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FAT Freebass FB383 / MAM MB33 - Acid FM mods: £70
For those of you who don't have a ridiculous amount of spare cash kicking around for a real TB303 (and we're willing to bet that's most of you) the Freebass or MB33 is a very close substitute, the only drawbacks being that '303' is all it really does and the filter kind of loses it with the resonance full up and the cutoff over 3/4.
BUT WAIT! as ever the nice people at circuitbenders swoop down to rescue you from the tedium of dull acid lines with our bin buggering Acid FM mods!
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Yes indeed ladies and gentlemen, our mods add 4 switches, 2 knobs and a jack input round the back to allow a whole extra smorgasbord of sonic mayhem. A veritable 3 course breakfast of orgasmic analogue delight! Something along those lines anyway :) These mods are applicable to both the FAT Freebass and the MAM MB33 in its many forms, as they are exactly the same machine inside the case. There's also something called the next! Spacebass 3.3 which was available in the USA and we are reliably informed is also the same machine but we have never seen one.
The mods consist of:
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VCO On/Off Switch: One of the most annoying problems with the Freebass or MB33 is the way that the VCO is removed from the mix when a jack is plugged into the VCF input. This makes it impossible to stick it in a rack without spending half your time reaching round the back trying to find the VCF in socket. We have solved this problem by preventing the VCO being automatically cut when a jack is inserted, and instead adding a VCO on/off switch to remove it manually if you chose to. This means you can now permanently wire the VCF input into a patchbay.
VCO Drive: In our experience onboard distortions tend to be rubbish and you'd do a much better job driving an acid line through an analogue mixer so this isn't really a super distortion but rather just drives the VCO into the filter to add a little more bite and dirt to the acid sound.
Resonance Boost Switch: Another annoying issue with these machines is that the resonance never reaches self oscillation (but then neither did the TB303) and also drops off considerably when the cutoff is over 3/4 of the way up. We've solved this problem by adding the resonance boost switch. With this switch activated the filter starts to squeal with the resonance about halfway up and then just screams at any higher settings.
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VCF FM Controls: These consist of three controls and a jack input. Essentially VCF FM allows you to modulate the filter cutoff at audio frequencies to create all kinds of clanging cross modulation and bizarre alien splatters & sweeps. This effect works best with the resonance cranked up into self oscillation which is where the resonance boost mod comes into play. The FM controls allow you to select one of four sources for the FM signal. The first is the normal VCF input socket round the back. This means you can run a sound through the filter section, but also use that sound to modulate the filter cutoff at audio frequencies at the same time. The second source is a new FM input jack on the back of the rack. Using this source allows you to run a sound through the filter from the VCF input, and at the same time modulate the filter cutoff with an entirely independent sound source at the FM in jack. The main VCO signal can be added to the mix at any time. The remaining two sources are the sawtooth and square wave signal from the main oscillator. These can be selected as sources completely independently of the setting on the VCO wave knob
The last controls in the FM section are the VCF FM on/off switch, which, in line with common convention turns the VCF FM effect on and off, and the FM amount knob. This final knob controls how much the source signal modulates the filter cutoff.
For demo mp3's of these mods click on the buttons below. The first demo mainly features the VCO drive and Resonance Boost, the second and third are some filter FM action from internal and external sources. The final demo is of two percussion loops sent through the filter section.
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FAT Freebass FB383 / MAM MB33 - VCF CV input : £20
One of the major annoyances of these machines is the lack of any MIDI knob control. While we can't add straight MIDI control this mods addis a 1/4 inch or 3.5mm jack (state your preference) round the back of the machine that will accept an external CV to control the filter cutoff. We can set up the input so that it will accept a CV input of either 0-5V or 0-10V (state your preference) which will allow you control over at least 95% of the filter cutoff range. Certainly more than enough for a rushing acid builder!
This mod also adds a switch on the front to toggle between internal and external cutoff control.
MOD DEAL - if you are getting the VCF CV input installed with the full Acid FM mods, or we have already modded your machine and you want this mod added it only costs £15 rather than £20
Korg Poly800 / EX800 'Polybeast' mods: £70
The Korg Poly800 and its rackmount / tabletop cousin the EX800 are odd beasts. They came from that strange era of Korg synths where they couldn't seem to decide between analogue and digital, and so came up with a selection of hybrid synths that didn't seem to excel as either sound. On paper the Poly800 was a pretty well endowed machine but in reality it always sounded a little thin and never really fulfilled its potential, which is where we step in with our Polybeast mods!
the mods consist of 3 main sections, Filter mods, FM mods and audio mods.
FILTER MODS:
Cutoff & Resonance Knobs: This mod can be found around the net under several different names and versions but essentially it adds knob controls for the filter cutoff and resonance parameters for realtime control. The resonance knob can take the resonance well into self oscillation and far beyond what is programmable from the front panel. This can produce the kind of screaming top end and subsonic bass that gives these machines a whole new range of sonic possibilities. The filter cutoff knob allows you to perform long filter sweeps for those squidgy burbling analogue lines that you knew your Korg was capable of but could never actually program. Both parameters are still also controlled by the normal programming methods which can set the range of the knobs control.
12dB / 24dB Filter Response Switch: Somewhat mysteriously the filter chip used in these machines has both 12dB/Oct and 24dB/Oct outputs but only the 24dB one is actually used. This mod adds a switch to select either a 24dB or less drastic 12dB filter response
VCF CV input: This socket round the back of the machine adds an external 0-5v control voltage input that controls the filter cutoff. The new filter cutoff control knob is disabled when a jack is plugged into the socket.
AUDIO MODS:
External Audio Input: This accepts a line level audio signal and inserts it before the filter and chorus effect so you can use it to process external signals. The input is set up so that a loud signal will slightly overdrive the filter for a dirty sound.
Input Level Knob: Its a knob that controls the level of the audio input. What more can we say?
FM MOD'S:
These consist of a source selection knob and an FM amount knob. Essentially VCF FM allows you to modulate the filter cutoff at audio frequencies to create all kinds of clanging cross modulation and bizarre alien splatters & sweeps. This effect works best with the resonance cranked up into self oscillation which is where the new resonance knob mod comes into its own. The source selection knob allows you to select one of four sources for the FM signal. These are DCO1, DCO2, Noise and audio input. The audio input takes its signal from before the input level knob so you can use the audio to mudulate the filter cutoff but remove the actual audio signal from the mix. The source knob also has an off setting.
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Click on the buttons below for mp3 demos of these mods.
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Korg Poly800 / EX800 backup battery mod: £20 / £10
Early model mk1 Poly800's do not have a memory backup battery and so unless you keep a full set of charged batteries installed at all times the program memories will be lost when you switch the machine off. This mod simply adds a small lithium cell backup battery that keeps the memory intact when theres no power source. If there is no original battery the mod costs £20
If your machine has a backup battery but it still loses its memory the chances are that the battery is well beyond its reasonable lifespan and is completely dead. For £10 we can replace the backup battery in a battery holder that allows for easy replacement in the future.
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We're working on a new contact system, in the meantime if you want your machine modded click the button on the left and fill in the form on the page that opens. |
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