An E-Mail

tube fancier after all.
     I have hooked up headphones to the line amplifier and the sound is just about perfect, so how do I preserve as much of that sound as I can? One idea I have is to build a solid-state amplifier that adds no gain or feedback, which means that the line amplifier will do all of the voltage amplifying and the power amplifier will do all of the current providing.
     The attached schematic shows two circuits: the first is a pure solid-state unity-gain buffer and the second is a hybrid buffer. What do you think of them? Which would be the better path to follow? Thanks in advance for your kind reply and the possible publishing my letter ;)
Tony F.
United States

     Tony, your first two emails were not published precisely because they were tube free, not because they failed to provoke interest.
     The original intent of this journal was to mimic the
Math CAD Journal, a magazine put out by the MathSoft people to asset users of their Math CAD program by providing math-related articles that illustrated how their software could be used. For example, users of Math CAD who explain how they found the program useful write many of the articles.
     Well that was the intent, but the
Tube CAD Journal went off in another direction altogether. Part of the reason was that many of the tube fanciers needed, as you pointed out, to be technically brought up to speed. Another part was my hope of expanding the tube-audio horizon, which I felt was collapsing into a few simple-minded topologies and practices.
     In fact, you are not the first to recommend widening the journal's range of topics to include all audio related circuit devices and topologies. But I cannot see too great a need to cover pure solid-state topics when
Elektor, Electronics World, audioXpress, and the solid-state manufacturers themselves (in their data books) do a good job on these topics. But then, maybe I am wrong on this. What do you, the readers, think? As for the circuits you submitted, you have an entire article as a reply...

Subject: Why Just Tubes?
     This is my third e-mail to the Tube CAD Journal and I thank you for your kind replies to the first two e-mails, which were quite lengthy and informative. However, those e-mails were never published in your journal. Was it that they were not deemed interesting enough to include or were they excluded because the circuits contained were pure solid-state? If the latter was the reason, then I must make a plea on behalf of the solid-state half of the world: your journal is one of the few places that audio electrical engineering is explained carefully and fully. Bless you and your writers. But limiting the journal to just tube audio is probably a big mistake. Here is why: my guess is that more than half of the journal's readers are from the solid-state camp anyway.
     I know from my group of audiophile friends--mostly fellow college students--that none of the tube guys are technically inclined in the smallest degree. They love tube sound and spend huge sums of money on single tubes, but they cannot tell you what a cathode is. (This deep division reminds me of the one between Linux and Mac followers, with Windoze users in somewhere in the middle; never ask a Mac user which CPU their system uses, for example.) This is not, however, a plea that you publish only solid-state articles, but that you just include a few pure solid-state articles for the other half of your readers. (I would love to read your explanation of current-feedback amplifiers, for example.)
    Now for the technical part of my letter, I like the warm and smooth sound from tube equipment, but I do not like the fat and shallow bass reproduction from tube gear. (Actually, I am sure the poor bass response comes from the coupling capacitors and output transformers and not from the tubes themselves.) Therefore, some sort of hybrid system would seem to be best: a tube preamp driving a solid-state amplifier for instances. This is what am currently using, with a tube line amplifier (your circuit) driving my 100 watt solid-state amplifier. This sounds better than either the pure tube or pure solid-state equivalent systems I have tried. But the sound seems to be too close to the pure solid-state side of the spectrum. Hell, maybe I am a closet

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