Bontempi B40, Confetti Kla4

Bontempi B40 (beginners keyboard with gritty digital lo-fi sounds)
Confetti Kla4

Bontempi B40

This keyboard of 1996 (PCB date code "4 96") sounds and behaves extremely similar like the Bontempi B50 (including ear tormenting beeping). The only main difference is that it has a few less preset sounds and rhythms and selects all functions through keyboard keys.

But unlike B50, the B40 does not seem to beep that excessively (or have only my ears gone bad?). Instead of pseudo-stereo, the melody voices here play only through the left and rhythm only through the right speaker, so it may be that in B50 mixing of analogue percussion with PWM DAC output in the same output transistor intensifies the beep.

different main features:

less DAC beep
left speaker = main voice, right speaker = rhythm.
22 preset sounds {leslie organ, brass, trumpet, clarinet, flute, jazz guitar, xilophone, marimba, vibes, harpsichord, vibraphone, jazz organ, accordion, horn, oboe, piano, banjo, bandoneon, ghost, telephone, fantasy 1, fantasy 2}
22 preset rhythms {rap, bossa, rock'n'roll, 8 beat, disco, latin, rock, 16 beat, rock blues, soul, rhythm & blues, polka, tango, samba, merengue, cumbia, mambo, cha- cha, paso doble, beguine, funky, fusion}
all functions selected through keyboard keys + select button
multi-chip hardware:

CPU= "Texas Instruments W 543GWY, COMUS2743335, 20031" (28 pin DIL, likely TMS370Cx1x)
rhythm IC= "Holtek HT3010A, 9544F" (18 pin DIL)

only 1 demo melody ("La Cucaracha", same like in B50) and no "PlusPlay" training mode.

notes:

Unlike Bontempi B50, all functions are selected through keyboard keys + "select" button (where the B50 has its power "on" button). The main functions are on the black keys, while preset sounds and rhythms are selected by the white keys (switch between both by selecting "basic sounds" or "rhythms" with black keys). The count of preset sounds and rhythms was likely limited to each 22 by the sound selection method, because the keyboard here has 22 white keys. The chassis has the embossed button hole row of B50 and even 2 empty PCB hole rows for those ribbon cables, which makes me conclude that the B40 came out later, but PCB date codes contradict (these however may indicate only a newer PCB revision of an existing model). On the PCB is a strange "B A" jumper wired to B; it may be that "A" originally intended for a panel button version. (I haven't examined the hardware closer yet.)

A simpler mono variant of B40 (same function select method) was the Bontempi B20.

BONTEMPI beginners keyboard with gritty digital lo-fi sounds

The Bontempi On Tour KE 3760 is a case variant of B40. In blue with magenta drumpad buttons it was less compact and had responsive midsize keys. (old eBay photo)

A special variant of this was the Confetti KLA4. It came out 1995 (PCB date code "43 95") as merchandise for the Austrian children TV series "Confetti" (something like Sesame Street?). The only difference to the normal KE 3760 is the orange case and the theme of the TV series as the demo melody (KE 3760 played "La Cucaracha").

Beside this, both are technically identical with Bontempi B40 (including the ear tormenting beeping), thus I only describe here the differences.

different main features:

different case with German language control panel writing
very responsive keys
2 slightly less bad sounding speakers
multi-chip hardware:

CPU= "Texas Instruments W 538GWY, COMUS2743362, 44015" (28 pin DIL, likely TMS370Cx1x)
rhythm IC= "Holtek HT3010A, 9542M" (18 pin DIL)

demo melody "Confetti" TV series theme

notes:

The name "Kla4" is a German pun, because in German language the word "Klavier" means "piano", while "Vier" is the number "four". This instrument is likely quite rare and was only released in Austria (the German language nation in Europe - not Australia).

*removal of these screws voids warranty...*

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