Guitar Amp Vacuum Tubes Part 1: Triodes and Tetrodes
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- Опубліковано 2 жов 2024
- In this 2-part video presentation, I discuss the characteristics and evolution of the vacuum tubes used in vintage and modern guitar amplifiers. Beginning with Triodes, the general design, strengths, and weaknesses of each type of tube will be discussed, and terms like secondary emission, parasitic oscillation, negative resistance, and inter-electrode capacitance will be discussed and (hopefully) clarified.
If you enjoy videos featuring classic vintage tube amplifiers, jukeboxes, assorted homemade electromechanical marvels, and clear, basic discussions of technical topics, then please subscribe to my channel. You will gain access to well over 100 videos and will be notified each time a new one is released. Thanks for watching !!!
Give Rusty a growl & 3 barks for me. Thank you for teaching us about electrical, electronic, electronics. The world is a ocean of electrons. Getting them to flow like water where we want them to & controlling them allows us to do all kinds of things.
You're welcome, Greg. Rusty passed away several years ago, but I'm sure he appreciates your courtesy.
Well, I can’t say I “get it” yet, but I am getting closer.
I understand what you’re describing, just not the whole picture.
But, you are one of the best teachers I’ve ever come across.
Thank you for your efforts!
That's good to hear, DM. Keep up the good work.
Hi Uncle Doug. I am a 20 year old portuguese electrical engineering student. I am also a guitar player for 10 years now. I already built my own transistor amps and effects pedals. I am digging into tube right now. Just want to say thanks for ALL of your videos. Such a nice gentleman. Hope you are doing good on this horrible lookdown. Cheers
Thanks so much, BB. Yes, we are all doing fine....but are more than ready for life to return to normal :)
@@UncleDoug We all are! Cheers
These videos are just such fantastic learning resources. I learn so much and demystify so many things.
Glad to hear it, LG :)
Dear Uncle Doug. May I thank you for the time and effort you and Rusty have put in to make these you tube videos. It's a pity that in 1974 when I was a College student studying Telecommunications we didn't have such superb AV lessons !. Kind regarde from England UK
I would just like to thank you very much for your explanations of the guitar tube amplifier, In watching your videos for a couple of hours has done more for my understanding of these circuits then years of trying to research them on my own again thank you for your time and consideration
You're welcome, Terry. We're glad to hear that the videos are informative :)
Superb and detailed description.
First class.
Thanks, Ian :)
Thank you for explaining vacuum tubes
You're welcome, Lee.
Very tasty info- enjoying the gray matter stimulation!
Glad you liked it, Michael :)
May I just say, you are a legend sir! Perfectly explained in the most soothing and radiophonic voice. Thank you!
Wow, thanks, Jon :)
Wow, finally someone who was able to simplify this highly technical info. into something I could understand ! tank you Uncle Doug for being so patient & methodical. Forever thankful !
You're welcome, Jerry. I'm glad the video was informative.
This is the 3rd video I've watched (of yours), and I have to say, you've done a magnificent job of explaining tube amplifiers!!!!
Thanks, Richard. I'm glad you enjoy our videos.
I appreciate all the time you've taken to make these videos. You are very clear and make it easy to learn. Keep on rockin!
Jay Stern Thanks so much, Jay. Rusty and I are glad you enjoy our videos. Thanks for watching :)
Lee De Forest was heck of a guy. It took him about 10 years or so to get his pattent. I heard a radio program from 1942 or so, where his lab assistant was interviewed. the program was called "Behind the Mic"; I'm into old time radio programs. He told how Mr De Forest was actually brought before a congressional committee on charges of fraud for what "they" considered attempting to pattent what ammounted to a light bulb and defreauding his investors. Poor guy, never even gained the respect he deserved much less the financial success.
I guess congressional committees wasting taxpayer money and making fools of themselves is not a recent phenomenon ;) DeForest, Tesla, and their ilk never did get the recognition they deserved during their lifetimes.
Guess that's sitll the way it is, otherwise, you'd be the star of all PBS stations.
Thanks, Remley. Better that than being grilled by Nancy Pelosi about my illicit use of current limiters :)
I didn't know that! It makes a lot of sense.
Is that first time when I understand the tubes.I have in my future plans ,to build a tube amp.👍
Let us know how it turns out, Dorin.
Very clear explanation. Good work uncle !
Thanks, Roland :)
10:50 I'm sure everyone will be astonished to hear Unc invented the triod back in 1906. Well done uncle Doug and congratulations on your century and then some. If you were in my country you'd have at least two telegrams from the queen by now, as well as a gong.
Thanks for the long-overdue recognition, R.D. In reality, however, it was my former assistant, Rusty, who actually invented the triode while working with his protegee, Nikki Tesla.
This was what I needed to see to tie things together. I understood most of these concepts, but I didn't quite get one thing. I was looking g a schematic and I noticed that the hot lead on one of the tubes ran from the cathode as opposed to the anode, and now I understand it was to get the opposite phase. It's interesting though, because I'm now realizing that tubes will send the signal out of phase when going out from the plate
Yes, depending on which interior structure you use to derive your output, plate or cathode, you can get an inverted or in-phase signal. This is the basis for most phase inverters used in push-pull amps.
Thank you very much for this. I'm building my first tube amp and your videos have provided me with invaluable information !
Dave Becker You're welcome, Dave. We're glad our videos have been helpful :)
Great video as always! Another brick in my "wall of knowledge" :D
Greetings, Nusior....always good to hear from you. Thanks for your kind words. Rusty and I are glad you enjoyed it :)
This was great,
Thanks, Mr. Mac....glad you like it :)
I hope you will go over every type of tube with us, you have a good way,that makes it easier to understand the concepts.. Thanks..Cheers.
In Part 2, and I don't want to "give too much away", but we will discuss the development of tubes like the 6BQ5, 6L6, and KT88, which are near and dear to the hearts of all guitar amp enthusiasts.
Uncle Doug, you are truly an Inspiration! I've learnt so much from your videos...thank you so much for sharing your awesome knowledge and ability to make complicated things simple and fun things even more fun! Please never stop!
Thanks so much, Perry. It's great to hear that the videos have been helpful. As long as Rusty and I keep getting nice comments like your, we'll keep making videos :) ^. .^
Great video, awesome explanations ! thank you !
You're welcome, John. Glad you liked it :)
Really intresting! Was nice to watch and I'm going to see part 2 :)
Klaus Sonnleitner Thanks, Klaus.....glad you liked it.
love triodes and Pentode 6sj7 my fav for preamp tube
ian forster Greetings, Ian. It's good to hear from you. Yes, I too love the 6SJ7 as a pre-amp tube. It gives the amp "character".
@@UncleDoug 6SJ7 = 6Ж8
@@АлександрЕрмаков-ю1э Thanks for the info :)
@@АлександрЕрмаков-ю1э I believe they are completely different tubes......incompatible.
"Parasitic oscillation" -that was one of the problems I had in high school.
It must have come from that toilet seat in the rear stall ;)
Thanks for a very interesting and informative video.
Best regards.
+GglSux You're welcome, GS......glad you liked it :)
Jon Ault: Your comment had no reply capability, so I hope you see this.
Your tube conversion should now make sense. Substitution of the Low-Mu (19) 12AU7 for the High-Mu (100) 12AX7 reduced the pre-amplification within your amp and allowed for a more "relaxed", clean sound. Looking at the Mu chart in the video, you might also consider experimenting with a 12AT7 (60) or 12AY7 (40) to get a little more volume while (hopefully) preserving the clean tone you desire.
Tetrode - Hiroshi Ando. " In 1914 Schottky discovered an irregularity in the emission of thermions in a vacuum tube, now known as the Schottky effect. He invented the screen-grid tube in 1915, and in 1919 he invented the tetrode. " Just found, " In Japan, Hiroshi Ando patented improvements to the construction of the screen grid in 1919. " and " The first true tetrode, with a screen grid designed to reduce grid -plate capacitance, was patented by Hiroshi Ando in 1919. "
Thanks for sharing this with us, P.
Finally I understood, why vacuum tubes are called that way. Why nobody told me, that this is because of the little vacuum-cleaner at the anodes, which sucks in all the popcorn from the cathode? So simple! Thanks Uncle Doug for this aha!-moment!
+PrinceOfBodom I love your interpretation of my analogy, PB. The more conventional explanation is that all the air is removed from within the glass envelope of the tube to prevent the filament from igniting.....like light bulbs sometimes do when they "pop". This absence of air within the tube is called a vacuum.
+Uncle Doug Oh, that explains the missing popcorn when i switch on my amps... But to be more serious - I recently watched most of your explanation-videos and they are all very well done. Also, it is impressive to see, you take the time to answer every single question of your viewers. Keep on this good work!
Thanks, PB. I do try to respond to each comment, but it takes a lot of time.....which keeps me away from wiring the Supro :(
Excellent, well done vid. Thx.
Glad you liked it, James.
Just a minor point: In the simplication, the plate load resistor was not included, which allows the plate to modulate the input signal by it's amplification factor. .Mu (amplification factor) and Gm (transconductance) to amplify the signal. G is the electronic symbol for conductance and m (lower case) I believe, stands for mutual.
SuperCarver2011 Thank you for your input, SC.
As always Doug, this is great stuff. Look forward to part two.
Thanks
Carl
You're welcome, Carl. Thanks for watching :)
The oldest and simplest triode was the direct heated triode where the cathode and the heater are ONE AND THE SAME element inside the bottle. Obviously, the heater supply is DC, floated above or below common earth ground. Audiophiles still like those 211s & 300s. 73s KI7AQJ
Thanks for the info, Seth.
Good lesson ,sir thx
Another masterpiece of teaching, thank you. You have really "amplified" my knowledge level. :)) The pencil acting really came alive in this one! :)) Rusty says "yeah, Ben can retrieve a ball, but he's no good at camera work". :))
Thanks so much, Andrew. No video is ever "official" without your input :) I stole the pencil from Martin Scorsese, so it darned well better look good on screen. Rusty was simply distracting Ben from noticing (and encroaching on) his videography territory. Next, he'll want to direct.....
Uncle Doug, "the" go to guy for tubes. These videos are addictive. I've never enjoyed learning so much. It's effortless to understand thanks to your outstanding teaching skills and depth of knowledge. If you see this Doug, do you work with RF at all?
Thanks so much for your very nice comments, Mark. I used to restore early radios (1920's and 30's) but have moved on 100% to tube amps.
Every time I re-watch Doug’s videos, a bit more sinks in.
That's good to hear, Will. Keep on watching :)
this is great
I’m going back through some of your old videos. It’s quite a body of work. A subject I don’t think you’ve touched on is the difference between AB1 and AB2. What are common push pull guitar amps running? Id also suggest an explanation of what tube data is relevant to guitar amp design and how to read the graphs and operating points. I’m just trying to tie up loose ends in my body of knowledge.
Several of your inquiries touch on topics so esoteric that they would probably not appeal to the vast majority of viewers, Jon. I began a video on load lines, but abandoned it due to its utter boredom and lack of applicability to 99% of viewers. There are videos and internet sites that do address these topics, however, and I suggest that those who are interested should seek them out. Good luck.
Hi Doug, and thanks a bunch for yet another very well made infovideo. I wish I had a teacher like you back in the 90's when I studied electronics! :) One question though... What would happend if you fed the plate with a lower voltage than recommended (nominal)? Lets say a triode has a recommended plate voltage around 150VDC but you would lover that to lets say 1/3 of that, about 50VDC.
Thanks, Robert. The voltage on the plate makes it attractive to electrons from the cathode. Lowering the voltage makes it less attractive......thus reducing the gain and probably the frequency response in that stage.
Uncle Doug, I think I have watched every one of your great video's...some more than once! I've learned a great deal about vacuum tube theory and application thanks to you. Your instruction style is clear and concise....is your background that of an educator? Anyway, thanks again for all the effort you and Rusty put into these amazing video's and I look forward to the 2nd part of the presentation. Pentodes and suppressor grids, perhaps?
Thanks so much for your kind appraisal, A55. Rusty and I really appreciate the positive input. Yes, I was a math and science teacher for 17 years. Re your guess on Part 2.....you're half right :) Stay tuned......
Thank you so much for these. I have learned so much, and the level of your lectures is just right. Your style, and even your handwriting, remind me so much of my Dad, who was an electrical engineer and taught me a lot. He passed away in 2001, and listening to you is almost like getting to sit next to him again.
I am quite flattered by the comparison, Jon. Thank you so much :)
I have been studying vacuum tubes for radio both AM/FM and shortwave. I have an extensive collection of vintage tube radios and simply have relished your easy and thoughtful presentations! I look forward to part 2!
hey joe. do you have any circuit schematics for am/fm radio. if you have can you share it with me ? I have VT-173 1T4 tung sol lamps. I would like to make a radio.
As usual, I learned a tremendous amount of useful information, this time about those not-so-mysterious tubes. Just the topic for dinner table conversations, and with a new pair of paws on the camera, the video is steadier than ever. The exposition is as engaging and informative as ever. Amplifier design appears to be about balancing trade-offs in every part of the circuit, so it can only be understood by grasping the intricacies of each component in the whole.
Another great video Uncle Doug. Question about the mu of the 12ax7 is it truly a 100x gain factor? Was this by design or did they just "make" that figure up when designing the 12a_7 series of tubes?
Cute pup btw, looks like Rusty has a playmate.
Thanks, Davo. Mu is a measure of voltage gain. Very simply stated it's the calculated ratio between the voltage of the output (plate) and input (grid) signals. I believe that 12AX7's actually have an output/input ratio of 100. Thus the value (100) is an actual measurement and not simply an arbitrarily assigned value. We were babysitting Ben during the video so I included him. By coincidence he is back with us this week, and although at least twice as large, still plays ball with Rusty.
Never hurts to have a bit of remedial lernin! Although I might have been tempted to start with a how a rectifier led to the triode.
God, when I think how many valves I popped throwing a cats n stuff in the early '70 as a kid because ... BC108 & 2N3055.
Going back and watching the classics again has made my holidays happier. Thank you for all you do, and Happy Hollidays UD! Cheers!
Thanks for the nice holiday note, FWR. Likewise to you all.
Rusty has more knowledge about tubes in his left paw than most people will know in their entire lives.
He would have been the first to agree, Ezra :)
Thanks a lot for this explanations, im too young for vacuum tubes, never got such a clear explanation.
You're welcome, Bruno. I think most of us were fairly young (or not yet born) during the heyday of vacuum tubes. To be honest, if it weren't for the current resurgence of interest in tube electronics, it would probably all be just a dusty relic of minor historical interest. Rusty and I are glad you enjoyed our video :)
Congrats again Uncle Doug. A very nice explanation on the triodes and tetrodes. Nothing better on UA-camland.
Thanks so much. Glad you enjoyed it :)
Hi, it's me again from Brazil
Would you allow me to put portuguese (pt-br) subs on this video of yours?
This is something I've never done but I'm pretty sure I can do!
Thanks a lot
Yes, indeed, Carlos. We would appreciate any help in getting our message out to all people interested in tube amplification.
The RCA Receiving Tube Manual is available through Antique Electronics supply for $22.95.
Sounds like a good buy to me :)
I have returned to this a few times to recharge and I wonder if you have found 1 or 2 top notch reference books on the relevant topic ($) you might recommend as resource.
Thanks. Best darn school on the tube.
You're welcome, Paul. To be honest, I have never used any textbooks in my study of tube electronics.......it's all based on internet sources and personal experimentation.
Uncle Doug, I was thinking... In order for the tetrode's to have a reduced Anode-Control capacitance, the distance between Anode and Control must have increased, and the Screen Grid might also be a poor dielectric, unintended for carrying current. Are these accurate assumptions? I don't have any of these components, but I suppose I could find some datasheets (if they are easy enough to find) and compare examine their properties.
I can't speak as to the anode-control grid distance, but screen grids do intercept electrons and generate a screen current. The presence of the screen grid between the Anode and CG is what reduces the capacitance between them.
I very much appreciate you sharing your knowledge with us...I look forward always to your videos..they are great...Eddie
Thanks so much, Ed :)
Thank you for another very clear explanation of valve tube technology.
You're welcome. Glad it was helpful.
Its and interesting history - is there also a future? - I assume there was a boom of production, when radio and furthermore television come up - suddenly tubes where everywhere (50ties) and cheap? Achievable for everyone (what was the price at that time)? How many tubes have been produces and which one are the most common? Patents and the trial of strengths between Europe and USA … I would appreciate a video about this history of development up to subminiature, nuvistor and the actual top secret microtubes - please.
I tend to specialize in vintage tube amps, Stivie, but I'll keep your suggestions in mind for future videos. Re the price of tubes, some of my vintage tube boxes have price tags as low as 50 cents. Thanks for watching :)
Failing other resources for that Sylania Tube Manual, here's the PDF for download:
www.rsp-italy.it/Electronics/Databooks/Tubes/_contents/Sylvania%20Radio%20Tubes%201959.pdf
Addy Adderson Thanks for the link, Addy. There are all sorts of tube manuals available on the Internet, and on Ebay. They are just too useful to do without.
These videos are great. By the looks of the company you and Rusty keep. The term "guilty by association" comes to mind. maybe i'd better watch with caution.
I always advise caution, Franky, when watching any UA-cam videos. In fact, as a safety precaution, I always watch the first minute or two with only one eye......particularly those Russian Pole Dancer videos :)
I live for the Rusty inserts….Thank Doug! Learning much from you!
Glad you enjoy them, DMT. That's good :)
Man these videos are excellent. I'm a service engineer working on Mass spectrometers and a keen guitarist and always wondering in detail how tubes worked and how the design of them changed the input signal.
A bit like our Ion optics elements and quadrupole mass filters in our mass specs except for elections rather than charged ions. And instead of tubes we use electron multiplier horns for signal amplification. I can feel myself going down a deep rabbit hole here and I love it.
It sounds like tube electronics should seem rather elementary after dealing with the equipment you described, D. Welcome aboard :)
the guitar signal's "jumping on the merry-go-round" which is spinning already, and being flung off butterfingers to the next ride... - I grab it... wow.
Hi Uncle Doug, this looks like it will be a very informative video series, good job once again. I was also wondering if at some stage you could do an A-B sound comparison of NOS Carbon comp resistors with Metal film resistors. There seems to be a lot of snake oil puffery around the use of the carbon resistors in amps producing a better quality sound, your input and opinion would be much appreciated. Thanks Colin.
Greetings and thanks, Colin. I don't currently have a recording method of sufficient fidelity to convey subtle differences in sound, but am considering acquiring one. Meanwhile, I agree with your assessment of the "boutique" component market, in which certain primitive carbon resistors and fancy capacitors are said to provide noticeably better sound than (good-quality, not junk) "regular" modern components.
I seriously doubt that, in a blind test, normal human hearing could discern the difference. I understand how these esoteric components can give believers a certain pride and confidence in their equipment.....and it's their money, so more power to them.....but I will continue to muddle along with metal film resistors and mundane capacitors until I become convinced of the demonstrable, cost-effective benefits of the boutique components.
@@UncleDoug I'm willing to bet that you're still not convinced.
just an idea if you know : why some tubes tend to be more British and some american. ie 6l6 vs el34. etc. did British and American amp companies base their circuits on tubes that were available? or did the specific tubes prompt them to build certain circuits? chicken or the egg.
By coincidence, Part 2 of this series will explain the parallel development of two very different types of power output tubes, in England and the USA......and further explain the differences in sound between VOX (British) and Fender (USA) amps (for example). So stay tuned................
Wow, thanks to these video's, it took me 45 minutes to understand the basics of a tube amp. Perfect teaching! Thank you sir!
That's great to hear, Koen :)
Brilliant video Doug.Really clear and concise explanation of how the various tubes operate.
Thanks, Stephen. Glad it was helpful!
Thanks Uncle Doug for another well-researched and interesting video. You are a natural teacher! I'm looking forward to the next installment.
Thanks so much, Robert. Rusty and I appreciate your kind words, and promise even more "thrills and chills" in Part 2 :)))
Novice question here. Could a tetrode tube then be used to make a guitar pedal that functions as an oscillator?? That could be fun!
My guess is no, Brandon, but you're welcome to try it and see for yourself.
Doug, Is there any advantage, or is it even feasible, to create a cascading preamp circuit where one preamp tube would drive another preamp tube?
In effect each pre-amp tube in every circuit drives the next tube in the sequence, Jeff. Amplification is created by a chain of driven triodes (usually).
another place I konw of is NJ7P tube database. most of their dat is entered from manuals.
Greetings Uncle Doug, Rusty and Jack and BIG BIG THANKS for all your hard work putting these videos together! I was wondering why the signal on the plate is 180 degrees out of phase when compared to the signal on the control grid yet when comparing the signal at the plate to the cathode they are in phase. Thank you!
You're welcome, Bill. The explanation is rather complex and is provided in several of my other videos. Check out the How Tube Amps Work video regarding the pre-amp section.
Thanks for the quick response and suggesting the video about how tube amps work regarding the pre amp section. I will look at it again. Every time I rerewatch a video of yours I seem to grasp a little more. Thanks again, take care and happy hollydaze.
Same to you, Bill.
Thanks for another interesting video!
It seems the tetrode suffers a bit from this, but if the grid is positive in a triode why is it not capturing the electrons but is instead giving them a push towards the plate? Is it because the grid is mostly air so not many electrons hit it even though it's attracting them?
Bear in mind that the grid is only relatively pos or neg relative to the cathode. Yes, the grid does capture some electrons, which is why all grids are referenced to ground to allow for the flow of electrons away from the grid......but the vast majority of electrons are accelerated and proceed onward to the highly positive plate.
Mu. It's pronounced myoo (mew) like what a cat says and not moo like a cow.
Wow....thanks, Fred. I hope it didn't detract too much from the video ;)
Please could you confirm in what direction the electrons are flying in an electron tube? Is that from Anode (+) to Kathode (-) or is it in oposite direction? I know that the electroncs are suposed to fly from (+) to (-) but following your video it looks that it is not the case. Thanks in advance.
Greetings, Sinisa. In chemistry and some other sciences, it is stated that electric current (electrons) flows from plus to minus, but in electronics, we know better. Electrons are negatively charged and only they can move, since protons and neutrons cannot. Any area with an excess of electrons is considered negative, and any area without electrons is positive. In an electron tube, electrons move from an electron-crowded negative location (i.e. the cathode) to an electron-deficient positive location (i.e. the plate).
Again, fantastic teaching. I've watched many vids and yours are by far the best. Now I understand all.
Wow, thanks, Ravi.
Nice little basic toppic, well and very *nice* explained, Thanx Doug!! Looking forward to see Part 2 soon:)
Thanks so much, TC. I always appreciate your input. Part 2 should be posted soon.
It amazing that when somebody draws the right picture, it clarifies everything. After watching a few of your videos on tubes, I could predict what you were going to say next.
Awesome video series. Electronics engineer past 30 years and got my first tube headphone amp a year ago. All I can say is the sound is WOW....until it started to malfunction. I must learn how this advanced alien technology works...as one of my 6080 outputs has a bias current problem. Not the tube and I have replaced all bias resistors etc... Very low bias current..as in 1-4 mA instead of 30 or so. I cannot go back to my solid state amplifier now...it has no "soul"; just harsh, dry and cold.
Waiting impatiently for part 2!
Thanks for the great videos!
Nice. Amperex. I think those were actually made by Philips in Eindhoven.
That's quite close to where I live.
Great theory and instruction, just what I needed. Looking forward to Part II so I can understand how to bias a happy functioning pentode.
Uncle Doug! Thank you again for all your great videos - you're greatest tube guru on the internet. You help us all learn more and build better amplifiers.
RIP Rusty. All love.
You're quite welcome, ID. Thanks so much :)
The way I was taught how Triodes worked, (a long time ago, (sigh)).
You're in a room facing a white wall with your back to the window on a sunny day, the blinds are closed. As you open the blinds more light gets through. The Sun is the Cathode, the blinds are the Grid and the wall is the Anode.The less light that comes in, the lower the voltage on the grid. Just thought I'd share.
Oh and the most precious book I own is the Telefunken 1966 book of valves. 613 pages of tech info for (almost) every single valve made. Audio/Radio/CRT/Transmitter and rectifier.With some even having example circuit diagrams. It's always been close at hand ever since I got it in 82.
Thanks for sharing this with us, Franko.
Hi Doug again .Not too sure if you can BBC 4 in the USA . anyway great video .
I'll definitely check it out tonight, Dave. Thanks again.
man, when I learnt this in the school (ages ago) it took us few months to learn what you showed in few minutes today - txh ;-)
power of YT nowadays
I'm glad the videos are helpful, ZH.
@@UncleDoug yeap, I am "back to school" as I am looking for nice headphone tube amplifier diagram that is my next project - if you happen to have one please share ;-)
the science of the tube has to electro-magnetics yes. AC wave on the grid changes the applitude of the magnetic field around the gird physical components and that in effect opens and closes the ability of electrons to past thru. Is that right???
Yes. The charge of the grid relative to the cathode dictates the level of plate current that can pass through to the plate.
You are correct, but it is a varying electrostatic field, not a magnetic field.
Wait, so you say that tetrodes were uncommon in guitar amps, but from looking at some schematics and talking to some people I thought the 6v6, a tetrode, was one of the more standard, common tubes out there.
Am I missing something? It feels like I'm overlooking something, and it's somewhat confusing.
Excellent video, by the way.
Never mind, just saw part 2, I understand now.
Hi! Is there any quick metode to calculate the gain of a tube gain stage? I'm a bit concern to not have too much gain in my bass preamp...
The methods are not particularly quick, but here is a discussion of them: www.triodeel.com/gaincalc.htm
For a fully bypassed gain stage (i.e. with a high value cathode bypass capacitor) gain is given by: Gain = -mu x Rp / (Rp + rp), where Rp is the value of the plate resistor, and rp is the plate resistance. ( mu and rp (or ra) are given on the tube's data sheet). The minus sign indicates the inversion of the signal.
E.g. A 12AX7 with a 100k plate resistor and a supply voltage of 250V:
100 x 100,000/ (100,000 + 62500) = 61.54.
Great explanation of how a tube operates. Love that you include the pets! I've been a ham radio operator for 25+ years and still learn from these videos. Now if I could only get my Shih Tzu to solder.
Glad it was helpful, Ryan. Best of luck with your pup assistant ;)
I'll keep them coming then. I'm a guitar player of 26 years. Spent a large portion of my 20's & 30's bouncing from wiring houses, building them, and escaping all that land based stuff and working on a commercial fishing vessel.
With the limited electrical knowledge that I have your videos are a huge help bringing me up to speed on the things I need to know to build my own tube amps.
I have always been curious about tube amps and recently bought my first, a Mesa Boogie Roadster, and I am hooked. I spent months researching different amp types before I finally decided on the Mesa Boogie.
It was during my research that I came across your videos and it has sparked a NEED (funny what you can get addicted to) build my own amps. I have begun collecting tools and a few books that should help me in that quest. I have about a billion questions and your videos are answering a lot of them.
Thanks a million for all the work you and Rusty do. Can't wait to learn more. .........og.
+Ogre Badogre It's good to know that the videos are helpful and appreciated, OB. Best of luck with your amp-building project :)
You're the far most amazing instructor of mine ever! Thank you Uncle Doug, just because of you I'm in the tube amplifier world and feeling super happy!
Thanks !!! We're glad to hear it, K.
Hi Doug I am a novice at this. I always thought that in an amplifier application, the cathode would have a constant DC charge, and the AC signal of the grid would turn that DC into an AC signal that is more powerful than the signal coming into the grid. But in an amplifier, there is also a signal coming into the cathode and that signal is in Phase precisely with the signal coming into the grid?
The cathode is connected to a constant source of electrons (i.e. ground) to facilitate release of these electrons as a current to the plate. This current is moderated by the signal grid. When that grid is positive, a lot of electrons flow from the cathode, making it relatively positive (in phase), while the plate receiving the electrons becomes more negative (out of phase).
@@UncleDoug Ahh - got it!
@2:25
grid is closer to cathode?
haven't seen this stuff since ELEMENTS OF RADIO, Marcus and Marcus, Prentiss Hall:)
I also read that wonderful book,from cover to cover.
Uncle Doug,
I've watched many, certainly not all, of your videos and I feel it necessary share my appreciation of the amazingly understandable way that you present and share so much very complicated material and concepts. Thank you so much!
Gene
You are quite welcome, Gene. We really appreciate your nice comments.
And then at the end HE thanks US?! Doug, you're a good dude.
My mother raised me to be polite, Chris :)
another interesting film that i don't understand,but i have changed a 12ax7 for a 12au7 in my little fender amp and get the best clean sound ever now so thanks for that .
I found this very helpful and informative. Thanks !
You're welcome, RA. We're glad to hear it :)
Dear Doug, i am recently began repairing/assembling some very interesting tube radios. But pardon my inexsperience, why there arent solders able to stick to the pins instead we must use a socket?
I don't fully understand the question, Stefano, but if you're having problems getting solder to stick to copper or steel, then use a soldering flux. You can buy it at any hardware store.
Thanks for stepping in here, SV. I had no idea that Stefano was lamenting his inability to actually solder the tubes into his circuit.
Where can i find a pdf of the russian tune manual and also a physical copy.
Heck if I know, Riff. You might check on the Internet and on Ebay. Good luck.