Let's design an build a vacuum tube amplifier from scratch

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Let's design an build a vacuum tube amplifier from scratch
In this video we begin the design of a vacuum tube audio amplifier. This design which starts from the classic Fender 5F1 circuit uses a 12AX7 as a dual stage preamp and a 6v6GT as the signle ended power amp. From here we will add in a Baxendall type tone circuit and build it all into a metal chassis and give it a test. Ths is part 1, designing the signal chain.
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1 июл 2024

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Комментарии : 419

@makarov138 2 года назад

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!!

@Noah-gq7pq 3 месяца назад

yes great another old schooler

@iangordon7283 Год назад

Please make a part 2 to this! I'm down the rabbit hole on amp builds and this is so helpful!!

@jimcatanzaro7808 Год назад

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

@tom1263 Месяц назад

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!

@joeyscott4299 3 года назад

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 !

@williamli4422 3 года назад

@Gerald Fisher stfu

@deanmlshredder 2 года назад

Every time I see something like this I am always curious what provokes these responses. RU-vid comment sections uses to be entertaining. Now they just delete all the offensive shit. Lol

@lordboogeth7862 8 месяцев назад

Have you built your tube amp yet? How did your project turn out?

@williswet 3 года назад

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.

@sfbfriend Год назад

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.

@UXBen 3 года назад

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!!

@cameronkrause4712 2 года назад

Ben, I agree 100%

@el_nestorvgc 8 месяцев назад

I am engineer and this 16 minutes video was the best master class in tube amplifier

@fahey7335 8 дней назад

No you are not.

@jogreeen 3 года назад

excellent video, hours worth of learning in 16 minutes.

@jaysusrockso2623 3 года назад

Dude thank you for this video. Really into wiring up stuff and you helped me understand how those paths work and why they work a little better.

@Whitewolf4869 3 года назад

Thanks this is great Finally someone explains this clearly

@GORF_EMPIRE 4 года назад

Nice, simple and elegant. Tubes are so nice to work with.

@chrisreich40 Год назад

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.

@aubreylunn2558 3 года назад

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.

@KissAnalog 4 года назад

Awesome video! Thanks Paul!

@markusrye9051 3 года назад

Just nice! Simple and easy.

@joshwest8882 2 года назад

Thanks man. You helped explain a big part of what I wasn't understanding

@ryanybos 2 года назад

Awesome video explaining everything & it's purpose clearly. So far the best fundamental explanation video I have found thank u for clearing up a ton of things for me. I am now a subscriber

@lionelpostwartrains 3 года назад

A great easy to understand video you have a great teaching method. Thanks for your instruction.

@thespiritof76.. 3 года назад

subbed 👍 I've been repairing amps for a number of years simply off experience of years using amplifiers with basic knowledge of components and the components purpose. however the actual signal path and wiring has been such a mystery and you have taught me more in 15 minutes about that then I've learned in the last 5 years. I believe this is because I do not know how to read schematics and do not have electrical background but your tutorial did not require that and it tied so much up in my understanding thanks a lot bud great video!

@davidward9935 4 года назад

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.

@makarov138 2 года назад

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!

@chadhoffman3890 2 года назад

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?

@opalprestonshirley1700 4 года назад

This will be fun. I've never seen how to design and build with vacuum tubes. Stay safe.

@yurkshirelad 3 года назад

A video from learnelectronics about a guitar amp? Auto-like! :)

@michaelpadovani9566 4 года назад

Look forward to the second video...building amps is addicting

@learnelectronics 4 года назад

And expensive

@thebeaner687 3 года назад

This is a good video. I have been trying to learn about tubes and this helps

@sandichhuu 9 месяцев назад

Pretty simple and easy to understand, thank you.

@JollyJam69 4 года назад

Great video exactly what I was looking for! Looking forward to part 2!

@learnelectronics 4 года назад

The whole series is there

@JollyJam69 4 года назад

@@learnelectronics thank you, is there another circuit diagram one for the power supply/distribution to all tubes? I might be being blind but I can't see it?

@billsutherland9193 2 года назад

@@learnelectronics I cannot find part 2?

@adailyllama4786 4 года назад

Awesome!

@billrogers1008 4 года назад

Thanks! I am learning every day and am pleased that I was able to follow you through each step and actually understand what the circuit was doing.

@JorgeTheilacker 3 года назад

Very cool!!! Thanks so much!

@GIBKEL Год назад

Is there a part two to this video. It was one of the best. I’m finally understanding and this confirmed it.

@renevanderbruggen731 3 года назад

What a great video - thanks a lot !

@michaelhyde9971 4 года назад

Thanks for the hard work. Stay safe

@learnelectronics 4 года назад

You bet

@miketoreno4969 4 года назад

Great video sir. Keep the videos rolling, I really appreciate them. Thank you for the effort

@Finom1 2 года назад

I just found your channel!!! I am now a new subscriber!!! Bless you for taking your time explaining the schematic, I am old and I am a visual learner:) Bless you for sharing your wisdom with us:)

@learnelectronics 2 года назад

Welcome aboard

@mohammadhushki96 4 года назад

Great video,, thank you so much

@learnelectronics 4 года назад

Glad you liked it!

@thevintageaudiolife 3 года назад

Thanks, very informative.

@mindstylah 4 года назад

Well explained :)

@Mega_trav 3 года назад

The most helpful video I’ve ever watched for a novice

@Mega_trav 3 года назад

Where would the tone stack go?

@learnelectronics 3 года назад

Between the pre and power amp sections

@pdx_angler9760 Месяц назад

Ignoring the plate load resistors is a significant omission as they determine stage gain and are an essential part of biasing each stage.

@Master_of_Chess_Shorts 3 года назад

how you get values for components could be nice to know...but great approach, keep up the good videos!

@jimcatanzaro7808 2 года назад

There are thousands of amplifier designs

@Master_of_Chess_Shorts 2 года назад

@@jimcatanzaro7808 I meant specifications, references like frank.pocnet.net/sheets/049/1/12AX7A.pdf

@jimcatanzaro7808 Год назад

Old circuit designs not too hard just keep trying

@pointlessvidz13 2 года назад

That is an iconic way to start a video

@jameswallace5967 4 года назад

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.

@zacboss467 3 года назад

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.

@keithking1985 4 года назад

was never really into tubes but thats coz i never seen them explained before. i know they can do loads of stuff like, transistors, op amp's, diodes, amplifiers, im sure voltage regulators & current too, and much more.. what im trying to say is i think!! NO!!! i know i like them now!! thanks again Paul.. : )

@satishvasane6812 2 года назад

Nice explanation, thanks brother from India.

@rcmanoj 4 года назад

Excellent video. One suggestion. If you can have another video where you could explain how do we arrive at those resistor & capacitor values & the reason or logic to use it. In fact that’s the fundamental aspects of circuit design. Thanks for uploading wonderful videos.. Keep up the good work..

@zacboss467 3 года назад

This is to do with the tube characteristic curves, these determine how anode voltage and current behave for a given load. vrps.org/documents/TubeTheory/TubeTheory.html The curves for a given tube are the key to determining the values for the cathode resistor and anode resistor. On another note, the coupling capacitors and grid leak resistors have to be chosen carefully as they act as a high-pass filter and the wrong values can lead to them lopping off the lower frequencies of your signal.

@josephrayle752 Год назад

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.

@issamkhatib 2 года назад

Very nice video !! Thank you for sharing your knowledge and explaining in details how the signals work and get amplified. Can you say what the rating for the transformer should be. The main and the output. Please! :) .

@antibrevity 4 года назад

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. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-d9O7oZEYALI.html ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-D5N82Qr6k78.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 ;).

@YiloQuinones 5 месяцев назад

Excellent!

@metalgarri4194 3 года назад

The anode resistors are also part of the signal path, otherwise there is no gain at all my friend...

@rrowan327 4 года назад

Hopefully your Dentist visit went well. Take care and save

@justmattnow1959 3 года назад

looking forward to part 2

@learnelectronics 3 года назад

All 4 parts are available in the playlist

@reynaldobuitizon4943 7 месяцев назад

Very educational!

@0tt0z 7 месяцев назад

I enjoyed this video! Great job!

@jimhenderson2308 2 года назад

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?

@4Nanook 5 месяцев назад

You should always use a push-pull final, finals will be driven into non-linear regions and with a push-pull output odd harmonics will not be generated and it will sound more smooth and less harsh when strongly driven.

@electronic7979 4 года назад

I like it

@stevecousins4441 3 года назад

I love the video and am interested in part 2 and beyond. Others have asked so I guess I'm not the only one that can't find it. You reply "playlist" but I cannot find part 2 to this in your playlist. Can you please provide a link? Or say what the name of it is? Thanks! Looking forward to it.

@martinfinne7259 4 года назад

Good to see you doing tube stuff, not too common nowadays. But if this was the whole designing part, hadn't it been good to also include a explanation to how you got your component values and why they are needed?

@zacboss467 3 года назад

Amp design is actually pretty difficult. To explain why some values are chosen can really amount to a lot of just trial and error. I'm an electrical engineer and I find tube amps can be pretty challenging to build because every small change effects another part of the circuit. Its really hard to explain the selection of a lot of these components without going deep into tube behavior. If you really want to know though go research tube characteristic curves and loadlines, they are the key to how tube amps work.

@jonsnow7092 5 месяцев назад

he's pretty much copying the values of a fender champ, this is just a simplified version of the amp and would probably sound like shit.

@felixblanco6591 Год назад

Great video. I've always had an interest in guitar amp design, pedals, etc. I find electronics, circuit boards etc very fascinating and mysterious. How does one begin with designing a guitar amp? Should a degree in electronics engineering be pursued, or is there a specialized certification for audio equipment electronics? I'd love to hear from you! -Felix

@mameylayalawson9240 3 года назад

Thank U fellow for uploading n sharing This Very interesting vídeo!! Tnks a lot!!!!!!

@s2pidmonkey 4 года назад

Thanks for the video, could you go a bit more in depth about what the passives around the tube are doing?

@learnelectronics 4 года назад

Keep watching the series...

@Songwriter376 3 года назад

It would be great knowing how the values were figured out too. .

@zacboss467 3 года назад

@@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.

@Songwriter376 3 года назад

zacboss467 Thanks for that answer!

@jimirox1928 3 года назад

Good job. You would want to use a 33k input R rather than a 68K with only one input. Fender's 68k's are in parallel when youre plugged in to the jack so your actually going through 34k ohms rather than 68k.

@smallbeans702 3 года назад

It's also a good idea to reduce the value of the input grid stopper resistor to reduce Johnson noise as well as place a capacitor to ground forming a low pass filter to filter RF

@enricoincognito8595 4 месяца назад

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

@SuzanneKowalski 4 года назад

Thanks for the video! A minor advice: you could give some more in-depth info for us newbies about the actual purpose of the caps and resistors added to the construction. I know that there are tons of videos about tube amps, but none of them seem to give enough explanation about the purpose of the individual parts and their values, just "a capacitor here, a resistor there, and you're good". You could also make a video about the characteristics graphs in tube datasheets and how to use them. That's a topic I've been interested in for a very long time, but never found a good video about making sense of those graphs.

@learnelectronics 4 года назад

This is just the first part of this series, lots more information will follow.

@SuzanneKowalski 4 года назад

@@learnelectronics Thank you, can't wait! :)

@jetblakink 8 месяцев назад

Excellent! What programme did you use for the schematic?…

@valakatz3967 4 года назад

Great video, thank you for sharing. Question: what program did you use to draw this project.

@learnelectronics 4 года назад

Easyeda

@vtrandal 2 года назад

Do you have a playlist of videos for building and testing this design? Awesome. This video says it’s part 1.

@HelmutTschemernjak 4 года назад

Thank you for explaining the tube basics, very cool. When I use a chinch input, is the input impedance right or what needs to be changed. Great video.

@robertgraf9265 3 года назад

That will not affect the input impedance, which is determined by the source. If it's from a phonograph, then you will want an inverse RIAA filter added to the circuit.

@jolox. 2 года назад

I got a Weller soldering iron for Christmas and now I have to figure out what to do with it! This video is such a great introduction, but way over my head! I'm going to subscribe and thumbs up to help your channel! Any suggestions for a good beginner project? I have a couple dead speakers. Any suggestions? Thanks again!

@eddiearnold768 2 года назад

Yes put in the negative feedback...thank you for doing this I hope the next video is coming soon...

@triclone123 Год назад

I was getting comfortable to use this to build my 5F1, but there is no conclusion. I am thankful though.

@GIBKEL Год назад

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-

@frankowalker4662 4 года назад

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.

@keithking1985 4 года назад

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!!

@Steve-GM0HUU 3 года назад

😄 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.

@abdulrahimghaus4545 10 месяцев назад

Good to start again after many many years

@PLASMAKVA500 4 года назад

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!

@derringraviel7540 2 года назад

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

@jcmcovers4487 Год назад

Love the video was there ever a part two? I can't find, with the power supply?

@IhabIAmer 3 года назад

Fantastic. Anybody knows what software was used above?

@etmax1 5 месяцев назад

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.

@AdventureswithJack453 3 года назад

How do you determine the values of the resistors and caps?

@JT-ei7qj 6 месяцев назад

Great video! I was wondering what circuit diagram software you are using. I really like that it has tubes as an option!

@larryshaver3568 2 года назад

do you plan to heat the 12axy as a 12 volt filament [pin 9 not used] or a 6 volt filament?

@yanfishtwig2356 Месяц назад

Thanks dude very helpfull

@JolicoeurAbear 2 года назад

nice video, which program are you using to visually create your schematic?

@julianmiles6604 Месяц назад

The input grids of valves should be connected to ground (0v) otherwise the operating current of the valve cannot be controlled. The purpose of the resistor from the cathode to ground is to apply a negative voltage on the grid wrt the cathode. Check your valve data book for details, every valve is different.

@julianmiles6604 Месяц назад

Forgot to say, the input grid is connected to ground via a large resistor, typically 1 mega ohm, not directly connected to ground!

@LitesLAB 4 года назад

Been waiting for this Paul! That was great! Will you be expanding on the signal path by adding a tone stack and more gain stages? Possibly an inverter? I’d be curious to see which type you go with. I prefer the Marshall values to get that sweet Marshall growl. However, a chimey Fender can be sweet to! I only ask due to this design being pretty close to the Champ you recently built.

@learnelectronics 4 года назад

Youve got a good eye and are intuitive. Ill be dding a Baxendall type tone stack, but no more gain stages.

@LitesLAB 4 года назад

learnelectronics Thank you Paul! And Awesome! I look forward to the rest of the installments.

@LitesLAB 4 года назад

learnelectronics I am sure you might have seen these, but here are a couple great resources for tonestacks: Duncan Amps Tone Stack Calculator web version: www.guitarscience.net/tsc/ Another great site: monster.partyhat.co/article/amplifier-tone-stacks/

@zacboss467 3 года назад

All extra gain stages would really do is increase distortion, they wouldn't necessarily increase the overall gain of the amp.

@kwacz 11 месяцев назад

how did you determine the values of the resistors and bypass caps?

@truckthrukk6940 2 года назад

Thanks for the great video; what's the name of the computer program you're using to lay out the amp schematic?

@jimcastillo8950 8 месяцев назад

Great video, I guess you can have a switch for negative feedback for (on or off) Thanks..............

@mike6l6 2 года назад

There needs to be a resistor from pin 5 on 6v6 to ground About 470 k . That gives you your negative bias on output tube , Otherwise the tube may cherry plate and distorted sound.

@SteveHacker Год назад

Where (or in what date range) can I find the next video in this series? I don’t see it in the playlists… Thanks!

@dampandrew 4 года назад

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

@LitesLAB 4 года назад

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.

@ku4nz 4 года назад

Good job as usual. BTW what software were you using to draw schematic? Thanks.

@learnelectronics 4 года назад

EasyEda

@kristophergamble8510 3 года назад

Very good video. Just wondering what program do you use

@styrenereplicas53 4 года назад

Great video. What schematic software are you using? Thank you, Dave

@vicvergauwe5736 4 года назад

I think Paul is using EasyEDAa

@learnelectronics 4 года назад

EasyEDA

@resist4resist 4 года назад

Great video Paul! I have been following your channel for a while now and I think it is one of the best RU-vid channels along with Mr. Carlson's Lab and w2aew. The way you take pains to describe some complex concepts and ideas is excellent. Though, I have a question and that is how do we determine what resistor to use (i.e. its Ohm rating)? What is the math involved in determining the which resistor to use like 68K resistor between input and 12AX7 or using 1.5 K resistor between pin 3 and ground etc. Your videos have been a great help. I am sure a lot of people are indebted. Thank you.

@Bodragon 4 года назад

I don't think he knows. I think he's just copying an existing design. This is something I would also very much like to know though. >

@robertgraf9265 3 года назад

The resistors are picked according to the desired operating conditions of the tube. There's usually a plate resistor that is sized so that the plate will be at about half the supply voltage, and the cathode resistor value is chosen to set the gain and those are chosen per tube characteristics.

@ronb6182 2 года назад

You could play around with values if you use a scope and see the increase and decrease of distortion. Also see if the wattage goes up or down. I wouldn't go to drastic in either direction, When it comes to values. 73

@bkw67 4 года назад

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 4 года назад

What I have covered this far is the exact signal path of the Fender 5F1 circuit.

@bkw67 4 года назад

@@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!