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I just started the video, so you will probably say it later, anyway... wouldn't it be better to actually have a capacitor on the voltage divider at the input on the second transistor (Q2) of the input diff. pair? I mean, the voltage divider works miracle for AC signal, but for DC ones you'll have a diff. pair which is not balanced, and as far as I know, that can't be good as far as common-motion rejection goes, right?

Hi..Thanks for the detailed video.How can pick an inductance value of speaker for simulation. Is it by sweeping speaker on an impedance analyser and find the inductance of the speaker for the frequency of operation? @25.00 is there any reason why which you didn't plot the power dissipation curve instead of differential of power dissipation

Using the +ve input of the MC34072 as feedback (made -ve by the mosfet) is begging for oscillation. I see the 150pf in the feedback, I hope it is enough, BUT it is part of a 150pf/1,000pf divider at higher freq.

12:45 Why is so hard to have a no-damaged speaker, this days? 🤣

Sir, i tried ur schematic on multism, the output is smaller than the input. May u give me some advice? what i did wrong?

An inverting loop made so by the mosfet inverting to positive input, your are BEGGING for oscillation, no matter the mosfet C!!!!!!!! ....SERIOSULY!!!!!!!!!!!!!!

Wow, the 100k will be dissipating 6.4Watts when the voltage is set to 0V output!

No over temp (high risk in this), no over current or short circuit protection. You might find what useful what a RUclips channel "FesZ Electronics" did. :)

Omg you are a madman

Well, it is now 3 years later... sadly there is no more video about your work on the amp. So i save my time and do not have a look at the 2nd part.

I made a similar circuit, used Fallstad simulator, i adjusted the circuit to deliver 1 amp @ 1around 9 V.p.p. swing from a 2 x 15 V transformer, so 2 x 19.6 V. Using BD137, BD140, it follows the input voltage perfectly, pcb made, on it's way. wonder how it sounds, also included 2 pole Sallen Key filter. How much watts would that be would your recon? P = U x I, states like 19 ,6 watts, right or wrong?

thank you very much

Magnifico, grandioso !! ⭐⭐⭐⭐⭐

This is excellent! Where is the rest of the videos?

Op amp drive huh🙃

just found this, its v good. any follow up?

Very well executed and thoroughly tested with great effort, I am very impressed! I am just wondering why the op-amps are functioning correctly, as they are controlled by two potentials: 15V from the power supply and at the sensor input from the output potential 0-150V. I did not know that this was possible at all. Or is it a special function of this type of op-amp? I assume that both potentials are referenced to ground, is that correct?

Hi.a question what is difference between video and audio amplifier pls answer me if you know

I wanna have your bench 😢 goddamn with your set up. At my pace , it would take me prob 10years to have those goodies. Thank you for the vid, I will copy it and test a few things. I can't believe I understand everything, I'm amazed at myself.

Very nice. Thanks.

I have a question when it comes to the inductance value of the load. What if you're designing a general purpose audio amplifier rather than pairing it to a specific driver of known parameters? Y'know, what a lot of car audio amplifiers are, what a lot of unpowered bookshelf speaker amplifiers are, what a lot of the DIY enclosures use, etc. Is there a good inductance value to use for this? Do you just pick a generalized range for inductance, such as if I'm looking at an amp for car audio subwoofers where the driver Le (the notation for inductance in T/S parameters) is commonly around 6.5mH at the high end with a handful of outliers being within the 8.5+mH range, just from glancing at some databases, would it be fair to just use Zl=Rl*1e-2 and just have the extra overhead for versatility? In the example of anything but car audio subwoofers, I know drivers are typically <<1mH, again from glancing at the same database, so would a general purpose amp just use Zl=Rl*1e-3 for the typical upper end with ample overhead?

Great job!

Out of my own curiosity, regarding Ideal #61-484, when you are in diode mode, and there is a short, does it make a beep noise like Fluke 87V? I am talking about when it is in diode mode. NOT in Continuity Mode with noise. Thanks.

Your dome is pushed-in. Not serious about the business.

Are you ever going to finish the 25W audio amp design? I has been 4 years since this was started and 3 years since you said you would restart/complete this series. Really appreciate this series but just looks like we'll never see it completed... 😒

which sensor you have used for feedback ?

nice!!!!

EXCELENTE VIDEO

I wish electronics was taught like this in college. Info is easier to absorb because of an objective which is to design.

no part 3? 😢

It's beautiful

Man this is unbelievable, thanks for the video

Hİ, which are you using books ?

Cool idea! Did you try it with only local feedback for the op amp?

1:40 This circuit has quite a few design flaws. The input stage has a very low bias current of abt. 1.7mA, leading to low transconductance and current starving of the voltage amplifier stage at frequencies above 1kHz, which in turn causes poor slew rate and distortion (mostly 2nd harmonic). It's also hugely disbalanced, because one transistor draws abt. 0.46mA (0.7V/1.5k), while the other one draws 1.7-0.46 = 1.24mA. The whole point of a differential pair is to be perfectly balanced. Deviations in transistor currents over 1% cause a significant increase in distortion (2nd and 3rd harmonic). The best solution here would be to use a current mirror - the increase in complexity and cost is negligible compared to the great improvement it makes. It's also beneficial to increase the bias current to abt. 6mA and add emitter degeneration resistors of abt. 33 Ohm to the differential pair. The dominant pole capacitor (220p) is too big. The whole point of the dominant pole compensation is to bring the open-loop gain down to unity just before the phase shift at the output approaches 180 degrees, thus turning an amplifier into an oscillator. The value of Cdom is determined by the current sourcing/sinking capabilities of the transconductance stage and the VAS collector impedance. The open-loop gain here is not that high to begin with, due to the aforementioned low transconductance and current starving of VAS. All of this leads to a poor slew rate and great increase in distortion at higher frequencies. The VAS collector is loaded by a current sink, which is correct, but there is never a need to adjust the exact current flowing through it, so the 10k potentiometer is useless. The 2.24k pot is placed between the Vbe multiplier's base and collector, which is a timebomb, because if it fails, the bias voltage will increase to a maximum, likely causing the output transistors to blow up. It's always a better idea to put it between the base and the emitter. The 3K resistor between the driver transistors' emitters is too big. Reduce it by a factor of ten and put a 0.1-1uF capacitor in parallel. Its purpose is to provide a small reverse-bias voltage to the output transistors, making them turn off faster. Doesn't hugely matter in this relatively low-power circuit. It's always a good idea to couple the lower leg resistor of the feedback circuit (10K) to ground through a large (470uF+) capacitor, thus bringing the DC gain down to unity. The input pair is never going to be perfectly matched, and you don't need to amplify the DC offset voltage. The 220K will then have to be reduced to the same value as the input bias resistor (10K in this case) to match the impedances. It's always better to keep the value of these resistors as low as practically possible to reduce the Johnson noise (the exact values will ultimately depend of the signal source's output impedance). It's also necessary to put a small (4.7-33pF) capacitor in parallel with the upper leg resistor of the feedback circuit. This circuit is likely to work fine without it because its dominant pole frequency and slew rate are very low and therefore the Nyquist stability is not compromised - but the noise and distortion figures most definitely are. That's all. :)

MAn i have been lookin at this .Symbolic amplifier design..There is only one book i have not been abel to get >and they use mathematica ..You solved all my needs

Outdated croc of shitt😮

Sir please explain the circuit , make a detail video on this circuit

High order harming is way too high, their bad can be described as n^2/n, not good performance on such design.

Great video thank you 👍👍🇩🇿🇩🇿

Very creative use of power rails, lol. I’m surprised it even works as well as it did - there must be all sorts of non-linearities between the signal and power line circuits in an op amp. Kudos for creativity.

Alvrg soy mexican. En estados unidos están a otro nivel. CHido el amplificador.

Nice video, thanks :)

There's no capacitor in Q2 after 10k resistance, so how to ground ?????

Hi, greate video and explanation!. Any progress with the video and schematic for the 800VDC regulated power supply?

All those scopes and analyzers and the one your probes are hooked to is a Rigol. 😢

Seu laboratório é incrível.

I guess you must have been on the recieving end of a company recycle, they often get rid of perfectly good equipment to justify getting the latest gear. Am I jealous? well-er-yes.

Good music..good courses