Modified FAT Freebass Demo. Quick demo of a modified FAT Freebass FB383, otherwise known as a MAM MB33. The YouTube audio encoding has made the really high frequencies go a bit strange, but you get the general idea. Add Your Listing. With analogues once you have modded one its fairly easy to work out how to mod another machine in a similar way although understanding the basics of analogue synth circuits is a massive bonus when avoiding killing things. The freebass is a fairly easy machine to work with but the main advice i can give is to not mess with the IC's or any of the power supply area on the left under any circumstances. They don't take kindly to it. Interesting point about the freebass. Apple quicktime player download for mac os x. The filter is actually designed to go into self oscillation but because its meant to be a 303 clone and the 303 filter doesn't self oscillate theres a resistor behind the resonance pot that retards the filter resonance. Bridge that and you've got a resonance boost. If anyone knows where to get schematics for the freebass i would be very interested in getting hold of a copy. I realized why my fb's midi part dead when i found this thread, i picked mine from ebay with 15 V DC (19 infact!!!) PSU. Never even thought it may be not original. There was problems with delay start after poweriing it up. Signal stopped during play. Got this thing for only few months. Often used it. Could you help me with that telling wich parts exactly are burned or any other options.? EPROM cover was not in it's place, when i opened the housing. May it be that it's ontents erased? Its not actually a problem with the power supplies as it turns out it doesn't actually matter if you use 12v AC or 15v DC. Once its gone through the circuitry and voltage regulators in the power supply area of the board its all the same anyway. We get at least two or three emails every month saying exactly what you have just said and i'm afraid to say that at the moment i don't actually know how to fix it. Rane ttm 57sl driver for mac. This appears to be a very common fault with all versions of the freebass. I have had 2 freebasses and an MB33 that displayed the same symptoms i.e you turn it on, the midi LED comes on and it makes a noise like its going to do the autotune start up it normally does but the midi LED never goes off, the autotune doesn't happen and the VCO doesn't respond to any midi messages. The problem isn't with the firmware EPROM as i swapped the OS chip with one from a working Freebass and the MB33 still didn't work. I've been through the circuit looking for dead components a few times and have come to the conclusion that its most probably something corrupted in the big Philips PCF80C31BH-3 12P microcontroller chip near the power input, but have yet to get around to trying to replace it as its a bit of a monster. A while back someone got in touch with me saying the same thing and said that they had somehow got in contact with an original MAM engineer who claimed they could fix this problem but wanted to charge more than a secondhand freebass to do so! If we could actually work out whats wrong with these things we could save a whole lot of machines from the scrap heap. I have a MB33 (which is the same as the Freebass I think). Better use DC adapter, since there is only a single diode as polarity protection and NO rectifier. Not good to use AC power, the whole circuit oscillates with 50Hz since only one halfwave is rectified thru the diode.
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