I answered. I can't hear the noise of the op amp.
Are all operational amplifiers. Including the cheapest jrc4558. I still can't recognize its noise.
If you want to tell me that you can recognize the noise of a certain model of operational amplifier. please tell me.
Listen carefully. I mean, listen with your ears. Instead of measuring with instruments.
I have APSYS 2722.
I don't believe anyone can recognize the noise of the operational amplifier itself.
If there is noise. That is also the problem of circuit design. Rather than the operational amplifier itself.
Has anyone looked at the new Hypex amp diy module and its new pwm ? Quite impressive. Too expensive for my pocket for a stereo pair but still affordable vis a vis a FM Acoustic...https://www.diyclassd.com/
Not sure why you call their 3886 amps impressive. From where i stand it was the exact moment JR amps turned into fast food with smart packaging. And stayed there.
Hard to draw any universal conclusions about BJT vs Mosfets from this. All Accuphase class A amps use mosfets and all of their class AB amps use bipolars. You may just as well conclude that class A sounds less dynamic and slower than class AB. Is it the transistors or the biasing? Or perhaps both have a similar harmonic signature ?
Like clockwork, every few years he comes out with a new world record class D design, the man has undeniable talent...
Oh OK yes, he seems a talented and nice guy but also very commercial (or the brands he is affiliated with?) which is his good right. However, the heavy marketing and buzz word content put me off so I never bothered with the stuff except seeing/hearing it at others. Prices are also quite high IMHO and I have diagnosed a few of such devices after failure. Maybe judged too soon but I skipped it all together.
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Ah well, of course cheaper would be nice, but I can't fault him for making money with his designs!
You heard that AD827 sounded worse than NE5532 - seeing as the AD827 is considerably noisier its quite possible you heard its noise but didn't identify it as such. What was the context of your comparison of these two opamps (gain structure, resistor values)? The AD827 DS shows its distortion as around -90dB 2H which I very much doubt would be audible.
In my opinion, class D amplifier is like a digital device.
Similar to mobile phones. Or tablet. It can constantly update some parameters that are useless in my opinion. For example, 400kHz and 800KHz. Then let customers continue to buy and upgrade. In fact, its essence has not been improved. It is difficult for traditional amplifiers to make more money. And it will hardly be damaged. Businesses don't like a product that can be used for more than 50 years. And the performance is very good.
It's not just a class D amplifier. DAC is also included.
I don't think DAC is very useful. People keep changing from 16bit to 44K Upgrade to 32 bit 384k
In fact, I didn't hear any improvement. But the number can always rise. isn't it?
Just like CPU.
That's true. I use a big earphone. Connect an OP amplifier circuit board.
There is a socket on it. I try to recognize the difference by constantly changing the Op.
I have many samples presented by Ti ad BB company. Including many expensive ops.
AD827 827 8610 8620 OPA2227,LM4562 ，4580 5532
There are many models. In fact, I didn't recognize the difference. I didn't recognize the noise either.
But I feel that ad827 is inferior to ne5532. But it is not very accurate. And I found that ad827 works at a low magnification. Oscillation will occur. Fever. Ne5532 does not have this phenomenon.
In addition, I also used APSYS to measure op a long time ago.
I found that the distortion of ne5532 may be second only to lm4562.
Ad827 opa2604 has very high distortion. I don't recommend it.
in fact. I have designed many amplifiers.
But I try to avoid discussing products designed by myself. Because such a discussion will make people lack impartiality.
In fact, I don't object to other people using MOSFET. After all. That has nothing to do with me. I just want to tell others my results. In fact, MOSFETs are widely used in my products. BJT is also used.
I know very well what would be better. Even for me. It's better for me that people like MOSFET.
Because I use MOSFET a lot. But in fact. BJT。 Especially BJT dedicated to audio.
For example, tta1943 5200 and 2sa1186 2837 are paired. Transistor for audio.
It is the best output semiconductor component I have found in the world. There is nothing better.
Well, pwm are also made to avoid expensive parts like big traffos, big heatsinks... For me his diy products are sold at the price of on shelves products good enough.
It is like the green houses and the new materials and modern building constructions technics. They are cheaper and faster to build the house but you pay more and the extra margin goes in the macons pocket.
They say it is global warming but they do all for you to continue to heat the world. I am going to make a Class A from Pass and maybe recap the pwm of my 22 yo Chord amp.
Anyway the op seems just to be one of the numerous chi-fi back kitchen designer without solid knowledge as everybody noticed.
Unsubscribed. Learned nothing.
"chi-fi back kitchen designer" is a title I would carry with pride 😀 Thanks for the laugh 🙂
That remark is to the point.
Let me give a simple example.
Used to describe PWM amplifier. Ordinary analog amplifier. And the principle of class a amplifier.
For example, we need to design a regulated power supply (the amplifier is actually a regulated power supply)
For example, we need to stabilize the DC voltage of 30V to obtain 12V DC voltage. No matter how 30V changes, or it will become 31 or 28V in a moment. But the output DC 12V voltage will never change.
Then we have two plans.
1. Use PWM regulated power supply. That is, PSU. Get 12V voltage. This is the same principle as class D.
2: Use LM317 regulated power supply to obtain 12V voltage. This is the principle of traditional analog amplifier.
3: If LM317 plus constant current source is used. Get 12V voltage. But it keeps its current at maximum. This is the principle of class A.
In fact, we can draw a conclusion through this principle.
No matter it is a good place. Or worse. We can all understand it easily.
For example, PWM will save power. But its output signal is worse than LM317. There is no purity of LM317 power quality. When the current fluctuates greatly. PWM may cause the output 12V voltage to drop more.
However, LM317 will have a high voltage difference. So it will generate relatively large amount of heat. Of course, this is related to the output current. The voltage is also related to the input voltage minus the output voltage.
So it's actually easy for us to judge. What are we doing. What kind of products are needed.
But many people don't understand this.
If the output voltage is very low. electric current. Then I think LM317 will be better for this regulated power supply.
If high current output is required for a long time. And it is not particularly sensitive to the voltage fluctuation of the output.
Such as TV. Charger. I think it would be better to use PWM power supply.
PWM= CLASS D。 Lm317= linear amplifier.
Ha ha🙂 you have a cynical view. Appreciated. Reverse logic and incorrectly dumbing down of environmental subjects are a weekly recurring issue.
I agree... though class D seems destined to overtake bipolar devices with GaN mosfet devices appearing in modules as per below. With user selectable slew rates between 25,000 to 100,000 volts/usec of the device indicated some extraordinary engineering seems necessary to realize such abilities. In other words no ordinary engineering. The results can go far beyond that suggested by simply doubling the PMW frequencies.
https://www.ti.com/lit/ds/symlink/l...ps%3A%2F%2Fwww.ti.com%2Fproduct%2FLMG3410R050