All the best wishes to you and Snickers. And may your health be perfect in these troublesome times.
@Gersberms3 жыл бұрын
Thank you for the very easy to understand circuit, I'll have to spend a bit more time trying to really understand how the negative feedback works. I like that you're highlighting the fact that mosfets use voltage to control a current, it's easy to see why that is so useful in this circuit.
@ao66403 жыл бұрын
I breadboarded one myself a few months ago using a K3878 (and similar ones I had lying around) using a zener to bias the gate. I thought it was pretty cool, untill I discovered chip amps and learned how to design a proper class AB output stage thanks to your videos.
@ivanlukic23603 жыл бұрын
Hi John! Greetings from Serbia. I've seen many of your youtube videos and I like them very much. It's nice that you test budget priced gadgets and explain simple circuits. For most users that's all that is needed for enjoyment of music. Spending too much money on the amps and speakers makes no sense, especially for home listening. A simple LM1875 project can bring a lot of fun and enjoyment for very little cash, while, sometimes, even hundreds of thousands of dollars can bring only frustration and headache.
@rolandmetivier44373 жыл бұрын
I like these types of amplifiers, lots of niceness coloring the signal
@iblesbosuok3 жыл бұрын
Glad to watch you again, sir.
@MichaelBeeny3 жыл бұрын
Great for people that like the valve sound, efficiency and heat.
@EngineeringEssentials3 жыл бұрын
By valve , you must be talking about soft clipping and 2nd order harmonics
@woodowoodo14053 жыл бұрын
even with the ordinary royalty free music, the sound was comparatively good to my ears. At a stretch, may be worthwhile developing an alternative JAT SE amp concept covering all bases and tastes ;)
@KissAnalog3 жыл бұрын
Thanks John - always look forward to your videos!
@copernicofelinis3 жыл бұрын
As a suggestion, on the schematics you could add the bias voltages and the bias currents. It will make is easier to understand the circuit. Voltages in green and currents in red will match the power supply s display.
@sixtyinsix3 жыл бұрын
From me: Nice video John, thx!👍 From my gf: Happy Birthday Snickers! 🎉🎊😺🎂🍧
@laxr5rs3 жыл бұрын
Cool! Thanks! [Sounds great. Good description]
@bobdavelisafrank_48502 жыл бұрын
I love these little single ended circuits! Not the highest performance, but simple and practical for low power loads -- I use a small scale one of about 20mW to power my headphones. The distortion cleans up a lot if you can put the gate-source 'junction' through a feedback loop of another amplifier, which was a popular old design!
@andymouse3 жыл бұрын
I always love theses ..keep meaning to play myself...must buy new scope ...cheers.
@ivanlukic23603 жыл бұрын
I also have one suggestion for future video. Since many of your projects are about small IC based power amplifiers, it would be nice to explain how to add headphones output in parallel with speakers output. The gain and power is usually too high for headphones, so some voltage divider is needed. The video could be about how to calculate values and power of proper resistors.
@AmazonasBiotop3 жыл бұрын
Thanks John! 15 year that is great. :)
@EngineeringEssentials3 жыл бұрын
👍😍 true
@springwoodcottage42483 жыл бұрын
Super interesting and educational. Thanks for sharing!
@mikedenallo69973 жыл бұрын
THE man is Back!
@SinaAtalay3 жыл бұрын
John thank you so much!
@researchandbuild17513 жыл бұрын
I built something like this a long time ago. Gets really warm lol!
@EngineeringEssentials3 жыл бұрын
Ita an electronic heater 😁
@dfn033 жыл бұрын
Me too, I was running it without a heatsink. Surprisingly it didn't die instantly.
@listerine-pr5lt3 жыл бұрын
Snickers doesn't look to be interested in Audio Amp anymore.
@ao66403 жыл бұрын
He's waiting for quantum amplification technology to arrive...
@researchandbuild17513 жыл бұрын
By the way, RF mosfets are lateral, and would probably work well for audio
@johnsonlam3 жыл бұрын
Thank you John, for such a simple circuit. Is it possible to step by step improving the circuit to make it better? This is also a kind of fun to see something improve by changing little by little. Also want to bust a myth, I don't believe change a component will have dramatically improve in quality, good sound should be: always improve the circuit first, then take care of the component later.
@EngineeringEssentials3 жыл бұрын
I agree 👍
@tenlittleindians3 жыл бұрын
The guy that invented Trainwreck amps did not share your opinion. A great story here: kzbin.info/www/bejne/j3iXnqd6rsied8U
@johnsonlam3 жыл бұрын
@@tenlittleindians When I watched the video, I just feel Fisher is "fine tune" his amp with different component and different layout, without coming to circuit design first. I didn't get the message of "component quality over circuit design".
@EngineeringEssentials3 жыл бұрын
That's a great video John, 🙏. Gain of this amplifier depends on the gate biasing resistors, can you do a video by changing value of gate bias resistors? Just want to know one more thing, is it possible to clean up output just by adding a constant current source?Or a negative feedback is a must? Thank you🙏
@jeffmassey48603 жыл бұрын
In addition to a Constant Current Source,how about trying an incandescent light bulb?
@jaybird578 ай бұрын
Havent seen thoes radio shack horn tweeters in years.... cool.
@jp0407593 жыл бұрын
Great video all around.
@Spentelectrons3 жыл бұрын
Id be curious to see the difference in output on an 8ohm resistor versus an 8 ohm speaker. For example I'm simulating my load as 8ohm but I'm physically operating it against two speakers in series that total a resistance of 6.4ohm to a standard volt/ohm meter. Is their a more accurate way of simulating a speaker? Maybe just a different ohm value? A resistor/inductor/capacitor in parallel? Does the difference matter?
@jeffm27873 жыл бұрын
Wondering why you don't use the FFT to figure out the clipping points, perhaps have both the FFT and Waveform on the screen at the same time. The FFT would show distortions that you would be hard pressed to see on the sinewave.
@JohnAudioTech3 жыл бұрын
Yes, that is the right way to do it but I'm just lazy.
@adaminsanoff3 жыл бұрын
Very educational and helpful video!
@robtitheridge97083 жыл бұрын
very interestin. i wounder if you could swop the big resistor for an out put transformer?
@killcar5nbike23 жыл бұрын
Yes, I've took the idea to extremes using a universal tube output transformer and a high voltage supply. The output becomes very linear as the current modulation through the MOSFET is in the ma range. However I ended up with having to use IRF840 to survive the voltage present across it. At clipping onset my design puts 500v across the output. I did a video on it, but it's more a badly phone recorded video of designing it, rather than the schematic and testing of a working amp. Most output transformers, especially single ended are going to be high turns ratio ones designed for valve impedance matching.
@JohnAudioTech3 жыл бұрын
I did this with a similar circuit using a bipolar junction transistor. I used an inductor as it is low resistance to the DC bias currents and passes them through. The varying signal voltage is high impedance to the coil and that passes through the speaker that is connected across the coil.
@jamesgilmore23893 жыл бұрын
Excellent video. Thank you.
@chronobot2001 Жыл бұрын
Nice 1950's swinger music.
@tenlittleindians3 жыл бұрын
So your using your preamplifier as a volume control? Adjusting your preamplifier up and down does what? Increase and decrease the voltage and the amperage? Does an increase in voltage or amperage have more of an effect than the other on this circuits input or are they slaves together and acting linear? I'm not too sure I have explained my questions without adding more confusion.
@JohnAudioTech3 жыл бұрын
I use the preamp as it has an easy to use dial control to adjust the source signal level. The music player volume control adjusts in large steps that is hard to fine tune. Also, the music player I use output is below standard line level so the preamp boosts it a bit to a usable level.
@Aris-wz4kq3 жыл бұрын
i have build one of your previous amplifiers (the Amazingly simple class A amplifier published by you in December 19) and i m very happy with the result. Do you think this one is better ? in quality and gain .Because if you think so i will be happy to build it.Thank you for your educational and intresting videos
@jamescox48236 ай бұрын
hi, was your scope on the drain or speaker for the 4x gain?
@roboticdart61383 жыл бұрын
Hey John, I always learn a lot from your videos and I have been wondering where the pilot signal comes from and what its purpose is, does it come from the preamp or from the scope?
@JohnAudioTech3 жыл бұрын
I made the test signal in a program called Audacity and added the 4.5KHz with 1% amplitude of the 1KHz tone. Its purpose is just to allow me to visually compare the harmonics (distortion) created in the amplifier on the scope.
@roboticdart61383 жыл бұрын
Thank you sir 👍
@boldvoltage6393 жыл бұрын
Seems like it could be a good headphone driver with maybe an opamp CC, would higher impedance be a problem?
@klaushollinetz74943 жыл бұрын
Please do another version with an equally simple CCS instead of the resistor - it could be another sort of a smaller Zen amp?
@ncuzdvarga49185 ай бұрын
Good day john, what serial of mosfet? Thank's.
@Lithium093 жыл бұрын
Please make a video on ground loop isolation. After connecting Bluetooth module my amplifier is making noises. Is there any way of getting rid of it besides using a separate power supply? There are dc transformers (isolators) in market but they are very expensive. They alone cost more than my assembly (Bluetooth module and amplifier) please help.
@dooda11932 жыл бұрын
keen
@trickyrick86213 жыл бұрын
Would love to here some your thoughts on the High Quality HIFI Digital CLASSD Amplifier Module MERUS MA12070 2X80W
@robertalabla3 жыл бұрын
Is the 4.7uF input cap a non-polar/bipolar or a regular electrolytic?
@davidgriffin793 жыл бұрын
Interesting. So, keeping it Class A, how would you remove the harmonic distortion?
@lenoircportfolio2 жыл бұрын
Hi John ! May I ask you what is the output level of your preamp ?
@danielauen77903 жыл бұрын
What do you know about the TDA8512J chip?
@aboveaveragejoe62913 жыл бұрын
Is it 1v p-p out of the preamp?
@PaiSiraseth2 жыл бұрын
nice cat
@com456dj3 жыл бұрын
Nice Video
@samppazzz2 жыл бұрын
This fet is not very linear for different voltages vs current...
@RexxSchneider2 жыл бұрын
As with most FETs, the transfer characteristic when used as an amplifier produces a drain current approximately proportional to the square of the difference between the gate voltage and the threshold voltage. This produces second harmonic distortion, but the ear tolerates that far better than odd order harmonic distortion. For comparison, a bipolar transistor has a transfer characteristic that produces a collector current approximately proportional to the exponent of the base-emitter voltage, which is far less linear. In all cases, we apply negative feedback in amplifier circuits that reduces the gain but improves the linearity. It also makes the performance much less dependant on the characteristics of the individual transistor and allows circuits to be reproducible.
@user-yh7zc9ke4s9 ай бұрын
@@RexxSchneider your comment is pure gold for me
@t1d100 Жыл бұрын
Fun
@basterma3 жыл бұрын
Snickers
@thekillerdog5228 Жыл бұрын
Anyone want to make me happy, if u can tell me why when i built this it worked but as soon as i build it on a breadboard it doesnt, just heats up so u think hmm easy bad breadboard right! New evga broadboards and same issue, so i rebuilt it by hand and omg! Still dont work, so now im like hmm maybe a blown part NOPE! 7MONTHS later and im still doing the same b.s i have over 100x transistors now and other parts and still still still cant get it too work! What! But i can build class ab etc no problem! Like im ether being haunted by a electronic ghost or all these videos are capper then bitcoin.