Bontempi GT 759

Bontempi GT 759 (digital keyboard with nice gritty zipper noise sounds and rhythms)

This is the bigger brother of the small Bontempi GT 509. It has the same gritty digital zipper noise sounds and features 666 sound combinations. Unlike the latter it has 49 midsize keys with accompaniment section and you can select 6 different timbres for manual chords. Unfortunately it only accepts standard establishment chords.

Thanks to the longer keyboard it has now a real bass range with nicely sonorous timbres. Also this specimen (I bought mine used) emits rests of the same awful solvent chemical odour like the GT 509. This instrument sounds and behaves extremely similar like Bontempi GT 509, thus see there for details.

different main features:

49 midsize keys
2 built-in speakers (10cm, reasonable sound, mono)
keyboard chord section
single finger & fingered chord modes (only standard chords)
6 preset accompaniment sounds {el. piano, mute guitar, piano, accordion, jazz organ, synth strings} (only for manual chord mode with rhythm off)
"chorus" is now labelled "diffusion"
separate accompaniment volume +/- buttons
8 bit sound generator sounds cleaner (less aliasing noise?) but has still nice zipper noise.
CPU "Texas Instruments A45031PH, WX 87A7TVW, COMUS2743389" (80 pin SMD)
no battery alarm
jacks for AC-adapter & headphone

eastereggs:

PCB has empty solder holes for 2nd power amp =>possibly upgradeable to stereo.

notes:

Despite this instrument has still nicely low bit resolution with much zipper noise, it sounds cleaner, slightly warmer and less harsh than the GT 509. I am not sure if only the speakers are better, or if the sound generator has less aliasing noise. With trilled keys each new note occupies a new sound channel, which produces a great phasing sound and volume increase effect. The demo melodies always roar at maximum volume and can not be set quieter; fortunately they are at least play not unbearable loud (unlike the older Bontempi KS 4600) because this keyboard plays not louder than high room volume.

The PCB has empty solder holes for a 2nd identical power amplifier; apparently the hardware was indeed designed in stereo, but the 2nd amp was omitted to cut down costs. Strange is only that both amps would be connected with the output of the same 8 bit DAC resistor array, but also my Bontempi BS 2010 multiplexes the output from a single DAC to generate stereo sound. Also the manual has a small note "stereo" in the technical data section, despite this instrument in its actual form is mono.

The accompaniment accepts only standard establishment chords because its fingered chord mode ("free chord II") simply ignores any non- chord key combinations (the same stupid rubbish like with e.g. Yamaha PSS-390 and many other modern sound bank keyboards). Although there are 6 different accompaniment preset sounds selectable, they only take effect in manual chord mode (with rhythm off). The accompaniments of the rhythms only use always the same boring e-bass (or e-piano?) timbre.

A shorter variant of the Bontempi GT 759 (40 midsize keys, 1 speaker) was released as Bontempi GT 709 and GT 709N (different panel colours). A fullsize variant (49 keys, 2 speakers, only 3 drumpads?) was released as Bontempi GT 809. Bontempi originally had bought this hardware technology from Farfisa, those released e.g. the variants Farfisa F404 (40 midsize keys, 1 speaker, no drumpads) and F498 (same like Bontempi GT 809?). The modern successor of the Bontempi GT 759 is the Bontempi GT 770, which has 100 preset "basic sounds" (instead of the only 36 of the GT 759), warmer timbres and 12 note polyphony; the corresponding GT 709 successor is the GT 720 (seen on eBay).

*removal of these screws voids warranty...*

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