Casio CTK 631/731/601/611

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Casio CTK 631

The Casio CTK 631 is a full featured,full size key,5 octave, stereo touch sensitive keyboard with backlit display. It has an onboard mixer and can store 2 whole songs. There are the 127 GM presets and 32 user areas to store voices you have made yourself from the synth section,which works by combining the same modules that make the other voices.

There are 8 drum kits and 100 rhythms - and a 4 type reverb unit which really makes a big difference to the flat sounding noises.There is a built in pitch bender (range adjustable), and a set of drum pads - which to be honest are not much use.
All of the drums can be played from the keys anyway and what's more they are touch responsive and pitch-bendable!

There is an assignable jack for Sustain etc and MIDI In and OUT - no THRU - the phones output doubles as the main output line and PSU is 9v.

As with most CASIO keyboards,there are 3 operating modes for the auto accompaniment - either it uses the CASIO chord selection method,or it cues off the normal chord layout. With this model there is also a full range selection which means the manual area of the split keyboard also changes the chord that you are playing along with.

The CTK631 also sports SYSx dumping - meaning you can store your voice settings on your PC with the use of a SYSx program such as MIDI-ox.
Whilst the output channel of MIDI can be altered,the control of the system clock is not available via MIDI which means if you are making drum patterns either the CTK has to be the controller or you have to send drum signals on channel 10 - which is what all keyboards seem to be doing these days rather than trigger the drum time synch pulse.

The CTK also has a section called "Free Session" which creates chord progressions according to which rhythm is selected - this is useful for practicing lead melodies as the progression cycles.

The onboard sequencer can record in REAL or STEP time - and be edited the same way - so if you are thinking of making chugging bass lines or Tangerine Dream style sequences then this is an option.

Most of the functions,including the reverb are under MIDI control and you can choose what channel the keyboard transmits on - you can turn local control off -separating the keyboard from the sound system.

Good points: The sound from this unit once the reverb is on is quite classy and considering you can double up sounds with layering and tune them out from each other,you can get thick juicy phasing noises which is great for brass and strings. Some of the sounds are part sampled - and as such vary over the keyboard to mimic the change on the real instrument - this is particularly impressive with the Overdriven Guitar patch (29) which sounds like Gary Moore playing Parisienne Walkways - holding a fedback note indefinitely - I suspect with the addition of a fuzz box,you could sound like Jimi Hendrix on acid without ever plucking a string.
There are some wierd patches set up in the user presets to start with - which do all sorts of arpeggio and pitch effects -clever use of these can create some quite impressive noises.Patch 140 for instance drops the pitch of a brass ensemble which adds to it's "stabbed" sound.Other patches create rising crescendos (Patch128) which continue to rise when you let go of the key - the only way to explain this in words is to imagine there is an ADSR for pitch as well as volume. Along with the ADSR envelope shaping and changing the volume according to key response - you can sound louder or softer the harder you hit the keys or make the sound bounce from left to right stereo channels.
Touch sensitivity is adjustable and good though tends to quickly fall off incommensurately with how hard the keys are struck,but who would complain given the price? It can also be made to react negatively which at first seems pointless - but when used with a layered sound - it is possible to have one sound turn into another one as you hit the keys harder,which can aid expression if you choose the right pair of sounds.It also means you might pan from speaker to speaker as you hit keys hard or soft for stereo effects.
The blue backlight is an excellent addition to the LCD display- so no peering up close in low light conditions,though not easy to read from low angles,which is why mine is at the bottom of my rig.

Niggles: Inability to synchronise the MIDI time pulse is always a bug bear with me. The main Grand Piano patch is not quite up to Yamaha standards but is passable with the reverb on.
Another problem with the 631 and probably the 611/01 is that when choosing bulk dump send or recieve,the unit only stays in that mode for a couple of seconds before reverting the display back to whence it came. This is an absolute pain when trying to transfer data either to a PC or another CTK and there is no way around it - this is more annoying than even Casio's "auto power off" battery saving features which cannot be switched off.

I had the good fortune to try this model's cousin the 611 which is just as good though I think short of a pitch bender - it was playing the 611 that made me get hold of the 631 when I saw it going for a song  (sic) in an exchange shop - don't miss out - these are great machines. Sound files featuring the 611/31 can be found at []

Expect to pay: £50+ for a decent example. The 601/611 might go for slightly less.

Note that the CTK731 is basically a 631 with added on board MIDI player and file storage system on a floppy disk. It also adds a filter to the dynamic response and removes the hand played drums (which were largely useless anyway,and puts in Registration buttons which recall panel settings. There is also a modulation button rather than a wheel to add vibrato.)

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