* Please don't suggest I install an Ad blocker.
I mean just in general it makes the web less awful. Webpages are so much easier on the eyes without all the crap they try to stuff in there.
And it can prevent malware, especially for those less tech-inclined.
And it means you use less data/bandwidth, since the blocker prevents the request from ever being made in the first place.
If you want to support a site, just buy a subscription or donate to them or something.
For clean sound, use compatible radio preamp tubes and bias the power tubes conservatively.
For distorted sound, use the lowest overhead preamp tubes you can find, and bias the power tubes as hot as you dare without them breaking within the hour. You can always change them after a gig, or between sets. :-)
The key diagram is the one that shows the signal path through the amplifier. Input feeds grid, plate feeds next grid, final output is from plate. Everything else is supporting circuitry.
Note that between each stage there's a capacitor in the signal path. That's to block DC. If you want an amp that amplifies DC, each stage has to run at a higher voltage than the previous stage. The plate must be above the grid in voltage. This was a huge headache in tube computers, both analog and digital.
Transistor circuits don't have the increasing voltage problem. Outputs and inputs are in the same voltage range. That's because transistors are current gain devices, not voltage gain devices.
You can also stick a voltage divider (and probably some diode clamping) in there to pull the signal off of the plate down to a grid compatible voltage for the next stage if you're just doing digital computing. That was the most common setup I've seen in tube based computing. They tended to play pretty nice with the resistors needed for the plate current anyway so it wasn't that much extra RC constant delay.
I'm trying to keep my tube computer I'm building down to ~3KW, and that's probably the biggest actual constraint on design complexity.
fsckboy•1h ago
for people who have not had much EE education, what is important about triodes and transistors is that they amplify. you can put a signal in (a signal like from a microphone responding to your voice), and put some power in (like from a battery) and these amplifiers can make an output "copy" of the signal which is more powerful/"louder" than the original.
from this basic function, everything that we think of as "electronic" flows. we would still have electric things like light bulbs, heaters, spark plugs, electromagnets, but basically just electric steam punk frankenstein machines, and nothing subtle. Amplifiers are termed "active" electronics; without them, we'd simply have passive electricity.
I didn't read this article because I already know how these things work, and the article looks extremely confusing, and I've already read my fill of explanations that don't explain anything and (not saying this is one of those) I don't want to even risk that again. it is very difficult to find explanations for how transistors work that make any sense at all.
kazinator•48m ago
That cannot possibly be true. Not knowing what exactly is going on with the charge carriers at the subatomic and quantum levels is not the same as not knowing how the amplifier works: like if we fiddle with the voltage at the base, we can influence the collector current, and all the rest.
What is true is that some early transistor designs of audio amps treated transistors like tubes: they featured a phase inverter transistor that fed two non-complementary push-pull stages whose output was combined by a center-tapped output transformer.
The excuse that well-matched complementary PNP transistors were not readily available at that time rings hollow, because it's possible to create an push-pull output stage with just NPN transistors. This is called "quasi complementary" (lots of search results for this).
Output transistors, if they have multiple taps in the secondary winding, do allow for different impedances. If the end users expect to be able to plug a 16 ohm speaker into a 16 ohm output jack and a 4 ohm into 4 ohm, then they will understand that kind of amp better.
kazinator•33m ago
The Owner's manual extols the advantages of using transformers for speakers and describes how to use the 70V output in conjunction with external transformers.
Quote:
For complex multiple-speaker arrangements that require many speakers and long runs of connecting wire, we recommend you use a line transformer (not supplied), available at your local RadioShack store.
[...]
There are several advantages to using transformers.
• You can connect speakers with different impedances without causing differences in output between the speakers.
• You can add or remove a speaker without having to recalculate the entire system’s impedance.
• You can reduce signal loss when you use speaker wire over 50 feet long.
LOL!
quickthrowman•8m ago
https://www.atlasied.com/speech-privacy-speakers?srsltid=Afm...
sethhochberg•2m ago
gizajob•23m ago