{"id":4095,"date":"2023-10-31T16:00:13","date_gmt":"2023-10-31T16:00:13","guid":{"rendered":"https:\/\/maffez.com\/?page_id=4095"},"modified":"2024-03-11T17:35:26","modified_gmt":"2024-03-11T17:35:26","slug":"mfb-522-the-heavy-heavy-monster-sound","status":"publish","type":"page","link":"https:\/\/maffez.com\/?page_id=4095","title":{"rendered":"MFB-522 \/ the heavy, heavy monster sound"},"content":{"rendered":"\n

Just scored a cheap MFB-522 and post a couple of PCB pics and descriptions here, which might come handy in case you need to repair yours. Check also my Dimonion1<\/a> and my Synth<\/a> <\/a>Pro<\/a> pages.<\/p>\n\n\n

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https:\/\/medias.audiofanzine.com\/files\/manuel-simple-mfb-<\/a>522<\/a>-478076.pdf<\/a><\/p>\n\n\n\n

https:\/\/archive.org\/details\/synthmanual-mfb-522-owners-manual<\/a><\/p>\n\n\n

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That frankensteinered capacitor is fat – and so is the sound of this little MFB (lol)…<\/p>\n\n\n\n

Processed stereo sum and ABL3 bass line<\/figcaption><\/figure>\n\n\n
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cheapo dremel style case fitting…<\/figcaption><\/figure>\n<\/div>\n\n
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three different types of screws – what’n not to love about that?<\/figcaption><\/figure>\n<\/div>\n\n\n

Quick inventory<\/strong><\/h2>\n\n\n\n

Power: PSU 15V DC, at least 300ma (best use 1000\/1200ma); 3x voltage regulators: L78L05 (+5V), L78L12 (+12V), L78L06 (+6V) — if I get this right, there is no negative rail in this machine. I tested op-amps for supply and all were +12\/0V… <\/p>\n\n\n\n

Digital Control: ATMEL AT89C4051-24PU Microcontroller; ATTINY13A Microchip; TDA8444T Octuple DAC; LC549C ADC; 24C64WP EPROM; CNY17-1 opto coupler<\/p>\n\n\n\n

2x HC505C shift registers;  HEF4053 switch (switches the \u201cB\u201ds –> RS, Clave); 2x HEF40106 Hexinverter (one for the metal noise); Dual op-amps are TL062.<\/p>\n\n\n\n

Transistors, diodes: BC487 NPN; BC587 PNP; BZX84C – ZENER DIODES (SOT23); single Schottky diodes too<\/p>\n\n\n

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Trimmers – adjusting sounds<\/strong><\/h2>\n\n\n
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Trimmer 1 (leftmost)<\/strong> – BD maximum length: Set decay to maximum and tune to minimum. Turning the trimmer anti-clockwise sets your max length. The latter can be near infinite.<\/p>\n\n\n\n

Trimmer 2: <\/strong>Tom\/Conga maximum length: turning this anti-clockwise increases the maximum decay of ALL toms\/congas. Best play a midi\/sequence loop going though all sounds and then adjust to taste while listening to that sequence. <\/p>\n\n\n\n

Trimmer 3 <\/strong>– Hi Hat Oscillators Tune: While Cowbell D-tune and Cymbal Tune affect these potions of the metal noise that are prominent in CB and CY, this trimmer here tunes those metal noise oscillators more prominently featured in the hi hat sounds. The scope is not extreme, but you can nicely tune in some in\/harmonic shimmer as per taste. <\/p>\n\n\n\n

Trimmer 4 (rightmost)<\/strong> – CLAVE length. Tuning this trimmer anti-clockwise lengthens the clave sound. <\/p>\n\n\n\n

Modifications<\/strong><\/h2>\n\n\n\n

Instrument Panning<\/strong><\/p>\n\n\n

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The instruments of the 522 have fixed panning, which is simply done by means of fixed resistors. Instruments in the middle pan position, such as the kick, simply have two identical resistor values for left\/right. For instruments which are panned, you have different values per left\/right. In order to shift their panning, simply change the resistors. As you can see in the pic above, tom\/conga instruments share some resistors. If you find any of the instruments generally too low in volume, you can also change this easily by reducing the corresponding resistor values.<\/p>\n\n\n\n

More snappy on the snare<\/strong>: the mfb snare is cool but I wanted some more snappy action, so I changed the snappy filter a little bit. On the picture you see a 3k3 resistor which I simply soldered over the 22k resistor that was originally there. No need to remove that 22k, just add your 3k3 on top.<\/p>\n\n\n

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sounds like this:<\/p>\n\n\n\n