Bontempi GT 509 (awful smelling 8 note polyphonic mini keyboard with many functions)

This is the smallest "666 sound" keyboard of the Bontempi "System 5 Plus" series. It is 8 note polyphonic and has quite a lot of functions for such a small beginners thing, although genuinely it has only 36 preset sounds those can be layered to produce 666 combinations.

The electronics (although "made in Italy" and not China) smells badly of chemicals; even washing the PCB in soap water didn't help. This keyboards was later re- released as Bontempi GT 520 and GT 510 (the latter with pretty blue case). I heard that this keyboard was also sold under different brand names (e.g. Farfisa, Tchibo and Aldi).

main features:



This is basically the smallest specimen of a typical modern digital keyboard. Besides tempo buttons and rhythm start/ stop there are no OBS functions on this instrument. Sounds, rhythms and effects are selected by 2 digit numbers. Main and accompaniment volume and chord functions are controlled by black keys pressed together with the "system 5/ volume" button. Basically what I like of this instrument are the many sound combinations and the 8 note polyphony, but due to the maladjusting chemical odours of this keyboard (those even didn't go away after some years) I can't enjoy to play it. :-6 (The thing smells even worse then most chinese toy keyboards - the PCB seems to continuously emit a toxic solvent like hexane or similar.) Thus I installed a fridge smell stopper (carbon coated foam rubber between 2 paper layers) inside the case; I hope it will eventually neutralize the chemicals. (Apparently it already helped a bit.)

The preset sounds are quite complex and at first hear they seem to sound natural, but when listening closer, the sample based sounds are thin, noisy and a little harsh (8 bit). They seem to be made each from 2 layered waveform samples with complex envelopes and contain sustain, chorus and reverb effect those can be also manually switched on or off by numbers. (Selecting a new preset sound always switches them back to its default.) Although technically similar, the timbres are not squawky like the Casio SA series sounds, but try hard to sound noble although partly with limited success. When not otherwise mentioned, all sounds include reverb. "Chorus" sounds (those contain 2 subvoices) half the polyphony unless the 2nd "chorus" voice is turned off. Any 2 preset sounds can be layered to achieve 666 sound combinations. The "piano" is more an e-piano, because it is made from a static waveform without chorus. "brass" is a brass ensemble. "musette" resembles a harsh accordion. "prophet" is a synth brass timbre that turns duller and brighter (wahwah chorus) while it fades silent (likely named after Prophet analogue synthesizers). The "toy piano" resembles a bright Rhodes piano (no reverb). "full organ" has a wahwah vibrato, which speed turns much slower in the bass range. "jazz organ" is rougher and harsher, and has the same wahwah vibrato. "clavinet" has here a brassy timbre with fast vibrato (6Hz, no reverb). "fifth organ" is a metal pipe organ rank chord that fades a bit duller during attack phase. "pipe" is a bright metal pipe organ rank with chorus. The "bassoon" has a slow wahwah chorus. The "mandolin" rings with a Rhodes- like timbre. The "accordion" is rather harsh. The timbre of the "harpsi" resembles a bright flute and has vibrato. "jazz guitar" is an acoustic one. "haw guitar" has a slow howling, halfway voice- like wahwah chorus effect and fast tremolo. The "jazz bass" is an e-bass with also wahwah chorus and sounds a bit brassy. The "funky bass" sounds hollow, has vibrato and resembles more a banjo. The "steel drum" sounds like made from a bright plain squarewave with chorus and percussive decay envelope (without chorus in becomes a harp). The "mute guitar" likely shall be a slightly muffled acoustic guitar (high notes resemble an e-piano). The "square" is a harsh and reedy electronic organ sound with vibrato, that resembles an accordion (with chorus off it becomes a flute). The "saw" is an even harsher and more reedy variant of this timbre (without chorus it turns brassy). The "cello" has vibrato and sounds harsh, but fairly realistic. "big ben" resembles tubular bells. "ghost" is a synth sound mixed from a fast (8Hz?) and a slow (4Hz) howling timbre that fades silent. (Both howl by about 1 semitone. Disabling chorus mutes the fast howling subvoice.) "ringing fly" is a ringing telephone bell layered with a sonorous synth piano (that has a dry multipulse squarewave timbre; disabling chorus mutes the piano). "telephone" is a electronic phone ring (a disharmonic sound made by fast toggling between 2 notes).

During rhythms the drumpads are used to play single finger chords (the set of 6 chords can be selected by entering a "chord code" number). Also without rhythm the drumpads can be used for chords by selecting any "System 5" mode besides 5 (press "system 5/ volume" and corresponding black key). The selected rhythm number here changes the chord sound. The "System 5 Plus" is a chord training feature with 5 different modes. When "rec." is selected, the power LED flashes and you can now assign chords to the 6 drumpads by playing the chord and then simultaneously pressing the drumpad it shall be assigned to. The finger combination to play chords changes (stepwise between single finger and fingered) depending on which "System 5" level number is selected. The accompaniments are unspectacular but not bad for such a small thing, although there are no fill- ins or other fancy tricks. The low- res sample percussion sounds thin and has very grainy looped hihats (nice for tekkno). The tempo can be set quite high but not very low.

The 4 demo melodies are made from a monophonic main voice (switches among a few preset sounds) and standard accompaniment.

A predecessor of this instrument without drumpads was released as Bontempi GT 504, which apparently later was re-released in a smaller case as Bontempi BT 604/N (shaped like their ET 202, seen on eBay). There are many other, bigger Bontempi and Farfisa keyboards based on the same "666 sounds" sound engine. An earlier predecessor was likely the Bontempi ET 202 (with nice howling synth sounds and arpeggio- like accompaniment). A 49 midsize keys variant of the GT 509 was released as Bontempi GT 759 (with less harsh and fatter sound but same great lo-fi zipper noise timbres).

 removal of these screws voids warranty...    
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