it is the same thing as placing an EQ after the reverb. The Delay controls operate inside the delay's feedback loop. This means that as the same segment of audio repeats over and over, it is filtered more and more each iteration.

This is similar to the Reverb's Dampening control, which darkens the tone of the wet reverb as it decays based upon its Time setting. However, while Dampening can only darken the wet signal over time, the Delay's tone controls can brighten or darken the signal over time.

I find that the most natural sounding delay and reverb tend to darken the tone over time, as well as apply greater reverb to the delay trails than to the dry signal. Thus, I often use the Delay's Bandwidth and Frequency controls set to slightly darken the trails, as well as use the Reverb's Dampening. I set Del/Reverb Balance about 30% right of center. I use the Reverb's Bandwidth/Frequency for any final tonal adjustments.

However, there are numerous unique applications for the interaction of all these controls I attempt to explore below...

MAB Advanced Reverb Effects

A big complaint about the KPA is its lack of great reverb effects, particularly a spring reverb. I attempted to create some advanced reverb presets that fill this void until Kemper adds them. See the MAB Advanced Reverb Presets page.

Differences in Delay Types

There are only 3 delay types, explained below.

Tap Delay uses the tempo on the rig (tapped or manually entered), with separate L/R delay settings defined in terms of 16ths of a beat. This offers the most flexibility between the left and right delays, offering ratios (3:5 or 5:7) that are not found in the other delay types. However, it is not capable of offering repeats as quickly as the other delay types because it is always tied to a tempo setting that cannot go fast enough to allow such.

Free Delay can use the rig's tempo or can be manually specified when tempo is disabled. This offers repeats as short as 1 ms! However, there is only a single Time setting. A Ratio parameter determines the ratio of left repeats to right repeats, with the only options being quarters of the other (1:4, 2:4, 3:4, 4:4, 4:3, 4:2, 4:1).

Analog Delay is the exact same thing as Free Delay, with the exception that if you change the Time parameter while repeats are occurring the repeats are pitch shifted as occurs on an analog delay pedal. There are no tonal differences to this type compared to the other two.

All three Delay types exhibit a tape delay simulation when using Feedback settings around 90% or higher. Anything lower is a straight digital delay.

Tempo Considerations

Tempo can be viewed, locked, changed, and disabled from the Rig block's settings. This mainly affects the Delay block's operation.

When tempo is disabled, the Free and Analog Delays use the Time parameter to determine how quickly they repeat. The Tap Delay uses a default tempo of 120 bpm. When tempo is enabled, the Delays ignore the Time parameter and use the tempo setting. The Tap Delay defines the left and right repeats separately in terms of a beat. The Free and Analog delays use a single Ratio parameter - the beat synchs up to the larger one. For example, a ratio of 1:4 on a 120 bpm tempo means the left delay is set to 30 repeats per minute and the right delay is set to 120 repeats per minute.

Pitch Shifter Options

The KPA offers chromatic and intelligent (harmony) pitch shifting effects, which function like traditional pitch shifters. The Harmony Shifter goes a step beyond and allows custom user scales to harmonize against. But even beyond these functions, the KPA's shifters offer somewhat unique options to adjust how the shifters work:

Smooth Chords

The Smooth Chords option disables the shifter's pitch tracking. Tracking is used to phase align the time-shifted audio segments, so that the resulting audio sounds smooth and natural. This works great for single notes but cannot work correctly for chords. Instead, it may jump between pitches as it detects them or phase-align one pitch while the others in the chord end up sounding more harsh. Smooth Chords prevents these awkward sounds when playing chords.

While Smooth Chords is designed to reduce artifacts when playing chords, it may be useful even for single notes depending on how convoluted the signal chain is. It can also yield more of the artifacts traditionally associated with pitch shifters, that while obvious and artificial, may produce a certain desirable sound.

Pure Tuning

This option harmonizes to the Pure Tuned or Just Intonation intervals instead of the 12-Tone Equal Temperament intervals. This makes the harmonized sound a bit more pleasant and harmonious when mixed with the dry signal, particularly when playing higher up the fretboard. See Equal Temperament and Alternate Tunings for more about temperament and tuning.

Formant

The Formant option enables a formant parameter which defines a resonant peak (formant) in the pitch-shifted part of the signal. Formants determine what the tone sounds like, with the human voice making use of different formants to create the different phonetic sounds of the alphabet, particularly for vowels. Thus, the pitch-shifted sound can become quite different from its normal sound. It can reduce the "Chipmunks" type sound to upwards shifted settings. It can also make the guitar sound like a different instrument altogether.

Emulating Real Devices

Most of the KPA's effects are generic - they are not modeled after specific devices (with the exception being several of the Distortion effects). Instead, they provide lots of parameters to make them fully tweakable. Some devices can be emulated by simply using the right settings for that type of effect. Others may require using multiple KPA effects in combination to get their unique sound. This WiKPA.org page contains lots of settings to emulate real-world effects.

Getting Good Fuzz Sounds

There are numerous complaints on the forums about the fuzz effects. The general advice is to combine a fuzz Distortion effect with a Recti Shaper effect and possibly additional EQ.