Building a Tube Amp! Does it produce better audio quality though? EB#47
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- Опубликовано: 7 ноя 2020
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In this video I will be having a closer look at a commercial vacuum tube amplifier aka a tube amp. I will show you how such vacuum tubes works and how to create a simple class A amplifier with them. At the end I will then show you why some people still like using them even 100 years after their invention, even though they offer lots of disadvantages.
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hi, i would like to point out some inaccuracies....
1 : your " amplifier" has little to do with a tube amplifier since it uses vacuum tubes only as signal buffers, everything coming out of that box is transistor generated.
2 : a true vacuum tube amplifier uses "final" driver tubes to generate the power to drive a speaker, but since they require high voltage as part of their working characteristics they have ust a high impedance output. this impedance is matched with an iron core transformers ( with some special characteristics to improve audio performance ) so in your amplifier you are bypassing about 3/4 of what a tube amplifier really is.
3 : the tube curves are less linear than transistor ones, but you are actually looking at the wrong graph to determinate linearity, audio specific vacuum tubes ( there are RF, IF, oscillator, mixer ecc.... specific tubes) have a grid voltage - plate current graph, si you see the variation of plate current versus grid voltage; this really shows linearity ( remember that tubes are transimpedance amplifier basically )
i also would like to propose an objective osservation, the audio quality can be strumentally measured with audio distorsimeters of fft analyzers ( or a scope fft ) as well as a frequency sweep, if you take a look at some videos by "ElPaso TubeAmps" channel you would see how a real tube amplifier is built and fully tested, a good tube amplifiers does not show distortion of any kind basically, you can achieve even 0.1% total distortion which is a remarkable result.
i do not want to be polemic, i just want to point out some inaccuracies :)
hope you reed this comment!
Yeah, i only have a high level understanding of tube amps, but every cheap circuit is still 80% silicon, the tube does nearly nothing. The parts that make a tube amp a tube amp are bulky and heavy, and pretty dangerous too. Like 400- 600v.
the problem with using tubes as final drive tubes is that it adds a ton of aliniarity the mentioned iron core transformer features a alinerar iron core which is a source of distortion add to that that those systems are rather inefficient and that they are only realy usefull for low powers and you have quite a lot of problems. also 0.1%thd is basicaly nothing in the world of silicon amps they usually run with a ton less untill they get out if their linear region.
not saying that tube amps have to place to be quite the opposite if you find that mix of distortion pleasing to hear thats a great option for you same with guitar amps where that distortion makes a guitar spring to life.
but just as a amplifier that has to create the most linear and accurate results tubes are not your friend
Tube sound superiority in hifi amplifiers is still a very contentious debate. There are many who believe that the amount of distortion is less important than the harmonic content of the distortion. The typical argument is that a strong 2nd harmonic is a pleasing "musical" distortion and tubes tend to distort in that way. It's a fine argument for guitar amps, but it kind of falls apart for audio amplifiers. Music usually contains complex a mix of frequencies and while a 2nd order harmonic might sound nice applied to a single note, with many simultaneous notes the resulting distortion products interact with each other in a very non-musical way creating a whole bunch of new frequencies not in the original piece of music. The result is a loss of definition of each individual instrument and a more noisy, veiled sound.
This.
Wait!! Let me get to the point.
So her 80$ audio vacum tube are trash product that scam innocent peoples to buy it because humor about tube sounds quality? 🤔🤔🤔🤔🤭🤭🤭🤭
As a tube amp designer, I would like to add on to your theory at the end as you were quite close to hitting the nail on the head. You will notice the curves for the tube not being evenly spaced unlike the transistor in which causes even order harmonics to be generated as opposed to the transistor in which (especially when driven into clipping) generates predominantly odd order harmonics (which sound terrible as they are not musically related notes). The dominant even order harmonic with a triode tube is the 2nd, being the octave. This brings rise to huge popularity using triodes as distortion generators for musical instrument circuits as all distortion generated is musically related to the fundamental frequency and although does contain odd order harmonics, all harmonics after the 2nd decay in even amounts from one another which has the result of the triode distortion not containing too much high frequency fizz! I'd recommend googling the harmonic distribution chart of a triode.
Most electronics channels of course always talk about hi-fi use when it comes to audio circuits but forget that there is a whole other world out there in which distortion is wanted- but you are right in saying that there is a taste for tubes in hi-fi. As I said with the distortion being musically relevent, it can have a nice tone to it. I built my first vacuum tube hi-fi amplifier when I was 18 and I still use it to this day!
I don't think it is that, but it's easy to find out, i suggest you get a spectrum analyzer and check the output of the Valve amp, i was thinking in do that, but I don't have the time. As a tube amp designer I think this will be great to do such a test, who knows put to a end to this discussion and legend :)
@@luigicfilho Many have done such a test and verified exactly what Liam wrote. ruclips.net/video/UcNKGagfMyg/видео.html
Electrons move more freely in a vacuum!!!
"Musicality" is a by product of distortion. Choosing the type of distortion, and it's amount of influence is the really difficult part of audio design.
Scott was looking at the wrong curves if he wanted to compare tubes with transistors. The curve that really gives the information is the one that relates input voltage to output current.
For a tube, the current out is approximately proportional to the square of the voltage in. When the input receives a sine wave of a particular frequency, the output current will mainly be a sinewave of the same frequency plus a lower amplitude sinewave at twice the frequency. That's second harmonic distortion and, for some reason, our hearing perceives that as a pleasant sound. There will usually be small amounts of fourth harmonic distortion and higher, but still nothing we tend to find unpleasant.
For a bipolar transistor, the current out is approximately proportional to an exponential function of the voltage in. When the input receives a sine wave of a particular frequency, the output current will mainly be a sinewave of the same frequency plus lower amplitude sinewaves at twice, three times, four times, etc. the frequency. That's still harmonic distortion, but our hearing generally perceives third order harmonics as unpleasant, and the same seems to be true for all odd order harmonics.
Nevertheless, well-designed amplifier circuits incorporate generous amounts of negative feedback, which will reduce distortion (particularly in transistor amps) to levels that are virtually unmeasurable against the background noise. It is very difficult to believe that anybody could distinguish the difference between an output signal from a tube amp and that of a transistor amp if sufficiently high levels of negative feedback were present to ensure that the output was a faithful reproduction of the input signal.
Oddly enough, field effect transistors have just the same sort of transfer characteristics as triode amplifiers, but we don't see audio enthusiasts complimenting the sound of jfet or mosfet amps.
One of the other differences between solid state and tube amplifiers is that solid state clips signals quite abruptly when overdriven, which effectively turns a sine wave into a square wave, A square wave is equivalent to a sine wave plus its third, fifth, seventh, etc. harmonics, which are just the ones that we find unpleasant. Tube amps clip much more progressively, adding extra harmonics gradually as they begin to be overdriven, so that may account for the different "sound" of the distortion found under overloading conditions.
Finally, the much higher voltages found in tube design allows more overhead before the output starts to stray from linearity, and the higher voltages and higher impedances of tube amps often require output transformers in order to match low impedance loads such as loudspeakers. Those transformers often restrict the frequency response and can introduce other nonlinearities into the amplification chain, and may themselves be significant contributors to the "valve sound".
I've been watching you for almost 6 years, and you're the best electronics teacher I've had. Your videos never fail to teach me something new, keep up the great work!
I've used to play guitar as my hobby for the past eight years. I'm really happy for this video and thanks a lot for you hard work and dedication. Looking forward for the upcoming videos.
I wouldn’t be years deep into my electronics addiction if it weren’t for GreatScott! Keep up the amazing work!
-Greetings from Texas! 🤘🏼🤘🏼
Well, he meant well !
Thanks😁
Same here!
@@greatscottlab your intelligence is the what help me make 50% of my tools, I am a student I can't afford to buy then so thank you for intelligence, I used to live in dueschland and y'all are amazing keep being creative!😸👍
I might have caught the tingle of it being a newbie electrical engineering student
Curves. Always good! And a tube amp in winter helps with heating.
Overdriven valves for rock guitar!
Old school RCA 12AX7s as a quad. Awsome tubes.❤
The way the camera focused perfectly on the "Hi there" made me smile
Yeah
I had a grandfather who worked with TVs based on tubes, back in the old days.. He loved when transistors went to market, as they get rid of many problems tubes had: high voltage, excess heat, fragility... Anyway, nice videos! Keep on with such great content.
I totally agree with your grandfather. In the 70s into 80s I earned most of the money to finance university by repairing all kinds of common tube devices (TVs, radios, PA-, Guitar & Bass-Amps). They always had to be repaired, esp. the TVs, because of damaged transformers, tubes and capacitors (because of the high voltages of about 300-500V, up to 25.000 in TVs), exhausted tubes (burnout), etc.
Switching to transistors and thyristors changed everything later.
Today from time to time I still restore some old guitar- or bassamps (at the moment a 'HiFi Binson 40WB' Guitar-Amp and 'Echolette BS40' bass amp both from the early sixties )
You have described why tube amps are popular with guitarists - overdriving a tube amp creates much more "pleasant" distortion than a solid state device, rumors have it because of the addition of even as opposed to odd harmonics, something you could easily verify, or not. Great episode!
You know....I want to thank you for your videos. I have wanted to do many projects and lacked confidence to get started on them. Your presentations have given me a greater understanding of process and method allowing me to do things I have put off for years.
Thank You
I love how you took the time to draw and illustrate everything you could with pen and paper. Very cool, thank you!
So, read this from Brazil: we love you and your work! Keep going, there is only success in your Future!
Opa
@@sdffsdafdsfsdfsd only you people don't care but others do
Agreed
@@sdffsdafdsfsdfsd TRU LUL
We asked espechally in your "electrically generated music" Video, because overdriven tube amps are used for the typical rock and metal sound.
So a lot of musicians use Tube Amps for their sound.
Indeed, tubes handle clipping more "gracefully" than SS, and are therefore still in great demand for guitar amps.
As mentioned below, an amp is not a tube amp because it has one single tube in it. Building a tube amp from scratch is a tedious task involving much planning, calculating and reading datasheets, while dealing with lethal voltages. I built a lot of real tube amps and i repair and service them regularly. Tube amps are fascinating and great fun and every visitor to my house likes the sound of my stereo or guitar amps.
Having owned a tube radio (1950's RCA Victor), it really is night and day between tube and transistor/ic. Listening to the audio as it faded in was something too, unless the tubes were warmed up already.
I love the thick rich sound of old tube radios, but trying to understand the old technology is another level.
No it's not at all. It's extremely easy and straight forward.
Trying to understand this subject with the "tube" amp he used is a falsehood. His explanation might have been correct but the tube amp he used to base his facts on isn't a true tube amp.
Posted 2 mins ago and already 27 comments and 200 views. You have an ACTIVE community! On a side note, BUILD IDEA: automated aquarium ecosystem w/ sensors
I can put it on my to do list :-)
Yes please
I Gonna wait for it AHHAHAHAH
Yes please
These videos are an amazing resource for electronics engineering students as everything is explained clearly. It is a great way of learning to watch RUclips videos on the subject. There are also real-world applications presented: it is refreshing after all the synthetic examples seen in school. These videos are about the same thing as the lectures, but way more inspiring to me. In this year, we need that more than ever, especially when everything is online and we have plenty of time to tinker around at home. Keep up the good work!
Audio knob here...
So yes you explained it right. Vacuum tubes have a non linear amplifying curve and such distort the signal a bit. In the music world, thats called "saturation" many people nowdays add this purposely onto their music to add this warmth and natural feeling because properly amplified and made music lacks that saturated feel. Most of the time the saturation acts more in the lower frequencies which makes the sound more bassy and such feel warmer.
Great video, and you can do more stuff with tubes, its very interesting. At the moment i am trying to build a whole simple computer out of tubes.
How about a diy oscilloscope?
That'd be sick
It is on my to do list
Heck yeah dit or buy !
I can make it. Just using my phone
Can't wait :)
Many audiophiles love that soft distortion and imperfection, that’s why both tube amplifiers and vinyl records are still a thing.
So true, I'll have made my system all tubes pre amp phono and power amps. I never go back to transistors.
Only half conducters I have got is my cd player ( modified teac vrds10se) and dac. If you build it right without any compromise it will preform very well. I better listen to even harmonics from tubes then the distortion from a Class D transistor amp. Cheers
Why I loved GreatScott? The pen used to write and draw. Such a pleasure to my eyes
And his diction is so precise and proper !
Great videos, "great Scott"!!
There's always something to learn in your channel. You do the work and I have the fun enjoying watching it!!!
If you really read all comments I wanna say thanks for inspiring me to work on projects like this! Keep it up!
You are welcome😁
As always, great video! And although I am not that much into tubes, it still was very interesting! Keep up the great work! I (personally) would wish that there were some more tutorials on how to use the ESP32 properly, with all its bells and whistles
This is a well constructed and presented argument that sounds logical. I don't have a counter argument, but I do have a tube pre-amp & power-amp combination that makes the music that I love sound absolutely stunning! There's a reason why audiophiles are prepared to pay the premium prices charged for high-end tube amps...because they've heard them. Cheap tube amps will probably sound worse than solid state amps of the same price because mass produced solid state manufacturing is cheaper, so I'd suggest that each technology is 'better' in it's specific niche. How lucky are we to have the choice! :)
I have exceptional difficulty making some people believe it's not all about the numbers (specs like power output, thd, power handling, etc.). While something such as an amplifier can be "perfect" on paper, it may not have a sound you find desirable. This video kinda proves this point.
I'd like to see you do an AC sweep for audio frequencies and do a Fourier analysis to see if the difference in sound quality has anything to do with the frequency response of the two amplifiers. Maybe even create bode plots for them and compare.
tube amps are nonlinear circuits so an ac sweep wouldn't be very accurate
@@5d51e2gyU6JD All circuits are nonlinear outside of their frequency response. An AC sweep would be accurate and useful over the range of human hearing
@@liam1253 tube circuits are highly nonlinear in the human hearing range as well
@@5d51e2gyU6JD and how do you determine the range for which an amplifier is nonlinear? With an AC frequency sweep. You have a circular argument
Hello Scott, good job! I admire you because of the time you dedicate on each video, providing detailed explanations on everything you think and do with the merely purpose of making everyone understand. Greetings from Buenos Aires, Argentina!
Primary advantage? Cool factor. Those tubes are rad as hell.
A well designed and built integrated tube amp (for hi fi ) will sound good if it's internal components are high end, if it's preamp and power tubes (and there are many brands and types) are compatible with each other, and if the amp has a good source like a great cd player and great speakers. there are so many things one has to go through to find the right equipment to form one great stereo system.
They don't want to hear that.
They're missing out a lot. Well, maybe not much if they listen to synthetic music.
As a little tidbit - Part of the distortion characteristic of tubeamps is that instead of clipping, they tend to compress the signal instead. This gives a much more tolerable sound when you begin to get any distortion, and can squash some of the highs downwards, giving that 'warm' sound.
I think greatScott needs to have a chat with Mr. Carlson.
I'm surprised at the number of Mr. Carlson fans there are here.
Now that guy knows EVERYTHING and can fix EVERYTHING, much respect.
@@JohnnyClavin Much more than you think
Bet their wives/gf's will not approve hehehehe
Yes
Thanks Scott.. I was thinking about a tube amp.. and you have answered most all of my questions. Merry Christmas Scott..
Dear Scott the Great. Electronics is my hobby since a few years. I watch all your videos and I learned so much that I wasn't aware of therefore thank you. And I hope you keep going teaching us
You read a lot of comments everyday, make sure this is one of them.
Is that a threat?
@@okashaarshad2371 GTA V quote.
only interesting and suggestive comments, not nonsense like yours
Sure✌
João Aleixo relax boy, this is a quote from gtav and it’s quite funny, for me atleast
That into never gets old.😀
It's well created i must say
A cheap Amazon hybrid is certainly not a decent evaluation of the sonic advantages of tubes over transistors. But, building real vacuum tube amplifiers involves skills and precautions beyond the scope of this channel. There are plenty of resources on the internet where would-be DIY tube enthusiasts can become dangerous enough to kill themselves.
Having said that, beware of audio equipment reviews that sound like wine tastings. “Spacious”, Warm”, “Pairs well with jazz”
Love your channel!
Thanks for putting so much time into making great videos! 😁😁
I was watching your channel for 2+ years, and your growth has been phenomenal!! Keep up the work!
Agree with most of presented about sound and distortion of tube and transistor amplifiers. As I remember from my university time, in general tube amps produce about 10 times more distortion than transistor amp. Main difference is that tube amps produce "even" harmonics that sound more harmonic or musical to our ear and this is main reason why it sounds worm and pleasant.
Thank you for making great educational content on youtube. Cool too see you doing some audio related projects!
I think the big advantage of vacuum tubes is that you can enjoy the old days and appearance, like playing retro games.
I've never used a vacuum tube before, but I do love the way they have such a vintage look with that orange glow.
As long as they don't put a disgusting blue LED underneath it.
Blue LEDs are cancer for my eyes
New one: DIY or buy Girlfriend
So you are saying i can finally have a gf?
@@cake-lord yeah my friends single days will be over............cheers
I've been DIYing for a while now tbh
Wait.....
DIY?
Now explain how!!!!!!
Seriously, this is my favourite youtube channel. Period
Another great video, thank you so much for all your time, knowledge and videos!!
Mr. Carlson: "Hold my oscilloscope"
Scott, thanks for your videos. I agree always that the tube amps add a character to the sound, if you want true audio then the best is a class A
This video sparked a memory for me... I remember tube tester stations with replacement tubes in electronic and hardware stores, you could test your tube rather than bring it into the TV repair shop... which our Magnavox colour TV spent probably 5% of its lifespan at.
As you stated you're reading all the comments, I use this chance:
Dude, your videos are awesome! Thank you :)
They're still popular in guitar amps mainly due to their overdrive characteristics. They can produce a really soft, mellow type of distortion which an overdriven transistor simply cannot create on its own. Synthetic valve distortion is achievable through some sophisticated electronics (as long as the transistors are kept out of overdrive) but that'll never be enough for a purist
The other component that you must factor into tube amps is the output transformer. OTs saturate and alter the shape of the signal, so even a linear input through an OT will have a “valve amp” response. Transistor amplifiers with interstage transformers have the same audio pleasantries that valve amps do. For example the PigNose and Baldwin-Burns amps sound like valve amps but are all transistor with interstage transformers.
First records come back, and now vacuum tubes
What the heckin beans
dude you are truly amazing!
-greetins from Turkey
7:42 This is the most sacrilegious thing i ever seen in my life!!!! But very good video about vacuum tubes :)
Not really a good tube description either, he's clearly a tube noob, wasn't even looking at the right tube characteristics (see other comments).
@@trevorhaddox6884 eh hmm... yes i know but everyone learns throughout their lives (including me) and I mentioned "good video about vacuum tubes" because he tried and showed up what he does wrong. For a beginner video is not as bad, he showed how triode works, and basic schematic of triode amplifier.
I love how he still kept the old intro
Thanks for yet another great video! Best regards from EU Lithuania!
I m glad finaly to get those interesting informations between the tubes like distorsions... Compare to the transistors. See you again
Linearity can be deducted by looking at the characteristic curves of an amplifying device not from the literal straightness of the lines (which has little to do with this) but by how constant the spacing between them is. With transistors, the distance between the top two lines is pretty much the same as the distance between the two bottom ones. With triodes, the right-most lines are much closer together than the left-most lines, it is that change in spacing what deforms the signal and adds extra frequencies that were not in the original input signal, not the actual curvature of each individual line ;)
Meh. You can add a NFB circuit to both and still hear the difference...
I remember when I was a kid going to the store and testing vacuum tubes.. all the stores had vacuum tube testers.. it was a draw so you might buy other products while you were there
One very important quality overlooked here is the slew rate of a transistor vs a VT. At least due to the higher operating voltage, if not the speed of electrons flying from the cathode to the anode (~10% speed of light), tube amps have much faster slew rates. This is really going to stand out with the shape of the transient note attacks, and that's a really key part of the sound that our ears pick up on because it is so frequency rich -- at least that's my understanding of it.
True said
I acquired a 1939 Philco cabinet radio 12 years ago it was in storage in a canvas bag from 1969 until i received it. I stored it and recently rediscovered it.
I was amazed it still worked when I plugged it in .. the only problem was the power cord had deteriorated and was cracking and falling apart the first thing that I received was a radio station from Pennsylvania and I am in Augusta Georgia. Sound was excellent i did not play it too long bc of cord. I think its a well built device. If i can find someone close for refurbishment will have professionally done. To me it amazing sound quality from this ancient instrument.
While there maybe the negligible difference in sound and tubes are energy hogs, tubes still outclass transistors for the true audiophile. Love that you showed (measured) the input/output of each circuit. Good video. 👍
are you serious?🤣tube amplifiers are much worse than transistor ones. you can find measurements of their parameters on audiosciencereview for example. measurement of noise, distortions, channels separation of tube amplifier are the worst of all other amplifiers
You must be an expert , no doubt about that ......Peter Quortrup would like to have a conversation with you ....he will be happy to learn from you .@@user-qi1cs3zg3n
@@user-qi1cs3zg3nMeasurements do not make music , some of the finest kit measures terribly.
@@user-qi1cs3zg3n there are 2 types of audiophiles, those that spend their time looking into measurements and parameters, and those that actually listen to music. I'll let you figure out which type is the true audiophile Andrew is referring to.
@@jonsnow7092 The main problem is that hearing differs from person to person. Trusting the ears of a stranger when choosing something is not very smart. This parameter is very subjective. In a blind test, "listening" audiophiles are unable to distinguish one amplifier from another. Measurements and parameters are much more objective. Manipulations about “two types” and that “those who look at the parameters do not listen to music” do not work for those people who love the scientific approach and critical thinking
If you ever revisit tube amps I would recommend passing in a sinusoid with a known frequency (say 100 Hz) and then perform an FFT on the output of the tube. That way you could see the frequencies of the distortions added by the tube (if there even are any).
Its pretty simple, tube amps add lots of even order harmonics. Thats it. Thats the magic. To our ears those harmonics sound good
Damn! Thanks for all this easily understandable informations!
I had built a vacuum tube amp in 2012. My reference was a book by Dave Hunter Guitar Amp Handbook. To this day it is a very good
Functioning amp. It produces about 10 to 12 watts depending what vacuum tubes you use. My total cost was at $500 for all components and enclosure.
It was not a difficult amplifier to build with paying close attention to the schematics.
it would have been interesting to measure the frequency response of the tube and see if it can be replicated with a BJT and a low pass filter.
No it can't. You can sort of approximate tube sound in software (or DSP) over an extremely low distortion SS amp, but even the best algorithms aren't all that good at reproducing the effect of tubes. They are still the best at what they do. Moreover the low pass filter is kind of a cliché; a proper tube design won't significantly roll off the treble (although some will do it on purpose because some like the sound). And that particular roll off comes from the output transformer, not the tube. Remember tubes can easily handle RF range, so audio frequencies aren't much of a challenge. In a preamp buffer like this cheap device, there won't be any roll off.
the answer is yes, but no. You need more than a lowpass filter, but overlaying frequency distortion is easy to do.
Not really. The roll-off comes from the OPT which isn't there in a pre-amp.
Besides that, it's not about "recreating the sound" (the sound is far more influenced by the speakers than the amp btw, unless we're talking about overdriven instruments), it's about building/owning the real thing.
I'm pretty sure you can modify a Prius to behave exactly like a Cadillac, even make the inside look like one with VR glasses, but is it a Cadillac? *NO.*
Jonathan Brouillet If FR looks like a tube, if slew rates are the same, if speakers are connected identically, any other type of amplifier will sound exactly like tube driven. This is physics. Everything else is subjective, personal, placebo.
@@jonathanvanier what the hell are you even talk about? You should run along and let the adults in the room talk electronics. Typical "audiophile" responses, zero EE knowledge.
listening to this video on my tube amp!
I have a Little-Bear P5 tube pre-amp between my PC and speakers. It really does make everything sound much warmer.
This man's intonation...Lovely !!!
Tube amps make most sense in the electric guitar amplification, where the tube overdrive is highly desired. Also the voltage for rich sounding amps may be up to 450 volts. And also the great influence on the sound is made by output transformers. And yes - digital anode voltage regulators are very noisy and should be tailor made specially for tube amplification
Yup, output transformers are a big part of the sound signature of a tube amp. That's why, say, McIntosh uses output transformers even on their SS designs. And that's why a proper tube amp (or a proper tube preamp) would have been a much better choice than a "cheap opamp and Class-D module with a tube buffer" for this video...
Consumer: Analog sounds so much better!
Also consumer: *uses bluetooth*
@@thewolfin I find aptx has a comparable quality to line in on my lgv30 with quad dac
tbh it can all be "fixed" using other circutry (like filters or even - god forbid - op amp chips)
@@boazcohen7992 and that opamp filters loads more then distortion.
I use discrete opamps. They do not much with the original signal.
FINALLY. Validation. I've been telling my friends every chance I get: "Warm" sound is distorted sound!
Wow! This video explains it all for me today. Thank you!
Then you learned nothing of fact, sorry to say.
Thank you for sharing, very informative.
Also, tube power amps have an output transformer which also affects the "pleasantness" of the sound.
If it's for hi fi audio reproduction, a well projected output transformer will have a flat response in the audible frequencies
class AB also have transformer
Or they don't and use big honking transmitter tubes that draw ridiculous filament current/banks of normal output tubes in parallel. It's called output transformerless or OTL.
I grew up on vinyl - i have a tube preamp for my turntable going into a bugara tube amplifier ! i like it - its warm natural and what you here is basically how it was recorded in the studio ! I thought i was 1 of only a few !
Made tube projects as work and hobby, from 1969 to 1978.
Regarding the audio amplifiers, I had two main reasons for a better sound.
Giving for granted the use of a push-pull output stage, the first reason for a good sound is that the odd harmonics of distortion (third, fifth and seventh) do cancels itself in the output transformer, where each of the two primary windings are driven with opposite phases.
The second reason for a good sound is the transconductance curve of a pentode (or a beam tetrode - slightly different): as the output signal approaches the saturation, the "amplification" of the pentode decrease linearly. This is caused by how electrons are emitted by the oxydes on the surface of the cathode. In this manner, while a semiconductor amplifier saturates suddendly producing a sort of "square wave", a power tube amplifier decrease linearly the output power without producing all that clipped waveform.
A need for a pure sound is the proper design of the phase splitter design. By the way it is made, the splitter has one output at the anode and another at the cathode of (usually a triode). This design impedance mismatch MUST be compensated with some proper multiple feedback, outside the range of practical experts, as it requires the use of some complex math. Last not least, the output transformer: the most expensive part, with separate windings for the screen grid and the anode, another tap for cathode feedbacks, some (secret at the time) peculiar winding criteria to reduce intra-winding capacitance; and the silicon-iron core, realised with "C" oriented granules. Preamplifiers using discharge gas tubes to stabilise supply voltage. Some filament design to avoid excessive potential difference between filament and cathode, the cause of the 50 Hz hum. A myriad of different criteria, which caused good amplifiers to be very expensive even in 1970 and before.
This said, was a rarely requested expertise. Most of my friends, guitar players, were happy with a three-tubes amplifier (one was the 6X4 a rectifier) with a 6AQ5 beam tetrode in class A, which I could make for today's 15 -20 euros of parts.
Thank you for the great video, definetively a trip down the memory lane. Very appreciated, and liked.
Hey Man!
Just want to throw in my 2 cents about tubes in audio. As an electronic component tubes have have some pros and cones:
+ Tubes can amplify voltage with spectacular effects. You can get plenty of volts at the output with very low distortion, especially compared to similar stage built with transistors.
+ Ton of headroom
+ Robust against EMC (kinda like JFETs)
- Heater losses
- High voltage required
- No P type equivalent
- Low current capabilities
As you can see, tubes can be useful in certain applications. Using tube with some kind of active load can make a wonderfull input stage for an amplifier, or a whole preamplifier in just one stage. Althoug I wouldn't recommend using them as power amplifiers as in all tube power amps. Even with output transformers they don't do it very well. Tubes also do best when used with silicon around them as support circuit, you can get some real crazy circuits that way.
me:2020 can't go worse...
2020: video from great scott that isn't sponsorized from JLC pcb
As always I have no freaking clue what you are talking about! But I really enjoy your videos none the less :D Keep up the awesome work Scott!
Your channel keeps me interested in electronics.
Nice illustration! Cheers 🍷
Guitar effects board you say? I'd certainly like a look at that. Hope you make a video on that (if not already) soon 😉
Id like to see you try DCC control. Its mainly sold for model trains to have multiple trains on the same track but controlled with signals sent through the two rails(if im understanding it correctly). At least one guy built an arduino library for it but it still requires quite a bit of electronics.
Nothing sounds like a great tube amp.
Tube amps are used in class D amps but so are Mosfets. They have both have very low input impedance and eliminate the biasing threshold of bipolar transistors. Tube types are power wasters however, evidenced by the heat dissipated, great if you want to heat your house in winter.
I like the audio related stuff! Tubes in the preamp do provide a softer clipping, but that's only part of tube amp. The prized dynamic and complex tube amp eq comes from the impedances in a tube driven power section. Also, an interesting way to visualize audio characteristics of a certain circuit is to run pink noise thru it into a frequency analyzer.
At least when something goes wrong it doesn’t sound like a dial up modem screaming into the mic 😂
I like your approach to the topic. You cover both sides, the feelings of the consumer, and what happens to the frequencies on the physical level.
And I like how you state, that some people love that particular tube sound, but still this simply doesn't apply so much for you.
Audio tube amplification is a strongly debated field, and you manage very well to state your observations and opinion without being too harsh towards other opinions.
He's not using a true tube amp. BTW, I like both solid state and tube.
I really admire your stuff. I'm old and learning new stuff but between you and Andreas Speiss and Bill over at Dronebot, I'm having a ball!
Dude I can't wait to see your drone
Plz at least make something about your quadcopter
How much time we'll have to wait
Ahhh, a face for the voice I have followed for years. Greetings from USA !
My main lesson from this was the appalling noise and frequency addition from on those dc converters. Just horrible. Lovely video
Hello Mr Scott,
I saw your video "Building a tube amp! Does it produce a better quality?"
I thought it was an excellently produced video and was certainly very informative and engaging. But if you were to build an all-tube amplifier, without any semiconductor components, then you will certainly agree that tubes are better.
Let me begin with radio. As a radio amateur I favor tube transmitter stages because they ARE efficient. If I want to transmit 100 Watts at, say, 14 MHz, then I will be using a 50Ω output impedance. This means that I need the amplifier to deliver 75 V R.M.S (200V peak-to-peak) to the antenna. By using Single Side-Band (SSB) my average power may only be 15 Watts, but with peaks of 100 Watts. The push-pull amplifier tube may be rated at, say, 250mA peak anode current, with typically 1000 V on the anode. But the amplifier tube can tolerate several amperes of anode current for a short duration. In other words the RF output has a clean spectrum and will not go up in a puff of smoke if there is a short duration overload.
A transistor amplifier intended for 12 V operation uses a pair of push-pull devices, each device will be sucking about 10 Amperes, or more, of collector current. Remember that there must be a significant standing current to avoid crossover distortion. The transistor power amplifier will need a ferrite transformer to step up the voltage from 12-0-12 to the 200 V Pk-Pk, and can only match to one specific output impedance. If the transistor is overloaded very slightly then it will "flat-top" and create harmonics throughout the HF spectrum. If the device is rated at 15 Amperes, then a 25 Ampere peak may destroy the device in a few milliseconds. Even the slightest overload will cause excessive distortion and widespread interference.
To loose 12 Watts of heater power is a small price to pay for greater linearity.
When it comes to audio stages, the vacuum tube is softer and does not create spikes of distortion. The currents in the circuit are much lower so that makes construction a lot easier. Transistors power amplifiers operate from a lower voltage and so limiting is much more pronounced and noticeable. Transistor amplifiers also require much better power regulation and DC filtering. Open up any 100 Watt transistor amplifier and see just how many huge electrolytic capacitors there are.
As you are aware, high value electrolytic capacitors have to be bypassed with smaller value capacitors since they have much higher residual resistance and inductance. A 47,000µF, for example, is great for lower frequencies, but it is much less effective at, say, 15 kHz. A transistor 100 Watt complementary audio amplifier needs to have an output capacitor at 20 Hz, with an 8-Ohm speaker, of more than 10,000µf. Alternatively the power supply circuitry needs to be designed so that the junction of the two complementary output transistors is at 0v DC with respect to ground to prevent DC through the speaker. Now the power supply unit is getting even more complicated since it requires a dual +ve and -ve power unit. The transistor power amplifier also requires very precise biasing to maintain that fine line between low crossover distortion and thermal runaway.
The tube amplifier you showed in your video is not a good example since the other semiconductor devices destroy any significant sound advantage, and the amplifier was only a tube pre-amplifier. Tubes stand out among the other devices for high power use, not pre-amplifiers.
Take a look at 85.226.187.247/power/transformers.htm and you will see a basic amplifier design using tubes. That was only a starting point, but I am making many more practical improvements during the ongoing design and construction. For example:
1 - Using a 3-channel equalizer - better suited for older ears (I am 70 years old)
2 - Moving the volume control between the tone and the power output stage - improves noise
3 - Making it a dual "single ended" (Class A) so it will work both for stereo or mono
Note the connections of the screen grid of the output stage(s). The screen also behaves like an anode, and using this connection to the transformer improves linearity a lot.
A tube power amplifier can be built using just one tube, one output coil, or transformer, two resistors and two capacitors. An audio transformer can be a simple mains 230V AC to 12V AC transformer, if the laminations are re-arranged to prevent core saturation. For RF amplifiers then the anode choke, one DC block capacitor, two variable capacitors and 20 turns of wire on a toilet roll core will match to just about any antenna impedance.
I thought your article was really excellent, but I feel that you may have been a bit unfair to vacuum tubes. Tubes really shine in power amplifiers, and they are difficult to replace with respect to power, design simplicity and most of all, robustness. But I was brought up with tubes so perhaps I am a little biased ;-)
Very best regards from Harry - SM0VPO
Nuclear reactor. DIY or BUY?
Government: don't!!!!!
Actually it's not that hard to make a simple fusión reactor at home
@@gcr100 It's certainly not cheap either ;)
@@BertGrink yeah, but with patience you can get almost all the parts on industrial junkyards for cheap
DIY, definetly!
This reminded me... Can you please do noise cancelling? I remember learning about the noise cancelling circuit in college but would love to see your take. Maybe a DIY or BUY?
Thanks man, You're great... Scott
I love the sound of tubes!