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New Article and Blog Entry Yes, it’s been a while since the last post. But I believe the wait was worth it, if you interested in, puzzled by, or even bothered by the circlotron amplifier… most tube practitioners are all of the above. Like an octopus hiding behind a cloud of black ink, the circlotron’s functioning hides behind the unfamiliarity of its topology. In the attempt to disperse the cloud of misinformation, we discover a new circuit topology that functions identically with the circlotron, but looks nothing like it. The Blog entry below should please the hybrid and simple amplifier enthusiasts.
Miscellany. My ISP viewed my mailing 800 email new-journal-posting notifications as a form of Spam. So it looked as if the “Please notify me when a new article is posted” portion of this site had to go. Fortunately, Yahoo! Groups provides a way out. Thus, if you wish to be emailed a notice when a new article has been posted or an error has been caught, join the Yahoo! Group “tcj_readers” by emailing to tcj_readers-subscribe@yahoogroups.com (Note: if you choose “special notices only,” you will not get the updates sent to you.) And, as always, be sure to give the Tube CAD Journal companion programs a good look, as I think you might find them quite useful. (Besides, they are dirt cheap and they help justify keeping this journal going, as they are -- for now -- the only income-producing portion of this site.) Please send in your comments and suggestions: Editor@glass-ware.com
October 21 2003 Unusual tube circuit Reader, Donald, sent in the following link. http://www.diyaudio.com/forums/showthread.php?s=014c2cc0e4d4f1c1e090b4f87346a828&threadid=20686 which then leads to the following link: http://www.ne.jp/asahi/evo/amp/el86/report.htm . |
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Interesting indeed—or is it? (The Japanese website held much more interesting schematics.) A generic amplifier (the original post only specified a gain block, which could be pure tube or solid-state) with a difference; namely, its feedback resistors pair is a triode: in other words, the triode’s mu (actually, mu + 1) is used as a voltage divider (a plate amplifier, see www.tubecad.com/email_2001/e0829/page18.html ). If used with a solid-state amplifier, then this circuit probably holds to the tubes-make-nice-distortion school of audio design, using a tube’s euphonic distortion to make a nice-sounding hybrid, a school of thought I adamantly oppose. I do not like tubes for their distortion, but in spite of their distortion. |
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Here's an analogy: imagine that fine wine is being siphoned from the oak barrel via a twenty-foot length of rubber hose, a hose that lends a slight garden-hose-on-a-hot-day flavor to the wine. People complain. Thus, over time, the rubber hose is replaced by a steel-alloy pipe, but which lends a harsh, metallic flavor to the wine that sends convulsions through some tasters, like aluminum foil against a tooth filling. Not surprisingly, many prefer the taste of the old rubber to the new metal, in spite of the technological advance that the steel pipe represents. Idiots! The many-advanced-degreed enologist explains that careful testing shows that the metal pipe only contributes a fraction of the suspended solids that the old rubber hose did and thus wine must taste better because of it. Well, while the argument runs on, someone purposes a remedy: the wine will be pumped through the steel pipe first, then through the rubber hose. Now everyone will be happy… Or will they? |
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The Experiment (12-01-2003)
I wanted to devise an experiment to see if the Tube CAD Journal could support itself, so I could drop another ball and publish once again a full journal each and every month, complete with readers' email, articles, and even a construction project per issue. For those who do not understand why putting out a journal once a month is such a big deal, consider the following. Aside from the job of picking the topics, writing the articles, deriving the formulas, drawing schematics, modeling circuits in SPICE, actually building circuits and testing them, creating two versions of the journal (one for HTML and one for PDF), and posting the journal, the real work lies ahead. The PDF on grounded-cathode amplifiers, for example, has been downloaded about 20,000 times since it was first posted. Now, let's say that 20% of its readers may have some questions or problems understanding some portion of the article, but only 1% actually get around to writing an email. Well, that means I will receive 200 emails. So what? How much work can answering 200 emails be over one year? First, some replies take several pages and require new schematics and graphs and added explanation. Second — and more importantly — that's not a total of 200 emails a year, but for just one article; and I have written over 50 articles already. If I start to publish the Tube CAD Journal every month, those 200 emails will soon explode into thousands. Do the math. The writing of an article is only "the anode cap of a very large sweep tube" of work (I could not bring myself to mention icebergs). What's the experiment? In the past, to support the Journal I have offered an ongoing metaphorical "bake sale" (the TCJ software); this has not generated enough income to allow me to break away from an existing commitment to bring out a monthly journal. Now, rather than continue to have the bake sale during the intermission of this concert (as it were), I would like to put the horse back in front of the cart by first offering the bake sale, to make certain the event can actually be funded. In other words, I have a new TCJ tube-related program for sale and if the sales are big enough to justify canceling some of my present commitments, I will put out a regularly scheduled Tube CAD Journal. If the sales aren't up to the task, I will continue to write the occasional blog entry and long article as my schedule permits. But what sort of program to offer? As I have received hundreds of emails asking for a push-pull software program, it seems that push-pull amplifiers are no longer shunned. So here it is: the GlassWare Push-Pull Calculator. With this program, you can quickly find out if your OTL or transformer-coupled amplifier project will produce your expected results. Eight different push-pull topologies are covered:
Cathode-Follower Totem Pole Amplifier Grounded-Cathode Totem Pole Amplifier Mid-Referenced Totem Pole Amplifier Circlotron Amplifier Right-Grounded Circlotron Amplifier Grounded-Cathode Transformer-Coupled (fixed bias) Amplifier Grounded-Cathode Transformer (cathode bias) Amplifier Cathode-Follower Transformer-Coupled
Twenty-four calculations (output wattage and impedance, distortion, dissipation, idle current…) are just a button-push away. Seven graphs display the details behind the tabulated results, including the output wave form and the combined plate curves (the Live Curves™ mathematical model powers the simulations). Screen captures are on the next page. "Sounds great! How much is it and how can I buy it?" you ask. The price will be only $19 USD for the rest of this year, then it will go up to $24 next year (January 31 2004). If you want a CD (to give friends as stocking-stuffers, say), those will be $3 more. As soon as it is ready to sell (about one more week; I should have known better than to try to finish a big project so near the holidays), it will be available at the GlassWare Yahoo! store. If you are part of the Yahoo! Group, you will get an email when it is ready for sale.
- John R. Broskie |