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Syntecno TeeBee

Analogue Synth Module By Martin Russ
Published July 1996

With prices for an original Roland TB303 as high as £1000 on the open market, it is unsurprising that the last two years have seen a number of manufacturers attempting to emulate the 303 in a cheaper, MIDI'd form. Martin Russ checks out the latest pretender to the throne...

Back in the days when I didn't have a receding hairline, a mortgage, and kids, I borrowed a TEAC 3340 4‑track tape machine from a friend, and also took up his offer of a couple of bits of silver Roland gear as well. Armed with a 2‑track tape recorder and a primitive electronic piano, I was now ready to record my first serious cassette!

This equipment may seem outdated to the modern SOS reader, but at the time, the silvery Roland boxes — a TR606 Drumatix and TB303 Bassline — completely changed my opinion about sequencers, drum machines and expanders. With the aid of a DIN cable, you sync'd the two boxes together, and could programme in your own drum and bass patterns. Commonplace now, perhaps, but not 14 years ago!

Of course, many would expect the passing of time to have consigned both of these devices to the scrapheap long ago. But just as popular musical styles seem to cycle round, musical equipment also seems to have periodic returns to favour, and as everyone knows, the TB303 has become a sought‑after collector's item, in common with many other analogue pre‑MIDI instruments (although the 606 seems to have been eclipsed by the later TR808 and 909 drum machines). Prices of the TB303 — which you could hardly give away 10 years ago — have risen to dizzy heights, so that people unable to afford the real thing have had to resort to sample CDs. A number of manufacturers have sought to plug this gap in the market over the past couple of years: Novation and Control Synthesis, for example, have had TB303‑soundalike bass synths on the market for some time, and Roland are now even providing their own alternative in the form of the forthcoming MC303 Groove Box. The latest MIDI‑equipped TB303 recreation is the unit I'm looking at here — the Syntecno TeeBee.

Hidden Depths

The standard black, anodised aluminium front panel of the 1U‑high, rackmounting TeeBee has little of the appeal of the '80s silvery original, and is confusingly labelled 'T303'. But appearances are often deceptive, and the TeeBee is no exception. Hidden behind that front panel are:

  • A monophonic bass synthesizer.
  • A 4‑channel MIDI‑to‑CV converter.
  • Five rotary controls which can act as MIDI Controllers.
  • An MTC (MIDI Time Code) to Roland Sync24 converter.
  • A simple real‑time sequencer.
  • An auto‑wah filter effects processor.

As you can see from the picture heading this review, the TeeBee's front panel features just a few controls, and at first it seemed a little hard to believe that all the TeeBee's functions were controlled by a push switch, a 'Sawtooth/Square' selector switch and five rotary controls. But the TeeBee manages to make the most of the meagre front panel furniture by using a very unusual audio feedback system instead of the more usual LED or LCD display — more on this shortly.

The rear panel holds 14 connectors, although eight of these are 3.5mm mini‑jacks for the 4‑channel MIDI‑to‑CV/Gate conversion. There are two MIDI Thrus, and the MIDI Out can be defined as an Out or a merged Out and Thru. The audio output is a standard mono jack, and the unit uses an external power supply. In addition, the front panel also features a jack socket marked 'Analogue In' — see 'External Processing' box for further details.

Unlike most other vintage monosynth reworkings, the TeeBee is not just an analogue synthesizer with a MIDI‑to‑CV converter attached. The positions of the front panel rotary controls are converted to MIDI Controller messages and made available at the rear panel MIDI Out sockets; they're also used to control the synthesizer parameters and even held inside the MIDI SysEx memory of the TeeBee. The result is that the rotary controls can not only be used to control the synthesizer sound as you would expect, but they can also be used as general‑purpose MIDI Controllers, if 'Local Control' is turned off. And because the synthesizer settings are derived from the MIDI Controller settings and not just from the front panel controls, external MIDI Controllers or SysEx dumps can be used to change the synthesizer sound. If you're having trouble visualising this.

The TeeBee does not have any internal sound memories. Instead the entire setup and front panel control positions (with the exception of the Square/Sawtooth switch) can be saved as a System Exclusive dump via the 'Program' switch. By editing the parameters in the SysEx dump and sending it back to the TeeBee, you can change both setup and sound. This means that a sequencer can be used as a way of storing sounds and setups — rather like the volume setting and instrument assignment that you find at the start of a General MIDI sequence file.

This intimate connection between MIDI and the synthesizer control voltages is reflected in the other use of the TeeBee: as a 4‑channel MIDI‑to‑CV/Gate converter.

Power Play

The TeeBee plays a short sequence as it powers up. Switching on the unit while holding down the Program button until this sequence has stopped accesses programming mode, where many of its features are found. Once in this mode, the TeeBee trills between two notes, waiting for you to start using it. Settings are made via the unit's rotary controls; each time you make a new setting, you press the Program button. Different pitches in the TeeBee's trill indicate what the next input needs to be. This is one of the most unusual user interfaces I have ever encountered, and it takes some getting used to. Having said that, the audio prompts are easy to understand (if a little annoying after a while) and the method is consistent, if slightly cumbersome.

The TeeBee's programming mode is used to define setup parameters, although you can also use a SysEx dump instead. If you want to use the internal sequencer, the front panel controls are the only way to record and play sequences. The controls use ternary coding (see the 'Three's Company Box' elsewhere for more on this peculiar system), and so only three positions are used: fully counter‑clockwise, in the centre, and fully clockwise. On the review model, these controls were quite stiff, and turning them rapidly to make changes was not very convenient. Unfortunately, the Tuning control is also one of the programming controls, and so the TeeBee's tuning almost always needs to be re‑adjusted whenever programming mode is used. This can be avoided by only using SysEx dumps to change settings, of course.

Switching the TeeBee's power on and off is required quite frequently, since this is how you access programming mode, and when you turn it off, there's a noticeable thump. It may be a good idea to get into the habit of turning your mixer fader down before doing this.

Back To Bassics

With only five controls, the possibilities for making sounds with the TeeBee are somewhat limited. Its bass sounds, however, are classic examples of late '70s and early '80s analogue synthesizer.

The Sawtooth/Square switch toggles between the woody, hollow timbres of the Square waveform, and the more synthetic‑sounding, bright timbres of the Sawtooth; the four rotary controls then enable the timbre to be shaped in more detail. The filter Cutoff frequency control alters the brightness of the sound, while the filter Resonance control changes the 'emphasis' of frequencies near the cutoff frequency of the filter. The Resonance control doesn't go high enough to force the filter into self‑oscillation, but this is consistent with the behaviour of the TB303. The Filter knob actually just controls envelope modulation amount, and finally, the Decay control sets the time over which the filter sweep envelope decays. The TeeBee's envelope is decay‑only, although with the filter control set to minimum, I was able to produce slight rising envelopes.

Two important elements of the TB303's sound were 'Slide' and 'Accent' (see TB303 box for some background on the original). Both of these functions are hidden on the TeeBee. Slide is governed by a MIDI Controller, which needs to be turned on and off to control the glide between notes, in much the same way as a sustain pedal. The TeeBee's synthesizer is first‑note priority, and the envelope does not retrigger if additional notes are played whilst the first is held down: strict monophonic operation.

Accented notes on the TeeBee have short decay times, producing a result that is more like a negative accent. It's selected by using the attack or initial velocity of the MIDI Note messages that are playing the TeeBee. From 1 to 100, the velocity maps to volume changes as you would expect, but from 101 to 127, the velocity causes decay to be set to the shortest time. This requires an unusual playing technique, and is probably better suited to detailed editing using a sequencer.

The Chips Inside

Because the TeeBee uses an external power supply, its case has plenty of space inside for the two relatively small printed circuit boards. The circuit board at the rear of the case holds the Intel 80196 micro‑controller, the MIDI Input and Outputs, and the MIDI‑to‑CV converters, whilst the front panel circuit board is home for the analogue synthesizer circuitry.

Although the TB303 is normally described as having a 2‑pole, 12dB/Octave resonant low‑pass filter, the circuit inside the TeeBee looks more like a 4‑pole 24dB/Octave design, whilst sounding like a 2‑pole filter! I was unable to confirm the number of poles in the filter with distributors Blue Systems.

The layout and quality of the PCBs is good, although there was quite a lot of hand‑wiring inside the case of the review unit, and the front panel switches had been mounted incorrectly, with the star washers on the outside of the case. This may be a deliberate cosmetic device, but it didn't appeal to my eyes!

MIDI In Control

Slide is assigned to MIDI Controller 0 as a default. This is an unusual choice, because it's the same as the MSB (Most Significant Byte) of the Bank Select message. This can cause one or two problems when you try to use the TeeBee with some sequencers, but it can be re‑assigned to any of the first 80 controller numbers instead, as can the MIDI Controllers from the front panel rotary controls. The default setting for the 'Tuning' control is also a little strange: it's assigned to MIDI Controller 10, which is normally used for Pan control. Controller 11 maps to Filter Cutoff.

Naturally, I tried out the MIDI‑to‑CV conversion, and found no obvious 'zipper' noise artifacts. However, the MIDI Time Code to Sync24 conversion could not be tested during the review period, since I no longer own anything which uses Roland's Sync24 standard!

The Bottom Line

The TeeBee is in competition with other monophonic bass synthesizers, like the Novation BassStation Rack, the Control Deep Bass Nine, the Spectral ProTone, and the Synthology Clone 3. None of these has quite the same approach as the TeeBee, however, and the user interface of the TeeBee is quite unlike any of the others. Making a price comparison is hard because of the mix of additional facilities that the TeeBee offers. You need to decide if you need these features, or just a TB303‑type sound.

If you can live with the unusual programming interface, mastering the TeeBee means coming to terms with the complexities of using the Slide and Accent functions effectively. Plain step sequences sound much the same on any monosynth, but the careful use of these additional TB303‑type features on sequences with large leaps in pitch can definitely produce that characteristic Bassline sound.

The underlying sounds of the TeeBee are classic vintage analogue, and beyond that we enter the realms of personal preference. They're certainly completely in character with the intended market, and are not lacking in authenticity. But the final choice has to be yours — give the TeeBee an audition and then decide if it can provide the Bassline you've always wanted.

Three's Company: Ternary Coding

The rotary knobs of the TeeBee use ternary coding to control its internal parameters. Ternary is a close relative of the binary coding that is used in digital equipment, but instead of having two different values (on and off, or 1 and 0), it has three. Ternary coding is used in some telecommunications applications, where the three states mean no current, or current flowing in one direction, or current flowing in the opposite direction. The XMIDI proposal also used the same ternary coding of currents in order to extend the numbering system used in MIDI.

Syntecno provide a reference table, which means that you don't need to learn how to count in ternary, but here's a comparison chart showing the first 16 decimal, binary and ternary numbers so that you can get a feel for how they work:


Digital Thru Analogue: External Processing

The TeeBee's front panel 'Analogue In' jack socket overrides the Square/Sawtooth switch setting and replaces the internal oscillator with an external audio signal. MIDI Note On messages are used to trigger the TeeBee's enveloping and the result is a sophisticated auto‑wah effect. Using the TeeBee to process my digital equipment produced an unusual mix of digital precision modified with analogue filtering. Lots of scope for experimentation here!

Silver Dream Machine: The Original Roland TB303

The TB303 is a simple monophonic synthesizer, with almost the bare minimum of controls. It follows the basic VCO‑VCF‑VCA format of many analogue synthesizers. The VCO (Voltage Controlled Oscillator) provides the raw sound source, with sawtooth or square waveforms. This is then processed by the VCF (Voltage Controlled Filter) a two‑pole, low‑pass resonant filter which is swept by a decaying envelope (just the decay stage!). The overall envelope is very simple: attack and release are both very fast, with the filter decay stage being the only part of the enveloping that can be controlled.

Before MIDI, some things weren't quite as predictable as they are now. Portamento was produced by processing the keyboard control voltage rather than changing a parameter on a display, and was usually controlled by a variable resistance with a dedicated switch/footswitch to turn it on and off. Accents and velocity control were not standard at all. New equipment tended to redefine standards, and the TB303 is an interesting example. The TB303's 'slide' control produces a glide (or portamento) between successive notes, but also prevents the filter sweep envelope from retriggering — in fact, the sound sustains until the 'slide' is turned off! In the context of a monophonic synthesizer this makes sense — most monophonic musical instruments do not retrigger the sound when you slide the pitch. But I suspect that the sustain that results from the use of the slide control is probably an artifact of Roland's circuitry! The TB303's accent is also unusual, since it affects the decay time of the filter sweep envelope.


  • Recreation of classic analogue bass monosynth sound.
  • Authentic control of Slide and Accent.
  • Lots of additional features.


  • Unusual user interface.
  • Power‑off thump.
  • High price — though this reflects its versatility.


For the person who needs the extra features, this could be a one‑box solution. But there are lots of other ways to get similarly authentic sounds, so let your ears do the choosing.