John Broskie's Guide to Tube Circuit Analysis & Design

16 october 2013

RMAF 2013
The Rocky Mountain Audio Festival took place in Denver once again. I made the hour-and-half drive on Friday and Saturday, but I could not summon the will to do so again on Sunday. Don't get me wrong here; I had a great time. My favorite story is when Rene Jaeger and I were eating lunch and a young man at an adjoining table comes up to our table and says, "It is you!" I was startled and he went on to say, "I was overhearing your conversation and I thought that guy speaks just like John Broskie writes. And it is you." When I returned to the show and told Frank Schroeder, he had a good laugh and recommended that I have this T-shirt made.

of course, 95% of the attendees do not know who i am, but the 5%, who do, tend do so in a big way, which is flattering, but also a wee bit disconcerting. say, for example, that i am in an elevator and one of my readers recognizes me and throws me a compliment. sounds good, but the other folks riding with us do not know who i am, but want to know who i am, so they start mumbling to each other, "who is this guy?" of course, if they had been told, they would have only been disappointed. no doubt, they would have been much more impressed had i been, for example, the first audio dealer in north dakota to sell linn turntables, a feat that they could understand and appreciate, truly something worthy of respect if not veneration, as they all could have done the same.

early on my first day, i got to meet one of my favorite audio reviewers, which was and yet wasn't a great way to start the show off for me. with an almost war-wearied attitude, drained and almost crestfallen, he proclaimed that the year is 2013, not 1978; that—in spite of all the $3,000 power cords and $50,000 turntables and $70,000 speakers—audio was, if not dead, certainly dying; that as we old audiophiles come to die, so, too, will our hobby, for there are no new young audiophiles in replacement; that whatever green-shoots counterexamples we might offer, such as the ever increasing sales of lps, are so paltry and insignificant that they simply do not register in anything other than our imaginations; that the triumph of modern education has brought into being the lamest, most self-centered, most mis-educated people in history; that the equally big triumph of a socialism-lite wedded to self-indulgence and purposeless consumerism, a toxic mix indeed, has destroyed the very artistic, ethical, and societal underpinnings necessary for audio to recover and thrive once again; and that all the illegal downloads of music have crippled the recorded-music industry beyond its ability to recuperate. thus, audio gear and recorded music—if not all of us—are doomed.

his was an often-repeated speech, i could tell, which might explain why he delivered it in such an oddly fatigued fashion. an interesting perspective and it matches mine own in many particulars. yet, perhaps because i am a cheerful pessimist, his prognoses sounded far too gloomy for my liking. thus, much like diogenes carrying a lamp in daylight in search of an honest man, i yearned to find counter evidence.

600彩这是专业的because it was friday morning, the retired male attendees overwhelmingly showed up, lending the assembly an old-folks-home quality. not that i have anything against the wizened and hoary, being one myself, but they do cast a pall that is not so much palladian as pallbearer-ready. repeatedly, i heard, "wait a second, will you? i have to take my medications" and "not so fast, my damn hip is killing me." and the many canes and a few oxygen canisters-on-wheels also lent a senescent aspect to the entire event.

Adding to the somniferous and decrescent tone was the overwhelming number of introverts. Let's be frank, Audio is a solitary pursuit; there is only one listening chair and one sweet spot. Headphones wall off the external world. Each audiophile is an island unto himself. With the advent of powerful car stereos and the iPod, most of the public have—if they ever knew—forgotten that audiophiles exist. Thus, the great attraction of an audio festival, such as the RMAF, as we aural loners and introverts can at last convene and commiserate. But as an aggressive sort of introvert, an in the Myers-Briggs personality types, I have some difficulty relating to the more passive introverts, as the passive do not instigate, but respond—if at all—submissively. No, I certainly wasn't at a Colorado cowboy convention; the boisterous and virile and optimistic were not invited. Instead, Thomas Malthus's ghost haunted many of the conversations, with dour pronouncements of impending ecological doom. I had the pleasure of hearing over and over again how global warming would kill us all in two decades—so why worry about audio's impending demise? Well, I am sure many who uttered such twaddle will in all likelihood be dead in in two decades, but the cause of death is not likely to be hyperthermia.

600彩这是专业的so far, the famed reviewer seemed to be winning, as things did look bleak.

On Saturday, I was happy to see the non-retired and non-male attendees show up, well at least there were a few. Children under 12-years of age were not charged an entry fee, yet there were so few. Go to a motorcycle or gun show and you will see children, lots of them. (Really, John, don't you understand that those parents should be charged with child abuse and put in jail or forced therapy! What could be more dangerous than motorcycles and guns? Surely, the greatest danger is excessively fearing the dangerous.) As a father and his ten-year old son exited a room, I overheard the boy say to his father, "I don't know, Dad, but do you still think that you make the best speakers?"


The Equipment
Speaking of loudspeakers, I have to say that I did hear some very good sounding systems at the RMAF. Unfortunately, all of them cost a fortune. Last year, the little speakers won my heart, but nothing like them in the same price range made an appearance this year. There were quite a few speakers that I wanted to hate, but I ended up liking (all super expensive, alas). For example, speaker struck me as frivolously out-there looking, but sounded excellent. Speakers that I expected to sound good, such as the and the , did in fact sound good, very good indeed. An other example, the produced a seductively spacious sound that made me forget about audio equipment and just listen to the music.

600彩这是专业的i walked by one room and looked in and saw a guy with a head scarf and speakers pressed against the sidewalls. my gut reaction was that if he doesn't know enough to move the speakers away from the side walls, he will not know enough to build a good speaker. i was majorly wrong. the sounded great and imaged extremely well and delivered taut bass—in spite of being next to the wall. the engaging and knowledgeable german rep told me all about how the speakers were designed and built. very impressive, with things like porous ceramic internal walls and no sound absorbent material and drivers matched within 0.1db to each other. unfortunately, the speakers cost $27k, if i remember correctly.


Best Bargain
The best audio bargain was truly inexpensive, at only $119, , a tube hybrid headphone amplifier that uses two pencel tubes.

First let me say that I love everything about —their products, their prices, their sonics, everything but their name. "Aurous" would far more suitable. But Jason Stoddard and Mike Moffat are far too ironic to ever adopt such a name. A pity really, as many will overlook Schiit's amazingly fine and amazingly sanely-priced products. Well, it's their loss. In the Can Jam room of the RMAF, where headphones and headphone amplifiers are found, Schiit displayed at their booth a new hybrid headphone amplifier that used a pencil tube as its input stage and a solid-state buffer output stage. Apparently, this little wonder is so new that it hasn't shown up on their web page yet. It looks much like their headphone amplifier and it sounds fabulous, with a jaunty, buoyant, and lively sound. Even if you already own a $2,000 headphone amplifier, this little gem is worth buying. Place it on your computer desk or next to your bed and live a happier life.


I Have Got the Blues
Back in 2005, after my trip to the CES, I wrote about the the modern obsession with blue LEDs. I hate them still. Rather spew new invective, I will just quote myself from blog number 28:

my two-year-old son’s favorite tv character is blue, the blue dog that leaves blue paw-print clues across the screen. so too, the favorite colored light to adorn hi-fi gear at ces this year was blue. (here’s a tip: buy stock in blue led companies.) picasso would have felt at home amidst azure, cerulean, cobalt, indigo, navy, sapphire, and windex glow. gratuitous blue light shone from every possible corner. blue power lights and blue back-lit knobs, front panels, and glass plates shone brightly. single points, bars, circles, and triangles of blue light fought for my attention. in the dark listening room, one amplifier’s blue power light so powerfully blinded we looked at the wall it faced to see if a burnt mark had developed.

now i know why many states prohibit the use of blue lights on cars other than police cars; the concern is not safety, but sanity. at first it was like the first sight of a new fashion in a magazine: perhaps charming, maybe striking, possibly alluring, but by the end of show—like at the end of a fad’s run, when everyone has adopted the super-flared pants or ultra-wide lapels—it was just fatiguing. and it wasn’t just high-end gear that glowed blue. at the big exhibit hall (the ces zoo proper), befitting a k-mart special, many of the small cheesy companies tarted up their dreck with blue lights (several of which i’m sure were cheaply produced by blue light bulbs, rather than expensive blue leds). i was reminded of how the new fashion fad starts brilliantly with runway models in glossy ads and ends bleakly on runaways turned hookers standing on street corners. basically, i got the blues after seeing so much icy blue, longing for some warm amber or cool wintergreen.


Why I Love the RMAF
600彩这是专业的 The best part of the show for me was seeing friends like , , , , , , , Walter Clay, and many, many more. But many were missing, such as Joe Roberts, John Chapman, Sean Ta, and Variac (the man behind DIYaudio.com).

John Curl roamed the hallways, but I never ran into him, alas. Or, perhaps, I did, as we have never been introduced, another alas. Fortunately, I met and got to hang out with David Fletcher (cofounder of Sumiko, SOTA, and Pacific Microsonics). Mr. Fletcher is 77 and a hoot. He has a million great stories to tell and he does tell them; just try to stop him ;)  I have only met one billionaire in my life and meeting David was a similar sort of experience, as I strove to shut up and to listen, for both men had invaluable things to say. I vividly remember that the rich man had only two rules for business success: 1) Never do anything illegal, ever. 2) Any business plan that assumes that other people are stupid, or will do stupid things, will fail, as people will always let you down by doing something smart. David Fletcher is as rich in audio knowledge—theory, practice, and imagination—as the billionaire was in money. I wish that either David lived in Colorado or I lived in Nevada.


RMAF Conclusions
600彩这是专业的 As a teenager, I was disheartened to discover that although had died in the year of my birth, he had died too late for me to be his reincarnation. (Well, at least I still had Albert Einstein.) Described as a "real Whangdoodle" and the writer of, as Joseph Wood Krutch put it, "the best prose written in America during the twentieth century," Henry Louis Mencken was truly great. We have all read his famous quips, such as "For every complex problem there is an answer that is clear, simple, and wrong" and "Puritanism: The haunting fear that someone, somewhere may be happy" and " Every election is a sort of advance auction sale of stolen goods" and " We must respect the other fellow's religion, but only in the sense and to the extent that we respect his theory that his wife is beautiful and his children smart." After Samuel Johnson, he is probably the most quoted writer.

Well, after all my adventures at the 2013's RMAF, after my desperate search for some evidence that Audio—the art, practice, and science of designing home-audio electronics—did not await its priest and Last Rites, I was reminded of what H. L. Mencken had written about another foretold demise. From an article Mencken wrote in the Baltimore Evening Sun600彩这是专业的, in 1935, titled "Capitalism," we read the following:

600彩这是专业的"all the quacks and cony-catchers now crowding the public trough at washington seem to be agreed upon one thing, and one thing only. it is the doctrine that the capitalistic system is on its last legs, and will presently give place to something nobler and more "scientific." there is, of course, no truth in this doctrine whatsoever. it collides at every point with the known facts. there is not the slightest reason for believing that capitalism is in collapse, or that anything proposed by the current wizards would be any better. the most that may be said is that the capitalistic system is undergoing changes, some of them painful. but those changes will probably strengthen it quite as often as they weaken it."

600彩这是专业的 substitute the word "audio" for "capitalism" and similar conclusion follows: audio will change, with some portions strengthened, while others weaken. if you look at only the traditional consumption side of audio, the sale of receivers and cd players, you can easily prognosticate the worst. but if you solder and build and create, then things don't look so bleak after all. i remember being told many times, over many decades, that tubes were dead. well, if they are, then someone forgot to notify me. the british philosopher and mathematician bertrand russell once wrote:

"The newspapers, at one time, said that I was dead, but after carefully examining the evidence I came to the conclusion that the statement was false."


Next Time
600彩这是专业的 The topic will be more circlotron circuits.







Kit User Guide PDFs
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e-mail from glassware customers

hi john,

I received the Aikido PCB today - thank you for the first rate shipping speed.
    Wanted to let you know that this is simply the best PCB I have had in my hands, bar none. The quality is fabulous, and your documentation is superb. I know you do this because you love audio, but I think your price of $39 is a bit of a giveaway! I'm sure you could charge double and still have happy customers.
     Looking forward to building the Aikido, will send some comments when I'm done!
   Thank you, regards


600彩这是专业的mr broskie,

i bought an aikido stereo linestage kit from you some days ago, and i received it just this monday. i have a few things to say about it. firstly, i'm extremely impressed at the quality of what i've been sent. in fact, this is the highest quality kit i've seen anywhere, of anything. i have no idea how you managed to fit all this stuff in under what i paid for it. second, your shipping was lightning-quick. just more satisfaction in the bag, there. i wish everyone did business like you.

sean h.

9-Pin & Octal PCBs

High-quality, double-sided, extra thick, 2-oz traces, plated-through holes, dual sets of resistor pads and pads for two coupling capacitors. Stereo and mono, octal and 9-pin printed circuit boards available.

Designed by John Broskie & Made in USA

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TCJ Push-Pull Calculator has but a single purpose: to evaluate tube-based output stages by simulating eight topologies’ (five OTL and three transformer-coupled) actual performance with a specified tube, power supply and bias voltage, and load impedance. The accuracy of the simulation depends on the accuracy of the tube models used and the tube math model is the same True Curves™ model used in GlassWare's SE Amp CAD and Live Curves programs, which is far more accurate than the usual SPICE tube model.

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Janus regulator user guide
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E-mail from GlassWare Customers

hi john,

I received the Aikido PCB today - thank you for the first rate shipping

wanted to let you know that this is simply the best pcb i have had in my hands, bar none. the quality is fabulous, and your documentation is superb. i know you do this because you love audio, but i think your price of $39 is a bit of a giveaway! i'm sure you could charge double and still have happy customers.

looking forward to building the aikido, will send some comments when i'm done!

Thank you, regards,


Mr Broskie,

i bought an aikido stereo linestage kit from you some days ago, and i received it just this monday. i have a few things to say about it. firstly, i'm extremely impressed at the quality of what i've been sent. in fact, this is the highest quality kit i've seen anywhere, of anything. i have no idea how you managed to fit all this stuff in under what i paid for it. second, your shipping was lightning-quick. just more satisfaction in the bag, there. i wish everyone did business like you.

Sean H.

High-quality, double-sided, extra thick, 2-oz traces, plated-through holes, dual sets of resistor pads and pads for two coupling capacitors. Stereo and mono, octal and 9-pin printed circuit boards available.

   Designed by John Broskie & Made in USA

aikido pcbs for as little as $24


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While the program's main concern is active filters, solid-state and tube, it also does passive filters. In fact, it can be used to calculate passive crossovers for use with speakers by entering 8 ohms as the terminating resistance. Click on the image below to see the full screen capture.

Tube crossovers are a major part of this program; both buffered and un-buffered tube based filters along with mono-polar and bipolar power supply topologies are covered. Available on a CD-ROM and a downloadable version (4 Megabytes).

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