Electrokinetica The Electro-mechanical Museum

The Sonatina

Manual split at middle A

One manual, no pedals

Although one of the smallest Electrones made, there is more to the design concept of the Sonatina than economy alone. The brochure explains the strange coloured keys and absence of pedalboard as follows:

Ingenious Compton technical design enables the player to produce from his single-manual Sonatina the effect of a two-manual and pedal organ. The combination of solo and accompaniment (great) sections in one keyboard, together with an ‘automatic bass’ facility, make this the ideal ‘graduating’ instrument for the pianist. Of instant appeal to the expert musician is the characteristic Compton tonal quality of the Sonatina.

In other words, like its predecessor the model 354, it is an organ made less organ-like so as to lend a helping hand to the pianist. Many provincial churches have experienced the situation in which no organist is available to accompany their services, yet a pianist is available who would be able to fulfil that role but for the lack of familiarity with the use of pedals. The manual has 61 notes that can operate as one division or two according to which stops are selected, while the automatic bass adds a pedal-type voicing to the lowest note played. Compton's illustration shows clearly how these functions work:

Circuit arrangements

The concept of a split keyboard is not new, having been used on harmoniums and similar instruments that would have served the same purpose in a smaller place of worship a century ago. What is slightly different is that the split is engaged only when stops on the solo division are selected. This is accomplished by a changeover switch operated by any of the grey stopkeys, which disconnects the upper section of the manuals from the harmonic busbars of the Great and connects it to those of the Solo. The automatic bass uses a rather precarious series chain of changeover contacts to identify the lowest note of a chord. Polarising voltage is fed in at bottom C, proceeding through the normally-closed contacts of every key in turn until it reaches one that is depressed, where the normally-open contact routes it to the note outlet crosswiring. Because there is only one changeover contact for each key, the automatic bass can operate only one generator tone, a flute-like prime tone at 16-foot pitch. Although extremely simplistic, this is not too far removed from a single rank of stopped bass pipes on a small pipe organ. The series-connection of so many contacts is a recipe for unreliability however, as one high-resistance contact in the chain will affect all notes above it. Although it is intended to ease the burden on the non-organist, the automatic bass actually increases the need for proper organ-style articulation in hymn playing, because any failure of the legato in the bass will cause not a momentary gap in the sound but an obtrusive jump to the note above. Conventional pianistic phrasing can result in regular blips of the tenor part booming out on the 16-foot stop, if care is not exercised on this point.

General interior view

General interior view

Automatic bass contacts

Automatic bass contacts

Voicing changeover switch

Voicing changeover switch

General construction

In all other regards the Sonatina follows standard direct-keying Electrone practice. The 2.5-inch single-sided generators are assembled into the narrow-cabinet layout and fitted with a lever-magnet type of tremulant. Amplification is provided by the 10-Watt 6-valve chassis incorporating potentiometer expression control, driving an internal dual-cone full-range loudspeaker.

Our Sonatina

This organ was tracked down for us by EK friend and supporter Peter Watkinson, who also laid in a store of spares from another, defunct instrument. Its serial number label reveals that it was assembled by the ubiquitous Fred Allen in 1964 when he worked for Compton, this being the second organ to arrive in our collection bearing his initials from the factory rather than from his involvement with it later in its life. It is generally in full working order and in a good state of originality, although the potentiometer-type expression pedal has been replaced with an imported unit in the past. Thanks to Robert Cook’s assistance we have an original replacement ready to fit when the organ is next under repair. The original bench is present, an important feature because it is of a type unique to the Sonatina, shorter and lower than Compton’s standard console bench despite being of identical style.

Compton Sonatina

Compton Sonatina

Serial number label

Serial number label

Name label on key assembly

Name label on key assembly

-----

All content © copyright Electrokinetica 2007-2021 except where otherwise stated • Valid XHTML 1.0Valid CSS