i am a subversive contrary bastard. and i make things with this in mind. it would be a lie against nature to deny it.
(rant alert: sometimes i just have to get it out… it won’t be pretty, but you don’t have to read it, either)
in addition, the “adult” world is generally a great disappointment to me. and, whatever it is, or purports to do, i don’t believe it… until i’ve seen it’s underpants and broom-closet.
but what good could nature possibly get out of me? does nature need contrary, or even give a damn? or is it civilization i should be worried about? am i just one more irritably discontent jerk in a sea of uncivilized assholes, raining on the parade or just messing with shit? it takes millions of well-meaning, orderly and faithful souls to put this world together… just so a few sour grapes can paint it black?
and if there is some good in contrary, what qualifies as quality, when it comes to going against the grain? are there better or worse kinds… what does it mean to make subversive things? what good could they do?
perhaps, it’s good for stirring up the pot when things get totally stuck or boring? increase the opportunities for natural selection? fluff the herd for an entertaining ritual sacrifice? start a revolution?
or is it just random pain in the ass on the evolutionary road, social friction, doomed to inevitable flattening (by a fat suburban douchebag in a hummer with a gun rack, rushing nowhere, with a supersized mountain dew and a mouthful o chick fil-A…)? well, it sure isn’t enough just to cross-dress and walk backwards (although, it certainly doesn’t hurt either…).
i have a suspicion there has to be an element of collective or general advantage to any successful subversive/contrarian effort, even if no one likes the way the medicine goes down, and in spite of the powers that be. real contrary is not simply opposite, it is an opportune break with the way things are. but what the hell do i know?
one thing is clear. i don’t feel like i have a choice in the matter. and it’s probably a bit of all of the above, which means it might be part natural. so there’s hope for me…
the present moment has never been particularly kind to contrarian jerks, but history has been downright generous. most of the heroes of the written record are contrary rat bastards. and despite the requisite hard knocks, even bottom trawling subversives such as myself do often get a fair amount of positive contemporary direct/indirect marketing… always have. not necessarily for their benefit, of course, but some do cash in. i can’t wait! (still waiting…)
in america, the mainstream leaves a little space for people like me, up to a point. this includes academia and industry. the marketing business often channels a little contrary mojo, just enough to carry a whiff of difference – scratch and sniff contrary – to imply a generic “new” relevance, dark edge, hipsterness or sometimes actually just in total desperation. a subversive patina appealing to some deprived sense of humanity, something missing, and therefore convince itself that it is capable of change (which it actually doesn’t want or approve of, and has no intent of ever allowing). apparently, civilization likes a little contrary from time to time. as long as it’s in the proper measure (no actual change at all).
yes, and there are quite a few brightly illuminated “contrary” motherfuckers around as role models… sadly not myself. pundits. mainly of the sort that smoke in the subway, or preach weird gospel for money, hawk conspiracy theories, or just sell things that will soon be thrown away. but all of them without actually contradicting the state of things. they hock the flipside. neo-nazis (and fox news) are often working this angle, for example. QUESTION: need to get a rise out of ordinary folk who never pay attention to anything outside of their own tiny expectations? what is the most exploitative, disreputable and unpopular political position a person could take these days… especially if one has no connection to what it originally meant, can barely read or write, and is completely dis-enfranchised by the mainstream? give a rebel yell… seig heil! this is actually idiot contrary, and not worth spending much time on. it does pay some, and there is plenty of it to go around, but it’s just more of the same, only upside down. libertarians fall into this category. american “survivalists” too. troglodyte rebels. the teenage hang behind the seven-eleven (smoking pot and drinking night train or colt 45) is similar… but much more innocent. that isn’t contrary, it’s desperately ordinary. self absorbed. mainstream. sniffing glue, chugging cough meds and smoking embalming fluid… now that is fairly contrary (and really skanky). but all of that still changes nothing, which is of course the point.
that’s not really what i mean…
i guess i am thinking of a more visionary contrarianism. something along the lines of babette’s feast (netflix it). something that de-constructs the dominant discourse, and posits substantial and timely difference, and simply by it’s very existence, flips the adult world the stink finger. and things are better afterwards. it’s been said before that whispering is often a better way to be heard, if everyone is yelling and screaming. whisper something really resonantly subversive, make them a nice sandwich, kaboom!
it is smaller, perhaps more durable transformations, that interest me. things that directly affect the withering reduction in quality of life that the industrialization of humanity has wreaked on the planet, on culture, on human relations. mass produced crap, that ends up in the garbage. mountains of garbage. disposable work and manufactured obsolescence. oceans of shit, carbon dioxide and plastic. a view of humanity as disposable. a view of nature as disposable. people who can’t tell the difference between fake and authentic because it actually doesn’t matter. fake is way more important than real, regardless. our civilization is totally invested in it, no matter what country you come from. and here you get a sense of my paranoid take on things: “they” are ready to prevent big changes… with media, guns and the law. big changes are scary and affect profits and planning for the future. but small contrary steps add up. governments and corporations can’t keep track of them so easily and when bigger things emerge, it is too late to stop it. this encourages me. i need some hope, myself. because i want many things to change and it seems unlikely. like i said, i am a contrary bastard. there has to be some alternatives to the right-wing religious pyscho fuckers… whether it’s al qaeda or the christian right. also the institutional systems designed to prevent all real innovation: state, church and industrial workplace. against wall street: the enemy of everything innocent.
the slow food movement, for example! it woke me up. very nice subversive work there. no one needs fast food, and it doesn’t help anyone but the 1%. okay, the occasional pommes frites is nice, but what goes for the most of it, is terrifying. not all food has to be healthy, sophisticated or good for the planet. but, most food? in fact, you can count me in for permaculture and rooftop jungle. farmers markets (hell no, monsanto!) bring it on. in seoul, a big concrete jungle if there ever was one, greens and spices are grown right in the city year round… why not in new york? there are so many wonderful small contrary ideas that could practically work. elephants in nebraska… roaming the plains? if the puritan english could move to the states, why not elephants? and black rhinos… let them in, i say. better them, than any more white europeans. it will be hard to keep the yokels from shooting them though. simply because they’re different. but i’d bet they’d do better in nebraska than in namibia… they used to live in the midwest anyway. my point is that contrary can and could be fun, and great for the place.
so, subversives can perform some service, to civilization and nature. it’s a dirty job, but someone has to do it. technology? what about craft? design? art is already steeped in the marketing of contrary, so i will leave that alone. but what about science and engineering? let’s get out our ipads!
todays engineers are generally cowards. most of them (high voltage folk exempted). and, like priests, almost incapable of self-reflection, remorse, or sense of larger context for the job at hand… (again, high voltage people exempted). yes, that is what i think. they live in a world of conventional and predictable details, expertly modeled, defensively distanced by the size and “objectivity” of the job description, and stubbornly convinced of the wisdom in it. it’s all figured out. and they are so NOT concerned with the potential consequences of the interactions of their work with the work of others. or with culture. not that i am totally against that, just that it is never deliberate. for these people, it is “not worth” considering…
it’s not completely their fault. engineering is taught that way, and the value of the work is proved in the marketplace. it’s not their job to think in wholes. you don’t get paid to think big. “context”, especially in emotional terms, is a tiny word in their vocabulary. yes, it is mean and probably foolish to make such sweeping generalizations, and sure, there are many exceptional people and visionary threads of development (if it is actual development, then it is already contrary)… but overall, the nature of this work is baby steps with avarice. suspicious, reluctant “non-progress”. and yet, when then rules do change, ultimately eager to throw everything into the garbage and forget about it. because profit, the uber value, stands over all of it. that hasn’t changed, not for some time. the measure of all things engineered.
by the way, there is nothing ever contrary about profit, except doing things for free. nothing more deterministic or mechanical. if there ever was a place that needed some subversive thinking, it is here. it is, but tucked away in the holes and corners of industry and society, hoping to avoid detection by middle management.
to be fair, there is so much specialization now it is not really possible for one person to have a comprehensive sense of the whole, much less do much with it. there are too many disciplines. those who handle the macro vision have little comprehension of the micro, and the other way around. there are too many layers of interaction. too many managers (“please don’t kill me, i just do eyes”…). our understanding of the physical universe has long passed human scale. so has the sense of interconnectedness. still, i’ll stick by my diss… they’re supposed to be the clever ones. they could try for some integration… they generally avoid it like the plague. it does make it easier for all of them to be exploited, by both the “scrupulous” and the not. that’s a good thing for some.
every month scads of new details about how things fit together, or don’t, are published, peer reviewed and disseminated. this is not to say there aren’t people or groups of people who have a perspective of what they are doing or what is changing… darpa for example (“creating and preventing strategic surprise”) still has graduate engineering and science students working on grant funded elements or components of enormously complex systems that are secret and sometimes very contrary. those working on the parts have no idea (?) what they are for. one nuance of computational linguistics, added to another algorithm for pattern recognition, networked to a specialized search function of a database (kept by the DOD), which now can be cross referenced with facial recognition software, and a fast frequency-hopping microwave uplink to a remotely piloted drone over yemen, with the results crunched by a new program for analyzing crowd behavior… and que theory, that relies on another 3D mapping technique based on stereoscopic, or multiple-camera overlay software recently adapted from work done in the 1890′s and in the 1940′s on stereoscopy. what the hell could they want that for? oh right, to find and kill people by remote control…
the point is that few of those working engineers and scientists ask why. its not their job. they solve the riddle of the immediate problem. what emerges from it is “someone else’s” problem. physics is too “flaky and impractical”. politics and psychology “have no place” in design work. yeah sure. engineers aren’t supposed to do “wet work”. this leaves the bigger picture to business managers and to marketing departments, and politicians… the “experts” on what is good for humanity. in systems that organize above a certain level of complexity, there is no question that this method of working and networking the work of many together, is powerful. think of apple, or mercedes benz, and their impressive list of accomplishments. but it also creates both blindness and sometimes disaster, which you can’t “see” until it happens. this fact, combined with the small mindedness and the tiny cajones, insure a constant supply of highly engineered gadgets that leave out crucial features, serve the interests of the wrong target group, or glitch tragically when the ride turns left. both the car industry and the covert drone warfare industry can attest to this (brakes that accelerate the car… and remote recon systems that can’t tell the difference between friend, non-combatant and foe), although they won’t do it loudly. and it can be a very subtle set of small interactions between disparate functions, from which emerge large and extremely undesirable behaviors. it can also be very hard to fix because the bug/s can be very hard to find. and the teams very much separated by culture, fear, and distrust. but, most of all, the success of their way of working apart, has an overall effect of diminishing the perspective these gadgets were meant to enhance.
these gaps and blind spots are the life blood of hackers, by the way. hackers are often undeveloped engineers with an acute sense of context. and the best analog engineering is hacking.
for example, some of you are sure to be circuit benders, or know of them. you/they can be asinine, especially if they come off serious… laughter is crucial for that kind of hacking, and in the right balance, a cure for the stuck industrial soul. it is a semi-sensitive manner of getting to some new sounds that might (generally not) expand the context of what can and should be meaningfully done. that is very difficult to come up with on your own these days. “new” is harder and harder to come up with. kind of like gecko stickiness. no human thought of non-chemical stickiness until they started looking at how geckos stick to things… it is becoming a “new” thing now. we didn’t come up with it. geckos did. but we needed to have a deeper sense of the value of sticky, before we could recognize what geckos did that was different and special. the key thing is that chance and the natural world gets a piece. that is circuit bending.
control is a relative idea. to “bend”, you follow wherever it leads. benders use hammers and icepicks. paper clips and handfuls of aluminum glitter. hairspray and coolant are also useful… even fire. breaking, shorting, glitching, and or otherwise destroying the normal function of an electronic musical or audio gadget for the purpose of getting new and unusual sounds – all is fair. this is the polar opposite of the modeling business. you can’t know ahead of time. i have heard my share of it… at it’s best, it is beautiful and exploratory. at it’s worst… well, there is plenty of dreck out there anyway. that is why it is especially important that the bender has a sense of humor. but, the interesting thing is the element of chance, and the complete rejection of the industrial arc. “you can’t manufacture this!” it’s a wild card. gives back a little power. a little sexy human power…
this edge is never pushed by the mainstream. but the mainstream relies on the undertow to give it relevance and even a sense of hope, even as it resents and stifles any and all significant change. at least until it really needs it and can’t wait anymore.
the design of analog electronics is rife with opportunities to do it contrary, break old habits and get some benefit. for music making, sound design and for research. slow food for the ears.
okay, today’s project is a variable filter arrangement that is particularly well suited for sound generation or processing… and it is based on one of the oldest and most durable circuits known: the twin T filter.
i think the tubed active filter is one of the most delicious applications… and one of the least explored. op amps have made it easy to make complex filters with flexible tuning and tweaking. and it would take lots of space and power supply to replicate that approach with tubes. it is not the only way. sometimes, it is worth looking closer at old tricks for clues and hints of new direction. cleverly simplified direction.
the twin T filter is mainly used in it’s most “tuned” form, shown below. in fact, it is unusual to see it any other way, these days. one could call this a special case of a bridge circuit, because the two legs are made to work in balance with one another. like most other RC circuits, the tuning frequency, f = 1/2piRC.
below you see a sweep of the filter, with typical values for 1 KHz. note the deep notch and phase shift characteristic. the phase shift in the two legs reaches 180 degrees together, and nulls out everything. also note the insertion loss is very small. there is very little attenuation outside of the attenuation band.
in order for this filter to perform as well as you see in these pix, very close tolerance parts are required. in practice, you will have somewhat less of everything. the loading of the circuit is also very important. loading it down reduces the attenuation and Q of the filter. because this is an RC filter, the attenuation characteristic is gentle and slow, and spreads across several octaves, either side of center. but you still get a lot of loss at the null.
okay, nice one trick pony with great features. or is it? notch filters can be turned into peak filters and oscillators as well. first thing to do is make it a part of a feedback loop in an amplifier. why? because now the gain of the amp will be maximum at the frequency with the most attenuation (least feedback), and will have much less gain at all other frequencies.
here are two practical arrangements: the first one uses a cascode amplifier and the second a pentode. multigrid arrangements have many ways to get signals into them… which is what you need. grids are generally high impedance inputs (the screen grid of of pentode is not) which makes things easier. a buffer will be a big help in order to get the low source impedance necessary to drive the filter and decouple the plate load of the cascode from the lower grid (the feedback input). there are many ways to do this, but this way is venerable, having been used in the 40′s and 50′s for radar and special applications (see valley and wallman). i used this approach to design the TUBeQ for electro harmonix.
and here is the sweep…
here below, is the pentode arrangement. note in this case that an additional cathode follower is needed to get the input signal into the low impedance screen grid. also note the pentode is loaded with a constant current source and a resistor to ground (a transconductance amplifier), which gives enormous gain. a dual triode/pentode is perfect for this job. i have used the 6BL8, which i like very much.
here is the sweep…
note the effect of having more gain in the amp… the Q is higher and the amp more selective. but the transitions are still “soft”.
okay, now lets look at a very useful modification that extends the usefulness of the peaking amp, even further. below, we see the cascode feedback filter with the “control” signal returned to the first stage through a series voltage divider: 50k/50k. this could simply be a 100k log pot. not only does this reduce the feedback level, but it increases the driving impedance ahead of the filter. it also increases that part of the feedback signal which is not frequency dependent.
here is the sweep… please note that not only has the voltage divider been added, but also the loading of the filter has been changed (to 2K from 1 meg). again, the legs of the filter have slightly different requirements for balance. you will find that for a range of input Z, there will be a widely varying Zload (R12) for perfect balance. for most practical uses, a 1 meg dual pot with 100K in parallel with one gang will work ok. for more precision, a 2 pole rotary switch with the right values for every setting could be used. the important thing here is that it is a relatively simple thing to vary the Q of the peak…
now, if one wanted to vary frequency, it would seemingly take a relatively complex switching arrangement, or expensive custom pots to vary all the resistances over a useful range… for this reason, and because of the finicky balance, very few people have used a twin T to make a variable frequency filter. op amps have made cheaper and simpler “brute force” filters practical. but you don’t see so many parametric filters using vacuum tubes. that’s too bad! i can’t accept that. there is, as always, another way to approach this.
photo cells, or “LDR”s (light dependent resistor) have been used as variable filter elements for a long time. but not much for twin T filters! (anthony barmentloo, a fabulously clever effect designer and analog hacker, and myself, have done a bunch of gadgets for electro harmonix that use this idea). R is simply replaced by one photo cell. R/2 is made by putting two photo cells in parallel. i have used silonex and perkin elmer photocells in this application without problems. buy them in batches and usually the characteristics are close enough for sound effect use. buy a bunch and measure if you are making a precision filter.
for those unfamiliar with the idea, an LDR in close proximity to a light source (lamp, LED, electroluminescent panel… etc.) in a light proof container creates a third component known as an opto-coupler. optos use light to control resistance. four matched optos can be combined to make the R, R, R/2 needed for a twin T. the C is determined based on the range of off to on resistance of the particular LDR. values from 1 to 40 nF are typical. depending on how precise you want the filter to be, and where the center frequency is meant to sit.
in any case, frequency can be varied now with a pot, or a control voltage or current, to the light sources in the optos. simple sweep controls and active level sensitive sweeps are simple to arrange, once you’ve gone this far. below is a solid state combo frequency control (pot) that can also be used with a boss type expression pedal… this will work well with the tube active filters shown above. the expression pedal would be plugged in with a 1/4″ TRS jack. R6 and R7 represent a 5K linear pot (hard to draw in LTspice). D3,4,5,6 are part of the 4 optos in the twin T filter.
you will find that some adjustment to the filter component values will be necessary for the most useful range with the most consistent Q. if you start with the Q maxed out at one setting, it will not practically be that way anywhere else. if you deliberately detune the filter a little bit, it stays more consistent over the range you sweep it. below i have detuned the C about 10%. with R = 10k, the sweep shows a peak at 2K, but at a much more modest Q than the highly tuned version above.
now, deliberately mismatching the value of one R to 100k and the other to 110k has no meaningful effect. the tuning frequency has shifted to 200Hz, a factor of 1/10. but the Q is not so different… it is hard to keep the component tolerance consistent over a sweep. this is important for practical musical instrument use, and even for post production effects… it’s good for tone generation too, but the input level will have to be higher.
the high Q peak filter is really useful for tone generation and resonator design, but not always the only way to do it. often, there is a practical narrowness of the peak that sounds good, beyond which there is small improvement. simply going for maximum Q does not ensure a useful audio filter… that is a big subject and worth going into more.
one or more of these filters, and perhaps two shelving filters (low bass and high treble) in parallel and with a common input, with the outputs summed, with some variable gain, would make a very useful tubed active filter good for music production. i have a tubed wah wah pedal that is almost exactly this.
this is enough for now. i will come back to this again.