Last month's Music Maker Equipment Scene introduced a new range of Casio keyboards intended, on the whole, to replace their existing popular products. Now we can take a more detailed look at five of these - the PT-20, PT-30, MT-65, CT-405, and the CT-501.

While these models largely offer new combinations of already existing Casio facilities, there are some new features to be seen, including some changes in the variety of sounds available, a new memory storage facility, and a new keyboard size standard.

Casio PT-20

Taking the new instruments in order of size, the smallest and cheapest is the PT-20. Similar in size to the original VL-1, it uses a new type of keyboard with the white keys about 1½ inches long and ½ inch wide. Because these are genuine sprung keys as opposed to calculator-type buttons, the PT-20 is easier to play than the VL-tone and is again monophonic, with 7 sounds available.

On the left of the keyboard, beneath the built-in speaker, are three rows of small buttons, comprising a single octave of notes to produce single finger chords and an additional row to give diminished, suspended 4th, minor 6th, 6th, major 7th, minor 7th, minor and 7th chords.

The sound produced by the chord buttons is a surprisingly powerful church organ effect, which is particularly impressive when amplified using the minijack output. This output is also capable of driving mono headphones with a suitable adapter.

The rhythm section of the PT-20 is an improved version of that on the VL-1. There are 12 patterns available including 16 Beat, Disco 1 and 2 and Enka, with a splash of white noise for snare/cymbals and a much lower tone than before to represent the bass/toms.

There is also a selection of arpeggios, of which arp. 3 is a 6-beat rhythm and arp. 4 is a 3-beat rhythm. These produce different arpeggio accompaniments to the rhythms, as an alternative to the repeated chord accompaniments on rhythms 1-12.

The PT-20 includes a 508 step memory for chords and melody. A melody note uses a single step, whereas a chord uses 1½ steps; after these are put into the memory, they can be re-timed to coincide with a rhythm pattern using the One Key Play buttons. The memory will only play through once on Auto; the PT-20 is also capable of assigning chords to memorised melodies by itself, and these can be changed if they are found to be unsuitable. The machine decides the key from the first and last melody notes, and selects chords according to the intermediate notes. The PT-20 will provide 3 alternative chords before returning to its original choice.

The basic voices are fairly typical, 'Mellow' being an interesting addition with a gentle tremolo which speeds up as the note decays. A preset underneath the instrument allows it to be tuned by plus or minus 1½ semitones.

Recommended retail price including VAT is £59.95.

Casio PT-30

The PT-30 features 2½ octaves of the new small standard keys, and again is a monophonic instrument with 8 basic tones and a set of single finger chord keys. Somehow the chord sound is not as biting as that of the PT-20, but this model has the advantage of an LCD display of the keyboard which indicates with a small spot which notes are being played, and with a set of letters and words which chord is held.

There are 12 rhythms with identical voicing to the PT-20, and 6 arpeggio rhythms ranging from simple octaves to rapid double-speed patterns. Otherwise the accompaniment is a repeated chord pattern; again the PT-30 can compose its own chord accompaniment for a melody, which can be altered if desired. Chords and rhythms are individually mixable on small sliders next to the overall volume slider.

The keyboard has a small tuning preset beneath it, alternatively it can be transposed 9 semitones down or 3 semitones up using the Transpose Up and Down pushbuttons. Tempo is similarly adjustable from minus 9 to plus 9. There are outputs at line level (¼" socket) and for the tape recorder memory interface described below.

The TA-1 interface is an optional accessory installed inside the PT-30. It enables the contents of the 508-step memory to be digitally encoded on tape, and is easily installed under a sliding plastic cover which opens to reveal a compartment with 7 bus contacts at its base. Tape dump and reload takes about 45 seconds; since the TA-1 contains CMOS circuitry the user is advised to remove it carefully from the PT-30 when not in use.

The keys of the PT-30, numbered 1 to 31, can assign a 'file number' to individual songs when loading onto tape, so that the song to be re-loaded can be easily selected at a later date. Any others will be skipped over, with a dot appearing on the LCD display corresponding to the relevant numbered key indicating which song has been loaded.

Although the LCD display is useful, it has limitations. To be visible it has to be viewed vertically, hardly a typical playing position, and if this is not done the dots on the black notes are not seen. Additionally, the degree of transposition which is displayed is lost if a chord is played, in favour of the chord symbol. These points notwithstanding, the PT-30 can be seen as a useful compositional tool and the cassette dump facility as an invaluable method of storing ideas for later recall.

Recommended retail price including VAT is £79.00.

Casio MT-65

The MT-65 is a more straightforward performance instrument, without the memory functions of the other models but with a versatile accompaniment section and some new ideas in the voicing facilities.

It's an 8-note polyphonic instrument with 4 octaves of miniature keys (the MT-31 standard, with white keys about 3 inches long and ¾ inches wide), a single built-in speaker and headphone and line level outputs. There are twenty instrumental voices, selected by ten pushbuttons and a 'Select' control, and the sounds range from organ and violin to harpsichord, funny and cosmic tone. Additionally, a voice modulation feature can expand the range of sounds available, as described below.

Accompaniment sections comprise rhythms, bass, chords and arpeggio. There are 12 rhythms with excellent percussion voicings including bass, snare, toms, claves and cymbals; the high-hat and crash/ride cymbals are at least better than a burst of white noise with a ring-modulator type of metallic effect, and the bass drum is full and driving. There's a fill in button which activates a variation running parallel to the rhythms; that is, it always fills in the correct amount to take you to the end of a bar regardless of when it is pressed.

There's a synchro start facility for the accompaniment sections, which are mixable against the rhythms and keyboard sounds. The Casio Chord facility gives single finger or fully fingered chords on the lower 1½ octaves of the keyboard, with a choice of four sounds varying according to the rhythm selected. Basically these are reed, flute, organ and brass, and if the rhythm section is started these repeat in different patterns, hold on, or play on offbeats.

The Bass section acts in a similar way, with four alternative bass sounds from bass guitar to organ pedal playing different patterns according to the rhythm used. The bass sounds can be played as a manual bass if the accompaniments aren't running.

The arpeggios again offer four options in terms of sounds and of melodies on each rhythm. Arpeggios, Bass and Chords all drop out when a Fill In is selected. The upper part of the keyboard is four-note polyphonic when the accompaniments are running.

The new voicing facilities are worth looking at in more detail. As most people know, Casio voices are made up of two components, known for convenience as a vowel and a consonant. These are digitally defined sounds with their own timbre, pitch and envelope, which combine to produce an overall sound with a certain degree of internal movement and interest. Hence the superiority of Casio voicings to those of inexpensive electronic organs, and the capability of the Casio 1000-P to produce a wide range of sounds by combining various vowel and consonant shapes in different ways.

The new voicing technique on the MT-65 is known as Modulation, but in fact has more to do with Envelope Shaping. The first control divides the preset sound into its component parts and adds a slow attack to the shorter component, effectively changing percussive sounds like harpsichord and piano into softer effects. Conversely, slower sounds are given a percussive element by shortening the attack of one component, so Cosmic Tone (a sort of clavinet sound) becomes a passable key-click organ.

The second modulation control gives an overall slow attack to percussive sounds and an overall fast attack to softer sounds. Both controls can be used together, and if this is done the sound is effectively completely changed. The effects are fairly unpredictable, but some of the results are quite impressive. A slow reedy attack can give way to a sudden thump in a quite different voice; sounds fade in and out at odd times and the first comparison that comes to mind is the PPG Wave's digital effects. Obviously the same degree of control over the effects doesn't exist, but the unusual envelopes and internal movement of the sounds bear some resemblance to a machine which costs about 20 times the price of the MT-65, and that can't be bad.

There are two more sound treatments available. One is Vibrato/Delayed Vibrato, which is fairly standard. The other is Sustain/Reverb, the latter part being another new idea which is simple but effective. Reverb is simulated internally by activating the sustain, but reducing it in level about five times. If the note is released, the appearance of a natural reverb is given. If it is held, of course, this simulated reverb can't function; still, a useful effect on percussive sounds or when playing staccato.

Overall the MT-65 is a no-nonsense machine with good percussion voicings and some useful new ideas. With a recommended price of £175 including VAT it's certainly the cheapest way to get some way towards those advanced digital voicings.

Casio CT-405

The CT-405 is a full size keyboard with a specification almost identical to the MT-65. It has a simulated wood finish and is mains powered, as opposed to the battery/transformer options of the smaller models. It has four octaves of full-size keys with a pleasant firm action, and although the control layout is quite different, its features and voicings are as for the MT-65, including the Modulation and simulated reverb.

There are two additions which make the CT-405 more practical for home use. The first is a 3-position Transpose switch, marked Off (C Scale), Transpose and Set. Any key may be pressed while the switch is at Set; on returning to Transpose from the Off or Set positions, the whole keyboard including chords, bass and arpeggios, is transposed as required. The degree of transposition is forgotten during switch-off, but this doesn't alter the fact that it's a useful feature for learning or accompanying singers or instrumentalists.

The other feature is Octave Down, which can lower the pitch of the keyboard while the accompaniment sections are running so that the melody needn't necessarily be too high-pitched. The rear panel has Headphone, Line Out, Foot Volume and Sustain ¼" jack sockets, together with a tuning control and Euro mains socket.

Recommended Retail Price including VAT is £325.

Casio CT-501

Lastly the CT-501, another full-size keyboard similar in styling to the 405 but with a slightly wider specification. It's a four-octave version of the CT-701 and is a bar-code reading machine with 20 polyphonic presets and an LCD display.

In fact the specification of the 501 is identical to that of the MT-70, reviewed in detail in the Mini Synth Supplement in E&MM November 1982. The 501 can be regarded as a luxury domestic version; briefly its specification is as follows.

There are twenty presets, ranging from Organ and Flute to Synth Bells and Chimes, and ten rhythms, with matched Chord and Arpeggio patterns. Chords can be fully fingered or one-finger; there are Synchro Start facilities and indicator lights above each of the top 3 octaves of keys to show which note is playing.

Tunes can be programmed by the user, entering a chord at a time and a melody note at a time, or by using the light pen supplied and passing it over sheets of bar codes corresponding to different songs. Editing of the memory is possible, and chord patterns can be repeated and chained. The user can follow the melody using the indicator lights, or step through it using the two One Key Play buttons supplied for re-timing against a rhythm.

The advantage of the 701/501 design is that tunes supplied in bar code form or the user's own compositions can both be programmed, giving a wide range of learning and performance options. Although the 501 is relatively sophisticated, it won't look out of place in the domestic environment.

Recommended Retail Price including VAT is £375.

The new Casios go some way towards increasing the voicing options and memory facilities of the range. As usual there are difficult choices to be made as to their exact application. The MT-65, for instance, might be interesting for stage use, but as it switches itself off after about 5 minutes of disuse you may find yourself leaping onto a completely silenced keyboard. The Modulation effects of the MT-65 and CT-405 voices are interesting, but don't produce any sounds which cannot be obtained on the CT-1000P or which are basically un-Casio like. As always, price and facilities will be the deciding factor for the individual purchaser.