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Yamaha PS20 Portable Keyboard

Yamaha PS20

The PS20 and the smaller PS10 are, literally, Yamaha's great white hopes for the future. The PS range employs the PASS system of voice production to achieve its range of sounds at a very reasonable price.

Whilst on the subject of money matters, the PS20 will be available in the shops at below £299.00, and the PS10 under £199.00.

Getting back to the PS20 itself, the casework is pretty stunning: it is made out of vacuum-formed high-impact 'whitish' plastic and looks very modern. The big selling point that Yamaha are trying to ram home is that it is a go-anywhere keyboard, and I have to admit that that is exactly the case.

The instrument has a '3-way power system'. This is a clever bit of design, enabling the PS20 to be run off the mains, a set of batteries, or a 12-volt car battery. This is achieved by using different power packs that fit snuggly into a recess on the underside of the instrument. Each power pack has the same terminals that plug into the main body of the machine, but with different input facilities. One pack contains transformer and regulating circuitry, and with a cable running to the mains. A second houses a set of six 1½-volt batteries, whilst a third system plugs into the car cigarette lighter socket and transforms the dirty 12-volt supply into a clean 9-volt one.

The keyboard that Yamaha use is built in one of their own factories in Hamamatsu, Japan. It has a particularly nice feel to it and there is absolutely no mechanical contact noise to be heard: the key mechanisms are also well-protected against dust, etc. As with most instruments these days, the keyboards are based on the key of C, i.e. the keyboard covers 4 octaves (49 notes), from C to C. Several instruments use 3½-octave keyboards, but these normally go from F up to C. It is very seldom that you come across an F to F instrument.

The PS20 uses an interesting new control switch mechanism. It could be considered to be a cross between a push button latching and a rocker switch with a bit of tablet thrown in for good measure. These switches, which make up 85% of the control mediums, are long thin plastic wedges sprung at one end, and they latch when pressed. This latching is cancelled by pressing another switch from the same bank. At the tip of each switch is a coloured inset which enables the switches to be coded.

The controls are split up into various sections, so, working from left to right on the photograph, the first bank is marked 'Orchestra'. These switches provide the basic voicings for the instrument. The PS20 will play up to ten notes simultaneously and independently (i.e. no shared envelopes, etc.). However, if the Automatics (bass and/or chords) are being used, then less notes are available. For example, during ABC (Automatic Bass Chords) playing, which we shall come to forthwith, the bass takes one note, the chords four, the arpeggiator one, leaving just four for the melody orchestral voices.

Yamaha have put two voices on each switch, so, if that switch is down, one of two voicings may sound: as to which depends on a master up/down switch. This, to my mind, is messy, and makes quick changes awkward. I would have far sooner seen a separate switch for each voicing, and put up with the extra couple of pounds it would have cost.

Internal view of the PS20

The actual timbre and character of the individual sounds wasn't, I felt, all it should have been. Yamaha claim that they can produce a perfect sound with this PASS system — if some of these sounds are perfect representations of the orchestral instruments after which they are labelled, then either I, or they, need our ears examining.

What this system has done, in the case of the PS20, is to enable what are pretty ordinary instrument voicings to be made available on a very low-cost instrument. The PS20 is an economic breakthrough, not an aural one.

Perhaps I should inform you of the voicings available:

Organ 1 — a basic pipe organ sound; Organ 2 — quite good, with a percussive bite to the attack; Trumpet — fair, but, in my opinion, not round and full-bodied enough; Strings — some funny harmonics are present in the lower octaves, otherwise a bit flat; Clarinet — traditionally a square wave, but, in this case, there seemed to be some overtones present that weren't quite right; Oboe — good, nice and reedy; Piano — probably the best of the presets, and better than most electronic simulations; Harpsichord — poor; Accordion — slightly too rich in harmonics; and Vibraphone — a nice warm sound with a slow modulation. Overall, the presets are good, especially when bearing in mind the price.

The rhythm unit employs a similar means of selection, two patterns per switch with a master. The rhythms Yamaha have incorporated include March, Disco, Waltz, Rock, Tango, Swing, Rhumba and Samba. A nice feature about this section is the 8-bar Variation facility, which introduces a fill every eighth bar. There is also Synchro Start, which is activated by any of the bottom 19 notes of the keyboard. The patterns themselves are well arranged; however, some of the percussion voicings, in particular the snare and bass drums, are a bit dubious.

The Arpeggiator has two possible variations on a theme, the theme being either the chord fingered on the lower section of the keyboard, or the automatically generated chord produced by Yamaha's single chord generator. And the variation is either a rising and falling arpeggio, or just a rising one.

Finally, we come to the ABC section, which, in fact, is similar to the automatic section of most present-day home organs. It consists of an automatic chord generator, which can produce a major chord from any of the notes played on the lower section of the keyboard. Yamaha have developed a tidy system for selecting minor and seventh chords of this root note. The minor is obtained by pressing any white note below this root. How do you get a minor seventh? No prizes for working that one out. All the other favourites are there: Fingered Rhythmic Chord, Memory, Multi Bass (a different bass pattern), and they all go to make the PS20 a versatile, all-in-one instrument.

Of course, to be a portable, go-anywhere keyboard, the PS20 has to have its own amp and speaker, and it has. You can see from the internal shot, that the speaker (elliptical 4" x 2½") isn't going to fill the Albert Hall, but, for domestic use, the sound it produces is quite adequate, and surprisingly full. There are also line outputs (phono plugs!) and a headphone output (jack) on the side of the instrument.

Internally, as you would expect from a Japanese company, construction is excellent. The keyboard switches and diodes are mounted on SRBP circuit boards, whilst all the major circuitry is on glass boards. The switches are directly mounted to the boards, and, overall, an impression of quality and ruggedness pervades. None of the chips are socketed, but, since most of them are Yamaha custom jobs, replacing them is going to be a service department job, should the instrument fail. The PASS technology makes modifications to the instrument a tricky and very limited possibility; however, there is plenty of room inside the case of the PS20 if it was felt that signal modifiers (e.g. graphic eq) were warranted and these could be installed into the body of the instrument with room to spare.

The PS20 is a very nice instrument. Some of the sounds are a bit dodgy, but, at the price, you can't grumble. I think that this is only the first in a long line of new products from Yamaha that are designed to shift the musical instrument market towards that of consumer electronics, and, along with Casio, whose new Casiotone CT-401 is making a bid for the same market, I think that electronic keyboard instruments are going to become increasingly cheaper and accessible.

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


Electronics & Music Maker - Jun 1981

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Keyboard - Home/Personal > Yamaha > PS20

Review by Dave Crombie

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