DIY Roland TB-303 Bass Line, clone




One  curious fact regarding the Roland TB-303, Bass Line is that it has become famous and super requested, only after its production ceased and by an “improper use” done by some young artists, that couldn’t afford expensive instruments. What was originally intended as bass sequencer to allow musicians, in combination with the TR-606, its sister drum machine,  to perform live over an electronic base, became the screaming lead or the hypnotic drone of the most extreme Acid House from the mid 80s.

The reason is that the TB was a pretty difficult machine to program, if you wanted to reproduce the typical bass line of a song with chords changes, but can be pretty easy to use, if your performing consists of a 3/4th arpeggio with just tonal changes. These machines were also very cheap and easy to modify. With only adding a resistor and switch, you could get a killer resonance monster!

X0XBOX, Roland TB-303 DIY clone

I owned a real 303, bought in the first 90s at my local music shop. It was a mint conditions used unit, at a very affordable price, as on those times a monophonic analog synth was so much out of fashion, to be unsaleable. I remember the  words of the salesman: “Be warned, it hasn’t any MIDI” But no problem, I was aware that this was the screaming tool of the recently born Acid House and in the studio there was a TR-808 waiting to party with, in Sync24! I know it can sound a bit crazy for a synth lover, but my TB ended traded in for a jazz guitar, the strangest musical instrument swap, in my life! Years passed and many emulations as well. I had a nice Novation Bass Station, sounding pretty well and several software synths pretending to sound identical to my missing 303, but nothing sounded as good as the real thing, to me..Until I could read about the Adafruit project and could assemble a X0XBOX








Assembling the X0XBOX

The X0XBOX is an authentic clone, everything is reproduced with fine detail, apart the front panel and the shape of the box and its sound is really convincing:

What really is unique on the TB, is its particular way of sliding notes and its accent combined with the filter envelope. Many very good sounding machines 303 inspired, could reproduce the sound well, but not this characteristic, not having the same sequencer.  The X0XBOX, clones have this same behavior, all is well reproduced, the PCB has the option to put the original Roland BA662A VCA, making even the attack transients identical to the original

Some years have passed and the project has developed so much that some of these clones were sold already assembled, under a company name, like if they were different products then an Open Source DIY project.



I recorded a couple of examples from my filter resonance modified X0XBOX, to give an idea of some of the pretty unusual and extreme sounds, it can create. The first is a loop recorded through a tube preamp and an analog compressor, with high resonance on, the second is with a lower resonance, but passed through an iron transformer preamp.




I recently read about a product that is having quite a success in reproducing the TB, still remaining in analog, the Cyclone Analogic TT-303 Bass Bot*.

ACID IS BACK!!, even Roland* is showing its interest and has recently introduced a virtual synthesis version of the TB, sounding excellent from the demo videos.



*Just reporting, I have nothing to do with these companies



A Zombie Chroma Polaris

I want to dedicate my first post to a machine that I’ve loved very much, even if it has given me lots of troubles and..well, it still does every time I dare to touch it!

Just starting from its name, things are pretty weird.. On its back panel there’s a metal label with Fender written on it, that looks suspiciously similar to my guitar amp one’s. Something never seen on a synth, before! :D

An other pretty strange thing, is the Portamento ON/OFF switch activated by the pedal, a useful but pretty unusual design.

When you try to rise it from its stands, it reminds you clearly the reason of its Rhodes name (yes, its complete name is Fender Rhodes Chroma Polaris, there should be an ARP too..)’s so heavy! Anyone aged enough to have toured with a vintage Rhodes electric piano, knows about the heavy weight and the sacrifice needed to carry it around, obviously having the mechanics of a real piano it’s heavy..but the Polaris is an electronic device! Opening my Polaris for the first time, I remember of having searched for the alleged lead bars, I imagined they had put by design, to increase the image of solidity of the product! :D

The Polaris is an analog/digital hybChroma Polaris front panel rid, where an analog CEM chips based, 2 oscillators/channel, 6 voices of polyphony, 24dB filter synth engine, is computer controlled by a 80186 microprocessor, giving amazing features for the beginning of the 80s standards.

It had 132 preset memories (100 more than a Jupiter 6), MIDI, keyboards velocity control, Internal 12 steps polyphonic sequencer and the sounding juicy characteristic: Extra fast envelopes, giving attacks as sharp as the recently before born digital FM, DX7.

The project was a cut down, cheaper version of the original Chroma synth developed by ARP, the company known to the public for the epic synthesizer present in “Close Encounters of the Third Kind“, too. It’s development suffered several problems as ARP closed and was absorbed by CBS, the owners of Fender Rhodes. The project started under Paul DeRocco and was almost completed when CBS decided to pass it to Rhodes, leaving the team with much less advertisements funds, in a moment when digital was surging as the new standard with the Yamaha DX7, Oberheim and Sequential Circuits were still at the top of the sales while Roland and  Korg were offering alternatives at lower prices (Juno 106, Poly 800). The Polaris hasn’t been commercially too successful, but was still a very good synth with a distinct character.

CEM chips
CEM chips based design

I should have get rid of it, when long time ago, it was officially diagnosed dead by my synth tech center. I sure overestimated my  qualities as repairer, even so what was really needed more then a tech, was a necromancer!

Failing ribbon connectors

The most common fail on the Polaris is the connection from the front panel to the PCB. The plastic film that holds the tiny copper connections, tend to dry with the years and brake, making the editing possible only through MIDI.

Not a big problem today, as we have free MIDI editors and cheap programmable control surfaces that can solve the problem. But mine unfortunately was victim of a flooding and some drops of water entered in it, making it literally drowning. Its synth soul abandoned it, but its corpse started having a new life, reacting to MIDI inputs, but in the funniest way possible! From there its nickname, Zombie Polaris.

When the mood is cool and in full moon, it is capable of such dreadful howls!

OSO Original Sounds Only

OSO Certification what??

The name is a parody of the  ISO quality management standards. The intention in the “certification” is to state that sounds do not come from pre cooked samples libraries, but from real synths/instruments and are tailored differently for each song and music parts are played for that song only. Apart the joke of the name, the promise to work only with original and different sounds for each song, is taken seriously.


Tools for production:
ARP Odyssey MkIII, ’77 Minimoog, Roland SH09, Roland TR-808, Crumar Spirit, Marion MRS-2 (Oberheim), Waldorf Pulse, Roland VT-3, Elektron AK & Octatrack, Korg MS-50/SQ-10 (my -20 died recently), X0XBOX DIY TB-303 clone, Roland RE-201 Space Echo, Yamaha Superbass 1200S, DIY Strat, Mu-Tron Bi-Phase, DIY U47 and C12 tube microphones, Reason 10 with Mix&Mastering Rig3

The human is an Italian musician, producer and singer, living in Spain. Fanatic lover of old analog gear, vintage synthesizers, tape recorders, DIY electronics, Sci-Fi and humor.
Aspiring to become an astronaut while he was a boy, he soon realized that twisting knobs and moving sliders of music machines was funny and the only possible alternative, to explore Space.
Sound sculpting:
Tracks are usually built using vintage synths and other, (often self built) unusual tools. Sounds from sound libraries, if used, are present on rhythmic parts only. Some are recorded on analog tape, some others are tracked with no MIDI, using the old DIN Sync24 and playing live the rest, to give a more “organic” sound.