Filter Mod for Casio HT-3000 (MT-600/HT-700/HT-6000)
The Casio HT-3000 uses the unique chip NJM2090, a 4-pole voltagecontrolled filter. It runs with (only) +5V supply, so that an optimized functionality for battery powered keyboards is guaranteed. There is one chip for the upper-tone voices and one for the lower tones. The useable cutoff swing of the filter is from 0V to 2.5V and the resonance runs between 0V and 3.5V. To control them by your own manually with pots, you need to eliminate the fixed voltages of the CPU, which values are dependent on the selected voices. The input for the cutoff voltage is on PIN 2 and for the resonance voltage on PIN 9. So you have to cut the traces which lead to these PINs. Now you can grab the +5V voltage and the GND from the IC supply (or directly from the power supply) and reduce it with a voltage divider to +2.5V (cutoff) and +3.5V (resonance). Connect the GND and +V to the outer pins of the pots and connect the middle pin to the cutoff/resonance inputs. Thats it. I dont`t remember the exact values of the pots i used, but i think it was about 100k for resonance and about 20k for cutoff. Just try and experience.

t eni arz cm ar

In his schooldays, at a time when his friends were emulating the medallists of the then ongoing Barcelona Olympic Games, Marc Martinez would instead keep precociously busy with the tricky taming of an Atari 1040ST with a keyboard Casio PT1 connected to large headphones. The attempt did not quite succeed, but the strongheaded 9 year-old little man would all the same spend most of his spare time testing a Playskool deck. The background music of his teenage remained bands like the Alan Parson Project or Pink Floyd. He advisedly took advantage of a dad working at a disc store. In 1995, Marcs parents left his hometown, Barcelona, to settle in Mollerussa and little Marc had to pack and follow. There he studied solfeggio and piano for 7 years at the town school. Creatively restless by nature, he soon grew confident to make his first compositions of classical music. The classically-trained young Marc wouldnt tour Europe playing Piano as geniuses of the past had done; he instead got his first synthesizer, a Casio HT-6000, and as he turned 15, was given his first personal computer. Marc was now put in command of a full, though made of silicon, philharmonic orchestra and he wouldnt wait a minute to set off creating his own stuff with programs like Audio Mulch, Cubase and Fruity Loops. In the year 1998 an epiphany happened: some may have gone to Mecca and saw Light; Marc went to the Sonar Festival (for the oblivious, this was the memorable year of the Brazilian girls). And he was luckiest: he won the lottery and got away with a sample of Akai Remix which greatly contributed to extending his creative resources. Roughly by this time he began to attend a course of Cubase at the University of Lleida, where he had to register giving his mothers name due to his young age. He also began to give classes of musical production. Electronic music had so far been an exciting pastime; now it was rapidly turning into an irresistible vocation. Soon Marc performed his first live acts at local strategic 'pubs' and 'raves'. A few years experience encouraged him to present his life performances on a portable Apple iBook 12". Since 2003, Marc lives again in Barcelona where he obtained the degrees in Audio Engineering and Sound Technology while working as a sound technician for the Mollerussa theatre and teaching musical production in the city of Lleida. Among other professional involvements, Marc has worked on various musical themes for both TV and Radio ads and has likewise collaborated in audio-visual projects.
Marc Marzenit has in recent times become one of the rising stars on the fast-changing landscape of electronic
music in Spain. With hardly any records to pride himself on, he nonetheless has already performed five times at a club such as Florida 135, gone abroad to perform in Berlin (Zurmbelfabrik and Pulp Mansion), plus other acclaimed appearances at various clubs and festivals across the country. Labels like Miga and Votox seem to be strongly betting on Marc Marzenit. Marc along with three other colleagues recently set up a new label, Paradigma Musik, which has attracted the interest and gained the support of one of the most important distribution companies nowadays on the market: Kompakt. With Paradigma Musik, Marc did already publish his first EP, Trozitos de navidad. Theres little doubt Marc still has a great deal to say

ra w ww.pa

u am m

co i k.