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Yamaha Professional System Effectors


The complete range of Yamaha Effectors.

The new Yamaha PSE, 'Professional System Effectors', range provides the musician with a very versatile signal processing system. The range includes ten effect units, a 'mini-pedal', noise gate, line selector and two flight cases with integral power supplies and patching options.

Each pedal is housed in a smart black diecast box with a large rubber pad covering the base to prevent the pedal slipping under pressure. The supply, provided by a standard PP3 battery, is connected when a jack is inserted into the input socket.

Effect 'on' is indicated by an illuminated LED situated above the input socket. The footswitch, which has been custom designed for the range, inspires confidence in operation as do the controls which are smooth, well positioned with clear legends.

A short description follows, covering each of the units in turn.

An internal view of the Phaser.


Phaser


The Phaser creates a pleasant 'cyclic' effect similar to that produced by a rotating speaker. Two controls are provided, these are Speed, which varies the rate of the phase shifting effect from one cycle every five seconds to ten cycles per second, and Depth which controls the range of the effect.

With no signal present there is no noticeable breakthrough of any phased noise from the circuit, an important point to consider with high power PA systems.

Chorus


The Chorus unit uses a custom bucket-brigade delay line to slightly modulate the pitch of the input. When this is re-mixed with the original signal, a rich moving texture is produced. This is similar in effect to several identical instruments playing the same note. The two parameters which can be adjusted are the Speed and Depth of the triangle wave modulation. The speed ranges from one cycle every three seconds to eight cycles per second. There is the option of a second output for stereo systems and this increases the effect dramatically as the signal appears to move across the stereo field. Some of the high frequency content of the input signal is removed when the unit is switched in, but this is inevitable due to the circuitry employed.

Flanger


The Flanger also uses a bucket-brigade chain to delay the input signal. When this signal is fed back to the input and mixed with the incoming signal an infinite series of notches are created in the frequency spectrum of the output. Audibly, the effect is similar to phasing but with a much deeper, metallic tone colouration. The Flanger has four controls: Manual, which sets the centre point of the comb filter, Feedback which increases the peaks and troughs of the comb (the same effect as resonance on a synthesiser filter), and the modulation controls, Speed, which varies the rate of modulation from one cycle every ten seconds to ten cycles every second, and Depth which controls the range of the modulation.

Effects Common Specifications

Input Impedance 1M
Output Impedance 1k-20k
Noise Level (0dB=775mV) -85dB to -100dB
Dimensions 70 x 65 x 125mm

There is no apparent 'click' when the footswitch is operated and with no input signal the circuit is virtually noiseless. Care must be taken, however, with the settings. When the Feedback control is advanced past seven on a scale of zero to ten, and the Manual frequency control is in the low ranges, self oscillation occurs which can reach a maximum of one volt peak-to-peak. This can be used to great effect to create some penetrating sounds, but can become a bit overpowering.

Although this unit was designed (like all the effects) for the guitarist, it must be one of the most compact and effective flangers available and works equally well on other instruments.

The SB200 stage board in use.


Octaver


The Octaver produces a signal one octave below the input. The input signal is 'squared-off' and then digitally divided by two. This signal is used to 'chop' the input, creating the octave below with similar tonal characteristics.

Three controls are provided, a Direct level, an Effect level and a polarity switch which inverts the effect waveform. Since the circuit must lock on to the fundamental of the incoming signal, only single notes can be played through the Octaver. This waveform must be as 'clean' as possible, so the Octaver should be the first in line if a chain of effect pedals are used. When the input drops below about 6mV, the unit can no longer determine the fundamental and produces the same output from Direct and Effect outputs, however, in normal use this action is not obtrusive as it takes place at the very end of the signal decay.

The unit works very well, producing a 'thick' bassy sound when used with guitar in the low and middle ranges and a powerful solo sound when played 'up the neck'.

Distortion


The Distortion circuit amplifies and 'clips' the input signal. This 'squared-off' signal then passes through a tone network to remove some of the higher harmonics. The three parameters which can be adjusted are: Distortion, which sets the level at which the signal is clipped; Tone, which ranges Soft to Hard and Output level.

Using both the Distortion and Tone in combination allows a large range of effects to be set, from soft 'fuzz' to a real Heavy Metal overload!

Tone Booster


The Tone Booster circuit consists of a pre-amp, tone control network and an output amplifier. There are four controls: Bass which provides +5dB/Oct boost and -8dB/Oct cut at 100Hz; Treble which provides +5dB/0ct boost and -7dB/0ct cut at 2KHz; Gain which has a maximum setting of 41dB, and Output Level.

Circuit noise is noticeable with no input signal present if the Gain and Treble are both set at maximum, so these controls should be used carefully.

Parametric Equaliser


The Equaliser is basically a band-pass or band-stop (notch) filter. The three parameters which can be adjusted are: Gain, which can be set to ±18dB; Frequency which controls the centre frequency of the band, ranging from 110Hz to 3.8kHz; and Band-Width which controls the resonance or 'sharpness' of the band. When the Gain is positive the equaliser has a band-pass characteristic, and when negative it has a band-stop characteristic. (The band-stop mode can be used to prevent acoustic feedback by filtering the related harmonics.) When used with the system board, the centre frequency can be controlled by a voltage from the 'Mini-Pedal' providing a sophisticated wah-wah.

Care must be taken when setting the equaliser. When the Gain is at full boost and the Band-Width set at maximum, circuit noise is noticeable with no input signal present. Operating the footswitch at these settings also tends to make the filter 'pop'.

Compressor


The Compressor uses a current-controlled amplifier to boost small signals and to attenuate large ones, thereby reducing the dynamic range. Three controls are provided: Sensitivity, which controls the rate of the Compressor action; Output Level and a switch to select between two Attack characteristics. The second position is used to emphasise the initial attack, useful for finger-picking.

The Compressor can, therefore, be used to limit excessive signal levels and to provide a measure of sustain to decaying signals.

Limiter


The Limiter is similar to the compressor in the fact that the circuit uses a current-controlled amplifier controlled by an envelope follower for threshold detection. Three controls are provided: Threshold which adjusts the limiter level; Release Time which determines the rate at which the gain is reduced to the threshold and Output Level.

The unit is useful for limiting excessive signal peaks or to smooth out playing variations. The limiting effect is noticeable when playing sustained notes with the Release Time set near its minimum.

The bottom half of a case removed.


Noise Gate


The Noise Gate cuts any undesirable hum or noise below a set threshold, while allowing the main signal to pass through undisturbed.

The two controls are: Threshold which sets the noise 'floor' level and Release Time which sets the rate of the gating action.

The circuit works well but with excessively noisy signals the Release Time must be carefully set to prevent a noticeable 'breathy' control.

Line Selector


The Line Selector is a circuit which switches between two chosen signal paths. The unit can be used to switch an input to one of two outputs, an output to one of two inputs or between two effect chains with one input and one output.

The active circuit works noiselessly and effectively, allowing a good combination of switching options. There is an LED for each line to show which one has been selected.

Mini Pedal


The pedal is basically a potential divider which can be used to attenuate an input signal i.e. volume control, or to provide a control voltage proportional to the travel (for use with Yamaha's System Boards).

The internal pot is operated by a rack and pinion type of arrangement. Dual pots (for signal i.e. volume control, and CV) operate from pedal movement and two small 'subpots' mounted under the heel of the pedal allows the output signal to be between 0-100% and 17-100% of the input signal.

The pedal is mounted in the same diecast case as the other effects, but this enclosure is not really suitable for freestanding use on stage. However, operation is perfectly satisfactory when mounted in the Yamaha system boards.

Analog Delay


One other effects unit in the range is the Analog Delay, although no units were available in the U.K. at the time of writing. It offers delays from 50 to 400 milliseconds, suitable for doubling, echo and reverb simulation. Compander noise reduction is utilized.


Complete Systems



Two system boards are available to complete the range. The SB100 will hold seven single size PSE units or six standard units with the Analog Delay which takes up two positions. The board is housed in a strong rexine covered case with a detachable lid. The case contains an integral mains supply to power the fitted units. To install an effect, the four screws securing each box are removed and the circuit with the top panel is fitted to a special plate which screws on to the board. The power and signal connections are made via a moulded connector fitted inside each effect box. In normal use the effects are connected in order, from the right bottom row, to the left top row. However, the order of effects can be re-routed internally. A feature provided is the facility to control the parameters of several of the effect units with a control voltage. This voltage is derived from the Mini-Pedal and can be assigned to one of the other six positions.

The SB200 board accepts up to eleven single size PSE units and allows the connection order to be rerouted externally. There are ¼" jack sockets for In, Out and CV for each of the eleven positions. If no jacks are inserted the order of connection is the same as for the SB100. Using this arrangement, re-routing of effects can be done quickly and easily on stage with patch cords.

A Mini-Pedal can be put in any of the eleven positions and the control voltage from the respective jack can be patched into the CV input of the required effect. The effects which can be voltage-controlled and the parameters varied are as follows: the Manual frequency of the Flanger, the Delay Time of the Analog Delay and the Frequency of the Parametric EO.

Other important features include three patch junctions, an instrument direct output, a 'Final In' which disconnects the selected chain when a jack is inserted, a 'Signal Cord Check' circuit which lights an LED with an in-circuit lead, an 'All pass' footswitch which disconnects the effect chain selected (this function operates automatically if the mains supply to the board disappears for some reason — useful in preventing an embarrassing silence!), a headphone output with an external input and a bargraph LED output level indicator.

The SB200 is also mounted in a rugged flight case with detachable lid and comes with a gooseneck panel light for on-stage setting or patching changes.

Conclusions



Yamaha have obviously put a lot of thought into the design of this system. Each pedal is extremely well made, combining mechanical strength, high quality signal processing and clear functional labelling.

The range of effects covers almost every possible way to modify an instrument signal. The system boards are a novel concept with their patching and CV options and provide a reliable, versatile pedal set-up for stage use.

The system is designed with complementing impedance matching and little increase in background noise, an important consideration when building up an effects range.

You could buy one effect at a time and eventually fit them into a system board. A complete system will cost you over £1,000, but no doubt the pro musician will consider it worth every penny!

Summary

Unit Order Ref. Retail Price (inc. VAT) Comments
Phaser PH-01 £52 Works satisfactorily, but lacks depth compared with other makes.
Chorus CH-01 £64 Best depth of effect in mono but for the rich thickening effect, which is the more usual application, it needs the dual output offered.
Flanger FL-01 £78 This one's a winner and for its compact size offers a wide range of flanging effects.
Analogue Delay AD-10 £179
Octaver OC-01 £58 A very good, if not the best, octave unit we've come across, following the guitar signal well.
Distortion DI-01 £44 A superior design with a useful soft to hard range.
Tone Booster TB-01 £45 This comparatively expensive unit will be a useful extension to any guitar's tone controls.
Parametric EQ PE-01 £64 A nice filter effect unit that is useful for removing hum, noise or feedback on wide bandwidth and picks out harmonics at sharp bandwidth. With the Mini-Pedal in the system board as a CV source, it turns into a great wah effect.
Line Selector LS-01 £54 Active unit with low noise. High priced, but professional.
Mini Pedal MP-01 £55 Don't buy this unless you plan to get a system board, since it tips over too easily when used freestanding, due to the small area of the base.
System Board SB-100 £299 This basic case comes with detachable lid, built-in power supply and CV feature, but nothing more.
System Board SB-200 £499 This has to be the unit for the serious professional as it allows the optimum choice of patching and units.



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

 

Electronics & Music Maker - Aug 1982

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