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Pearl Effectors

Pearl are the latest Japanese company to offer the musician their idea of the ultimate choice in sound processors. These units are intended to be used with guitar, bass, vocals, keyboards or any other signal which terminates in a ¼" jack plug.

The range is split into two sections; firstly, five 'Sound Splice' processors which include Flanger, Chorus, Phaser, Compressor and Overdrive and secondly, three 'Sound Choice' dual-programme processors Chorus Ensemble, Analogue Delay and Phaser.

Each effect is packaged in a very attractive matt black die-cast aluminium case, the pedal switch being formed in die-cast zinc. The control pots are smooth with positive action, the panel layout is clear and simple, and even the knobs have been specially shaped to feel comfortable between the fingertips and to complement the rounded contours of the case. A 'chunky' rubber pad attached to the base ensures stable operation of the pedal.

Power is supplied, when the input jack is inserted, by the standard PP3 battery or from an optional mains adapter which can be connected via a DC socket at the rear of the case. The pedal is a press-on/press-off type with the electrical switching performed by a CMOS FET circuit, which helps to prevent obtrusive transients caused by mechanical switching. Status indication is provided by a red LED above the switch.

Sound Splice Processors

The pedals may look and feel great but the important thing is, what do they sound like? Starting with the 'Sound Splice' effectors, they performed as follows.


The Flanger uses a 1024 bit bucket-brigade delay (BBD) line to provide a delay of between 1.8 and 20mS. The delayed signal is added to the incoming signal to produce a notch spectrum characteristic of flanging.

Internal view of the Flanger.

All of the range have four parameter controls above the LED. In the case of the Flanger these parameters are: Manual which sets the BBD clock frequency (i.e. delay time) and therefore shifts the centre point of the comb filter, Feedback which adjusts the amount of delayed signal which is reprocessed, and the modulation controls, Speed which can be varied from one cycle every twelve seconds to ten cycles per second and Depth which controls the amount of modulation.

These controls allow a wide range of unusual effects to be obtained, and with careful adjustment can include Phasing, Flanging, Metallic reverb and even Chorus.

The Feedback control has to be set with care, as with most flangers of this type, since settings above seven cause the circuit to oscillate. Setting the pot just before oscillation provides a very deep 'metallic' sound which, when used with no modulation, creates a very interesting 'vocoder' type effect on vocals.


The chorus unit also uses a BBD chain to provide the analogue delay of between 1.8 and 11.5mS. In this application, however, the delay is used to produce pitch modulation or vibrato.

The four controls provided are: Speed of modulation which can be varied from one cycle every three seconds to ten cycles per second, Depth which varies the amount of pitch modulation, Mix Balance which can be adjusted from all input to all effect and Tone which provides treble cut.

The Mix Balance control is very valuable, and when used in conjunction with the Depth control, can produce many pleasing chorus sounds. Care must be taken in setting Depth as the control is rather coarse. It would be better to have less modulation depth available to allow finer adjustment of the chorus effect to be made.

The Tone control is also a useful addition since without noise reduction circuitry the BBD line is noisy.


The Phaser circuitry produces two notches in the output frequency spectrum. When these notches are moved up and down the spectrum the phase cancellations which take place audibly produce the characteristic 'jet-plane' Phaser sound.

The four parameters which can be adjusted are: Manual which adjusts the centre point of the notches in the spectrum, Feedback which increases the peaks and troughs of the notches, and the modulation controls, Speed which can be varied from one sweep every five seconds to ten every second, and Depth which controls the range of the sweep.

The phase effect produced is very warm and mellow suiting many different playing styles. The Feedback and Manual controls are very useful for tailoring the sound but phased circuit noise is evident even with no input signal.


This unit uses a transconductance amplifier to control the gain of the circuit, limiting excessive peaks, such as those found when finger-picking, and amplifying small signals to provide a measure of sustain on decays.

The four controls are: Attack which allows the speed of the compressor action to be adjusted, Tone which provides treble cut, Sustain which controls the extent of compressor operation and Level which obviously adjusts output signal level.

The Compressor works satisfactorily and with the Attack up full creates a very 'punchy' sound.


This is an interesting unit which combines parametric equaliser and distortion circuits. The parametric sections can be configured as a band-pass or band-stop filter.

The controls provided are: EQ Gain which adjusts the filter gain by ±15dB, Frequency which sets the filter centre point between 100Hz and 4kHz, Overdrive which adjusts the level of distortion and Output Level with a gain of 40dB.

The parametric section may be used separately by setting the Overdrive control to zero and adjusting Gain and Frequency to suit. The distortion section can also be used separately by setting the Gain of the equaliser to zero.

The range of effects possible is very wide including an almost 'valve' sound when used with a transistor amplifier, but watch out for noise with the equaliser on full boost at high frequencies.

The complete Pearl Effector range.

Sound Choice Processors

The following three effects belong to the 'Sound Choice' range, which allow two sound settings to be selected with a second footswitch.

Chorus Ensemble

The Chorus Ensemble can be used in two modes. The first, Program I, produces a chorus effect with rate variable between one cycle every fifty seconds to four cycles per second. The second, Program II, features chorus with the same rate range, chorus ensemble (which is chorus with vibrato) and delayed vibrato or delayed ensemble.

The controls provided are: Input Level which should be set with the aid of the Peak LED, Chorus Rate I, Chorus Rate II, Vibrato Depth, Vibrato speed which is variable between 1.5 and 8Hz, and Vibrato Delay (with an integral on/off switch) which varies from 0 to 1.5 seconds. The Program I/Program II status is displayed by an LED above the selection switch.

The programme selection switch is also used as the delayed vibrato trigger when Vibrato Delay is on.

There are two outputs provided on the back panel. When each socket is used individually Output 1 is used for chorus and vibrato and Output 2 for vibrato only. When both sockets are used together Output 2 now becomes an out of phase version of the chorus signal to provide an enhanced stereo image.

The unit can provide some very thick sounds when chorus and slight vibrato are added together. The delayed vibrato feature is very useful for adding expression to sustained notes or chords but the maximum delay time of 1.5 seconds could be extended.

Analog Delay

The Analog Delay unit uses a BBD yet again to provide delays from 20 to 350mS. With this unit the player can select between two delay settings with the program change switch.

The six controls are: Input, used to adjust input signals to below the Peak level, Delay Level which alters the amplitude of the delayed signal, Program I controls; Delay Time I which adjusts the BBD clock frequency and Feedback I, which sets the amount of reprocessed delay signal and Program II controls; Delay Time II and Feedback II.

The two outputs provided are Direct and Effect for use in stereo systems or external mixes.

Internal view of the Chorus Ensemble.

The problem with analogue delays of this type is the compromise which has to be made between delay time and input bandwidth. Pearl seem to have decided that the delay time is more important and have limited the top end of the frequency range to 4kHz to provide a maximum delay of 350mS. As a result the delayed signal tends to sound 'dull' especially with 'bright' signals such as guitar or synthesiser.

However, the unit is quiet in operation, utilising a compander for noise reduction, and for general reverbs or short delays is quite satisfactory.


This box is similar in operation to the Phaser described earlier except that the circuit produces four notches in the output spectrum making the phase effect more pronounced. The unit has similar control parameters except for the Speed which can be adjusted between two settings. Program I is the slow speed which can be varied from one sweep every thirty seconds to three sweeps per second. Program II is the fast speed which can be varied from three sweeps per second to eighteen per second. The rate selected by the programme switch does not change instantaneously but gradually. Therefore switching between speeds produces 'wind-ups' and 'wind-downs' just like those produced by a rotating speaker.

The controls provided are: Input level, to adjust the instrument level below the Peak setting, Manual which adjusts the position of the notches, Feedback which accentuates the depth of the effect by increasing the peaks and troughs of the notches, Depth which sets the amount of modulation, and the programme options; Slow and Fast Speed.

Two outputs are again provided for use with stereo systems. Both outputs contain the dry signal but with phase opposing phase shifted outputs.

Optional Accessories

AC adaptor and Voltage Regulator.

Although all of the boxes have their own internal battery supplies they each have provision for AC adaptors. The 'Sound Splice', processors require 9V while the 'Sound Choice' processors require 12-18V. Pearl supply two adaptors for this purpose the AC-90 and the AC-120.

If you decide to buy several of the small effects you can use one 12V supply in conjunction with the Voltage Regulator VR-5 which provides five 9V outputs from one 12V input. The VR-5 is supplied with all of the connections required.

The three 'Sound Choice' units have provision for external footpedals for remote switching. The FS-1 is a single footswitch and the FS-2 a double. Either of these can be used to provide remote switching which means that the effects box could sit on your amp or somewhere else near to hand for quick and easy setting changes.

Lastly, an Extension Plug EP-1 can be used to create a stereo output from single output effectors, and a specially moulded rubber ring can be supplied to go over any of the control knobs for foot operation — neat idea!



Sound Splice
Input impedance 1M
Output impedance 10k
Dimensions (mm) 57x79x136
Weight (gms) 480

Sound Choice
Input impedance 470k
Output impedance 10k
Dimensions (mm) 180x61x136
Weight (gms) 930

Although Pearl have not introduced any technical innovations in the design of these effects they have produced a range of processors which are well engineered and playable.

Some of the effects tend to be noisy but a trade-off has to be made between the processed signal bandwidth and circuit noise (within reason!).

The voltage regulator, separate adaptor and five supply leads is not really the answer to the power supply problem for stage use. The musician really needs to have some form of interconnection board for both power and signal paths.

Overall the effects offer good value for money, are attractively styled, mechanically sound and, above all, musically creative.


Unit Order Ref. Retail Price
(inc. VAT)
Flanger FG-01 £65 Good for normal flanging sounds and 'weird' metallic effects with manual setting.
Chorus CH-02 £61 Difficult to set a good chorus sound without vibrato, but good range of modulation.
Phaser PH-03 £50 Excellent variable phaser sound due to the inclusion of a feedback control — recommended.
Compressor CO-04 £47 With attack/sustain controls good range of effects can be produced. Excellent for maintaining signal levels without noise.
Overdrive OD-05 £43 Comprehensive distortion unit enhanced with the addition of Parametric EQ.
Chorus CE-22 £114 Very wide range of thickening and Ensemble modulation options with a very expressive delayed vibrato section.
Analog Delay AD-33 £129 Good range of delay parameters but delayed signal sounds less 'bright' than input spoiling the effect.
Phaser PH-44 £97 Our favourite effects pedal in the range with the best electronic simulation of a rotating speaker we've heard.
Voltage Regulator VR-5 £29
9V AC Adaptor AC-90 £8
12V AC Adaptor AC-120 £8
Single Footswitch FS-1 £13
Double Footswitch FS-2 £13

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Casio CT1000P

Electronics & Music Maker - Copyright: Music Maker Publications (UK), Future Publishing.


Electronics & Music Maker - Sep 1982

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