readers have asked where the Tube CAD Journal’s
mail from readers section has gone. Beyond the work required to
assemble (and edit) the letters and replies (and draw the illustrations),
something else has bogged down this portion of the journal: many
of the emails received have been secret:
Our amplifier sounds kind of dull and lifeless compared to
other 2A3 amplifiers and sometimes it even breaks into oscillation;
it also hums, so much so that I am almost embarrassed to charge
$6,000 for the pair. Maybe the transformers are to blame? Who
makes the best output transformers? Which one should we use?
I hear that 3k is a good impedance. We are using US Army pulls
RCA 2A3s; should we be using 211s instead? Or would a new input
circuit be better? What is a White cathode follower? Could
it be used?
70% of our parts budget goes to the single gold-foil, extra-virgin olive
oil coupling capacitor (NO OTHER CAPACITOR IS WORTH LISTENING TO), so
any modification that costs more than $40 is going to hard to
justify. We were thinking that power supply regulation is needed.
Is a shunt or series regulator better? What is the difference
between the two? Could a regulator be added for less than $40
in parts? How would we hook it up? Can you draw us a color-coded
diagram? Could the 211 or 845 be used so as to make our Japanese
customers happy. Please provide a circuit and WIRING diagram,
Phil, who does all our wiring can't read schematics that well.
Speaking of Phil, he is convinced that you do not know what you
are talking about, as you wrote that it was impossible for a
single 2A3 to put 27 watts and he says that since our amplifier
sounds much louder than most single-ended 2A3 amplifiers, which
everyone agrees put out 25 watts, ours must be putting out
at least 30 watts. Do you fully realize the legal consequences
of slandering a company’s product in that way? Our attorney
tells me that he could easily win a six-figure judgment against
such a slander.
IMPORTANT! Do not publish or show anyone else this email or the
attached schematic. TOP-TOP-SECRET. Reply expected no later than
tomorrow (use only DFX files for schematic revisions and the chassis
Acme Tube Design
makers of the world’s best-designed, best-sounding
See and hear our amplifiers this weekend at
the CES, Hilton, back of room 1132.
An exaggeration, of course, except the line specifying Top Secrecy.
And it isn't always a business that is shy about sharing schematics.
Many individuals have submitted circuits under a cloak of top-secrecy
and seldom (with a few glorious exceptions) have the circuits
been anything but derivative (and I am not talking about the
ratio of the change in a function to the corresponding change
in its independent variable). So I am not sure why secrecy was
required. Still, most individuals do not retain an attorney.
Once, in a moment of extreme stupidity, I signed a non-disclosure
form, as the business owner who was so nervous over his highly
original tube circuitry that he could not speak to me otherwise.
For about six months afterwards, I was nervous about including
a tube differential input stage in this journal, so as not to bring
the wrath of voracious lawyers upon me.
Yes, that was his big trade secret, two triodes sharing a common
cathode resistor. Yes, that circuit has appeared in this journal
prior to his showing me it; it also appeared thousands of preexisting
products, BW TVs, oscilloscopes, voltage meters, test equipment,
and dozens of amplifiers, but would any of that necessarily hold
off a hungry lawyer or persuade the jurors of the OJ trial?
can imagine a dramatic scene in which my attorney would bring
in a large wheel barrel overflowing with old electronic textbooks
and user manuals. “Your honor, each and everyone of these
old books holds a drawing of a tube-based differential amplifier
and we have seven more wheel barrels in the backroom, should this
evidence prove inconclusive.” Unfortunately, I can also easily
imagine the prosecuting attorney’s reply (imagine John Edwards' drawling voice):
and gentlemen of the jury, I think we all know what the accused
thinks of you all. He thinks you and all those fine, honest, hard-working
folk who served on the OJ jury are idiots. He’s said as much
in his journal. But we are not idiots are we? We know he didn’t
sign a non-disclosure form with the writers of all those books
in the wheel barrel. Of course, believe me when I say that I’m
sure of this: all those writers are sure happy they didn’t
sign one with him.”
legal hassles, there is the general problem of constraining this
journal’s scope, which is at odds with its mission to
inform and reveal the art and science of tube circuit design, not
to form an exclusive club or, even less, a confessional booth.
For example, a perfectly good-natured reader writes showing and
describing his new circuit, but requests secrecy. Now, even if
his circuit is not as newborn as he imagines nor as not obvious
as thinks, I do not want him to feel betrayed, when I publish the
circuit or a similar circuit in this journal; yep, it’s the
differential circuit all over again. And what is imagined to be
wildly bold and startlingly creative can be as trite and tiresome
as using a 100k grid resistor instead of a 1M or 47k resistor.
So rather than risk court time
or hurt feelings or a constrained journal, please do not send me
any schematics that you are not willing to share with your fellow
Kit User Guide PDFs
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visit our Web site :
Do not publish or show anyone else this email or the attached
was his big trade secret, two triodes sharing a common cathode resistor.