Building the simplest, best sounding, yet most inefficient Audio Amp! || Class A Audio Amp Tutorial

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  • เผยแพร่เมื่อ 17 ธ.ค. 2024

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  • @EasyElectronics2412
    @EasyElectronics2412 3 ปีที่แล้ว +279

    After 4 years of engineering some of my basic doubts got cleared😂 thanks for the video🙌

    • @greatscottlab
      @greatscottlab  3 ปีที่แล้ว +52

      Happy to help

    • @Harismanniyil
      @Harismanniyil 3 ปีที่แล้ว +6

      True 😂

    • @electroquests
      @electroquests 3 ปีที่แล้ว +8

      Agreed, same here. I wish that they taught us like this in engineering.

    • @shiftyjesusfish
      @shiftyjesusfish 3 ปีที่แล้ว +8

      @@electroquests I have learned more from this one man's work on TH-cam than any 1 teacher I ever had in school. Gotta love the time we live! We have almost infinite acess to information, and so many good people sharing what they know to help us all learn and create.

    • @dhaka88o28
      @dhaka88o28 2 ปีที่แล้ว

      good job

  • @navid9852
    @navid9852 3 ปีที่แล้ว +253

    Really like your writings and sketches. They are so helpful.

    • @greatscottlab
      @greatscottlab  3 ปีที่แล้ว +38

      Glad you like them!

    • @mimimi9170
      @mimimi9170 3 ปีที่แล้ว +2

      Yeah keep going! I also like that left-handed drawings

    • @christopherwiley5859
      @christopherwiley5859 3 ปีที่แล้ว +1

      Strong agree!

    • @mcintoshdev
      @mcintoshdev 3 ปีที่แล้ว +1

      100% agree! I love how he explains each step in the process too. One of my favorite subs.

    • @cabasse_music
      @cabasse_music 3 ปีที่แล้ว

      i just realized he's a fellow leftie too. LHFTW

  • @nobodyleftbehind
    @nobodyleftbehind 3 ปีที่แล้ว +14

    It is 25 years since I studied class A amplifier calculations, what a great explanation. I wish you had been my teacher at the time, you would have made it much easier! I built several BJT amps for college projects, always satisfying plugging them in and seeing the Vin vs. Vout.

  • @Ni5ei
    @Ni5ei 3 ปีที่แล้ว +142

    Probably the biggest challenge of this project is finding a phone with a headphone jack ;)

    • @Epsicronics
      @Epsicronics 3 ปีที่แล้ว +6

      you can get a usb c audio card thing i believe? then the unit only needs the usb c port!

    • @Ni5ei
      @Ni5ei 3 ปีที่แล้ว +2

      @@Epsicronics USB-C (in fact ANY USB connection) only carries digital signals. So you'd need something that does digital to analog conversion plus supplying you voltage to run the amp.
      That makes it quite more complicated.

    • @Epsicronics
      @Epsicronics 3 ปีที่แล้ว +3

      @@Ni5ei I don't fully agree, i understand what USB is, and while this is more hacking than building, you could take a small usb c to audio jack adapter and fit it in the same case as the rest of the circuit, giving you both audio and power through the USB C interface.

    • @MrD0r1an
      @MrD0r1an 3 ปีที่แล้ว +8

      @@Ni5ei no, it can also support analog audio via audio accessory mode, although this is not implemented on all phones (one plus, Xiaomi have it, but not pixel, Samsung).

    • @coccoborg
      @coccoborg 3 ปีที่แล้ว +3

      If you want to do this with an external DAC, why not have a more powerful amp integrated after that DAC anyway? Fiio makes a few, either bluetooth or wired.
      Bonus: LG V/G series owners can use the built in DAC in high impedance mode, it essentially does just this, look it up!

  • @Asu01
    @Asu01 3 ปีที่แล้ว +633

    _We all know that to achieve the best sounding hardware, you'll need to gold-plate everything. The connector, the wires, the PCB, the insulators._
    /s

    • @GeertGoossens
      @GeertGoossens 3 ปีที่แล้ว +26

      hahaha nice one! :D

    • @matejpavel2296
      @matejpavel2296 3 ปีที่แล้ว +51

      the enclosure... :D

    • @greatscottlab
      @greatscottlab  3 ปีที่แล้ว +224

      Dammit, I forgot that.....

    • @AndrewGillard
      @AndrewGillard 3 ปีที่แล้ว +88

      Ah, that explains all the gold-plated optical S/PDIF / Toslink cables for sale!
      👀

    • @hempbear
      @hempbear 3 ปีที่แล้ว +70

      And you need to use cryogenically frozen, unobtanium coated power cables made by nude virgins in utopia land for $9000

  • @coccoborg
    @coccoborg 3 ปีที่แล้ว +28

    Lovely! Will steal the design and build a higher voltage one for my 400 OHm headphones
    Edit: I've done it! Adjusted the resistors to match the higher voltage and current required by my AKG 340 and it sounds unreal! Way better than it has any right to. Can be powered for hours on end with just a small 3s lipo as the power consumption is so low. I could also boost the 5V USB power from the phone up to 12, but I fear it would add noise...
    Mods I did are: increase current to 30mA, adjust the bias voltage divider to work correctly at 12v (2.2k + 22k) and replace the bc337 with two bc238 (they were what I had lying around, as a bonus they have a Gain product of 250)
    Edit2: been using it for days, it's downright amazing! So much so, that I've ordered all the necessary parts to build a proper one, with integrated battery + charger, and isolated 24V boost converter. I think I'll 3D print a cute case for it to make it pocketable and make it a daily carry gadget. I don't really care that it's not power-efficient either, since it'll be pushing 200mW per channel at most...

    • @tgirard123
      @tgirard123 2 ปีที่แล้ว +2

      Hey Francesco, It's been a year or so but I wanted to ask if you ever built your final amp and if you still use it? I'm gonna dive into it as well for my Sennheiser HD569s (28ohm). Is the amp pretty loud with your AKG's? Do you still like the design? Have you made any changes or has there been any issues after a year? It looks like a really fun project

    • @coccoborg
      @coccoborg 2 ปีที่แล้ว +4

      @@tgirard123 hi! It worked, but I couldn't make it produce decent sound reliability, I ended up using a speaker amp to power them.

  • @matejpavel2296
    @matejpavel2296 3 ปีที่แล้ว +61

    I keep being surprised how simple most electronics are. For the longest time I had this block in my head, telling me to not even try understanding.

    • @greatscottlab
      @greatscottlab  3 ปีที่แล้ว +31

      As soon as you properly understand the basics, everything else will fall into place ;-)

    • @aljosagajst8725
      @aljosagajst8725 3 ปีที่แล้ว

      Just keep learning :)

  • @KekTekDe
    @KekTekDe 3 ปีที่แล้ว +354

    Upcoming:
    Buílding the simplest hearing aid device

    • @YourRealMother
      @YourRealMother 3 ปีที่แล้ว +21

      *yet most inefficient

    • @Herr_Bone
      @Herr_Bone 3 ปีที่แล้ว +19

      I visited the Danish hearing aid producer Widex already 15 years ago. At that time they just started to give their hearing aids a modern and fresh design, because their customers were not any more the 60 year old roadworkers but the 20 year old ipod kids. Your „it is not loud enough“ might be already a sign of a hearing loss. Take care.

    • @willofirony
      @willofirony 3 ปีที่แล้ว +4

      Pardon???

    • @Herr_Bone
      @Herr_Bone 3 ปีที่แล้ว +3

      @@willofirony 🔇🔕🦻🏼🦻🏼

    • @SianaGearz
      @SianaGearz 3 ปีที่แล้ว +3

      @@Herr_Bone Oh bullshit. iPod hearing loss is a hoax and a typical media scare. Hearing loss is induced by the city, with loud traffic, loud work environments, previously by machines in manufacturing jobs, now by open plan offices, disco and concerts if weekly, and drugs, amphetamine, molly and lsd can help you tolerate loud noises, but don't do much to protect your hearing, and there has always been some hearing loss in very young people just due to genetics, it was probably merely ignored previously, and the kids instead got punished for bad behaviour when really they just couldn't hear very well. I have spent all of my life in headphones, a lot of it in those with pretty high passive attenuation, a lot of it to suppress outside noises, but also listening to music a lot. I had done a hearing test a couple years ago, in my mid 30s, and i maxed out their measurement rig, i had an exceptionally good hearing threshold for my age group.

  • @lernenmitrobin
    @lernenmitrobin 3 ปีที่แล้ว +110

    Scott, you really make "complicated" things simple. It's education and entertainment as well. Stay tuned ;-)

    • @nibba7614
      @nibba7614 3 ปีที่แล้ว +4

      Not to mention, he make simple things - complicated :) Like you can just use software audio volume increase, there is a lot of options :)
      .
      .
      .
      .
      .
      .
      .
      .
      .
      .
      .
      for sure im joking, but

    • @mr.coolio4321
      @mr.coolio4321 3 ปีที่แล้ว

      He's not called Scott XD

    • @lernenmitrobin
      @lernenmitrobin 3 ปีที่แล้ว

      @@mr.coolio4321 what would be correct?

    • @mr.coolio4321
      @mr.coolio4321 3 ปีที่แล้ว

      @@lernenmitrobin his real name is Jeremy Pascal, I'll send you the video link

    • @mr.coolio4321
      @mr.coolio4321 3 ปีที่แล้ว

      @@lernenmitrobin here m.th-cam.com/video/0Xo0oKr8Thc/w-d-xo.html (it's not a Rick roll, I hate that stupid song)

  • @victorbarroscoch
    @victorbarroscoch 3 ปีที่แล้ว +4

    Wow, I feel like this is one of your best videos! Very short, simple, clear explanation and useful application. 10/10

  • @bur1t0
    @bur1t0 3 ปีที่แล้ว +145

    When you started comparing the headphone audio I was expecting Scarlet Fire to play :-D

    • @AfsYan
      @AfsYan 3 ปีที่แล้ว +5

      Headphones go dankkkkkkkkkkk

    • @dentjoener
      @dentjoener 3 ปีที่แล้ว +4

      @linus femboy tips DankPods.

    • @1976kanthi
      @1976kanthi 3 ปีที่แล้ว +2

      DankPods

    • @johnbuchman4854
      @johnbuchman4854 3 ปีที่แล้ว

      Reunion: Life is a Rock
      "Gotta turn it up louder--so my DJ told me!"

    • @gauravmarve
      @gauravmarve 3 ปีที่แล้ว +1

      Dankpods!!

  • @shinnok4941
    @shinnok4941 3 ปีที่แล้ว +1

    Man... I recently started studying electrical engineering in Germany (Elektrotechnik) and it's pretty much mission impossible... Huge respect for your work GreatScott, keep it rolling!!!

  • @GauravSharma-dy8xv
    @GauravSharma-dy8xv 3 ปีที่แล้ว +7

    It's really cool that LG still provides built in 32 bit dacs in their phones.

    • @mygfleftmeforatrans3593
      @mygfleftmeforatrans3593 3 ปีที่แล้ว +3

      True bro

    • @GauravSharma-dy8xv
      @GauravSharma-dy8xv 3 ปีที่แล้ว +3

      @@mygfleftmeforatrans3593 your name. Damnnn

    • @lotrbuilders5041
      @lotrbuilders5041 3 ปีที่แล้ว +2

      32-bit DAC’s are a scam though

    • @mygfleftmeforatrans3593
      @mygfleftmeforatrans3593 3 ปีที่แล้ว +1

      @@lotrbuilders5041 how?🙄

    • @SmallSpoonBrigade
      @SmallSpoonBrigade 3 ปีที่แล้ว +2

      Now if only they could engineer a phone that lasts longer than 6 months. I had 5 of them over the course of 2 years and they all failed due to bad solder allowing the chips to come loose over time.

  • @paulho446
    @paulho446 3 ปีที่แล้ว +1

    I started watching your channel from the very beginning and I had no idea what you were talking about. It's taken me 2 years at uni and now I finally actually understand!

  • @nitfumble
    @nitfumble 3 ปีที่แล้ว +35

    More audio DIY's, they are so useful!

    • @greatscottlab
      @greatscottlab  3 ปีที่แล้ว +16

      I will see what I can do :-)

    • @MohitSharmaxp
      @MohitSharmaxp 3 ปีที่แล้ว

      @@greatscottlab simple multi connection wireless audio circuit!

    • @springrollwang4441
      @springrollwang4441 3 ปีที่แล้ว

      @@MohitSharmaxp then just build a bluetooth receiver, there're super cheap half done products

  • @vickielawson3114
    @vickielawson3114 ปีที่แล้ว +2

    I like your Queen playlist at the beginning of the video!

  • @gregory9211
    @gregory9211 3 ปีที่แล้ว +120

    having a jlcpcb cooperation but soldering the components in a curde way on perforated board.😂

    • @trentjackson4816
      @trentjackson4816 3 ปีที่แล้ว +8

      Lol. You make good points ironically. But this guy I have to admit is a professional. It does make sense though to have him doing PCBs in collaboration with his sponsor.

    • @gregory9211
      @gregory9211 3 ปีที่แล้ว +12

      @@trentjackson4816 of course, I watch him since this channel exists. But still think it’s a bit funny that he fist talks about the professional/cleaner way and then continues with the “quick and Dirty”.

    • @trentjackson4816
      @trentjackson4816 3 ปีที่แล้ว +2

      @@gregory9211 mmmm I like the super neat and complicated handwriting. I am not going to throw any stones at any authors since I know that I could not provide the content and entertainment that they give. I lack the self-confidence and overall 'ability'

    • @waleedraza7195
      @waleedraza7195 3 ปีที่แล้ว

      lol yeah i noticed that too😂

    • @wesleymays1931
      @wesleymays1931 3 ปีที่แล้ว

      in a curd way? did you mean cursed? crude?

  • @james-barnett
    @james-barnett 3 ปีที่แล้ว +1

    The best quote that is in every one of your videos, `Let's get started!`

  • @ganopterygon
    @ganopterygon 3 ปีที่แล้ว +8

    Great video! If I remember correctly from my classes at university, input and the output create a high pass filter, so input's cut frequency in your circuit with 10uF and an equivalent resistance of ~657 ohms (R1//R2//(Re*Beta)) is 24Hz which is fine but for the output you would need to have around 220uF to have a cut frequency of ~ 38Hz instead of the current ~837Hz you currently have. so you will hear more bass, which might not be so important if you are listening to audiobooks :)

    • @ot4kon
      @ot4kon 3 ปีที่แล้ว

      I post the same comment. True, this need a bigger cap in the output.

    • @RexxSchneider
      @RexxSchneider 2 ปีที่แล้ว +1

      Actually, you're missing the point that the output impedance of the amplifier (130R) is considerably greater than the load impedance (probably around 20R to 32R), and so the sum of those impedances is what determines the high pass roll-off frequency, which is actually more like 100-120Hz in this case. Using a 22μF capacitor would be fine as I seriously doubt that the headphones have any usable response below 50Hz.

  • @Leon-ts1nl
    @Leon-ts1nl 3 ปีที่แล้ว +55

    Could U show how to build an RF Power amplifier for Ham or Pirate Radio? Would be really cool.

    • @greatscottlab
      @greatscottlab  3 ปีที่แล้ว +41

      I can put it on my to do list :-)

    • @andy_liga
      @andy_liga 3 ปีที่แล้ว +1

      @Darren Munsell that can easily be fixed using a router such us the ac68 from Asus (tossing a random one there, just cause I'm familiar with it) and changing the stock antennas some some directionals one.
      Run the router in access point mode, point the antennas where you need signal and you are done :)
      Seriously thou, amplifying WiFi signals it's not an easy feat with DIY electronic, it's rather complex and really cost inefficient.

    • @Leon-ts1nl
      @Leon-ts1nl 3 ปีที่แล้ว

      @@greatscottlab great👌

    • @circuitsandcigars1278
      @circuitsandcigars1278 3 ปีที่แล้ว

      That's a can of worms yargggghh lol

    • @zeendaniels5809
      @zeendaniels5809 3 ปีที่แล้ว +2

      @Darren Munsell Take a look at LORA communication... Maybe that's what you want.

  • @Mojomanultra
    @Mojomanultra 3 ปีที่แล้ว +53

    greatscott: And just like that you can make an audio amplifier.
    Everyone else: :0

  • @savitaray9992
    @savitaray9992 3 ปีที่แล้ว

    I don't know why but I was stuck with class A amplifiers the time you posted the video. May be god heard my prayers! And (saving your reverence) the tutorial was fucking good.

  • @technicaldhruba7406
    @technicaldhruba7406 3 ปีที่แล้ว +11

    You are my electronic teacher

  • @mohibullah6215
    @mohibullah6215 3 ปีที่แล้ว

    I thank youtubers like you, Electroboom, Electrnoob, Explorer and others. Thanks

  • @D.Axtmann
    @D.Axtmann 3 ปีที่แล้ว +27

    A follow-up with designing a PCB would be nice. I think this could actually be a project you could sell as small DIY-kits as it is actually practical, you can learn something and it is simple enough to solder it yourself :)

    • @coughcough5839
      @coughcough5839 ปีที่แล้ว

      I feel like the point is to buy the needed parts yourself and learn a few things about eginering along the way

  • @genkidama7385
    @genkidama7385 2 ปีที่แล้ว

    such a reliable electronics channel.

  • @decee1157
    @decee1157 3 ปีที่แล้ว +10

    I like your approach on this video. Keeping it simple and not bother with the advanced details, and ofc it works so why bother changing it.
    BUT There are a few details tho when it comes to audio. You went with "Best sounding" in the title so a little slap on the wrist doesn't hurt ;)
    Tental capacitors in audio path are typically a nogo as their capacity change versus the voltaqge which is across it. therefor you actually can get a different frequency response and distorsion.
    Typically you also add a capacitor between collector and base to reduce oscillation(the easist explaination) Also known as "Miller cap"
    A pulldown resistor on both input and output capacitor may save you a pop under startup
    And more minor things but the tentals surely caught my eyes when i saw this video.

    • @matejmeza3930
      @matejmeza3930 2 ปีที่แล้ว

      Miller capacitor on a single common emiter stage ? :) really?

    • @RexxSchneider
      @RexxSchneider 2 ปีที่แล้ว +1

      You're right that tantalum capacitors in the signal path are frowned on in hi-fi applications, but if you look carefully, the voltage across each capacitor doesn't actually change at frequencies in the pass-band of the amplifier, so the change in capacitance with applied voltage has no real effect here. It probably doesn't matter with earphones if the cut-off frequency varies by a few Hz for frequencies below 100Hz because the earphones won't have much response there anyway.
      It wouldn't hurt to add a small polyester capacitor (maybe in the range 30pF-300pF) from collector to base to roll off the highest frequencies - only bats would be likely to be affected if listening through the earphones. But it's really rarely necessary in a single stage common emitter - especially one with hardly any voltage gain.

  • @thinlayyoeser8486
    @thinlayyoeser8486 3 ปีที่แล้ว +1

    You gotta be the most creative electronic engineer out there ....big fan ....

  • @kingoftennis94
    @kingoftennis94 3 ปีที่แล้ว +69

    Imagine walking into the plane with that plugged in

    • @rkiwee
      @rkiwee 3 ปีที่แล้ว +5

      “uH sIr”

    • @jeteloriaga
      @jeteloriaga 3 ปีที่แล้ว

      Anirudh Krishnan lol

  • @4DRC_
    @4DRC_ 3 ปีที่แล้ว

    Just want to thank you for always name-dropping JLCPCB. We designed some PCBs for at-home kits for engineering classes last semester and used JLCPCB to bulk fab them all way cheaper than anywhere else. And I only knew about them because of you. You saved the day for us!!

  • @andrewkieran8942
    @andrewkieran8942 3 ปีที่แล้ว +3

    Thanks GS for another excellent video.
    Please be careful with amplified earbuds. In a lot of cases, you can't fix damaged hearing.

    • @mhansl
      @mhansl 2 ปีที่แล้ว +1

      That can not be stressed enough. When they started teasing me, I told the guys on my crew, any time you hear a ringing in your ear, it is permanent hearing damage. They all wear plugs now.

  • @ZonymaUnltd.
    @ZonymaUnltd. ปีที่แล้ว

    I’d like to say I really enjoy your handwriting and design styles.

  • @RealDids
    @RealDids 3 ปีที่แล้ว +10

    I can't believe it took me this long to realize you're left handed, yet you don't smudge anything with your hand while writing.
    What is this sorcery and tell us all your secrets! :D

    • @Broken_Yugo
      @Broken_Yugo 3 ปีที่แล้ว +1

      Fast dry inks or learn to hover over the paper.

    • @Eververcetti
      @Eververcetti 3 ปีที่แล้ว

      @@Broken_Yugo lol

  • @marklatimer7333
    @marklatimer7333 3 ปีที่แล้ว +1

    Back in the eighties I had a Musical Fidelity A1 100Watt Class A amp, it was great, listen to music and make yourself a toasted cheese sandwich at the same time.

  • @avejst
    @avejst 3 ปีที่แล้ว +4

    Great video as always 👍🙂
    Thanks for sharing your knowledge to all of us 👍😊

  • @codebeat4192
    @codebeat4192 6 หลายเดือนก่อน

    I made a similar device in the past but with a class D amp inside that can be used with a set of audio speakers. In the past it only worked with several phones with a powerful OTG connection but now since USB-C it is not a problem anymore. Let the party begin, grab some speakers and take it to the garden and enjoy 2x5w of audio. 😀👍

  • @dwdadevil
    @dwdadevil 3 ปีที่แล้ว +5

    What about creating an esscencial class AB amplifier?
    I've seen some with those C5200 A1943 transistors which are super simple for it's power.
    (Not those class A ones, those don't work)

    • @alexstone691
      @alexstone691 3 ปีที่แล้ว

      Im pretty sure you need to tweak the resistors a lot so both are in cutoff so its a pain

  • @tlange5091
    @tlange5091 3 ปีที่แล้ว

    You play music on your phone over your headphones which is picked up by the microphone, put in your video, uploaded to TH-cam, downloaded by me and listened over headphones.
    You are right this is quite inefficient. Thanks for the video.

  • @brainfarth
    @brainfarth 3 ปีที่แล้ว +8

    FYI: if you solder around your phone like that, cover the screen with something because the solder spatter can damage the screen.

  • @Alan_AB
    @Alan_AB 3 ปีที่แล้ว

    Brilliant project. I am hard of hearing and usually like to have the volumes turned up on most things when using earphones. This is the perfect project for my phones and tablets. Thank you.

  • @gregf9160
    @gregf9160 3 ปีที่แล้ว +3

    Superb explanations usual. But doesn't having such a small value 10uF capacitor on the collector limit the bass response through your earphones? I would have thought maybe 100 or higher?

    • @RexxSchneider
      @RexxSchneider 2 ปีที่แล้ว

      Since the amplifier has an output impedance equal to Rc (130R), the output at the earphones (likely around 32ohms impedance) is reduced by a factor of 32/(130 + Xc + 32), where Xc is impedance of the capacitor at a given frequency. When Xc is negligible at high frequencies, the reduction is fixed at 32/(130 + 32). So the -3dB frequency occurs when Xc = (130 + 32) ohms, not just the impedance of the earphones. A quick calculation show that 10μF has an impedance of 162 ohms at a frequency of about 100Hz. Although a 22μF capacitor might show a little improvement in bass response, I think you'll find a 100μF capacitor would be no improvement on that, as I seriously doubt anybody building their own amplifier owns earphones with a bass response extending down to 10Hz.

  • @sgoskz
    @sgoskz ปีที่แล้ว

    ive been having trouble understanding amplifiers and this made it easier for me to understand. thank you for including the links in the description as well!

  • @ErtugrulOzdemir-mf1gl
    @ErtugrulOzdemir-mf1gl 3 ปีที่แล้ว +28

    do you keep reading my mind? i was thinking about building a class a amplifier to modify my little sisters toy with a microphone and small speakers

    • @greatscottlab
      @greatscottlab  3 ปีที่แล้ว +27

      I do read minds.....

    • @94mac
      @94mac 3 ปีที่แล้ว

      @@greatscottlab would it be possible to use an audio amplifier for iphones?

    • @ThePunischer1000
      @ThePunischer1000 3 ปีที่แล้ว

      @@94mac sure just use a Bluetooth I2S Module

    • @ErtugrulOzdemir-mf1gl
      @ErtugrulOzdemir-mf1gl 3 ปีที่แล้ว

      lol its just a cash register toy

  • @craigleemehan
    @craigleemehan 3 ปีที่แล้ว

    As an old engineer, this tutorial was quite good. My process to choose R1 and R2 is different, but mathematically the same. Very good job.

  • @prisedeterre1356
    @prisedeterre1356 3 ปีที่แล้ว +39

    "A bit of hot glue for stability"
    Great Scott , 2021

  • @BillyNoMates1974
    @BillyNoMates1974 3 ปีที่แล้ว +1

    Back in the college days I used to make and sell headphone boosters with LM386 amps running from a 9 volt battery.
    Worked alright and 0.6 watts per channel went loud enough to make my ears ring. ha ha

  • @attackaffection5444
    @attackaffection5444 3 ปีที่แล้ว +4

    My seeing a greatscott notification .Finger go brrr...

  • @synqelectric6163
    @synqelectric6163 3 ปีที่แล้ว

    I always like the final part. "Stay creative, and I will see you next time!!!!"" 👍👍👍

  • @excorvalan
    @excorvalan 3 ปีที่แล้ว +11

    Make an AB class amplifier! Will be interesting see that 😁

    • @kennmossman8701
      @kennmossman8701 3 ปีที่แล้ว

      I believe he has already.....as mentioned in the video

  • @MustafaGARGI
    @MustafaGARGI ปีที่แล้ว

    I built this project with a PAM8403 and an OTC plug. It worked well but I was not sure if the otg was cheap enough for such a simple project. I have the same male type c plug. Thanks to you now I know how to supply my project with a cheaper and space saving 5v solution.

    • @MustafaGARGI
      @MustafaGARGI ปีที่แล้ว

      Further question. Is it possible to rearrange the type c plug to charge the phone at the same time? Or is it too much to ask from a simple project like this one?

  • @franzhagemuller6413
    @franzhagemuller6413 3 ปีที่แล้ว +8

    Nice Work. For the future you could make an Upgrade with only a USB C connetion and a high quality DAC. Than it would be even more neat.

    • @shockwavecity
      @shockwavecity 3 ปีที่แล้ว

      I'd like to see him design and build an R2R dac.

    • @NiHaoMike64
      @NiHaoMike64 3 ปีที่แล้ว

      The DAC chip used in those USB-C adapters is hard to get by itself for less than a complete adapter and often are in very difficult to work with packages like WLP.

  • @fernandocouto9064
    @fernandocouto9064 3 ปีที่แล้ว +1

    Your videos are realy well made, thanks for improaving the TH-cam

  • @WarningHPB
    @WarningHPB 3 ปีที่แล้ว +12

    Is there any chance of a version that is a USB DAC and Amp?

    • @greatscottlab
      @greatscottlab  3 ปีที่แล้ว +5

      Not sure.....sorry.

    • @rhalfik
      @rhalfik 3 ปีที่แล้ว +2

      Just add a usb dongle. Go to aliexpress and search for ALC5686. You'll see $10 circuit installed in a USB plug. It sounds like a dream. You'll need to add a battery though.

    • @warmesuppe
      @warmesuppe 3 ปีที่แล้ว

      @@greatscottlab Ich beantrage eine Version mit DAC. Da hier ja noch mehr Ohrgenuss herausgekitzelt werden kann.
      Leider ist hier das Angebot gerade im >100€ Bereich eher mau.

    • @Legofan2676
      @Legofan2676 3 ปีที่แล้ว

      I mean the FiiO uBTR is a bluetooth and maybe USB DAC that you can connect to your phone over bluetooth or hook into a computer via USB and hook in a set of headphones or earbuds. Only runs $20USD on amazon. Or if you wanna shill close to 100USD on amazon theres the FiiO BTR3 bluetooth and confirmed USB DAC.

    • @christianstrati3872
      @christianstrati3872 3 ปีที่แล้ว

      @@warmesuppe Antrag wird unterstützt!

  • @albertcaupin5889
    @albertcaupin5889 3 ปีที่แล้ว +2

    Great Scott : with JLCPCB you can make custom pcbs that are super convenient for projects !!
    Also Great Scott, 30 seconds later : so I used this piece of perfboard for my project

    • @jonny11bonk
      @jonny11bonk 3 ปีที่แล้ว

      Its hard order a custom PCB and then wait week or more to deliver it. Maybe they weren't able to send the boards because of "health concerns in our current climate"

    • @LC-hd5dc
      @LC-hd5dc 2 ปีที่แล้ว

      there's no need for ordering a custom pcb for such a simple project, bit wasteful of money

  • @chanakasampath9138
    @chanakasampath9138 3 ปีที่แล้ว +5

    Dear, Great Scott this is good and usefull vedio,and may you explain about "mosfet driver transformer".

  • @twistah
    @twistah 3 ปีที่แล้ว

    This what I've been looking for
    2years man I've been looking for this😭😭

  • @MrDexter9i3
    @MrDexter9i3 3 ปีที่แล้ว +3

    You should do an update on the great scott intro, with a next gen LED PCB :)

  • @Bajicoy
    @Bajicoy 3 ปีที่แล้ว +2

    My first audio amp was a pair of random mosfets connected to the audio pins of my pc and drawing 5V from a spare power supply pin on a bread board. A really fun and simple way to give my pc some decent sound and volume. Next time I should build a soldered one because loose pins vibrated and added static

  • @penguiin12
    @penguiin12 3 ปีที่แล้ว +10

    i love how he says cay-culate lol

  • @DJRY360
    @DJRY360 7 หลายเดือนก่อน

    love your videos. Just wanted to chime in as somebody who has calibrated transducers for audiologists. the correct way to couple an insert earphone with a microphone is to use a coupling cavity that simulates your ear canal. you just need an air tight link between the mic and transducer that is about 20 cubic centimeters in volume. This will more accurately present the sound to the speaker in the same way you would have it presented to your ear. not really necessary for this application where you are taking a quick look but for any more precise determinations this is the proper method. Thanks for creating such great content for us!

  • @md.mustafaabdullha2166
    @md.mustafaabdullha2166 3 ปีที่แล้ว +23

    Raspberry pi pico project, tutorial!!

  • @SongLyricsHD
    @SongLyricsHD 3 ปีที่แล้ว +2

    Oh damn I thought this was going to be for speakers. Still good video!
    But... Am I the only one that powers 2, 4 ohm Alesis Point 7s with an iPhone XS built in amp? Honestly I just did it for fun one day. Results are surprising. Distortion? A little not as much as you'd think surprisingly. Volume? About the same as a portable 10 watt Bluetooth speaker at 60% volume (Yes I tested this). Quality? Not too shabby, definitely not audiophile quality but if you don't care then its really not that bad. Lighting adapter get hot? Hell yes it did. Battery drop rapidly? Oooh yes. Why am I explaining this? Because I can.

    • @BIGMIKEGaming1
      @BIGMIKEGaming1 3 ปีที่แล้ว

      damn that's actually really cool. Makes sense though.

  • @ZXRulezzz
    @ZXRulezzz 3 ปีที่แล้ว +12

    Tantalums in audio path? What kind of 1960's madness is it? :D

    • @racingmadman7238
      @racingmadman7238 3 ปีที่แล้ว +2

      You are right. They sound horrible in the audio path. They should only be used for decoupling. Use a small mks, mkt or mkp instead.

  • @lor0the0fallen0angel
    @lor0the0fallen0angel 2 ปีที่แล้ว

    Perfect. Just what I need. (Simple class A equations)

  • @emorag
    @emorag 3 ปีที่แล้ว +3

    Fun project

    • @greatscottlab
      @greatscottlab  3 ปีที่แล้ว +6

      Thanks 😁

    • @osa1121-
      @osa1121- 3 ปีที่แล้ว +1

      Video came out today ur comment is one week ago

    • @attackaffection5444
      @attackaffection5444 3 ปีที่แล้ว +1

      @@osa1121- Patreon supporter

    • @ShahZahid
      @ShahZahid 3 ปีที่แล้ว +1

      @@osa1121- patreon exclusive...

    • @osa1121-
      @osa1121- 3 ปีที่แล้ว +3

      @@attackaffection5444 oh now I understand

  • @davecool42
    @davecool42 3 ปีที่แล้ว

    I love your handwriting so much.

  • @blanana_m
    @blanana_m 3 ปีที่แล้ว +3

    How have I never noticed your one week break?

    • @greatscottlab
      @greatscottlab  3 ปีที่แล้ว +4

      No idea. I do it for 2 years now though.

  • @jbuchana
    @jbuchana 3 ปีที่แล้ว +1

    Interesting timing, last week my wife and I wanted to watch a movie and the sound level through my computer speakers was way too low even with the volume all the way up. I wound up designing almost this same amp to use between the output of my computer and the speaker input. I just left it on proto-board, as I doubt I'll need it again, it was just that one movie with the low sound. I powered mine with 12V from a bench supply. I learned to design amplifiers like this many years ago by reading a book called "Transistor Circuit Approximations" by Malvino. I think it's still in print, I highly recommend it.

  • @hassanzahin1534
    @hassanzahin1534 3 ปีที่แล้ว +30

    Watching the intro, I thought this video was sponsored by audible

  • @1900OP
    @1900OP 3 ปีที่แล้ว +1

    A few things to consider.
    1. At the collector you have an impedance that is the parallel combination of the collector resistor (100 ohms) and the load resistor ( impedance of the headphones). With 22 ohm emitter resistor, this circuit offers no gain or attenuation with headphones at or below 32 ohms impedance, and it explains why attempts at lower bias current weren't successful because emitter resistor was big and the collector resistor was relatively small.
    The final results shows some decent amplification which means the headphones used were higher impedance.
    2. If you want a 1 volt peak signal, for example on a 32 ohm speaker, there will be a peak current of 1 V/ 32 ohms = ~31 milliamps, so the ~20 milliamps flowing in the circuit will have a hard time with that requirement for lower impedance headphones. Emitter followers are great for driving lower impedance loads such as headphones (they represent a simple solution).
    3. 10 microfarads at 1 kilohertz is 15 ohms worth of impedance, lower impedance headphones will have more gain for higher frequency audio signals than for lower frequencies signals. 100 microfarads seems a good deal, some electrolytic caps rated at 16 volts are small enough to fit in that case.
    4. The base sits at around ~1 volt, would be bad if there was a loud signal with 500 millivolts+ peaks, would bring the base voltage below 0.6 - 0.7 volts required and cause distortion.
    And, good video, transistors and op-amps are worth exploring, we have many in our computers and smartphones :)

    • @RexxSchneider
      @RexxSchneider 2 ปีที่แล้ว +1

      1. The collector current determines the output impedance (and input impedance but that doesn't matter in this case) and nothing else. I agree that the headphones used must have had a higher impedance than 32 ohms, otherwise there would indeed have been no overall gain. At lower collector currents, the ratio of Rc/Re would remain constant (hence the unloaded gain would be constant), but the effect of the larger collector resistor would naturally reduce the overall gain because of the increased attenuation into the fixed, low-impedance load.
      2. The other way of looking at it is that a 32 ohm load would attenuate an unloaded signal by a factor of 5, so you would need a 5V peak signal unloaded to get 1V peak loaded. And getting 5V peak out of a circuit with a 5V supply is tricky. Emitter followers look like a good solution until you realise that they still have to supply that peak current into the load, so an emitter follower stage would have to have a high enough emitter current to have a low enough emitter resistor. You might as well just increase the collector current in the common emitter stage and do away with the complication of a second stage. (Note that this only applies in this case because lowering the _input_ impedance of the stage won't cause a problem because of the low impedance drive from the phone.)
      3. 10μF at 1kHz is around 16 ohm impedance, but that's still negligible compared with the 130R output impedance. The -3dB frequency is when the capacitor's impedance equals the sum of the output and load impedances, which would be around 100Hz for a 30 ohm load. Maybe use 22μF, but anything more is a waste of space and money. Check that the voltage at a 32 ohm load is given by the resistive divider formula: 32R / (130R + Xc + 32R). That shows why the -3dB frequency is when Xc = 162R, not when Xc = 32R (as it would be if the amplifier had a very low output impedance).
      4. You really need the base to sit at about 900mV to maximise the gain, but the circuit is crippled by the load impedance being so much smaller than the output impedance. If you raised the base voltage to say 1.5 volt in order to cater for 500mV inputs, you'd have to increase the emitter resistor to around 42R to keep Ic=20mA. But then the gain of the loaded circuit would be reduced below 1, which kind of defeats the purpose of the project. Also, a negative 500mV implies a 1Vp-p signal input, and this circuit hasn't the supply headroom to amplify that by very much anyway, without worrying about the input excursions.
      Actually, although I've criticised some of your commentary, I very much appreciated that you've considered so many factors. I probably agree with a lot more of what you wrote than I disagreed with, apart from the fine detail.

  • @sparshdhiman72
    @sparshdhiman72 3 ปีที่แล้ว +15

    Watching on my iphone and crying near a corner

  • @PrajjalakChattopadhyay
    @PrajjalakChattopadhyay 3 ปีที่แล้ว

    I was thinking why you omitted the emitter bypass capacitor. It provides negative feedback that stabilizes the amplifier. But then at 8:35 I saw my favourite swamped amplifier! 😍
    You're THE BEST.

    • @RexxSchneider
      @RexxSchneider 2 ปีที่แล้ว

      Using a split emitter resistor with part of it bypassed is fine for small signals and large voltage supplies. But when you have just 5V supply and you're trying to get enough voltage swing to drive speakers, the bypassed emitter resistor is simply a waste of headroom. It's far better to bias the emitter to around 250mV (ten times the thermal voltage to swamp the intrinsic emitter resistance) and get the dc stability by using a feedback resistor from collector to base, replacing R1.

  • @Gurux13
    @Gurux13 3 ปีที่แล้ว +4

    How to break off headphones jack and type-c in one go :)
    BTW, if _some_ of your audiobooks are quiet, the amp is not the solution - raise the volume of the audio in software.

  • @Nono-hk3is
    @Nono-hk3is 3 ปีที่แล้ว +1

    Thank you for the amplification basics video!

  • @itsrahulsonii
    @itsrahulsonii 3 ปีที่แล้ว +3

    Where's JLC PCB?

    • @greatscottlab
      @greatscottlab  3 ปีที่แล้ว +1

      You can find their ad after my intro ;-)

  • @maniys
    @maniys 3 ปีที่แล้ว

    Not only the diy, the facts, comparisons and details about circuit elements are the most important (for eng,tec students.) Excellent.. 👌
    Thank you ❤

  • @vijayendirangiridharan6113
    @vijayendirangiridharan6113 3 ปีที่แล้ว +8

    Rest in peace those guyys with no headphone jack!😂

    • @arwlyx
      @arwlyx 3 ปีที่แล้ว +1

      Actually in this case it would just make the box smaller because you can get audio and power from just the USB C connector.

    • @rockytom5889
      @rockytom5889 3 ปีที่แล้ว

      You could pass audio through the usb c / micro port, though that requires more complex solutions.

    • @greatscottlab
      @greatscottlab  3 ปีที่แล้ว +2

      Not sure if getting the audio from USB Type C is easily possible with such a USB Type C breakout board.

    • @rockytom5889
      @rockytom5889 3 ปีที่แล้ว

      @@greatscottlab
      Yeah, you would need something to negotiate with the phone to pass audio, and a DAC on top of it.

    • @jonny11bonk
      @jonny11bonk 3 ปีที่แล้ว

      @@greatscottlab well, there are some breakout boards with both.

  • @orcofnbu
    @orcofnbu 3 ปีที่แล้ว

    it is great project. it is not only a tutorial. it is like an education. great work. thanks a lot

  • @bibeksaha4830
    @bibeksaha4830 3 ปีที่แล้ว +4

    Fun fact: You can do this with out any hardwork,money with full efficiency with basic apps that amplify sound

    • @greatscottlab
      @greatscottlab  3 ปีที่แล้ว +2

      That's true!

    • @bibeksaha4830
      @bibeksaha4830 3 ปีที่แล้ว

      @@greatscottlab yup
      Thanks for replying ☺️

  • @stask85
    @stask85 3 ปีที่แล้ว +1

    it's satisfying to watch you draw the cirtuits. but what i miss at all is the link to the final ciruit you build in the description.

  • @aterack833
    @aterack833 3 ปีที่แล้ว +4

    Hardware solution to a software problem

  • @TechPill_
    @TechPill_ 3 ปีที่แล้ว

    I could easily give answers to any questions because of you bro thanks to your detailed explanation

  • @lifeai1889
    @lifeai1889 3 ปีที่แล้ว +3

    video:47second ago
    comment:4 days ago

    • @nopparuj
      @nopparuj 3 ปีที่แล้ว

      Patreon

    • @greatscottlab
      @greatscottlab  3 ปีที่แล้ว +2

      Patreon supporter can watch earlier.

  • @theorangeapple5851
    @theorangeapple5851 3 ปีที่แล้ว

    Love your music taste

  • @urla.tejaswitaruneee2483
    @urla.tejaswitaruneee2483 3 ปีที่แล้ว

    Nice explanation of the circuit diagram.

  • @eddyyu7091
    @eddyyu7091 3 ปีที่แล้ว

    Very basic audio circuit and with your explanation it becomes a very good tutorial indeed. Good job !

  • @rollbot
    @rollbot 3 ปีที่แล้ว +1

    nice amp project... er.. automatic deafening apparatus! I will build and gift to people I do not like!

  • @j.t.johnston3048
    @j.t.johnston3048 3 ปีที่แล้ว

    Thanks for the clear and simple explanation of the class A amp. I knew some of this bit learned something, too. Always enjoy listening to good teaching.

  • @ManicQuinn
    @ManicQuinn 3 ปีที่แล้ว

    I'm gonna subscribe for more audio projects!

  • @sang7873
    @sang7873 3 ปีที่แล้ว +1

    not to be rude or something. but for your information.
    so here we go, 10:07 notice that capacitor output(C2 C4) is only 10uf.
    the typical headphone is around 32ohm (not linear to every frequency but simplify sake ). output capacitor aside from coupling for dc, it also you as it will also act as a High pass filter.
    reference for calculation and formula.
    www.learningaboutelectronics.com/Articles/High-pass-filter-calculator.php#answer1
    10uf is cut off very high for the minimum. most manufactured use around 100-220uf.(examples would be headphone amplifier, sound card, or headphone output of motherboard) so it cut off lower.
    around 20-50hz(minimum human ear perception but that also depends on age and individual)
    and I think just increase the Values of the Capacitor won't more complicate the circuit and make it better.
    sorry about my broken English.

    • @RexxSchneider
      @RexxSchneider 2 ปีที่แล้ว +1

      Since the amplifier has an output impedance equal to Rc (130R), the output at the earphones (likely around 32ohms impedance) is reduced by a factor of 32/(130 + Xc + 32), where Xc is impedance of the capacitor at a given frequency. When Xc is negligible at high frequencies, the reduction is fixed at 32/(130 + 32). So the -3dB frequency occurs when Xc = (130 + 32) ohms, not just the impedance of the earphones (as it would if the amplifier's output impedance were much lower than the load). A quick calculation shows that 10μF has an impedance of 162 ohms at a frequency of about 100Hz. Although a 22μF capacitor might show a little improvement in the bass response, I think you'll find a 100μF capacitor or more would offer no improvement on that, as I seriously doubt anybody building their own amplifier owns earphones with a bass response extending down below 10Hz.

    • @sang7873
      @sang7873 2 ปีที่แล้ว

      @@RexxSchneider can you tell me where Rc = 130R come from? C output directly connected to transistor. Did I miss something?

    • @RexxSchneider
      @RexxSchneider 2 ปีที่แล้ว +1

      @@sang7873 The collector of a transistor is a high impedance point, which means changes in voltage across the transistor does not alter the current flowing by much. You can see that by looking at any transistor datasheet that shows Ic vs Vce curves, where the current stays essentially flat as Vce increases. So the output impedance of a common emitter circuit is simply the value of the collector resistor.
      The output of the circuit is a voltage source with an internal impedance. If you understand Thévenin's theorem, you can see directly what the internal resistance of the voltage source is. If not, then consider connecting a load that draws 1mA from the output. That current has to come via the collector resistor and so will cause an extra voltage drop of Rc x 1mA across it, which will lower the output voltage by Rc x 1mA. If a voltage source drops by (Rc x 1mA) when delivering 1mA into a load, then it has an internal impedance of (Rc x 1mA) / 1mA = Rc.
      In many common amplifiers, the output impedance is designed to be much less than the expected load impedance (usually by using negative feedback), so you will probably be accustomed to ignoring the output impedance of the amplifier when considering coupling capacitors and just working with the load impedance. However, in this case, the output impedance is higher than the load impedance and dominates the frequency response of the R-C high pass filter.

    • @sang7873
      @sang7873 2 ปีที่แล้ว

      @@RexxSchneider thank you very much. I am just a hobbyist. I did not know that deep.

  • @tranxn7971
    @tranxn7971 3 ปีที่แล้ว

    I really like that kind of project with simple components and good explanations to cover the basics. Thank you very much !

  • @kadimivenugopal8033
    @kadimivenugopal8033 3 ปีที่แล้ว +1

    Really It greatly satisfying my curiosity.👍

  • @Darkshadow799
    @Darkshadow799 3 ปีที่แล้ว

    Noting better than a break from study with great scott upload notification

  • @fatheraabed
    @fatheraabed 3 ปีที่แล้ว

    That "Weed" album is great!

  • @electronic7979
    @electronic7979 3 ปีที่แล้ว +1

    Excellent project

  • @danielsalloum3006
    @danielsalloum3006 3 ปีที่แล้ว

    This makes me want to go to the basement and not come up until I have an amp for my phone. Super straightforward project. Thanks!

  • @Cylon39
    @Cylon39 3 ปีที่แล้ว +1

    FYI adding a 10uF capacitor across the collector resistor will increase your gain considerably.

  • @FedericoGigena-s3k
    @FedericoGigena-s3k 3 ปีที่แล้ว

    I like how you put separations for each part of the video good job

  • @tinkeringwithelectronics
    @tinkeringwithelectronics 3 ปีที่แล้ว

    Thankyou, thankyou, thankyou....your video and links got me over a hump on tranistor amps.

  • @seimyemane2772
    @seimyemane2772 2 ปีที่แล้ว

    i love your accent my man 😂😂
    thanks bro