Potex - Light Mixer

POTEX

Light

Mixer

tekkno toy keyboard with light sequencer, many effect samples & rhythms

This is another stylish tekkno toy tablehooter by Potex; its sci-fi retro design looks straight like an item from the classic Star-Trek or Space Patrol TV series. It has many sound effect samples and lo-fi background preset music pattern loops, but the most spectacular feature is the RGB colour changer globe with many different programmable light effect modes.

The behaviour of the instrument resembles other Potex/ Beat Square tekkno toys, however it has less sound features than e.g. Kid's Com - Mix Me DJ. Like there the keyboard ignores key press duration and only plays short unlooped samples, and the tempo control simply changes the sample playback rate of preset background music samples, much like changing the speed of a phono record. And also the scratch disc simply starts one preset sample per direction without any pitch or speed control, which has nothing to do with real record scratching. The light globe flashes by 3 LEDs (red, green, blue) in all colours. It can be switched in to various modes, including even a light sequencer that works similar like the "custom drummer" of a Letron MC-3, with the difference that it records and plays back colours instead of percussion sounds, using 3 drumpad- like buttons.

Annoying is that the digital volume control responds quite course, can not be set really low and the instrument always switches itself on with a loud startup drum pattern as soon any key or button is pressed, which makes the so-called power on/off buttons pretty useless. Generally the user interface has some flaws and can totally lock up by pressing the wrong button. But the sounds are partly even fairly warm and bassy and include a couple of nice retro timbres.

The instruction sheet calls the instrument "Item 676" and has a Potex and Beat Square logo.

main features:

25 midsize keys (Keyboard ignores key press duration. Black keys need a bit much force.)
built-in speaker (with enough bass)
keyboard polyphony up to 4 notes
10 preset sounds (selected by 2 buttons those each cycle through 5 sounds)

1-5 {piano, orchestra hit 1, string, jazz organ, synth meow}
6-10 {leaf spring, e-guitar, orchestra hit 2, string down, buzz spring}

18 preset background pattern loops (mislabelled "rhythms")

1-6
7-12
13-18

tempo +/- buttons (8 steps, control "rhythm" sound loop sample playback speed)
separate volume +/- buttons for "instrument" (keyboard + scratch disc) and "rhythm" (each 6 steps). Rhythm volume control steals bit resolution.
no master volume control
scratch disc (triggers 1 sample per direction, ignores speed)
10 preset "disc effect" samples {fast high scratch, laser piu, tremolo boom, synth ring up, base scratch down, bass scratch, synth parrot voice, synth ring, reverse scratch, clap}
all sounds based on medium low resolution 8(?) bit samples (with audible aliasing noise by low bit resolution).
CPU= "Potex W0676AA7101" (44 pin(?) COB)
RGB light globe
RGB light pad buttons
light sequencer (record/ playback of 8 colours, no edit)
4 light effects {rhythm mode, colour mode, fade mode, keyboard mode}
light speed +/- buttons (6 steps)
auto power-off (play mode = 3 min, demo = 15s)
AUX/ CD jack

scratch disc contacts

3 LEDs inside the lamp globe mix RGB light.

eastereggs:

crash: The CPU locks up when you press "play" to play a recorded light sequence after the instrument was powered off. Even the power switch fails by this and the light stays on, so you have to take batteries out to prevent battery leakage and get it to work again.

notes:

Exciting is that the futuristic case design with the unusually short keyboard embedded in the center of a much wider console reminds to antique small pipe organs or various very special sounding electronic instrument prototypes those never found their way into mass production (e.g. Mellotron, Rhythmicon, Subharchord and the like). And yes, there are even some strange spring- like preset sounds on it, those can make it sound special, and also the unlooped fixed- length lo-fi samples give it a retro appeal. However the fairly oversized bulky plastic case is here almost empty and contains only some small PCBs with few components. Interesting is the mark "Pb-free" on it; it seems to be one of Potex first examples of unleaded electronics. (I haven't analyzed the hardware further yet.)

After power on or touching any(!) key or button, the instrument wakes up from standby with a drum pattern at full volume (that can be truncate by turning the scratch disc). On the case bottom is a demo/ play switch, but it only switches the auto power-off time between 16s and 3 minutes. A real power switch would have made much more sense. So long the instrument is on, the light globe flashes in all colours. The colours switch with about 4Hz, or in the tempo of the running rhythm when on, but it can be switched into several other modes. The loudspeaker makes some bass and sounds quite good for such a cheap sound toy; of course it rumbles a bit when loud, but I have heard much worse ones. Unfortunately their is no sound output jack, and all buttons beep or play the selected sound, which disturbs live performance. The beep even ignores volume setting and always stays fairly loud. Generally the user interface is no great design. Starting or switching any "rhythm" switches tempo and rhythm volume back to default (quite loud). Many preset functions are stepped through by a group of multiple buttons those each cycle through a subset of them. Unfortunately each button in the group invisibly remembers the previous item number it was stepped to - even when another button of that group was used later; this complicates the use, because each button does not always start with the same item. The CPU even completely locks up when you try to play a recorded light sequence after the instrument was powered off; you have to unscrew the battery cover and take batteries out to get it to work again.

The keyboard preset sounds are plain low resolution samples and sound quite bright, grainy and a bit thin. They are all quite short (maximum about 1s) and unlooped samples, have a key split zone in the middle and ignore key press duration. Nice is that when a key is trilled, each new note occupies a new sound channel, which produces a nice phasing sound and volume increase effect although this eats up polyphony. The sounds have only numbers instead of names thus all sound names were chosen by me. "piano" is an acoustic one. "orchestra hit 1" is a percussive major chord sound; it somewhat resembles a slap bass noise that was turned into a chord by a harmonizer. "string" is a synth chorus timbre that reminds to bee buzz, "jazz organ" is a dull electronic organ timbre with semi- percussive attack; lower keyboard half is more sonorous, while upper half sounds like plain squarewave with chorus. It sounds nicely antique, and the fixed note duration gives it a special trashy appeal. "synth meow" is a resonant filter sweep timbre that goes "meow" with slightly bubbling attack. "leaf spring" is a dull and resonant spring- like noise; it slightly resembles "frog" on Casio MT-60, although it is less dry with a duller bass range and somewhat reminds to a buzzing ruler on a table or a chirping locust. "e-guitar" is a distorted lead guitar timbre. "orchestra hit 2" is a string orchestra sound. "string down" is a squeaking kind of violin that pitch bends down. "buzz spring" is a more massive variant of "leaf spring", that reminds to a circular saw.

The "rhythms" are genuinely loop samples and include a lot of complex tekkno synth patterns. Setting rhythm volume low strongly reduces their bit resolution, which can be used as a sound effect. The "rhythm" pattern loops are:

1:
tekkno with fat base and "synth parrot voice"
tekkno with "a ahaa!" vocoder voice
funky e-bass + flute + drums
thin distorted drum kit snap
walking e-bass reggae pattern
eurobeat(?) with piano + e-bass

2:
piano + e-bass boogie (or bluegrass?)
fat latin breakbeat with drumrolls + quiet voice
acid house
fat tekkno beat + distorted TB-303 toot
eurobeat(?) disco loop with synth chorus
squarewave synth + bass + clap

3:
orchestra hit staccato + acid bass
distorted tooting e-guitar rock
oriental flute + drums + clap (jerks, breakbeat?)
distorted synth ring oriental tekkno + orchestra hit
warm C64 disco bass pattern
bright harpsichord + distorted latin percussion

The scratch disc can be switched through 10 preset samples using the "disc effect" button, but only the clockwise sound changes; the anticlockwise one stays "clap". Only when the clockwise sound "clap" is selected, the anticlockwise one becomes "synth ring". The presets contain beside scratch sounds various videogame- like laser zap noises.

The light mixer has 4 modes:

rhythm mode:
Colour switches synchronized with the rhythm (behaves like "colour mode" with rhythm off).

colour mode:
Colour switches randomly at fixed speed.

fade mode:
Light fades between different colours and dark. The pulse width dimmer algorithm flickers a bit and mixes a quiet grainy buzz noise into the sound (which can be used as a tekkno sound effect).

keyboard mode:
Colour corresponds to the last played note; the keys from left to right show alternatingly red, green, blue, red, green, blue and so on. The mode behaves like "colour mode" when no key is pressed for 6s.

The "effect" button cycles the mode through {fade, rhythm, colour, keyboard}. Selecting the keyboard mode can be identified because the lamp goes out for some seconds when no key is pressed. The "random" button makes the light automatically toggle every 10s between fade and colour mode. The tempo can be changed with the "speed" +/- buttons, and the "light stop" button (the one below "play", not the "stop" button of the rhythm section) can freeze the actual colour at any time; a 2nd press continues the effect. By holding any of the 3 RGB light pads you can instantly change the light colour to the one of that button; holding multiple of them mixes their colours.
To record a light sequence, press record. The globe will flash white 3 times. You can now enter your sequence in realtime with the light pads. (You can press multiple pads for mixed colours, but unlike in fade mode, there are no different brightness levels available. The memory holds only 8 steps and the pads sound a beep when the memory is full.) Press "light stop" to finish. Press "play" to start the light sequence in a loop. To stop it, press "light stop". Annoying is that the speed buttons don't work with the sequencer. Also the timing resolution is very coarse, which makes the result a little random. The only good thing is that all sound related keyboard functions (rhythm etc.) work well also in record mode.

caution: Do not press "play" after the instrument was switched off. Else it can lock up and you have to take the batteries out to turn it off and get it to work again.

*removal of these screws voids warranty...*

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