my new favorite song is “jawbone” by The Band. just an ecstatic melody throughout it & the vocal peformance, no one else has ever quite sung like Richard Manuel does there (at the chorus, notably): “i’m a thi-e-i-e-f & i dig it…. i’m up on the be-e-e-e-e-f & I’m gonna rig it”…

i’ve been trying to figure out what the bass guitar does in the verse & then in the first measure of the chorus but it’s a step or two over my head at least until I crack it

when the sample rate ≈ 600kHz

Casio MT-100
Casio MT-100

I was wondering if it could be true that the Casio MT-100 really has “an internal sample rate” of 600kHz as I had found this information posted online. I quote:

The MT-100 and its cousins (such as the MT-68 and the MT-65) employ the NEC D931x chip to digitally synthesize sound. Two short waveforms, stored in a sort of “stairstep” format (instead of being stored as simple quantizedsound like PCM, the waveforms are stored in essence as a series of instructions meaning “amplitude goes n steps up/down”), are crossfaded with each other to produce each instrument sound. This was internally referred to as “consonant-vowel synthesis”, due to the usual form of each instrument patch — a sharp percussive “attack” waveform segues into a droning sustain phase.

The MT-100 has a wonderfully sharp and clear tone, with no distinguishable aliasing at all — perhaps due to the fact that its internal sample rate is approximately 600kHz. The output of the sound chip has 17-bit depth, with each of the 8 polyphonic voices internally processed at 14 bits.

This seemed crazy, though. CDs are around 45kHz. 600kHz is 12x that fast.. The highest audio resolution that is common on computers these days is I think 96kHz. That’s still just 1/6 as fast as 600kHz. How could a consumer keyboard made by Casio in 1982 and targeted at home musicians be capable of such an insanely high sample rate.

Twitter user @ahihih pointed out that the documentation seems correct, and that “running at a high sample rate is no problem when the DSP is computationally simple.” From the documentation:

The 931 produces a 17 bit audio word every 8 clock cycles - at a rate of about 600 KHz. This is an extremely high sample rate by digital audio standards and is of great significance to the bright clear Casio sound. In a sampled audio system, any harmonics of the signal which are above the Nyquist frequency (half the sample rate) are reproduced below the Nyquist frequency rather than above it. For instance in a Yamaha DX7, which has a sample frequency of about 50 KHz, if you try to create a sine wave X KHz above 25 KHz it will come out at X KHz below 25 KHz. If you tried to make a 40 KHz sine wave it would in fact be audible as a 10 KHz sound. This is a problem in the Yamaha DX7 because some of the more complex FM sounds have very high harmonics which can fold over the Nyquist frequency and become objectionably audible - for instance the Sitar voice played in the highest octave. Similarly when a recording is 
being made for a Compact Disk which samples at 44 KHz, the sound must be put through a really mean filter to remove all signals above 22 KHz which would fold over as "Aliasing Distortion". Since the Casio sounds are all made of step waveforms, they are very rich in upper harmonics which will extend way beyond the audio range - these waveforms would sound terrible from a DX7 because virtually every sound would have a significant harmonic content above 35 KHz and so would fold over unmusically to below 15 KHz. Since the 931 samples at about 600 KHz only those harmonics above 1185 KHz will fold down to below 15 KHz to become audible, and since the harmonics are getting rather low in energy at this frequency, there is very little "Aliasing Distortion". 

I’m not sure, but I think this means that there must be a lot of supersonic overtonal frequencies interacting with the audible ones — like modulators, almost.

marking time

I would like for these thoughts, these sentences I am posting here, to be anonymous, not tied to my name, or to be at least semi-anonymous (what would that mean?). You may have to dig. I am not so naive as to think that one can do anything online in 2019 anonymously. What am I afraid of? Being cancelled? I cancel myself.

What I know,  I have not been able to bring myself to set down my thoughts in writing but very seldom. One loses the reflex, the capacity, the routine. I am leaning into middle age, disaffected, consumed by routine, familial duty, seeking an outlet, a fleeting escape from this year that has been so unusual for my family and myself. Several years ago, in my early thirties, I had begun to joke about my mid-life crisis, because I like to anticipate things, and because my sense of humor skews ████. Perhaps this tiny collection of writings can be a small part of it. The crisis I mean. Writing as a certain kind of anonymity appeals to me. Like a certain someone, who only ever wrote to burn his name to the ground. (He never did succeed, at least not yet.)

Someone will find me out. That is no challenge, it won’t be hard.

my vintage Casios

When I was growing up, we had only one musical instrument in our house, at least until I started taking drum lessons around 1995. It was a truly tiny Casio keyboard, the PT-87. This keyboard, which my parents still have, is monophonic and really one of the least interesting keyboards Casio ever made.

In 2016 or 2017 at the thrift store I saw a vintage Casio for sale, and this was the first of many Casios I would buy over the next couple years. I found them all either on Kijiji or in Value Village, the local thriftshop.

As you see them in these photos, the boards look pretty clean and in excellent condition, which was sometimes true when I acquired them. Some were very grimy and have been duly cleaned.

~ the collection ~


Casio PT-10
Casio PT-10

We begin with the Casio-PT-10, a tiny and relatively primitive keyboard that fits in my back pocket. If memory serves, it cost me just $4 at the thrift store..


Casio PT-100
Casio PT-100

PT-100. No line output. Good sound. The keys stick.


Casio MT-35
Casio MT-35

The Realistic Concertmate-400 (a.k.a. Casio MT-35) has six dull sine wave tones, and not very many options otherwise. I purchased this one for $10 from a guy who said his mother, a church organist, had used it as her preferred instrument after her mobility became limited in her later years. (Her name and phone number are scratched into the bottom of the casing.) Though the sound is nothing to write home about, the form factor of this board is wonderful — very light, beautiful color contrasts, and very narrow. The mini-keys are also somewhat wider and more solid feeling than the mini-keys of other boards in the MT series.


Casio MT-70 (1982?)
Casio MT-70 (1982?)

The Casio MT-70 is an exceptional keyboard. It has analog sound, an excellent drum machine, and a wide variety of tones. It’s strikingly beautiful, too, if quite heavy. I bought it from a woman who said that her husband had bought it in 1980 or 1981 while in Japan and serving in the Royal Canadian Airforce, and that her children had learned to play on it before graduating to other types of instruments.


Casio MT-100
Casio MT-100

Grating drone. Casio MT-100. In many respects, very similar to the MT-70 above. But the MT-100 has an EQ. I’m not sure if this is digital or analog sound generation.

MT-140 (Circuit-bent)

Casio MT-140 (Circuit-Bent)
Casio MT-140 (Circuit-Bent)

The Realistic Concertmate-750 (a.k.a. the Casio MT-140) was something I found when I was looking for a first substantial circuit-bending victim. I bent it using Reed Ghazala’s schematic in his book Circuit-Bending.


It must have been almost four years ago that I came upon this Casio MT-240 in my local thrift store. I still didn’t know jack about playing keyboards but I was drawn to this lovely looking object and the price seemed reasonable, or I at least had the $20 to spare. Around this time I was trying to teach myself to play on a different keyboard with one of the James Bastien Adult Beginner piano books that I had studied out of almost two decades before. I really like a lot of sounds on this, especially “strings,” “synth reed,” “chorus,” “jazz organ,” “funky clav.” There are also ten timbres that can be accessed only via MIDI program change, including “Strings 2,” “Fantasy” and “Miracle.” (I am almost certain “Fantasy” (or is it “Miracle”?) is heard on Beach House’s “Lemon Glow.”) Yes, that’s right, the MT-240 has MIDI, and three-part multitimbrality. I really like the sound and resonance of the built-in speakers and the form factor of this keyboard. It’s substantial but not heavy or bulky. Bonus: The demo song is fire.

Casio MT-240
Casio MT-240

SK-1 (Circuit-bent)

Casio SK-1 (1986; circuit-bent)
Casio SK-1 (1986; circuit-bent)

Reed Ghazala provides a schematic for these modifications, which I followed to a T. I spray-painted the keys, obviously.


Casio SA-5
Casio SA-5

Casio SA-5 (a.k.a. Concertmate-380). Ghazala also provides a schematic for this, though I haven’t done anything to mine.


Casio Rapman
Casio Rapman

The Casio Rapmaster, a pretty happening board that includes a voice effector and some beats that aren’t all bad.

Further Reading

If you find this topic interesting, I recommend the two-part “History of Casio Keyboards: 1980-1988” that gen.error posted almost a decade ago:

Recent listening

One reason this blog hasn’t gotten off to much of a start (updated) is that I haven’t found my way around the WordPress editing modules. At my other blog I used to struggle with the limitations of the post “format” especially when I wanted to embed videos, problems with dimensions & layout. So this is a bit of a test.

Kari Malone – The Sacrificial Code

Beautiful & moving organ drone music, wonderful chords. The church organ was mic’ed close, I read, & as a result it sounds as organs do not usually sound. You hear the pipe valves open, little gasps. Bass tones that envelop you heart & soul.

Sharon Van Etten – Remind Me Tomorrow

I am in awe of the talent & feeling Van Etten displays on tracks like “Jupiter 4” & “Seventeen.” What an intense revisitation of adolescence, so poignant — for me at least, leaning into middle age.

Antlers – Familiars

I don’t know anything about this band but this album has been a part of my life & it is graven on my heart. An epitome of beautiful music from grief.

And some other recent and not-so-recent discoveries:

Vortex – Special Request

J-E-T-S   – Zoopsa

Koeosaeme – Obanikeshi

Charles Bradley – Changes

Tiny Tim – Live! at the Royal Albert Hall

Julius Eastman – Unjust Malaise

Chemical Brothers – No Geography

My Body Dissolves as I Watch and Dissolve – Burial Grid

Piano Nights – Bohren & Der Club of Gore

Beach House – 7

Aromanticism – Moses Sumney