The Vacuum Tube and the Invention of Radio

In today's episode of technology connections, we take a look at the vacuum tube. This simple device had tremendous implications for sound reproduction. We explore how vacuum tubes revolutionized radio, and why they were necessary to make radio practical.
Vacuum tubes made possible the next advancements in sound technology. Subscribe to see more weekly videos form the Technology Connections series, as well as our Tech Explorations mini-videos!

[@macronencer]

When I was a boy (early 1970s), my uncle (who worked for the British telephone service, the GPO, which later became British Telecom) gave me one of the best presents I've ever had. It was a kit for making my own crystal set. I put it all together and it worked just fine! I remember sitting in my room listening to radio from around the world on my headphones... and it never needed batteries, of course. Such an educational gift, and he must have put quite a bit of work into it. I'm eternally grateful for his thoughtfulness.

[@goddammeme900]

Y'know, there's a certain charm to this old intro... I'd like to see this make a comeback in 2020

[@MinerAC4]

dodododa ddoodo

[@grigorirasputin996]

Watching in 22 and I agree.

[@myrealusername2193]

@@grigorirasputin996 same, it’s just so… nice

[@James2210]

I'm missing the annotations, though...

[@donotworried]

2023!

[@UXXV]

In under 11 minutes you explained stuff I had no clue about for decades and now its all laid out there! Superb content!

[@simontist]

Agreed, this is a seriously great explanation.

[@xgford94]

Yep I just joined you club of understanding

[@matrixmirage2148]

I love Keknology Tonnections

[@ClintSprayberry]

Yep, I've been struggling to understand the "how" of radio and sound for years. I'm still struggling, but this and the preceeding videos have helped me more than thousands of hours of reading, other videos, collegiate lectures, etc. ... I'm so glad I found this channel!

[@scottotto402]

@@simontist uh uuu

[@petestrasser7287]

This is the best and most succinct description of "tubes" I have seen, and I have been working with this stuff since 1967. Great job.

[@nekad2000]

You obviously didn't hear senator Ted Stevens' lecture about how the internet is a series of tubes. In all seriousness though I agree with you.

[@twistedyogert]

Why do tubes need so much power to work?

[@nathanczaja]

@@twistedyogert the filaments of vacuum tubes need a lot of power to heat up and allow electrons to easily flow.

[@BaronVonQuiply]

@@twistedyogert Because of all the internets going through them.

[@davidgriffin79]

@@twistedyogert With a vacuum tube you require heat to release the electrons. The electron source is a heater which wastes the vast majority of the energy applied to it as infrared radiation; with only a very small remaining fraction of the applied energy as the released electrons. Like many, many things in our history of physics/engineering we initially learned empirically and used accordingly; then, we built upon this knowledge, through research, using our understanding of the world through mathematics. The world of quantum physics, and the mathematics derived for it, allowed us to finally build so called "solid state" semi-conductors which used the interaction of electrons and "holes"; this is where we are at now.

[@danatmonst3594]

I'm visiting from 2023 and I feel like I'm in the archive section of the museum! What a treat! So glad you've never lost this passion, TC ❤

[@notmychairnotmyproblem]

We need more people like this guy in the classrooms.

[@AttilaAsztalos]

Listening to the local AM radio station with nothing but a metallic-diaphragm headphone speaker with a germanium diode connected across, one side going to a really long wire as the antenna and the other side grounded to the pipework used to be pretty much on par with magic. No power source needed...

[@Lagggerengineering]

Isn't it... magical? I'll see myself out.

[@mikewosowski342]

If

[@nakayle]

If the signal is strong enough you can hear it from a tin roof. Rust on roofing nails acts like a diode detector and the resulting current causing slight vibration of loose tin panels. But you have to be near the transmitter for this to work.

[@artpitkin883]

@@nakayle That's very interesting. I would like to experience that! Speaking of "you have to be near the transmitter . . .", though: My first year in college, my good friend lived down one floor from me (in the dormitory) and one or two rooms to the side (not directly under my room). I had a hi fi (that's what they called "a stereo" back then, in 1964), and we rigged up a speaker in HIS room, running off a wire from my room, hanging outside the building, going down to his room, and in through the corner of his (slightly opened) window. Worked fine at first, no problem. A few days later, my friend told me that he heard the nearby radio station coming out of the speaker! From the TIME that he had witnessed this . . . I'd had my stereo turned OFF at that time! What a puzzling phenomenon! But the EXPLANATION was apparently just that we were "near the transmitter", as you stated. An athletic person could have thrown a baseball and hit the transmitting antenna for WJOY-AM, we were THAT close! I guess a simple speaker connected to 20 or 30 feet of "lamp cord" will ("detect") the AM signal, in SOME kinda way! We never did anything with this amazing information though. --Even though we were living in the Electrical Engineering freshman dorm at the time. That's what it reminded me of, when you said "you have to be near the transmitter for this to work." I would really like to hear a radio station broadcast by merely listening to a tin roof (as you described), though! I think I've truly "missed one of life's experiences" by not ever witnessing that particular phenomenon, first-hand! "Rust on roofing nails acts like a diode detector . . . ." Your post wouldn't be NEAR as good without the EXPLANATION. It would be just baffling and confusing.

[@nakayle]

@@artpitkin883 An AM signal is easy to demodulate with anything that acts like a diode which can be rusty or corroded connection. People living near high power AM transmitters often have to install filters and grounds to prevent this. Doesn't happen with FM.

[@timgore829]

I've been studying radio since the late 80's and have been an FCC licensed amateur (ham) radio operator for 25 years. You did a fantastic job explaining the "magic" of radio and vacuum tubes. Your video on the "superhet" was also fantastic!

[@diegogarbus]

Thank you for remembering one of our heroes from the Brazilian homeland, Father Roberto Landell de Moura

[@BrianBullington]

Vacuum tubes are one of those phrases i have heard for years but never understood. Thanks for the work you do on these channels. They are consistently fascinating.

[@JasonArmond]

No, radio isn't magic. *moments later* This thing makes sound with CRYSTALS.

[@08pipster]

crystals.. of course! ..d'oh!

[@Rainbow__cookie]

Ah yes Crystal radios

[@rdaltry777]

There are two types of radios: FM, or Freakin' Magic, and AM, Also Magic.

[@08pipster]

@@rdaltry777 Lol

[@ryankendrick6350]

Sorry to be offtopic but does someone know of a way to get back into an Instagram account..? I stupidly lost my login password. I appreciate any help you can give me.

[@rikuurufu5534]

"Thermionic Valve" sounds so much cooler than "Vacuum tube"

[@oliverkeating4894]

Thanks for this video, I have never understood the basics of how AM radio works until now, despite having a degree in physics!

[@ncmattj]

Vacuum tubes have always confused me. I was not REALLY sure how they worked. You provided the best, most simplistic explanation I have yet seen. AWESOME WORK and THANKS!

[@baronvonlimbourgh1716]

Haha, he still has the same jacket. Cool lol.

[@force311999]

a wool jacket and good dry cleaning should last a lifetime

[@force311999]

he sounds so much younger in these 5 year old videos , different mic?

[@Shaun.Stephens]

@@force311999 More like less self-importance.

[@matrixmirage2148]

Tony Soprano: ,,What's thisss?" Ritchie Aprile: ,,"What's this?" It's the jackeett!" Tony Soprano: ,,The jacket?" Ritchie Aprile: *,,THE JAAAAAACKKEEEEEEETTT."* (The Sopranos, 1999)

[@RobGrognerd]

@@force311999 I've taken very good care of mine, yet it keeps shrinking; it's quite snug now

[@wimwiddershins]

The best explanation of radio valves I've ever heard. Just brilliant!

[@MrThepatrickshow]

This channel deserves to be way more popular, and should probably be part of PBS digital by now! Keep up the great work!

[@Wallyworld30]

Well in the five years since you made this post this channel really did take off! You were right about it deserving to be bigger and people noticed!

[@Mattz9]

I just wanted to say, I love your channel. Keep up the great work! So interesting and your explanations are awesome!

[@metalsmyth6945]

I agree, I was only disappointed to see there were not more videos so keep them coming! I like your way of explaining things

[@SeattleScotty]

Great video, I've watched a number of videos about amplifier tubes, but this one really helped me understand how they work! I still use them in my guitar amplifier (1966 Fender Deluxe) so it's nice to know how they work!

[@Clarinetboy82]

Thanks for making this video! I have a couple of non-working tube radios from the 1930's and 1940's. My daughter is 4, but when she's about 7 we'll work on them together and get them working, that way she'll be able to learn how they work.

[@soupalex]

hey, i see this comment is 3 years old… i hope you and your daughter are doing well; have you got around to fixing up the tube radios?

[@robocobrabot]

I’m just now discovering your channel and I think it’s amazing. You teach things in a very clear, humble, and humorous manner!

[@sixstringedthing]

How great are these old videos in their straightforward and no-nonsense (one might even say "rushed and nervous") delivery? Loving it.

[@TheOneG36]

your explanatory skills ROCK!

[@devonnewest7990]

If you were a teacher, or professor, the students would have a great edge in learning. YOU ARE GIFTED.

[@cmatiolli13]

Thanks for recognizing Landel de Moura. That's why I follow your channel. You're great , man.

[@bullettube9863]

I made my first crystal radio in shop class when I was 15 and when I showed it to my son in 1980 he was amazed! Yes it works and doesn't need a battery! The following year I made a transistor radio, and put it in a 3inx4inx1in plastic storage box. The biggest components were the the speaker, 9 volt battery and the channel dial, the actual radio components were tiny! My teacher told us eventually every thing would be so miniaturized that wrist radios-TVs, and miniature telephones would be possible. I wish he were alive today he would be amazed at the new tech!

[@xw591]

Respect

[@mattburland8105]

That is the clearest explanation of how amplification works that I've ever heard. It makes perfect sense. Thanks!

[@SkyOctopus1]

Nicely done. I was aware of all of the individual bits, but you've put them together into a coherent story and without getting too bogged down with implementation.

[@8MoonsOfJupiter]

Great explanation as always - you make difficult concepts/science really easy to understand; keep up the good work!

[@brandoncurnutte8235]

I'm a ham radio operator and this is the best explanation of how vacuum tubes operate that I've ever seen. 73

[@TheSulross]

one of the best explanations of the working of a vacuum tube that have come across

[@antonnym214]

Okay, that's it. You are now officially my hero because I understood your explanation of how triodes amplify signal. It was like a light bulb coming on. THANK YOU! I have subscribed and gave you thumbs up. All good wishes! P.S. Good explanation of how speakers work, too. I was pretty good on that already, but it was still helpful. -AN

[@SergisleyMatias]

Uau, you are the fist person outside Brazil that I saw talking about Landell. You really now your facts.

[@lordfizzz]

You're a legend dude! As soon as I leave class and get home, I search your channel for whatever we were taught. Always super helpful!

[@bryangadow1459]

I've been collecting & tinkering on old radios since the 80's. I've tried but just couldn't quite understand how exactly a detector & an amplifier work...until now! Great work!

[@llpBR]

I can't believe you mentioned Landel de Moura... Pretty nice.

[@edaluz]

Absolutely!

[@LoganLopez]

I would love to see this video re-done. You have come a long way and today's video's are much better. Great content either way!

[@ronjones4069]

This is the first time i have heard anyone explaining why the diode is necessary.....without it, the average voltage will be zero. Youe explanation is excellent.

[@northof-62]

Congratulations! You're the first on YT that has made me understand the amplification bit in a tube. Even beating Mr. Carlson's Lab.

[@syl20bou]

Best explanation of the vacuum tube I heard so far! Thanks.

[@rdutrabh]

Thank you for pointing out the amazing work that professor Landell de Moura did!

[@jemlittle1787]

watching your old school videos about old school radio is so awesome. Glad you are still doing great content.

[@EIGYRO]

I wish you'd been around in the 70s when I was studying radio electronics to be a ship's Radio Officer. Brilliant explanation.

[@BrentBlueAllen]

I like this new character Bill Hammack (The Engineer Guy) has created

[@AlexWitney]

I can usually follow your videos. But this one went right over my head.

[@HighSEAL]

I love your expllenations man! This is so easily similated and well explained

[@youreale]

Great job dude, love your channel!

[@punkeyes8401]

Just discovered this channel and am diving deep into all this cool stuff. Keep up the great work! Love it

[@gmcjetpilot]

Great video..... I'm a degreed engineer, use "radio" at work as a pilot, and my hobby from the time I was a boy was radio, now an armature radio operator (ham). I restore old tube equipment, radios, test equipment.... Even though I know all of this, I found you stripped down but accurate explanation and graphics fascinating. Of course radio typically has IF ( intermediate frequency ) internally, where all signals received through the tune front end are up or down converted to a single IF frequency. This allows all the circuits to be tuned to that one frequency. There may be several IF stages (at the IF Freq 455Khz for AM radio and 10,7 Mhz for FM aradi) to boost the signal to the point an audio amplifier can reproduce audio. Consumer AM RADIO (Amplitude Modulation on the MW - Medium Wave band, or BCB - Broadcast Band) and FM RADIO (Freq Modulation on VHF - Very High Frequency) use IF stages to boost the RF (Radio Freq) signal before the Audio amplification. The history of IF or Intermediate Freq radios known as superheterodyne radios is interesting; "An intermediate frequency concept and application used in the superheterodyne radio receivers, was invented by American scientist Major Edwin Armstrong in 1918, during World War I. A member of the Signal Corps, Armstrong was building radio direction finding equipment to track German military signals..... After the war, in 1920, Armstrong sold the patent for the superheterodyne to Westinghouse, who subsequently sold it to RCA. The increased complexity of the superheterodyne circuit compared to earlier regenerative or tuned radio frequency receiver designs slowed its use, but the advantages of the intermediate frequency for selectivity and static rejection eventually won out; by 1930, most radios sold were 'superhets'." (Wiki). The short (long) answer of why this is amazing (changing or converting one Freq to another using heterodyne) is the early radios of the day (regenerative and tune radio) had to tune many stages to the desired incoming frequency. This was difficult, complicated and expensive. With a "Superhet" radio you still had a tuned circuit for the desired frequency at the "front end" of the radio, the frequency you wished to receive, but that was converted through heterodyning, By converting the desired incoming signal to one Freq regardless of the incoming signal Frequency the radio was design to amplify only one Freq the IF.... Then all stages of the radio could be the same and tuned accurately. Having more than one stage or stages by the way is a way to boost a very weak RF signal, with each stage boosting the signal more. There is only so much gain one stage can get. So by putting them in series you can boost very weak signals. Typically a cheap radio had one stage. Better radio's with more sensitivity had at least 2 or 3 stages. Some radios also had a wide RF amplifier at the front end before the tuning circuit, to boost all frequencies on that band before entering the radios tuned circuit. *This use of hetrodyne where the desired incoming signal was converted to the IF for the radio to amplify. greatly simplifying made the radio have far better in sensitivity and selectivity than any other design. This was Armstrong's invention or discivery.* The most simple tube AM radios from 1930's to early mid 1960's are called "All American Five", for the 5 tubes it had inside. The first stage is the converter which coverts the incoming signal Freq to the IF Freq. The second stage is the single IF stage which boosts the RF signal. The third stage is the detector as this video shows cuts half of the AM or amplitude modulation to get a usable Audio signal. The 4 the stage is the Audio amp to drive a loud speaker. The fifth tube was a rectifier or diode to turn AC to DC. as the radio ran on DC. The rectifier was the "pwr supply" to drive all the vacuum tubes heaters that emitted the electrons. Some high end radios had 2 or 3 IF stages and even a Pre RF amplification stage, adding 3 or 4 more tube's. Some deluxe radios by the end of the 50's and early 60's had 9 to 12 tubes. This is also when FM radio was just starting to enter the market, so it was two radios in one, an AM radio and FM radio, with the radio sharing some of the same circuits for both the AM side and FM side (amplification, power supply). However AM radio is in the 600 to 1700Khz range and FM 80-108Mhz range required their own IF tuned sections. Also the method of "detection" of AM audio is different than FM, often called demodulation or demodulator. AM and FM differences are interesting but simply put the audio sent with AM is accomplished by changing amplitude at one set frequency, and audio using FM is sent by changing frequency (at one amplitude). This is why static in the atmosphere say due to a storm affects AM radio as the static is picked up as amplitude, where FM radio ignores changes in amplitude. So FM is less (not immune) to static. However if there is RFI (radio Freq interference) at the desired frequency it can make FM radio noise. With anything operating in the FM radio band from ab 76Mhz to 108Mhz. FM radio although introduced in the 50's did not catch on. In part because there were not many FM stations and AM radio was so imbedded in the market and culture. Also an AM/FM radio was more expensive. However by the 1970's with the advent of rock stations playing full albums, FM radio took off and out stripped new AM stations, with the better audio frequency range and resistance to static over AM radio. By the 1970's transistors were now most of the consumer radio market with smaller lighter less power hungry devices. However audiophiles still use Tubes but mostly for the Audio amplification. (My be Tech Connect can do a video on difference in sound between transistors and tubes?). Ed Armstrong is one of my favorite people in Radio who also invented FM radio which as you know is static resistant. His life ended tragically partly because RCA stole is FM radio and used politics to change the FM radio band making his early radio stations and radios obsolete. He ended his own life after years of legal battles and spending huge sums to fight the massive corporation run by a true prick (David Sarnoff), but never the less Armstrong's contributions to radio with superheterodyne and FM radio's were ground breaking and long lasting with implications all through the electronics of today. However now with solid state and digital signal processing it is a different story. There are many ways to encode and decode information on an RF signal, but for the most part it has been been the superhetrodyne radios of Armsrrong that has been used since the 1930's to present day. If you have not already done it, consider doing a superhetrodyne video....

[@tehberral]

1:50 oh my heart. It's adorable how you used to once care about silly things like "time constraints". Saying this as someone who's watched the CED videos like 4 times now.

[@nthgth]

Ahh love that "trilogy"

[@jlmaynard]

Perfect description. I’ve always wondered about the radio and tube relationships

[@andrewsimmons3874]

Discovered your channel recently and randomly watching your videos. Yours videos are great educational tool. Keep up the good work. 👍👍👍👍👍 Subscribed!

[@keithlehman8095]

I learned a lot from this video. Thank you for all the great work you do on these videos.

[@presto709]

Your explanations are great. Thanks

[@Cypeq]

This the best explanation of triode amplifier I've heard.

[@c.j.t1061]

there haven't been really many videos made - which is shame, i really enjoyed the way he simply explained everyday tech.

[@neverthere5689]

i think you just got 500 subs in 1 day? thats awesome. Im glad i know how Vacuum tubes works. Thanks man, keep up the good work.

[@fellipec]

Kudos for mentioning Landell de Moura. Not everyone remembers the Brazilian guy.

[@carter7246]

Thx so much for the enlightenment ! Triggered so many wonderful thoughts in my brain.

[@Albyint]

I just discovered this channel and I love it so much. I cant believe (from your other vids)I know how speakers and shit works I always assumed it was magic. You are a good person doing good things.

[@edwardallan197]

Extremely clear and helpful!

[@seankayll9017]

This video is superb. 3:47 is the eureka moment for me. I knew that diodes detect the signal but never really understood how. It stops the RF signal averaging to zero. Of course!

[@flyingdutchman28]

Ok, you are great, what an awesome channel! Just wanted to say that. Binge watching your videos now...

[@raykall]

Thank you for such a great video. I learn so much from you!

[@kjamison5951]

This takes me back to university - I studied Electronics and Communications Engineering (Marine) and it’s covered Radio and Radar systems. It’s funny now but we touched on ‘mobile communications’ with cellphones and how systems were established across a city.

[@sharedknowledge6640]

Awesome video. This might be your best yet technical video and you got it almost exactly right. One very minor point is only relatively modern speakers have rubber surrounds. Foam surrounds, which tend to rot and fail, were popular before rubber and before that it was mostly paper pleated surrounds. You're forgiven for being too young to know such things.

[@gingertimelord5]

Where is the mention of Nikola Tesla?????? You seem to have overlooked a few points in this history

[@jayrogers8255]

Also Edwin Howard Armstrong, who, according to Empire of the Air, knew what the tube was doing, whereas DeForest, who just “thought in terms of a patent” & couldn’t explain what the tube did.

[@johnny6171]

Thank you for your brilliant bud guests! Outstanding!

[@edgeeffect]

That example early triode is brilliant it looks like it's made out of two old broken light bulbs glued together... and if it's from De Forrest's lab, it probably IS just two old light bulbs glued together.

[@scothohl4586]

Really good video Alec, you do a great job on your stuff! I liked the one about the Sony Playstation duplicating.

[@punknoodles0]

Thank you so much for the crystal radio part!!! I learned alot!!

[@hebrewhammer1000]

Thank you for sharing. Amazing video.

[@MsLila44]

great explanation of the vacuum tube.. going to watch the vacuum tube vid now..

[@ronboff3461]

thanks dude! i learn a lot from you! i think its the way you present things!

[@georgerudawsky1083]

Wonderful explanation!

[@konradkubit6525]

Very nice explanation of how vaccum tubes work

[@IPv6Freely]

This is the best channel on KZbin. And, it's not even close.

[@bytorsnowdog5885]

Your videos are just awesome. Tehcnical enough for the layperson to gain new understanding without wading too deep into engineer speak.

[@GreenForce82]

Your tech kung-fu is strong! I really enjoy your videos. I used to live in Rockford IL, it's too bad I didn't find your channel before I moved north of Madison WI. I have some stuff I would have happily given you to use in your videos. I have an amazing working auto flip laser disc player with the "xenomorph" CD tray included. It is a beautiful work of end of the laserdisc era art. I also had some very classic speakers and other such stuff that I had to get rid of before moving. Anyway, thanks for the awesome vids. Keep up the amazing work my friend!!!

[@jonathanj.7344]

Those vacuum tubes used to work TVs also when I was a boy. You had to wait 5 minutes for the set to "warm up" before you get a proper picture.

[@renakunisaki]

Fun fact, a CRT basically is a big vacuum tube.

[@brucewilliams6292]

I like the explanation. Thank you!!

[@ScottRedstone]

I remember radios before transistors. I know how transistors work. Thanks for a very clear response explanation of a vacuum tube. When you finished my brain said, “That makes sense.”

[@camtron0]

I love the old theme song! Great video

[@bassblaster505]

8:50 the surround keeps the cone centered, but you forgot one part, the spider. its what makes the cone return back to center. almost like a spring but its a kevlar and cloth "hybrid". now very early loudspeakers from the early 1900's did use an actual metal strip as the spider.

[@quantumleap359]

Maybe Alec is afraid of spiders....

[@BaronVonQuiply]

What if we just use an itsy bitsy one?

[@ATLTraveler]

Thank you, clearest explanation if seen. I get it now, kind of.

[@tiredoffindingnick]

Great explanation and presentation.

[@stephenirwin2761]

Nicely done!

[@SomethingNewEveryDay]

Great channel thank you :)

[@edgeeffect]

I love the theme-tune on these older videos... it reminds me of something from The BBC in the 1960s.

[@jimlanigan7298]

Great explanation

[@johncoops6897]

I am watching this in February 2023 and it's just as good as more modern Alex productions. It'd be great to do re-makes of these old videos, as they would be exposed to a brand new audience.

[@passivate]

Excellent!

[@Antilles1974]

0:10 When that mains hum kicked in it really got me

[@parachuteman4]

DeForest didn't know what to do with his tube. Edwin Armstrong is the person who really made them powerful through his regeneration discoveries. One of the great travesties of history is that Lee Deforest continues to get credit

[@michaelmoorrees3585]

DeForest also insisted that some gas still be present, as opposed to a complete vacuum. So his own devices are technically thyratrons, which were fine with telegraphy, but not with audio. True vacuum triodes operate more linearly (not perfect though), which is great for sound amplification. Armstrong invented a lot of what became radio, and is still used today. It includes superheterodyne, and FM. But he was not perfect. His insistence of developing FM, while Sarnoff (CEO of RCA) wanted focus more on developing television, which started the riff between the two men. Armstrong was at one time RCA's largest shareholder. They started a big legal battle, which siphoned a lot of Armstrong's wealth, and Sarnoff's tactics were often less than honorable (see FCC shift in FM band). But as is most civil cases, sometimes no side wears the white hat. Armstrong, I feel, was too obsessed with FM, which he really didn't have to do. I don't think it would have expanded radio listening that much. Most of your market has tin ears, and AM is just dandy. Look at the low resolution of MP3 sampling today. Sarnoff made the correct business move, with TV. It proved to be a much more profitable market. You sell to the mass market, and not to the audiophiles (aka audiophools) ! Let the niche mom-n-pop outfits sell to them.

[@allanrichardson1468]

Armstrong has received credit for many early developments in radio and electronics: using feedback from plate to grid to create a smooth alternating current (the oscillator; there are several ways of doing this, and the one developed first is called the Armstrong oscillator circuit); the regenerative detector (a single stage amplifying detector using feedback to add more amplification); the SUPER regenerative detector (a quenching circuit added to fix the regenerative detector’s habit of making its own signal with too much feedback); the superheterodyne receiver, which this channel has promised to cover in a later video; even frequency modulation (FM)!

[@sam-ms4hl]

love you chanel. you always have fun things to talk about

[@TRIPPLEJAY00]

Hey Alec nice to see some of your early work.

[@yamakawa511]

Another great explanation. Y

[@soulagent79]

I use vacuum tubes in my studio and in my guitar amp. It's amazing how organic and rich they sound compared to solid state amplification.

[@KuraIthys]

Just shows you how subjective the 'quality' of sound actually is. All of that stuff basically results because the vacuum tubes are quite unreliable and cause a lot of distortion, especially at lower frequencies. You're basically enjoying that your sound is being mangled and reduced in quality. (objectively speaking, not subjectively - it is a non-perfect reproduction of the original waveform) Then again, deliberately creating distorted sound is a large part of what makes electric guitars popular. Almost all of their characteristic sounds result from what is effectively poor quality sound reproduction. (Which isn't a negative, because it's distinctive and interesting, but it still basically arises because the amplifier and guitar are doing a rather bad job of replicating the waveform that the vibrating string produces. Though... I guess that's true of instruments in general; A lot of their character and unique sounds come from not being that great at cleanly reproducing the fundamental waveform. A pure sine wave is actually a pretty nasty sound to listen to ironically.) Eh. Sound. You can learn all kinds of physics and engineering about what it is and how to reproduce it, and none of it explains the 'feel', or really even anything at all about music.

[@DryPsylocibin]

I think the choice of words people make like "organic" and "rich" is a great indicator of what makes such sound distortion actually sound good. It introduces variability and complexity, which capture our attention. Just like you say, a pure sine wave is a very uninteresting, even unpleasant sound. A square wave adds a lot of harmonic frequencies and instantly is more enjoyable. And that's probably key to the analog vs digital debate. With solid state electronics you can get the same result very reliably. The effects on the signal are highly predictable. Whereas with something like vacuum tubes, even tiny differences from one tube to the next will make for slight variations in output. It's noticeable in other things as well. The distinct hiss of cassette tapes, crackle from vinyl, the combination of audio quality and visual artifacts in video tapes... They all create a very distinct profile, "organically" emerging from the media used. It's surprisingly hard to imitate well using digital tools. And while they're all basically imperfections and today's tech can objectively provide better quality in many ways, things can end up feeling sterile. Another word that, not coincidentally, is used often in that context. I believe I started appreciating the power of the imperfect when I learned to enjoy cigars, and found that the hand-rolling process and variations in tobacco selection are what make them so interesting. Within the same brand, the same model, even from the same box, no two cigars will be exactly the same. Whereas cigarettes are designed to ALWAYS deliver the same experience. Maybe things like these are why the more powerful and accurate consumer electronics are becoming, the more we see counter-movements like the new appreciation for vinyl.

[@soulagent79]

Well said. It's the same with tape saturation.

[@alexstevensen4292]

My hifi tube amp from the 60's sounds way better then most transistors. Offcourse you can make a good sounding transistor but you really have to know what you're doing. Tubes never really go wrong. Transistors circuits have a tendency for parasitical HF oscillations which messes up the midrange you get that harsh sound. A teacher told me it was emmitter oscilliations but I can't back that up. With a tube guitar amp it's a double win, the triode's have a much nicer distortion and the end stage just sounds better because of what I just mentioned. I suspect there also a diffence in 'interacting' with the speakers tubes have a easy going way of driving the speakers. With transistors there's seems to be some tug-o-war going on combined with overal feedback it's a recipe for messy sound. These articles kind of dive into these things education.lenardaudio.com/en/12_amps_8.html education.lenardaudio.com/en/12_amps_3.html

[@underworldent4817]

@@KuraIthys actually , it is more to do with the emphasis of certain harmonics , and the way valves clip. nothing subjective about that.

[@mikeklaene4359]

Good job. By the way, as a kid in the late 50's, I had a tube tester very much like the on behind you. It took me a while to figure out how it worked.

[@ianbatty3947]

I *love* this site, and have referenced it in some of my lectures. However, you talk about turning the electron flow ON and OFF - you are describing a digital device. The fact is that the electron flow is (roughly) *inversely proportional* to the grid bias voltage: zero bias - maximum anode current, half of cutoff bias, half anode current, full cutoff bias, zero anode current. It's an analog device. Although beyond the scope of a talk such as this, the first vacuum tubes had *very little* gain (maybe a factor of 2 or 3) - they could amplify *fairly well* by being able to drive into low impedances such as headphones, while presenting a near-infinite impedance to the driving source. They were, in effect, transformers with a bit of voltage gain but with an infinite input impedance and zero circuit loading - therefore giving a substantial *power* gain. Thaks for your site and keep up the good work! Ian.