it’s always delightful and deeply satisfying when loud and intensely righteous anti-gay pundits, priests and politicians are found in public toilets, bus station phone booths, or even the back seat of a cab, getting or giving a 20$ blowjob. maybe it’s 200$. doesn’t matter… it’s heavenly! it makes for excellent headlines, is fabulously entertaining, and quite sad. yes, they do usually make quite a scene… the drama is somehow supposed to excuse the hypocrisy (20$ is a bargain!). i suppose one can’t blame them for trying to wiggle out of a tough spot (robert allen, larry craig, ed shrock, troy king, for example… there are many many more)? heterosexuality with “issues”, if you will. hahhahahha! that is a direct quote by the way… (ted haggard). what a nice conservative republican concept.

it is much the same joy that comes welling up when intensely “socially conservative” institutional or aristocratic racists are found to have out of wedlock children with their brown skinned “servants”. (strom thurmond comes to mind, but he is also far from the only one…) not to mention the stalwart drug-testing pro-gun anti-foodstamp cracksmoking legislators, like congressman trey radel. oh, it fills me with hope! not that i condone the abuse! far from it.

the exposure of such behavior often has a wonderful fallout… a sensible and compassionate correction of the view that such people have anything important to say at all. and, that there is something inherently dishonest and strange with their intense vision of right and wrong. ahhh… sometimes truth is blissful.

unfortunately, the attention span of the contemporary homo sapien is very short. and these are hard times for most people. there is also so much delusional malice in the air… (stirred, not shaken) it’s distracting. who cares about the “news”? it’s mostly pulp these days, anyway. and these little moments of loud truth are very brief events. not to mention the vast resources available to such people that can assist with the cleanup of their “misdeeds”. so it is often quickly misplaced, or “forgotten” (which is now primarily a verb) just how hypocritical and creepy many of the “especially righteous” are, all the time.

it’s not like they’re the only ones who bang one drum in front of a camera or mic, and another in private. don’t get me started on bankers, or even “journalists”… i know there are good ones still out there, working. they just aren’t working for CNN, FOX, MSNBC or anything connected to rupert murdoch. thank goodness for conspiracy theories, cable tv series and the iphone. we really don’t need to know this.

i get all my real news from comedians anyway… it’s much more honest and you can laugh, even if it isn’t funny at all.

if we are relatively sensible about these things, there is the shortcut: assume all of the hyper righteous are creepy fucks. such safety is inexpensive, but i suspect it actually contributes to the level of distraction, and it isn’t completely honest either…

see, it isn’t only a question of dishonesty when it comes to your basic public display of righteousness… humanity has a well known and highly rationalized knack for laziness! yes, laziness. the easy way out. it absolutely takes effort to learn about the world as it is. it is possible to learn about the way things really are. scientists and researchers do it all the time. even buddhist monks make a general practice to accept things just as they are, without more or less. yes, there really is “too much” to think about anymore, with all it takes to get by. and there are new connections made between everything, discovered every day (and the occasional random discontinuity). but it is still possible to chip away at it, and what’s more, there’s something honorable about trying. my point is that there is also an element of slacker jive to any and all intense “righteousness”. the one replaces honest effort and knowledge with loud scary finger wagging and bible beating. many people recognize this behavior in themselves, and follow along. the path of least resistance…

why would anyone have to wind themselves up into such a frothy rage over the way things are if there was no resentment, no fear and no desire for it? it’s a strange kind of morality that pits itself so intensely against the world and all its possibilities. to insist it all be reduced to one particular point of view… far from anything real. as if real was the problem, not fantasy.

but it’s so much easier to yell at people. then there’s time to watch reruns of “dr. who”, or “breaking bad”… “house of cards” is doing it for me these days. or play computer solitaire. pass me the chips.

what is scary for me… if you slack off, suddenly there’s “creationism” in the news. as if it is news. hahahhahahah! wtf! “creationism”?! if it wasn’t coming to a school near you, it would be really funny. mutton dressed as lamb. i got my kid out of there before it got any worse. there is so much old crap dressed up as something righteous these days. if you get too distracted, all hell breaks loose and you “didn’t see it coming”.

in any case, the zealously righteous often seem to have a nasty little weak spot somewhere, and it’s wonderful fun when the two sides (the loud and the real) meet up in public (the face eats the ass, which poops it out again in a magnificent feedback loop. the poop loop!). we all make mistakes, but it’s miraculous when those sad twisted creeps make some. why not just be openly “degenerate”, like the rest of us? you are only as sick as your secrets…

now, if you think i simply want to take this opportunity to rag on right-wing religious or nationalist and military superiority nutjobs and “charter school” advocates in the name of rationalism, humanism, or just an “objective” scientific perspective… you’d be out of your mind! how about plain common sense? i wish it was so simple. have you ever hung out with an avowed atheist for more than 15 minutes? those freaks are generally just a bunch of shrill and annoying assholes. much as are the zealous vegans, yoga nazis, and anti-porn crusaders. who gives a shit if they’re right!? and they might be! but much of that crap they spew is insane. and it often leads to bad behavior, too. for example, “loud” animal rights groups, like PETA, are total fucking hypocrites (just take a look into their “shelter” system and attitude towards pets, pit bulls for example… pets in general, actually. fuck PETA! but, prepare to be horrified). it makes the good that they have done almost meaningless (they brought much needed attention to unnecessary medical and cosmetic testing on animals, and significantly influenced mainstream opinion to change things). sadly, the crap they pull affects the status of other more sensible and compassionate work in the area. please support the humane society! (you guys in nyc are amazing!!!) barc rocks!!! the usa does need better animal rights laws… good luck with that. PETA is part of the problem.

so, it seems like there is always something weird about the exceptionally “righteous”.

righteous audio/musical pundits are no different. the really strident ones might seem confident and self-assured from a distance, but i’m telling you it’s just a question of time before you find them in a stall, huffing poppers with a man in a lampshade bopping to the “wrecking ball” (with lipstick on their asses and a sunflower sticking out of it). if they weren’t trying to hide it, i think it would be dull and uninteresting, and totally okay. but that isn’t at all the case. do you have any idea how many right-wing defense industry manufacturers and consultants are also connected to the “high end” audio world? oh, you might be surprised! and some very well known reviewers also work a shift at the heritage foundation and in the defense analysis community. i find this fascinating. although, it shouldn’t be too surprising… anywhere concepts like “purity”, or “precision”, “power”, “speed”, “progress” and “technology” abound, you will find these lurkers and their strange hypocritical perspective. keep your eyes peeled.

anyway, today’s project is a little extension of the important concepts of mixed, dirty, vague, lossy, distorted, slow, and uncontrolled… and funky! authentic synthetic hybrids. all in the service of sensual booty fixation. am i talking about a sex toy? well, maybe… okay!

a tube amp power supply… adapted particularly for guitar amplifiers. of course you can use it for any amp, and i have. but it has special magnificence for electric guitar.

one of the main features of a really good tubed guitar amp is the way it compresses. no, there is rarely an intentional leveling circuit added to guitar amps… although, they are sold as pedals. but, nearly all such amps are class AB, have insufficient power supply capacity, have “current limiting” resistors on the screens of the output tubes… wimpy high impedance driver stages, and other “anti hifi” features. all these things combine to create a circuit that has more gain at small signals, and a squishy gain reduction when the signal gets bigger. the trick is the “touch”… the right gain, with the right amount of squash over the right amount of time.

when it comes to guitar amps, there are myths involved. many “well versed” repair people and hotrodders have attributed mystical characteristics to the tube rectifier, in terms of amp compression. and they do play their part, but not by themselves. not as much as one might think… tube rectifiers have plate resistance, and it typically ranges from about 200 ohms up to 800 per section, depending on the tube and the operating point. having this in series with the power supply will definitely drop some volts when the current draw changes. which it will when an AB amp slides over into the B side. there is a transition from the small signal power supply level, to the large signal power supply level, which could be several percent up to ten percent less B+! that will change the operating point and lower the gain. especially if the amp has a “fixed” bias…

some commercial amps go so far as to add extra rectifiers (in parallel) to “get more compression”. of course this actually reduces it by reducing the series resistance… ahh marketing. however, if one was to put the tubes in series, that would definitely increase the squash. no one has done this commercially, to date. it would drop a fair bit of B+… could be interesting?! but bad for marketing. less B+ also means less watts in the load.

it was hip for a time to use a variac with the amps and deliberately “brown out” the supply by under-powering the power transformer. 105 volts AC into an amp designed for 120… etc. that can be nice in a fugly stoopid manner, but it is not really that squishy in this case, just quickly clipped. good for certain types of metal, and noise music, though.

but, the idea of a droopy B+ has merit. especially if it is level sensitive.

in order to really do this nicely, there also needs to be a built in deficiency of stored current in the reservoir. so that when the B+ droops on the attack, it then takes just the right amount of time to pop back up. not too fast, and not too slow. most tubed guitar amps have just enough capacitance in the supply to smooth the ripple and little more. it was a matter of economy and nothing else from design. there is also a limit to how much inrush current a tube rectifier can handle. not much, as it turns out. but plenty enough for the typical impedances we see in the tube world. today, we understand that this is a feature, and not a problem. all of the better guitar amps also have a choke in series… this helps with the smoothing but increases the compression effect too. series resistance means drop. negative regulation from the chokes also speeds up the recovery (a nice snap, after the squash).

but there is more. an understanding of how tetrodes work (or don’t) helps get with the squash, as well. most guitar amps exceed the voltage and current rating on the screen grids of the output tubes. some of them by 15 or 20%. this is a consequence of using the same B+ for the plates as the screens (saves money). the too high B+ is because they are after watts for the marketing people (what headbanger wants a wimpy little pufftah amp). in order to get the poor tubes to live beyond the warranty date, large value resistors are often inserted in series with the screens. 4.7K is typical. of course, it is insane from a performance point of view. a 10 or 15mA spike (slamming or overdriving the amp) will drop 40 to 60 volts to the screen… and if the quiescent screen current is only 3-5mA, you find yet another handy gain reduction mechanism built into the output stage of your typical guitar amp. although, i personally think this last one is a sucky idea… because it mainly sounds like shit.

still, this is largely unexplored territory. boutique designers of guitar amps do play with these things, but radically NOT! it’s a very conservative world, the musical instrument electronics business… in some ways much more so than the hifi world, which already has a legendarily tiny imagination.

here is a trick i do that is fun to mess with… please don’t be alarmed at the choke in the ground circuit. it makes no difference there, compared with the more common location up at the B+ side of things. although it is safer with just a few volts across it. if it makes you too uncomfortable, just put yours in the ordinary spot.

what’s the big deal?

by using a standard power tube as a rectifier, you can easily and cheaply get a range of more or less plate resistance to add in series with the supply. it is slower turn on than most typical rectifiers (good and safe), and you can tube roll to get your own preference. one nice feature is that if you have an amp that is barely reliable because of the high B+, you can safely knock it down to something more sensible. and more interesting. it is better than using a variac to starve the supply too… the heaters get up to their optimum temperature and the cathode will last longer. keep the first cap to something between 22uF and 47uF. and just play with the tubes you plug in. the grids can be connected to the cathode to start with, but please try the other connections too. you can connect 100 ohm resistors between the grids and plate, if you connect them together.

it is NOT RECOMMENDED to limit the current/voltage for use in bass amps. you will lose bottom. deep bass requires all the current and power you can get out of an amp. if you want compression for your bass, get a pedal. i recommend the electro harmonix “soul preacher”… yes, i designed it. the “white finger” is pretty excellent for bass, too. (i also did that one…) but guitar amplification is fundamentally different from bass amplification.

for those of you who are aware of all the effort van halen’s tech people went through to make the “variac” thing work on his 100 watt heads, you’ll probably be shocked to consider the obvious next question: “why not simply use a smaller amp?” yes, it never occurred to him… he knows his amps, the preamps (most importantly), and it has not sunk in that there is no connection whatsoever between the sound, distortion, and power output of a given amp… in most ways, a 100 watt amp is an idiotic choice for guitar. unless of course you are playing in an arena! but putting a variac on the AC supply to the amp and screwing it down to 80% normal, clearly does make the amp “smaller”! it is in no way even close to 100 watts output (they only make that output with carefully marketed specifications anyway…). still, there are 144 perfect ways to make anything work perfectly. he got this to work right.

there are other ways to skin a cat, or a snail…

turning a power tube into a rectifier might seem inefficient or wasteful, to some. but i’m going to remind you that in this case, the entire discussion is irrational considering the contemporary DSP and class D solutions for the same demand. why don’t tubes just die already! they are so hot and the rectifiers suck! they are high impedance, big and inconvenient… even if they are soft starting and soft recovery.

you can absolutely make a low Z supply using this arrangement! just use a power tube with a large peak current and lots of cathode surface area… regulator tubes and sweep tubes are ideal candidates. i have done this for hifi for some time. with the shortage of good “audio” rectifiers, it made sense to explore this.

when the tube is warmed up, it will drop 10 to 200 volts, depending on the tube and the current drawn. it is important to keep an eye on the power dissipated in the tube at the larger drops. if you have a pp 6V6 type amp, which will draw around 80mA at full tilt boogie, try an EL34 as a rectifier. it’s cathode can source 110mA continuously, without damage. but drawing more will definitely put some brakes on. it is a lower rP tube than a 6L6. it makes a great rectifier. try tying the grids to the cathode and then to the plate. it makes a difference. a 6550 will do 160mA. get the idea…? all of these will drop a fair amount of voltage, so you need to start with more B+ than you need. most guitar amps have too much to start with.

if you want clean impact, low impedance current dumping power… just pop a 6080 in there. or, try a sweep tube. 6DQ5, 6AV5, or any of the bigger weirder ones. color tv sweep tubes are probably the “best” rectifiers ever made, as far as conventional high vacuum tubes go. there is still the hydrogen thyratron… (a good candidate for synchronous rectification, for the really adventurous among you…). they make great rectifiers. the added feature of sharing the same heater string as all the other tubes is convenient. i prefer to put the tube in the center tap of the power transformer secondary, or from the negative end of a solid state bridge rectifier. in this case, a tube with a plate cap goes to plate to ground, or through the choke to the same place.

one additional note, i actually like silicon rectifiers. they are low impedance, they have no heater, and they’re cheap. but they do some crappy things too… they have a nonlinear capacitance that is both voltage variable and has weird hysteresis. they will store a charge and then discharge it in the “off state”. if there is a large inductance behind it, there will be a pulse of the opposite polarity into the load. this is exactly the situation one encounters in a step up power transformer such as one sees in a tube amp. by including a tube rectifier in the mix, one gets both a soft yet fast switching with good damping of the reverse spikes. putting the rectifier in the ground circuit, instead of the plate circuit keeps the heater to cathode voltage rating within range, and you only need one tube.

many modern amps have done away with the tube rectifier. this is a smart way to get it back in there without a 5 volt winding.

okay, this is fun, but now for the public toilet angle…

adding a resistor in between the grid and cathode transforms the “power tube rectifier”, into something else… now you have a “sloppy rectifier”. it will change it’s plate resistance with “signal level”… this means when the current draw goes beyond the class A point. together with a marginal power transformer, shitty choke and insufficient energy storage, will create perfect conditions for a variable gain amplifier. in a particularly level sensitive and designed for manner. in the amp pictured below, i am using a replacement marshall 50 watt power transformer, which makes way too much B+ for 6V6s. 51 ohms was enough to drop it to 390 volts… much better. and, along with other finesses in the amp, perfectly squishy.

 

of course, no one has done this commercially! even though it seems so obvious. please remember you saw it here. it’s in the creative commons! enjoy!