Just so you know, I'm coming from 70 years of life, and my beginning in electronics with tubes started in 1965 working on TRF radios like Atwater Kent and RCA! I just love this video! I just love the low orange glow of that tube doing what its supposed to do! And that sound! Don't get me started!!
A good way to learn is buy books of amplifier builds from the 1940s and 1950s Heathkits and draw out the schematics and get a few bins and save up parts and build it’s a fun hobby I need to start selling
With all due respect to everyone who commented that they learned a lot from this video, from the title I expected you to describe how one reaches the values of the components. Instead, all I saw was a schematic of pretty much a *copy* of an existing circuit, with no explanation for the selection of the values of the components. That's what I expected, based on the title.
Great Work! Actually Fender used 68K input resistors but wired in in parallel when you plugged in the high impedance jack making it a 34k R, So when building a single input and still wanting to stick to Fender specs you would use a 34k (33k is closest) R.
Great video ! I've been building small to mid size transistor audio amps for a year or so and I've wanted to make a tube amp for a while . This is a big help to me . I also play guitar so It will be cool to build an amp to play through . Tube amps are so expensive this will be a rewarding and cost effective alternative to buying one . Thank you !
Every time I see something like this I am always curious what provokes these responses. TH-cam comment sections uses to be entertaining. Now they just delete all the offensive shit. Lol
I got a kick out of this video. The nice part is that this is a proven, basic class A circuit and you can add anything you might want by adding a pot or different valve. Add a tone pot or tremolo circuit, how about a more powerful output valve with a different output transformer or more B+, the combos are endless and can be built with scrap parts or different valves you have on hand, that's the fun. Personally I like repurposing old electronic equipment and some of the amps that come out of that process are just crazy and built for practice and fun and some are standouts. If you like to tinker it's the hobby for you and there are many kids that need a practice amp to get their talents started.
I have watched a TON of videos trying to understand signal paths in tube amps and they always start with an existing schematic with complicated preamps, etc. This was an extremely helpful 16 minutes! Thank you!!
I used to assemble tube Amplifiers years ago, using 6V6, 6L6, EL 84, EL 34, mostly in push pull for higher output. The cost was largely dependent on the requirements of the guitarist. I see that in your 6V6 grid, there is no grid leak resistor. Is that done on purpose or otherwise? I used grain oriented stampings, for the output transformer. Heavier bass response!! I am now running 80 years and this my obsession!!!! I now use 5200 and 1943 Toshiba Transistors. They are Heavy duty and give astounding Bass! Drives a 12 inch DJ speaker.
This is the exact thing I've been looking for. Gonna attempt my first recap of a vintage Marshall and I really like understanding the circuity. This explains it so easily. Thanks!
Should there be a capacitor between the input and the tube/valve to prevent DC getting to the grid? If you put any pedals between the Guitar and the amp, there will be DC voltage on the input in addition to the AC signal from the guitar.
@@learnelectronics I would vote for the negative feedback.. it will make it much more Pedal friendly. You might consider adding a master volume and effects loop. I have been thinking on building a tube amp and this might be the project!
Great video on showing just the signal chain but why doesn’t the grid of the output tube reference ground thru resistor like for the grid on 12AX7 but with a fixed resistor rather than variable resistor for volume control?
Which is seperate from the output transformer. I know this is a 6 month old comment. I answered anyway incase someone else was wondering the same thing
Any reason why a tube head wouldn't switch from clean channel to distortion channel ? Bought a used blue voodoo 60. Had no sound but fixed that, second problem it won't switch channels
Hey, I am having huge difficulty with op amp circuit used in TA7642 radios, I cannot figure out how to attach the lm386 chip to have a gain of more than 200 (10 u cap between pin 1 and 8) if I give it too much signal in 50 k ohm pot then the radio just makes a farting noise. My problem is that I need to figure out which lowpass or highpass filtrations between the speaker pin 5 and the 470 n capacitor and which resistors I need to reduce the hissing noises without any distortion or clipping when I try to make it louder
Moist Andy The gain cap for an LM386 is 200. To remove the distortion, you either need to cap the gain at a level below 200 by using a fixed resistor in series with the 10uF cap or adding a gain pot. You’ll need a 1k pot for a smooth transition. Check out the datasheet! Also, for the Zobel Network from pin 5, the resistor-cap to ground, the datasheet recommends 10ohms.
This is awesome! Wish I found it earlier. Simple and excellent tutorial. I have a tombstone radio chassis that I want to become a Bluetooth receiver and an MP3 or other type player. I have wanted to use a tube amp setup, I want a rich and not tinny sound. Yes I know I can buy one, but so much better to build. I'm retired from the aerospace industry, not an engineer but a builder for the engineers which included some electronics. I was certified in soldering. This is exceedingly helpful. Thank you.
Yes, you can. But, to do that you would need one tube to use as a phase inverter, and you would be losing a gain stage so you might want to add another tube.
Hello Paul! If I may make a suggestion, I really think that you should put a capacitor between the input and the grid resistor in the first stage. Especially if you want to use the amp as a HI-FI amplifier. It is a form of protection to you, and your equipment. Also, I hope that your dentist appointment went well! Stay safe and keep up the videos!!
@@Songwriter376 they are determined by some calculations from the tube datasheets. the tubes have graphs relating the anode current at a specified voltage. These passive components determine what the quiescent current and voltage is and determines the amount of signal headroom.
Question: how do I take a 5 watt circuit like demonstrated in the video and bump it to 15 watts? What kinds of changes are needed? More tubes? Different (more powerful OT? & if I can raise the wattage, do I need to change the caps/resistor values ?
In my Champ 5F1 build I needed to change the value of the cathode bias resistor from 470 ohms to 750 ohms in order to reduce the plate dissipation to 12 watts from the 19 watts I got with the 470 ohm.
So all that did was shift you right along the loadline for that stage and decrease your quiescent plate current. Did you notice any decrease in distortion? It may have been more appropriate to adjust your load resistor instead.
If you don't have a resistor from J1 to gnd when you unplug the input grid will collect electrons and shut off completely so that when you plug in the input again there will be an almighty crack as that voltage is discharged to ground. Also without a resistor from V1 grid to ground, V1 will shut off allowing only the peaks of the incoming signal to get through. Typically the grid to ground resistors are 1M to 10M. And BTW you will never get a true HiFi amp using valves.
Thank for sharing knowledge! Could someone ecplain what c1 is for and if r1 ist just current limmitation or something else with the cap in parallel. Thanks in advance
Paul, I love the glow of tubes. It has been a very long time since I worked on a Fender amp. The Champ is a classic. I would use the feedback resistor, but put a switch in to take it out when you want or make it variable. Since you said the amp could be used with other input devices, I would recommend a blocking cap on a second input port to protect the input devices. I would hate to see any stray voltages get loose. I hope the dentist trip goes well and you have a safe trip there and back.
My father had a Champ that I used as a boy to amplify the minute signals from my home-built crystal radio receiver. The night I heard, from way down in Mississippi, the top-forty music from WLS Chicago got me hooked forever in electronics! That glow of those tubes in the Atwater Kent and RCA TRF radios I worked on was magic!
Do you have any videos that speak to the different caps, and depending on where in the circuit,and the preferable cap materials that better handle sonics vs just being a workhorse. I hear different interjections on this subject but haven’t found a good explanation of except when folks rave about bumblebee caps in the Paul’s. Maybe I’m. It searching correctly. Fantastic walk through. Cheers-
I never fiddled with tubes but have had a lot laying around many years ago. As I always wondered and when you say that the grid thus the voltage of it, is that the negative or positive voltage of it? If it's the positive this must make it 180 degrees inverted, right? since then the electrons will stop there instead of continue to the plate. If it's the negative then why even leave the cathode as it "won't see" the plate as much as it's being choked by this grid.
Well THAT I know, lol, as I asked the it's the negative part of it or the positive. Think of it as if I probed it as if the input was just one short digitized pulse and in that moment it was sampled it was either positive, negative or zero, all the values AC can be. Sorry... as you see on my name, English ain't my native language so... Hope you understand what I mean with this.
A minor point, just to stop any confusion, you labled the 12AX7 as T1 instead of V1, which made the 6V6 V1 (instead of V2), and the output transformer as T2 (it should be T1). Sorry. It's a bit pedantic I know, but having worked for many years (late 70's - early 90's) on design and repair of valve equipment I can get a bit like that. Again, sorry. Great vid.
😄 This just reminded me that, many years ago, when first learning about electronics, I saw an American circuit where the valves were labelled T1, T2, T3, etc. I could not understand what the "T" signified. In the UK, "tubes" are called valves and that's what my theory books called them. There was no Internet in those days to quickly look things up. It was only later, when I came by an old American ham radio book, that I realised valves were referred to as vacuum tubes (T for Tube). I still can't decide which term I like best - vaccum tube nicely describes what it is, whereas, valve describes what it does.
Pak bos saya mau tanyak tube vacum tipe EZ90 yg deket sama trafo input itu klu putus atau tiba2 mati mendadak apakah bisa menyebabkan kerusakan pada yg lain kah
With no bypass cap, there is a signal at the cathode which works in opposition to the signal at the grid, reducing the gain of the stage. Adding the cap removes the signal at the cathode, allowing the stage to attain its maximum gain.
i recently took apart a 1950's lemco model 45 ignition coil/condensor tester that uses a ken-rad 6-48 4 pin vacuum tube but cant find info on specs but the heater is ok @ 5.0-5.5v. i dont know tubes very well but im wanting a vacuum tube tesla coil. could I use it for a vttc??? any info would help .thank you paul!
How did you work out values for the resistors and caps? Whats your operating point etc? Why are you Not using a plate resistor? How will voltage be carried to next stage by just 1 capacitor? Did you actually build this?
He isn't covering power supply design in this video. IMO, plate resistance is part of the amplifier stage, not the power supply, but it isn't my video. The capacitor blocks the DC plate voltage and allows the audio frequency to pass to the next stage.
Excellent video, I've studied electronics on my own for a bit, in the schematic I'm assuming that the electrons are coming from the GROUND and feeding into the cathode in order to get the electrons going via cathode-grid-anode ? Thanks............Jay
Maybe someone has commented on this but I didn't read all of them. Shouldn't there be something like a 1 meg resistor from the tip connection of the jack to ground?
This is interesting, the question on feed back, I am curious why its a question, are there overwhelming reasons why you would or would not do the loop?
Negative feedback is used to extend bandwidth, but it decreases gain. Also decreases distortion, but it can cause unwanted oscillation, depending on the application. The cathode resistors provide localized negative feedback, and they are there for stability, and they affect the gain of the stage they are part of. Feedback from the output back to an earlier stage is referred to as 'overall' or interstage feedback.
Just a suggestion, but you glossed over the bypass capacitor requirement. i think it's important to understand the requirements for DC biasing resistors etc and it's affects on feedback, hence the need to bypass them for the AC signal.
There's nothing wrong with using a tube amplifier for music, but a Champ circuit will not produce a "HiFi" music amplifier. I suppose that this depends on your definition of "HiFi", though . The reason that these old circuits are so desirable for guitar amps is *because* they add tons of color to the sound; they are not neutral. For music reproduction, we generally want uncolored amplification. There are no rules, though, so if someone likes the sound of music through a guitar amp then they go right ahead. I just want to let people know they will not get a distortion-free amplifier if they build this project. They will get a simple Fender-like amp design that is great for classic guitar sounds. This is a relatively affordable tube amp to build due to the minimal parts count, but it will add color/distortion to your music at high volumes, the bass may be "flabby", and the sound may vary widely from speaker to speaker. Impedance matching is critical for tube amps. Many modern speakers have low efficiencies and need lots of wattage to get loud, whereas this circuit will produce up to 5 watts. Distortion *will* be audible at 5 watts, however, so really this is probably a sub-1-watt music amp. I recommend a solid-state amp based upon a proven IC for a beginner-level music amp project; it will much be less expensive and less dangerous to build and provide cleaner sound with tighter bass. th-cam.com/video/d9O7oZEYALI/w-d-xo.html th-cam.com/video/D5N82Qr6k78/w-d-xo.html But I love tubes and tube amps, so build this project anyway if you already know what to expect. If nothing else, this Class A amp will make an attractive room heater ;).
Use Ohms law to solve for the current through each component. You know the voltage, you know the current you want, so you solve for the resistance. As for the caps, different caps for different frequencies.
Hi. Thanks for the video. very helpful. Are Capacitors C1 to C5 coupling capacitors or electrolytic capacitors? Also are 2 watt resistors power rating sufficient for all of the resistors in the design? David.
Is there a follow-up to this video. I found your other videos that predate this video, but they just describe what takes place in a tube amp and you building the "Bud Tube Amplifier". I am having trouble finding the video on adding power and soldering the components on your PCB from PCBWay in your usual educational method. Just curious.
After watching 75% of your video, the question in my mind becomes: since you are essentially using class A amplification, why would we need negative feed back? What would be the purpose in this stage?
Question: Why is there no capacitor between the input jack and pin two of the tube? Is there any chance of a shock hazard? I see pin two is not hooked up to the power supply, but if something failed, OUCH! Thanks Paul and have a great weekend.
Nice video! Can you tell me what is the purpose of the bypass capacitors which connect in parallel to the ground resistors? And how can you determine capacitance value? Thank you.
I've learned more about guitar amps from this video than anything else. I've been playing rock'n'roll for 40 years. COVID has me doing more stuff at home, including electronic projects. I'll watch the rest of these videos, but can you point me to a resource that explains *why* components are used? In particular, I'm curious as to why the capacitor is in parallel (?) with the pot. Thanks for this.
Just so you know, I'm coming from 70 years of life, and my beginning in electronics with tubes started in 1965 working on TRF radios like Atwater Kent and RCA! I just love this video! I just love the low orange glow of that tube doing what its supposed to do! And that sound! Don't get me started!!
yes great another old schooler
Ignoring the plate load resistors is a significant omission as they determine stage gain and are an essential part of biasing each stage.
I am engineer and this 16 minutes video was the best master class in tube amplifier
No you are not.
Please make a part 2 to this! I'm down the rabbit hole on amp builds and this is so helpful!!
A good way to learn is buy books of amplifier builds from the 1940s and 1950s Heathkits and draw out the schematics and get a few bins and save up parts and build it’s a fun hobby I need to start selling
With all due respect to everyone who commented that they learned a lot from this video, from the title I expected you to describe how one reaches the values of the components. Instead, all I saw was a schematic of pretty much a *copy* of an existing circuit, with no explanation for the selection of the values of the components. That's what I expected, based on the title.
Great Work! Actually Fender used 68K input resistors but wired in in parallel when you plugged in the high impedance jack making it a 34k R, So when building a single input and still wanting to stick to Fender specs you would use a 34k (33k is closest) R.
How do you determine the values of the resistors and caps?
Great video ! I've been building small to mid size transistor audio amps for a year or so and I've wanted to make a tube amp for a while . This is a big help to me . I also play guitar so It will be cool to build an amp to play through . Tube amps are so expensive this will be a rewarding and cost effective alternative to buying one . Thank you !
@Gerald Fisher stfu
Every time I see something like this I am always curious what provokes these responses. TH-cam comment sections uses to be entertaining. Now they just delete all the offensive shit. Lol
Have you built your tube amp yet? How did your project turn out?
do you plan to heat the 12axy as a 12 volt filament [pin 9 not used] or a 6 volt filament?
Where (or in what date range) can I find the next video in this series? I don’t see it in the playlists… Thanks!
I got a kick out of this video. The nice part is that this is a proven, basic class A circuit and you can add anything you might want by adding a pot or different valve. Add a tone pot or tremolo circuit, how about a more powerful output valve with a different output transformer or more B+, the combos are endless and can be built with scrap parts or different valves you have on hand, that's the fun. Personally I like repurposing old electronic equipment and some of the amps that come out of that process are just crazy and built for practice and fun and some are standouts. If you like to tinker it's the hobby for you and there are many kids that need a practice amp to get their talents started.
I have watched a TON of videos trying to understand signal paths in tube amps and they always start with an existing schematic with complicated preamps, etc. This was an extremely helpful 16 minutes! Thank you!!
Ben, I agree 100%
I used to assemble tube Amplifiers years ago, using 6V6, 6L6, EL 84, EL 34, mostly in push pull for higher output. The cost was largely dependent on the requirements of the guitarist.
I see that in your 6V6 grid, there is no grid leak resistor. Is that done on purpose or otherwise?
I used grain oriented stampings,
for the output transformer. Heavier bass response!!
I am now running 80 years and this my obsession!!!!
I now use 5200 and 1943
Toshiba Transistors. They are
Heavy duty and give astounding Bass! Drives a 12 inch DJ speaker.
This is the exact thing I've been looking for. Gonna attempt my first recap of a vintage Marshall and I really like understanding the circuity. This explains it so easily. Thanks!
Fantastic. Anybody knows what software was used above?
Excellent! What programme did you use for the schematic?…
This video was very helpful, thank you! I’m looking for part 2 now but not having any luck, do you have a link by chance?
Why would you want negative feed back ? Will it suppress osculations or ? ???
It creates more "headroom" so it doesn't go into distortion at lower volumes
You are correct, the negative feed back will make the amp more stable, and less likely to oscillate.
how you get values for components could be nice to know...but great approach, keep up the good videos!
There are thousands of amplifier designs
@@jimcatanzaro7808 I meant specifications, references like frank.pocnet.net/sheets/049/1/12AX7A.pdf
Old circuit designs not too hard just keep trying
The most helpful video I’ve ever watched for a novice
Where would the tone stack go?
Between the pre and power amp sections
Should there be a capacitor between the input and the tube/valve to prevent DC getting to the grid? If you put any pedals between the Guitar and the amp, there will be DC voltage on the input in addition to the AC signal from the guitar.
What I have covered this far is the exact signal path of the Fender 5F1 circuit.
@@learnelectronics I would vote for the negative feedback.. it will make it much more Pedal friendly. You might consider adding a master volume and effects loop.
I have been thinking on building a tube amp and this might be the project!
how did you determine the values of the resistors and bypass caps?
what schematic program are you using? is it free?
Great video on showing just the signal chain but why doesn’t the grid of the output tube reference ground thru resistor like for the grid on 12AX7 but with a fixed resistor rather than variable resistor for volume control?
10:18
How do the 12AX7 plates get B+ voltage?
From the power transformer
Which is seperate from the output transformer. I know this is a 6 month old comment. I answered anyway incase someone else was wondering the same thing
The anode resistors are also part of the signal path, otherwise there is no gain at all my friend...
Any reason why a tube head wouldn't switch from clean channel to distortion channel ?
Bought a used blue voodoo 60. Had no sound but fixed that, second problem it won't switch channels
Hey, I am having huge difficulty with op amp circuit used in TA7642 radios, I cannot figure out how to attach the lm386 chip to have a gain of more than 200 (10 u cap between pin 1 and 8) if I give it too much signal in 50 k ohm pot then the radio just makes a farting noise. My problem is that I need to figure out which lowpass or highpass filtrations between the speaker pin 5 and the 470 n capacitor and which resistors I need to reduce the hissing noises without any distortion or clipping when I try to make it louder
Moist Andy The gain cap for an LM386 is 200. To remove the distortion, you either need to cap the gain at a level below 200 by using a fixed resistor in series with the 10uF cap or adding a gain pot. You’ll need a 1k pot for a smooth transition. Check out the datasheet! Also, for the Zobel Network from pin 5, the resistor-cap to ground, the datasheet recommends 10ohms.
i was thinking about taking out the feed back loop in my amp to get more gain,,you dont need it ,,correct
Can you tell me the purpose of the bypass caps and R1?
can i use one cathode bypass for two cathodes?
This is awesome! Wish I found it earlier. Simple and excellent tutorial. I have a tombstone radio chassis that I want to become a Bluetooth receiver and an MP3 or other type player. I have wanted to use a tube amp setup, I want a rich and not tinny sound. Yes I know I can buy one, but so much better to build. I'm retired from the aerospace industry, not an engineer but a builder for the engineers which included some electronics. I was certified in soldering. This is exceedingly helpful. Thank you.
what would negitive feedback do?
What about the anode voltage for the 12AX7 tube
Could you use the two sides of the 12AX7 to handle the left and right channels of a stereo signal?
Yes, you can. But, to do that you would need one tube to use as a phase inverter, and you would be losing a gain stage so you might want to add another tube.
Hello Paul! If I may make a suggestion, I really think that you should put a capacitor between the input and the grid resistor in the first stage. Especially if you want to use the amp as a HI-FI amplifier. It is a form of protection to you, and your equipment.
Also, I hope that your dentist appointment went well! Stay safe and keep up the videos!!
what wattage should the 1 meg pot be?
excellent video, hours worth of learning in 16 minutes.
Thanks for the video, could you go a bit more in depth about what the passives around the tube are doing?
Keep watching the series...
It would be great knowing how the values were figured out too.
.
@@Songwriter376 they are determined by some calculations from the tube datasheets. the tubes have graphs relating the anode current at a specified voltage. These passive components determine what the quiescent current and voltage is and determines the amount of signal headroom.
zacboss467 Thanks for that answer!
Question: how do I take a 5 watt circuit like demonstrated in the video and bump it to 15 watts? What kinds of changes are needed? More tubes? Different (more powerful OT?
& if I can raise the wattage, do I need to change the caps/resistor values ?
A pair of 6V6’s or EL 84’s make 15 watts in amps like mini-Marshall’s or the EVH 3. Likely in a push-pull configuration.
A video from learnelectronics about a guitar amp? Auto-like! :)
In my Champ 5F1 build I needed to change the value of the cathode bias resistor from 470 ohms to 750 ohms
in order to reduce the plate dissipation to 12 watts from the 19 watts I got with the 470 ohm.
So all that did was shift you right along the loadline for that stage and decrease your quiescent plate current. Did you notice any decrease in distortion? It may have been more appropriate to adjust your load resistor instead.
Where can I find part 2?
I want to make it 60 amps instead of one amp. Do I just use a bigger transformer or do I have to change the tubes?
You will need to change your output transformer, probably add two more preamplification gain stages, and two more power tubes.
what simulator are you using?
That is an iconic way to start a video
Hello, what software do you use for drawing the schematics? Is it freeware? Does it have all the elements in the library?
If you don't have a resistor from J1 to gnd when you unplug the input grid will collect electrons and shut off completely so that when you plug in the input again there will be an almighty crack as that voltage is discharged to ground. Also without a resistor from V1 grid to ground, V1 will shut off allowing only the peaks of the incoming signal to get through. Typically the grid to ground resistors are 1M to 10M.
And BTW you will never get a true HiFi amp using valves.
What program were you using?
4:32, what is the drawing software you are using?
Hi sir, can you send links for the next part of your video
Thank for sharing knowledge!
Could someone ecplain what c1 is for and if r1 ist just current limmitation or something else with the cap in parallel.
Thanks in advance
Thanks this is great
Finally someone explains this clearly
Paul, I love the glow of tubes. It has been a very long time since I worked on a Fender amp. The Champ is a classic. I would use the feedback resistor, but put a switch in to take it out when you want or make it variable. Since you said the amp could be used with other input devices, I would recommend a blocking cap on a second input port to protect the input devices. I would hate to see any stray voltages get loose. I hope the dentist trip goes well and you have a safe trip there and back.
My father had a Champ that I used as a boy to amplify the minute signals from my home-built crystal radio receiver. The night I heard, from way down in Mississippi, the top-forty music from WLS Chicago got me hooked forever in electronics! That glow of those tubes in the Atwater Kent and RCA TRF radios I worked on was magic!
what program are you running for the schematic design.
Can't find part 2 l, does it exist?
Do you have any videos that speak to the different caps, and depending on where in the circuit,and the preferable cap materials that better handle sonics vs just being a workhorse. I hear different interjections on this subject but haven’t found a good explanation of except when folks rave about bumblebee caps in the Paul’s. Maybe I’m. It searching correctly.
Fantastic walk through. Cheers-
Please tell me the software you use to build the schematic
Easy eda
Hi, is there a part 2?
hi I have old circuit maker software. I'm interested to refresh again. is this a free?
Yep
Like your work and thanks for the help . What computer program do you do the designing on. Richie
wath program is it?
I never fiddled with tubes but have had a lot laying around many years ago.
As I always wondered and when you say that the grid thus the voltage of it, is that the negative or positive voltage of it?
If it's the positive this must make it 180 degrees inverted, right? since then the electrons will stop there instead of continue to the plate.
If it's the negative then why even leave the cathode as it "won't see" the plate as much as it's being choked by this grid.
The signal is AC
Well THAT I know, lol, as I asked the it's the negative part of it or the positive.
Think of it as if I probed it as if the input was just one short digitized pulse and in that moment it was sampled it was either positive, negative or zero, all the values AC can be.
Sorry... as you see on my name, English ain't my native language so... Hope you understand what I mean with this.
A minor point, just to stop any confusion, you labled the 12AX7 as T1 instead of V1, which made the 6V6 V1 (instead of V2), and the output transformer as T2 (it should be T1).
Sorry. It's a bit pedantic I know, but having worked for many years (late 70's - early 90's) on design and repair of valve equipment I can get a bit like that. Again, sorry. Great vid.
i know Paul is not a guy who take affiance to what you pointed out. he's one of the nicest guys on YT.. FACT!!
😄 This just reminded me that, many years ago, when first learning about electronics, I saw an American circuit where the valves were labelled T1, T2, T3, etc. I could not understand what the "T" signified. In the UK, "tubes" are called valves and that's what my theory books called them. There was no Internet in those days to quickly look things up. It was only later, when I came by an old American ham radio book, that I realised valves were referred to as vacuum tubes (T for Tube). I still can't decide which term I like best - vaccum tube nicely describes what it is, whereas, valve describes what it does.
Is there a part two to this video. It was one of the best. I’m finally understanding and this confirmed it.
Great video. What schematic software are you using? Thank you, Dave
I think Paul is using EasyEDAa
EasyEDA
Pak bos saya mau tanyak tube vacum tipe EZ90 yg deket sama trafo input itu klu putus atau tiba2 mati mendadak apakah bisa menyebabkan kerusakan pada yg lain kah
I'm a beginner at electronics, and I was just curious, what does the cathode bypass capacitor do?
With no bypass cap, there is a signal at the cathode which works in opposition to the signal at the grid, reducing the gain of the stage. Adding the cap removes the signal at the cathode, allowing the stage to attain its maximum gain.
i recently took apart a 1950's lemco model 45 ignition coil/condensor tester that uses a ken-rad 6-48 4 pin vacuum tube but cant find info on specs but the heater is ok @ 5.0-5.5v. i dont know tubes very well but im wanting a vacuum tube tesla coil. could I use it for a vttc??? any info would help .thank you paul!
Great video - what software are you using there?
What schematic software do you use that supports valves
Easyeda
How did you work out values for the resistors and caps? Whats your operating point etc?
Why are you Not using a plate resistor? How will voltage be carried to next stage by just 1 capacitor?
Did you actually build this?
He isn't covering power supply design in this video. IMO, plate resistance is part of the amplifier stage, not the power supply, but it isn't my video.
The capacitor blocks the DC plate voltage and allows the audio frequency to pass to the next stage.
Excellent video, I've studied electronics on my own for a bit, in the schematic I'm assuming that the electrons are coming from the GROUND and feeding into the cathode in order to get the electrons going via cathode-grid-anode ? Thanks............Jay
Yep
@@learnelectronics Thank you , I've always thought of ground as a positive source--you cleared that all up for me....
Maybe someone has commented on this but I didn't read all of them. Shouldn't there be something like a 1 meg resistor from the tip connection of the jack to ground?
Yes. A 'grid leak' resistor is essential to its operation, and in this circuit would be 1M.
This is interesting, the question on feed back, I am curious why its a question, are there overwhelming reasons why you would or would not do the loop?
Negative feedback is used to extend bandwidth, but it decreases gain. Also decreases distortion, but it can cause unwanted oscillation, depending on the application. The cathode resistors provide localized negative feedback, and they are there for stability, and they affect the gain of the stage they are part of. Feedback from the output back to an earlier stage is referred to as 'overall' or interstage feedback.
@@robertgraf9265 Thank you very much for taking the time to explain that.
Just a suggestion, but you glossed over the bypass capacitor requirement. i think it's important to understand the requirements for DC biasing resistors etc and it's affects on feedback, hence the need to bypass them for the AC signal.
This is just part 1
Can you tell me what software you used to create the schematic?
There's nothing wrong with using a tube amplifier for music, but a Champ circuit will not produce a "HiFi" music amplifier. I suppose that this depends on your definition of "HiFi", though .
The reason that these old circuits are so desirable for guitar amps is *because* they add tons of color to the sound; they are not neutral. For music reproduction, we generally want uncolored amplification.
There are no rules, though, so if someone likes the sound of music through a guitar amp then they go right ahead. I just want to let people know they will not get a distortion-free amplifier if they build this project. They will get a simple Fender-like amp design that is great for classic guitar sounds.
This is a relatively affordable tube amp to build due to the minimal parts count, but it will add color/distortion to your music at high volumes, the bass may be "flabby", and the sound may vary widely from speaker to speaker. Impedance matching is critical for tube amps.
Many modern speakers have low efficiencies and need lots of wattage to get loud, whereas this circuit will produce up to 5 watts. Distortion *will* be audible at 5 watts, however, so really this is probably a sub-1-watt music amp.
I recommend a solid-state amp based upon a proven IC for a beginner-level music amp project; it will much be less expensive and less dangerous to build and provide cleaner sound with tighter bass.
th-cam.com/video/d9O7oZEYALI/w-d-xo.html
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But I love tubes and tube amps, so build this project anyway if you already know what to expect. If nothing else, this Class A amp will make an attractive room heater ;).
How do you determine the needed values for the resistors and capacitors?
Use Ohms law to solve for the current through each component. You know the voltage, you know the current you want, so you solve for the resistance. As for the caps, different caps for different frequencies.
What value did the potentiometer go with it?
Most likely a 1 Megohm logarithmic pot.
is there a Part 2 ? i was really getting into this
what software is that??
Great video, thank you for sharing. Question: what program did you use to draw this project.
Easyeda
What schematic software is this?
Hi. Thanks for the video. very helpful. Are Capacitors C1 to C5 coupling capacitors or electrolytic capacitors? Also are 2 watt resistors power rating sufficient for all of the resistors in the design? David.
C2 is a coupling capacitor. The rest are bypass capacitors, and their values pretty much dictate the use of electrolytics.
Great simplified discussion.
Love the video was there ever a part two? I can't find, with the power supply?
what software is he using?
Unlike AC circuit math, I get this. What class amp is it? Could it handle a 1.2v input signal. My Icom 7610 generates little volume.
Do you have a playlist of videos for building and testing this design? Awesome. This video says it’s part 1.
Don’t put neg FB. But what CAD are you using?
I think that was Diptrace
Is there a follow-up to this video. I found your other videos that predate this video, but they just describe what takes place in a tube amp and you building the "Bud Tube Amplifier". I am having trouble finding the video on adding power and soldering the components on your PCB from PCBWay in your usual educational method. Just curious.
There's a playlist
After watching 75% of your video, the question in my mind becomes: since you are essentially using class A amplification, why would we need negative feed back? What would be the purpose in this stage?
Negative feedback loops are to reduce distortion at higher volumes.
Nice explanation, thanks brother from India.
Question: Why is there no capacitor between the input jack and pin two of the tube? Is there any chance of a shock hazard? I see pin two is not hooked up to the power supply, but if something failed, OUCH! Thanks Paul and have a great weekend.
We have not reached the power supply connections yet..
@@learnelectronics
Oh, my bad. 🙄
What is the software you are using to draw your schematics?
Easyeda
Thankyou@@learnelectronics
Welcome
OK, where did you get the software to do this?
aren't you going to put a coupling capacitor in the path of the speaker?
No need, cause already coupled with transformer
Nice video! Can you tell me what is the purpose of the bypass capacitors which connect in parallel to the ground resistors? And how can you determine capacitance value? Thank you.
As per my knowledge , the capacitor is used for better frequency response as well as gain.
I've learned more about guitar amps from this video than anything else. I've been playing rock'n'roll for 40 years. COVID has me doing more stuff at home, including electronic projects. I'll watch the rest of these videos, but can you point me to a resource that explains *why* components are used? In particular, I'm curious as to why the capacitor is in parallel (?) with the pot. Thanks for this.