I did not make these videos or bend this board, I don't know who did. but they are extremely my shit
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.
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.
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 ~
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..
PT-100. No line output. Good sound. The keys stick.
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.
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.
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.
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.
Reed Ghazala provides a schematic for these modifications, which I followed to a T. I spray-painted the keys, obviously.
Casio SA-5 (a.k.a. Concertmate-380). Ghazala also provides a schematic for this, though I haven’t done anything to mine.
The Casio Rapmaster, a pretty happening board that includes a voice effector and some beats that aren’t all bad.
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:
Last fall I set up a Youtube channel ("Astral Keys") with the intention of posting some videos showing some of my circuit-bent keyboards & such. Here's one of 'em I posted a while ago (Sep 26, 2018, apparently), a Casio MT-140. I never did put the keyboard up for eBay auction, still have it. I really like some of the sounds this produces, as they are totally unique.
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
Why this site, hyperaudiosensitive? For a long time I thought that was the proper name for my condition — only after many years of not knowing I had any condition at all. Even today I’m not sure just quite how atypical I am. A day will come, I will go and see an audiologist, and they may describe my condition to me. They will surely not use the word “hyperaudiosensitive,” they will say “hyperacusia” (actually I will say this) who knows what else. I know this but I won’t consider it even half the story. Until that day I am undiagnosed, or self-diagnosed.
Self-knowledge can take a long time. One thinks back to childhood, things that happened, that happened incontrovertibly, that were surely atypical. It helps to have the memories of others to confirm what self-doubt scrambles. Here’s what I know, a snatching: I would complain to my mother about the sound of my clothing. Specifically, the sound of friction of certain fabrics rubbing against themselves — blue jeans, many types of pants actually, but most especially winter coats or fall jackets of a certain type — the “ski” kind. An intolerable dryness and synthetic rustling in my ears. Is that odd? To me it was as natural an aversion as could be.
But there was one incident that confirms my early and ongoing susceptibility to sound — my hyperaudiosensitivity — more than any other. It was a yearly tradition at my elementary school for there to be held in the gymnasium a wheelchair basketball game between the faculty and the eighth graders. I must have been around seven, eight, or nine that year. I did not know what was happening. The sound of the students screaming and pounding on the wooden bleachers all around me, 360°, was excruciating. I was beside myself. The pain in my head was excruciating, I felt helpless rage at those in the crowd around me. I couldn’t understand what was happening. After some time, who can say how long that lasted, a teacher noticed the state I was in and removed me from the situation. The rest of the memory is lost.
At some point after that, perhaps owing to the gymnasium incident (perhaps it was something else?) my parents took me to see an audiologist. Why was the room dimly lit? It was determined that I have sensitive hearing.
Don’t think that this means I couldn’t tolerate loudness — in fact I sought it out in many forms. I can remember being home from school and having the house to myself and turning up The Downward Spiral to level 8 or 9 on the basement hi-fi, pressing play and running as fast as I could away from the CD deck as I waited for the blast of noise. From thirteen on I took drum lessons and later played in rock bands, marched with the marching band to Holst and Tchaikovsky. I can remember my ears ringing for hours after an MXPX concert around 1999. My ears still ring.
This website is simply a place for me to explore my experience of sound, music, audio. I have another website/blog, ██████████████ ████ ████. Over the past few years, as I have gotten into circuit bending and also learning piano, I’ve been tempted to post thoughts on music and sound to ████, but I have refrained from doing so. My reasoning is that most people who read at █████ do so because they are interested in ███ ██ ███, not music, sound, or audition considered as subjects in themselves.
It would be hard to overstate how important sound and music have been to my life. My experience of music in my adoloscence, mainly through the mediums of FM radio, MTV and CDs, has been every bit as formative, if not more so, than my experience of books. It’s absurd to try to compare the two, so different and yet so linked. Sound clearly comes first (infantile conditioning). Frequently my book reading led me to seek out different recordings, somewhat less frequently my listening compelled me to a certain book. My love of Satie’s music led me to read his own writings, and to read several biographies of him. I only discovered the music of Charles Ives after reading an interview where ██████ mentioned the “haunted montage” that is his 4th symphony. Due to this constant overlap it seems almost ill-advised to begin a second blog when I barely update the only one I’ve had since 2012.
All I really know is, my sense of hearing is (and has seemingly always been) atypical when considered in relation to others. Oftentimes I believe it operates normatively or almost normatively. It’s my hope that by creating this space I’ll be giving myself an opportunity (and a reason) to think through the matter more fully.
Thanks for reading, I hope you’ll come along.