YONGMEI YM-6700 stinking keyboard with realtime programmable rhythm & trashy orchestrion accompaniment

Despite Yongmei's transistor tooter age is over (see Golden Camel 7A), they still makes the definitely worst built keyboards I ever saw! While the concept and operation of this sample based fullsize tablehooter from 2002 (printed PCB date) is like a normal modern sound bank keyboard, 2 severe flaws make it almost unusual - in new state it stinks unbearable acrid and always a very disturbing loud static noise of fixed pitch mixes into all sounds (unless you modify it). It also has only 29 instead of pretended 100 preset sounds; the rest is simply identical to fraud customers. But the ancient fairground organ accompaniment styles are lovely.

When new, this thing stank so horrible of toxic chemicals (styrol, phthalate, organic solvents, formaldehyde?) that I got headache and a sore throat whenever I played it for longer than 5 minutes, thus I had to vent out the keyboard in the bathroom for 6 weeks(!) to reduce the remaining odour to a bearable level. The case of the YM-6700 is made from heavy and reasonably robust plastic and also the keys here don't rumble but feel sufficiently firm, which is very untypical for Yongmei. Also the electronics looks well engineered and far less messy than with all my other Yongmeis, thus I think  it was manufactured elsewhere. But this all helps nothing because all sounds are mixed with a very disturbing digital buzz noise of fixed pitch (key matrix noise), which follows the sound volume envelope and at low volume settings drones as loud as the sound itself. Because the digital volume control steals bit resolution from the sound and (in unmodified state) the lowest volume setting still yells louder than ambient volume through the big and bassy speakers, the problem is worsened to unbearability. Also during pauses the digital noise is still present, although it toots quieter than during sounds.

I also really don't understand why Yongmei decided to annoy their customer with fake duplicate preset sounds to pretend a modern 100 sound bank; even when there was really too little memory left to store more samples or 100 individually programmed presets, they should at least have filled the rest with algorithmically generated envelope variants of the given sounds. The older(?) Yongmei YM-2100 did this without problem, which was much more honest and useful.

The preset sounds and rhythms are made from slightly dull medium resolution samples those theoretically wouldn't sound that bad when there wouldn't be the annoying digital noise. There is a sustain and vibrato button and even a pitchbend wheel, although the latter responds a bit slow and has fairly low step resolution. The percussion is made from medium low resolution samples; the keyboard percussion mode has 61 sounds including various strange effect sounds those may be nice for tekkno; 8 of them are also playable through drumpad buttons. The 20 preset rhythms have each intro, fill-in and ending and there is a programmable rhythm pattern. The accompaniment styles are quite complex arranged but unfortunately accept only standard chords; many patterns have a lovely cheesy fairground organ style, which sounds wonderfully trashy when the bit resolution is reduced with the digital volume control. There is also a realtime programmable drum pattern (not combinable with accompaniment) and a polyphonic record/ playback sequencer.

Attention: On eBay there are often false claims that the Yongmei YM-6700 would have velocity sensitive keys and/ or 1000 preset sounds (which formerly was also claimed on the Yongmei site). This is definitely wrong; at least my specimen has no velocity and far less than 100 preset sounds. Also the writing "61-keys Teaching Electronic Keyboard" means nothing since (unlike DL-2300 or YM-3300) there are no dedicated play training features built in.

This keyboard was also released in a silver version.

main features:

61-KEY TEACHING TYPE ELECTRONIC KEYBOARD



The pitchbend wheel uses no potentiometer, which is quite unusual.

modifications:

notes:

The case of the Yongmei YM-6700 is annoyingly oversized and was likely inspired by modern bulky brand keyboards, but at least it is fairly robust and heavy and has little common with the flimsy thin plastic of other Yongmei tablehooters. On the back are even 2 golden 6.3mm jacks those look much more professional than the wacky 3.5mm jacks of other Yongmeis. Also the loudspeakers don't appear that cheap; they make enough bass and don't excessively distort, although they were likely rather designed to play loud than natural because they sound somewhat dull and have a tubby midrange resonance that makes loud play unpleasant. Even the electronics looks mechanically similarly well constructed like in newer Yamaha or Casio keyboard and has nothing common with the horrible wire mess inside older Yongmei tablehooters (see e.g. Golden Camel-11AB or MeiKe MK-320B); the digital part here is a multi- chip PCB and the power amplifier even has a big heatsink, thus I think it was made in a different factory. Only the Engrish misspellings in the sound and rhythm list hint where this keyboard came from. But the clean looking hardware design did not prevent the digital key matrix signals from leaking into the amplifier, which mixes a very disturbing tooting noisy tone of fixed pitch into all sounds and makes the instrument almost unbearable. There is also some mains hum. In my specimen the internal audio cable between main and amp PCB was plugged in wrongways, thus instead of the audio signal the supply voltage lines got the shielded leads, but re-plugging it correctly didn't help much. Also the range of the volume control was so badly chosen that the lowest setting was still too loud although it reduces the sample bit resolution badly. I added an analogue volume potentiometer to turn down both to a bearable level, which also reduces the key matrix noise, but the noise still toots too loud despite I have rewired various GND lines. Like with Yongmei YM-3300 the LED display after 3 seconds always returns to the tempo setting instead of showing the currently selected preset sound or rhythm number, although here this disturbs a bit less because the YM-6700 has separate pilot LEDs for various buttons (only the "vibrato" one was forgotten) and buttons don't beep when you press "timbre" or "rhythm" to see their number. The tooting key matrix noise turns the louder, the more LED display segments are lit, thus there is possibly a design flaw in the sound chip that causes the pulsed display current to modulate its audio output voltage. (Perhaps it will help to insert a driver IC into the display output lines to reduce the display current, but I haven't examined the hardware further yet.)

Bright notes often hiss unpleasantly harsh because the sounds either contain strong DAC aliasing noise or intermodulate with the key matrix noise. Possibly as a questionable attempt to fix this, the highest octave in some preset sounds employs a keysplit zone with a too dull sample. The preset sounds are made from medium resolution loop samples; many timbres remind to Hammond organ sounds. Due to most samples employ no split zones, the bass range of many sounds is unrealistic; e.g. some wind instruments grunt with very slow attack by the too slow sample playback frequency. Sounds with built-in sustain ignore the sustain button. The length of added sustain depends on the preset sound. Nice is that when a key is trilled with sustain, each new note occupies a new sound channel, which produces a great phasing sound and volume increase effect although this eats up polyphony. The vibrato button adds a weak 5Hz vibrato. Both buttons also affect held notes (selecting a preset sound doesn't). Unusual is that the pitchbend wheel (called "Gliss Wheels" in the Engrish manual) moves instead of a potentiometer a digital multi- contact switch, which may be less wear prone (the remotely similar Sankai 01504H still had a custom made pot). But this construction also reduces the resolution to 5 steps per direction and makes the pitchbend respond a little slow. Slowly bending down even makes the pitch jump up again between the steps. The wheel also sometimes gets stuck , thus it works in no way better than a cheap pot. Like with Yongmei DL-2300 the preset sounds have lots of fancy fantasy names but most sounds resemble not remotely what their name suggests and many preset sounds are simply identical to fraud the customer; I have listed these doublets separately.

The "Grand Piano" sounds quite realistic in mids and high notes, but by the lack of split zones  the bass range is a bit too dull and resembles rather a well synthesized FM piano. (Yongmei YM-3300 has a better piano.) "Bright Piano" is an e-piano with Hammond organ timbre and weak tremolo in the quite dull bass range; high notes (2nd split zone) are dull. "Elect Piano1" has an even duller timbre that turns quieter with high notes. 2 has slower attack and a kind of duophonic e-bass or hollow nylon guitar timbre in mid and low notes; low notes are very dull. "Honky-Tonk" is no piano at all but sounds like a reedy wood pipe organ timbre with halfway buzzy bass. "Flat Piano2" is also no piano but sounds like an oboe or bassoon; higher notes resemble a metal flute. "Organ" has pipe organ envelope (slow attack) on the same organ timbre like "Bright Piano". "Percussive Organ" sounds like a xylophone but doesn't decay. "Church Organ" is a metal pipe organ rank with sonorous bass range. "Reed Organ" is a pipe organ timbre with dull bass range (not accordion- like); "Accordion" is another pipe organ with buzzier bass range, but the bass is far too dull and the sound too fat to sound realistic. "String1" sounds like a slightly harsh french horn timbre which slowly fades louder with some zipper noise and has sustain. "String2" is another piano made from the "Honky-Tonk" waveform with piano envelope. "Violin" sounds halfway realistic; it has a scratchy attack phase and no vibrato; in the bass range the attack of the sample turns too slow and thus unrealistic. "Pizzicato String" is a fast decaying synth brass sound using the "Strings1" waveform; high notes remind to a steel drum. "Synth String2" is a sort of vibraphone (without vibrato) that quickly howls down during its sampled attack phase. "Tremoto String" is a dull synth vibraphone with sustain and a very strong 7Hz square vibrato, that jumps up and down by an entire semitone. It resembles much the lovely "ghost" sound on various Bontempi keyboards. "French Horn" sounds with mid notes halfway realistic; high notes sound like a piccolo flute and low notes are noisy and too dull with slow attack. "Trumpet" sounds quite realistic (like with Yongmei DL-2300); bass range resembles a tuba. "Calliope" is another organ timbre; it resembles a dull metal pipe organ rank and has semi- percussive attack (timbre is a duller "French Horn" variant). "Flute" sounds fairly realistic like a metal flute with wind noise during attack; low notes growl dull with too slow attack. "Synth Brass2" resembles in the bass range a dull e-bass and with mid and high notes a sort of e-piano. "Synth Brass3" is a variant of "Pizzicato Strings" with "French Horn" timbre. "Wood Pipe1" sounds like a xylophone; 2 is the same sample with more compact envelope and stronger clicking attack (perhaps a marimba). "Recorder" is instead of a flute a fast decaying dull picked string or steel drum. "Jazz Guitar" sounds like a mandolin (fast decay, doesn't ring). "Yang Qin" is the xylophone "Synth String2" with sustain. "Metal1" decays fast (like a picked string) with "Church Organ" timbre.

doublets (identical sounds):
 
00 Grand Piano = #07 Clavinet, #51 Electronic Guitar, #80 Celesta
01 Bright Piano = #08 Harpsichord1, #52 Clean Guitar, #81 Marimba, #87Tubular Bell
02 Elect Piano1 = #09 Harpsichord2, #59 Mandolin, #83 Dulcimer
03 Elect Piano2 = #05 Flat Piano1, #42 Bottle wood Pipe1
04 Honky-Tonk = #15 French Organ, #23 Viola, #25 String Ensemble2, #57 Steel Guitar, #71 Synth Bass2, #75 Rock Bass, #78 Overdriven Bass1, #96 Metal2
06 Flat Piano2 = #16 Harmonica, #56 Overdriven Guitar, #84 Bell
10 Organ = #17 Drawbar Organ
11 Percussive Organ = #88 Glocknspiel
12 Church Organ =#19 Rock Organ, #27 Synth String1, #73 Jazz Bass4
13 Reed Organ
14 Accordion = #18 Jazz Organ
20 String1 = #24 String Ensemble1, #70 Synth Bass1, #98 Bowed
21 String2 = #37 Synth Brass1, #50 Piano Guitar, #63 Soprano Saxophone, #67 Oboe, #79 Overdriven Bass2
22 Violin = #72 Synth Bass3
26 Pizzicato String = #55 Rock Guitar, #77 Picked Bass
28 Synth String2 = #74 Acoustic Bass, #89 Vibraphone, #93 Synth1
29 Tremoto String = #53 Harmonic Guitar, #76 Finger Bass, #86 Musix Box, #90 Fantasia, #99 Science Fiction
30 French Horn = #32 Tuba, #60 Baritone Saxophone, #64 Jazz Saxophone, #92 Holo Pad
31 Trumpet = #35 Charang, #62 Alto Saxophone, #68 English Horn
33 Calliope = #36 Square Wave, #46 Ocarina, #66 Clarinet
34 Flute = #48 Synth wood Pipe2, #61 Tenor Saxophone, #69 Bassoon
38 Synth Brass2 = #47 Synth wood Pipe1, #54 Muted Guitar, #91 Warm Pad
39 Synth Brass3 = #44 Bottle wood Pipe3, #49 Synth wood Pipe3, #65 Synth Saxophone
40 Wood Pipe1 = #43 Bottle wood Pipe2
41 Wood Pipe2 = #82 Xylophone
45 Recorder
58 Jazz Guitar
85 Yang Qin = #94 Synth2, #97 Crystal
95 Metal1

The percussion is made from medium resolution samples those like the rest of the keyboard play rather bassy. Unlike Yongmei YM-3300 here also the keyboard percussion mode is real and indeed has one sound per key. Some sounds are re-used for 3 or 4 pitch variants, but this is nothing bad. Unfortunately the pitchbend wheel does not take effect on them. Beside normal standard and latin drumkit percussion there are also some nice synth toms, synth zaps, strange shakers and grainy gun shot and explosion noises those may be great for tekkno. Like everything else also the percussion is mixed with the annoying key matrix beep noise, although for tekkno this even may be suitable as a sound effect.
The custom drummer works in realtime like a recorder and is very simple to use although it is not really well designed for live play tricks. To program a rhythm press "program", which starts a metronome. Now play your rhythm on the drumpads or keyboard keys (keyboard percussion mode is always on during recording); to finish press "program" or "playback" (which immediately starts the user pattern). Press "playback" again to stop it. Also the sequencer works polyphonic in realtime and records any sounds (but it can not be edited). It can even record fairly long melodies (according to the manual 6000 notes). Nice is that note and rhythm sequencer both keep their content independently, thus you can alternatingly run your user pattern and a programmed note sequence. But you can not play live to a track stored in the note sequencer; only the drumpads and rhythm controls still work when the sequencer is playing.

The accompaniments are nicely arranged and some have a cheesy organ staccato chord line that sounds like an ancient orchestrion or fairground organ. Some have complex walking bass patterns and grooving bass (boogie woogie style) while others are less orchestrated and more versatile. But generally they sound nicely trashy and fulfil the tablehooter cliché in a positive way. It has so stereotypical old fashioned intro, fill-in and ending patterns that they sound like from an old cartoon or comedy movie or like some odd kind of circus band. I yet never found another keyboard with only that kind of oldie accompaniments. During fill-in the accompaniment pattern continues. Unfortunately the fingered accompaniment recognizes only standard establishment chords and ignores other key presses. (Yongmei YM-2100 and DL-2300 did this much better.) Odd is only that in fingered chord mode single finger presses trigger minor chords (with most such keyboards they do nothing). But there seem to be also various small glitches those make the patterns sound special; e.g. in some accompaniments they are selected by the currently played chord (not by chord changes). Depending on the selected rhythm, the accompaniments use different sounds, but usually there is an organ chord with more or less grunting bass and everything has a nice dose of analogue distortion (like from an old Hammond organ). But there is no manual chord mode without rhythm.

The demo melodies are mainly polyphonic piano tracks, but their names are not listed in the manual.

The 5 demo melodies are:

  1. (a classical piano fugue, sounds like Bach)
  2. (Chinese Piano tune)
  3. Chinese music (vibraphone with violin)
  4. Wa Haha (Russian tune?, on piano, same like on Angeltone DM-200)
  5. (rural polka, somewhat resembling "Twinkle Twinkle Little Star", )
The demo melodies can be selected by holding any of the 5 leftmost white keys while pressing "demo". When demo is running, press the cipher +/- buttons for next or previous song.

A close variant of this keyboard with only 20 (claimed) preset sounds was released as Yongmei YM-6600 (aka Cronenwerth CEK-660, slightly different control panel, silver case).
 

 removal of these screws voids warranty...    
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