Upgraded to Audio Note J - and other musings.

[benil]

"What historical fact? You seem to be implying that SET amps are obsolete when you referred to them as being primitive."

The historical fact IS that the SET amplifier is the first and oldest amplifier design. There is no dispute of that.

won't argue with that. just don't use the word primitive. its derogatory.

Tetrodes were designed to overcome the problems of triodes, pentodes were designed to overcome the problems of tetrodes, and beam power pentodes were a later development yet. The 6L6 was invented by RCA in 1936. I don't know where you get your history or electronic theory from but if I were you I'd study a textbook, not advertising copy.

a history of electonic theory and technology is exactly that: history of theory. That may have little to do with the commercial aspect of amplifier history. Can you categorically say that the emergence and popularity of tetrodes and pentodes and their dominance were a purely technical phenonomenon and had nothing to do with economics or commercial history? New technology is not necessarily better technology.

Here's a good one I used myself; Analysis and Design of Electronic Circuits by P. M. Chirlian Published by McGraw Hill. Too complex for you? Try RCA Receiving Tube Manual. I have the 1964 edition in front of me right now. The front of the book has an elementry primer on how vacuum tubes and tube electronic circuits work. The bulk of the book has data for all of the popular tubes RCA manufactured then on the market (virtually everything you'd ever see in a consumer product.) The back has schematics for different projects. You can build a class A 1 watt amplifier using a 35W4 rectifier tube and a 50EH5 pentode power output tube which has only about a dozen parts including the tubes and output transformer (page 593.) It's the first amplifier I ever built. Want a little more power and flexibility in a triode amplifier? Try building the 8 watt unit using a 6L6GC output tube, a 6EU7 and a 6AV6 for preamp tubes and a 5Y3GT full wave rectifier which only needs about 45 parts, mostly resistors and capacitors and of course 2 transformers (page 592.) These were considered primitive designs for beginners 40 years ago.

Didn't I tell you i'm not a techie person. All i know is that my favorite topology for a SET amp is the 300B tube amp which has a pair of 6sn7 driver tubes, 5u4G rectifier and a superbly designed output transformer. By the way, did the book ever use the term primitive?

For low output SET amplifiers, all that changed between the 1930s and 1960s was better parts, not the design philosophy or the circuit topology. The design of low powered vacuum tube audio amplifiers hasn't interested many people since. Except for this niche market, nobody really cares today either. There are NO new tubes, NO new circuit designs, NO new anything except for higher and higher prices. They are lucky there are people eager to pay them. I never would have thought so.

Oh yeah? You don't seem to that informed after alll. SET amps don't have to be expensive. Didn't you say that you yourself had a SET amp project in high school that i bet didn't cost you much.

One can actually build a SET amp based on ones budget constraints. Very recently, for example, a group of audiophiles in our area offered a US$200 kit (including the tubes) for a great sounding 3wpc 2A3 amp. The designers offered an upgrade path for transformers (e.g. tango, tamura, james, audio note), capacitors (auricaps, blackgate) resistors (tantalum) and other parts for those who can afford them.

As for tubes, have you not heard of Eastern European and China made tubes? For example i use a pair of TJ/Sophia mesh plate 300B tubes made in China which are not even 1/3 the price of NOS 300B tubes Believe it or not, there are even less expensive brands from Valve Art, Golden Dragon, Sovtek Svetlana that compete pretty well with rare NOS tubes.

Again, the loss of interest in low powered vacuum tube audio amplifiers was probably not because it is inferior but it had less commercial viability in market that wants to try something new but not exactly better.

Demand for multi-channel 24-bit digital home theater is strong and AV receivers are taking over two-channel systems pretty fast. Its new, yes but does it sound better?