So my friend, Calum, came over for a visit and brought with him a knackered old Yamaha CS-10 that he'd found in a skip many moons ago. There was nothing internally wrong with it but it sounded a bit rough and it was in a terrible state cosmetically. The portamento slider was snapped off and about half of the knobs were missing. To give Calum his due, he had patched up the missing end cheeks with some scraps of plywood but had then liberally splattered the whole thing with a mixture of cornflour paste and mould (it was an art thing). Of course there was crackliness abounding around the area of all the controls and a lot of time served gunk had accumulated in every crevice. I wish that I'd taken a few 'before' shots now.
Anyway, suffice to say, Calum in his wisdom and generousity, entrusted the said synth into my safe keeping until such time as he needs to cover it with oobleck again. I promised to look after it and give it a good 12,000 mile service. And indeed it was a pleasure to treat the poor neglected beastie to a good internal and external clean up; Servisol-ing the contacts, replacing missing knobs and crafting a new set of rather grander wooden end cheeks (as befits such a stately old synth). I haven't been able to do anything for the sliders yet. I'm on the lookout for a slider knob to fit the pitch bend control. And if anyone has any top tips on how to fix a broken slider shaft, I'd be eternally grateful.
In celebration of fixing the thing up and getting it sounding a whole lot better, I thought I should lay down a new track. So here we have the glorious CS-10, accompanied on the piano (well, the Hohner Pianet T and DigiTech BP8 actually) in a little improvised sketch for live performance.
Tah dah!
For anyone who is interested (and lets face it why else would you have got this far down the post) here are a few technical details about this recording. The CS-10 has a cracking multimode filter, but it won't self oscillate unless provoked. In this case I've split the output signal (using the dry output of a analogue delay pedal) and fed it back into the synth's audio input. This overdrives the filter and unleashes all kinds of self-oscillating consternation. The Pianet is going through my favourite Pianet treatment, the Digitech BP8. The whole thing is just improvised live into Cubase and spat out as an mp3 for the interweb.
Saturday, 21 July 2012
Casiotone 701 (1981)
I can't find a lot of information online about this keyboard, so I thought I'd better post a few observations before this one goes up for sale. It's a great performer and I love it to bits. However, I'm having to make a few sacrifices in the pursuance of an Arturia MiniBrute I so ardently desire.
According to Casio's own textbook, the CT-701 derives all its keyboard sounds from a mixing of LSI generated sine waves. These are put through D/A converters, D/A shift circuit, sample/hold and analogue filters before reaching the output. The percussion sounds (Kick, snare, low and high congas) are all single pulse analogue signals, the frequency of which are determined by capacitors and resistors and the decay time set by variable resistors. The cymbal and hi-hat sounds are simply filtered white noise.
As usual, Casio were trying to cover all bases with this keyboard. In addition to it being eminently playable and very useful sounding, this keyboard is equipped with a melody reading facility that, by use of a light scanning pen, could memorise barcode encrypted music and play it back either as an accompaniment or as a teaching aid. For my own purposes, this was merely a gimmick and of no real value, but at the time it was manufactured it must have seemed pretty advanced. It also boasts a very primitive sequencer in the form of a note and chord memory and playback facility. I never really explored this. Partly this was because it seemed quite complicated for what seemed like a fairly limited feature and partly because the battery compartment, used for storing these sequences on power-off, was pretty corroded with old battery 'juice' and I didn't think it was worth cleaning up for something I'd be unlikely to use anyway.
All in all this is a beautiful example of this classic early Casiotone full-sized keyboard. Its upper body is metal and its end cheeks are chipboard, all tastefully finished in a very fetching 'wood effect' livery. Its base is genuine plywood! This is the larger forerunner to the mini-key MT-70, which Hot Chip used all over their second album, 'The Warning', and almost all the sounds are exactly the same (I've just bought the MT-70 and compared the two).
Here's the spec:
61 keys (5 octaves)
8 note polyphonic
20 preset sounds:
Pipe Organ, Brilliant Organ, Diapason, Wood Wind, Tibia, Full Tibias, Flute, Piccolo, Jazz Organ 1, Jazz Organ 2, Piano, Electric Piano, Vibraphone, Marimba, Celeste, Chime, Oboe, Bassoon, Funky, Wah Brass.
Sound Effects:
Sustain, Vibrato (4 Types) and 2 Electronic Sound Effects
16 Rhythm Patterns:
Rock, Rock 'n' Roll, Disco, Slow Rock, Swing 1, Swing 2, Bossa Nova, Samba, March, Boogie, Waltz, Jazz Waltz, Rhumba, Beguine, Tango, Mamba.
11 different Fills
Tempo Control, Rhythm Balance Control, Tempo Indicator
Memory play functions:
Note storage capacity...Max. 345 steps
Chord storage capacity..Max. 201 steps
Pitch tuning +/- 50 cents
4" Speaker
One shouldn't expect any of the sounds to be much like their names. Remember this is from long before the time of PCM 'Tonebank' type Casio keyboards and has more in common with a preset analogue synthesizer. As all the sounds are formed from combinations of sine waves this range of Casiotones have a distinctly different range of voices from the usual 'Consonant-Vowel synthesis' employed in later Casiotones. Sine wave additive synthesis doesn't allow for the same flexibility, but the sounds it does produce have fuller, clearer tone, in my opinion. Many of the sounds, when compared to my MT-65 (which uses the consonant vowel method), whilst not so close to the instruments they are attempting to emulate, have a richer and more atmospheric sound of their own. I would describe them as more like an original synthesizer sound, with their own character. The combination of sine waves has a rich history of providing new and interesting keyboard and synthesizer voices, from the Hammond Organ to the Yamaha DX7.
The drums are a particular highlight of this model, sounding every bit the classic analogue kit that they are, especially when used with the funky touch sensitive 'fill' strip, and the patterns presented here are a useful addition to anyone's percussive toolkit. In fact it's almost worth having this model for the drums alone. They certainly trounce the drums on my MT-65, which is rightly praised for its analogue drum sounds and useful patterns. Similarly, I find the accompaniment chord, arpeggio and bassline patterns and voices punchier and altogether more useful than the ones on the MT-65, although there aren't as many options.
I can't remember where, but I found somewhere online the Casio Text Book for this model. This provides a complete breakdown of the electronics of this keyboard. I did contemplate keeping hold of this synth and making a few creative mods. I've already seen examples online where people have added individual outputs for each drum sound, melody and accompaniment. All the circuit boards are easily removed, clearly laid out with large form components and plenty of space surrounding them so it's very tempting. However, I need to raise some cash, so this one's got to go.
I should round up this little synopsis with an audio demo or two. The only things I've got at hand feature the CT-701 going through an effects pedal, so it's not completely objective. However, to be realistic very few analogue synth sounds ever get used completely dry, so it don't feel it's too misleading.
Most of what's going on here is preprogrammed into the classy Casio's step sequencer and then played back in a live recording. It is ably supported by the, post 'moogslayer' modded, poly800 and given plenty of delay.
Okay, this is that other post. A split cable is coming from the mini mighty Lorenzo and into the VCO F and ADSR Gate on a Doepfer A-111-5. Then through the usual BP8.
This is what it sounds like...
A few weeks ago I picked up an old mini-combo organ at a local charity shop. At first sight I assumed it was a reed organ as it has the simple chord button array usually found on such instruments and the grill covering the speaker looks perfectly poised to blow air. I gave it a whirl in the shop and instantly recognised that characteristic divide-down tone. It sounded a bit scratchy at first as though it hadn't been played for some time, so I wasn't immediately certain about taking a chance on it. However, it was in very good general order and after another turn around the town, it dawned on me that it was the best looking thing I'd seen all day and pretty much the best thing I could ever hope to see in our County town, so I decided to go back and buy it on looks alone.
As you can see, it's a little stunner. It's clearly modeled along the lines of a contemporaneous electric piano, a-la Rhodes or Wurli, but of a rather more diminutive stature.
Those Mini-Wuli stylings
It's a lightweight affair and, with the legs packed away into the lid, highly portable. I guess it must have been aimed at the crossover home/pro market. However, the keys are slightly smaller than full size and, with only a built-in speaker, there would be no easy way of amplifying it for stage performance. This seemed such a shame as its raw organ tones create quite a characterful 60's racket that are begging to be put through effects pedals.
Output Jack fitted (left), remaining blanked off hole (right)
So obviously the first mod I had in mind was an external output. Opening up the case revealed two unused holes at the back where jack sockets would normally be. They were covered with tolex on the outside, so maybe there was another 'professional' model that used the same case. Anyway, it was a simple matter of fitting an auto-switching mono jacket socket, in series with the speaker, so now if I plug the thing in to an amp or mixer the internal speaker is muted. This is probably the simplest and most valuable mod for this organ. The dry sound, from the built in speaker is a bit raw and unforgiving. However, putting it through a combo guitar amp or any kind of effects pedal opens up a whole new universe of possibilities for this little diamond in the rough. I've even put it through my Doepfer modular synth, but that'll have to be another post.
The external Jack socket blending in with the cable strap press stud
Having a bit more of a poke around for further potential modifications, I noticed a trim pot on one of the circuit boards. It looked like the board might be some kind of LFO. Sure enough, when I adjusted the trim pot, the vibrato rate increased or decreased depending on which way it was turned. It was a fairly sensitive thing though and the slightest movement would completely knock it out of whack.
The yellow wires show where the trim pot lived
Removing the trim pot showed it to be a 22k job. I reckoned a 10k potentiometer would help make it more controllable. It was tricky deciding where to site the vibrato pot though. Attaching anything to the front panel would ruin its good looks and anywhere outside of the case lid would leave it vulnerable to damage in transit. The obvious place was on the plastic end cheek at the right hand side of the keyboard. However, the plastic was glued to a solid wooden block and it looked likely to wreck the thing if I tried to shift it. Patience paid off, and I finally managed to prise the plastic cover off and chisel out a comfortable housing for the pot. All that then remained was to source an acceptably period looking knob and bob's your uncle!
Knice Knob
Having variable vibrato may only sound like a subtle mod, but it's really worth it. The ability to speed up or slow down the vibrato is a really effective performance control. Particularly as there is a slightly ramped lag in the way the speed is affected. It's a bit like how a Leslie effect accelerates and decelerates.
Noise maker number one
The voices are both square wave derivatives: 'Flute' scopes out as a 'Fair Low Frequency Response' while 'String' comes in with a 'Poor Low Frequency Response'. Each can be used independently or together. A volume mixer would have been nice. Not a difficult mod, but where to put the knob?!
Those original controls in total
Part of the keyboard assembly clearly showing the makers name
One of the first things I noticed, when staring into the guts of the thing, was the legend 'EKO' clearly etched into every circuit board. It's slightly dispiriting to realise that this little effort wasn't dignified with the public identification of its own manufacturer. I wouldn't know exactly what year this organ originates from, but it pleases me to imagine that it may, at some time in its production, have shared an assembly line with an Italian made Vox Continental!
So there we have it. The Eko Lorenzo Electronic.
I'll endeavor to get some audio example up here as soon as I can but, in the mean time, here are a few more shots:
I've been giving the old Yamaha TX7 some hammer lately. It's been pretty much permanently hooked up to my Behringer BCR2000 midi controller and alternating its output through either the trusty Digitech BP8 or the, more chronologically appropriate Yamaha REX50.
It got me wondering about how much a revolutionary synth, like the DX7, changes the course of popular music. If Yamaha had managed, at the time, to squeeze all those rotary encoders and other real-time controllers onto the fascia of its best-selling keyboard, I wonder if we would have had such a glut of glossy, shimmery, glorified lounge music coming from this synth's players, or something a little more eccentric and experimental?
Anyway, for the record, here's some of my recent imaginings of the potential outcome of this alternate history of synthesizers. You may be glad Yamaha went for the cheap option!
Well, I can't put it off any longer. I've ordered all the parts and they've all arrived. I must grasp the nettle and finally get down to the electronics project I've promised myself for a few months now. Since I can't afford to buy a Control Voltage Step Sequencer, I'm just gonna have to build my own.
The path of least resistance, for a novice like me, seems to lead to an idea based on the Velleman LED sequence kit, available at most major electrical suppliers (I bought mine from Maplin). This very helpful video tutorial on turning this kit into a CV sequencer was posted on YouTube by a guy calling himself MirlitronOne.
Expanding on this idea, another YouTuber, acidjack303 has added pseudo gate switches to the CV pitch pots and posted a video demonstrating it in action.
This is the model I'm aiming for. I particularly like how this guy has designed and laid out his box. It's given me something to think about at least. Also, he was generous enough to share with me a schematic for the layout of these switches.
Anyway, hopefully I'll have something to show sooner or later. Watch this space...
