I am with John, except I do not try to use "as little feedback as I can". I try to use either zero, or as much as I can. But practically other factors play the role, like using some parts that have better other parameters, while have excess voltage gain. If compensation does not screw down phase response it is acceptable. If it does, it is "too much". Sometimes it is better to use 2 stages with local feedbacks than one, even if one can provide enough of gain with less feedback. Especially with opamps, when it is better to use dual opamp in place of single one.
Also I am in love with nested feedbacks. They remind me human body: combination of nervous and endocrine systems.
That's nice, but the key point is that you are quite obviously unusually enthusiastic about sound reproduction.
THAT, and not the parts, is what produces great audio gear.
Wavebourn, it's not just that, I think much more of a problem is that there are way too many gadgets around to occupy the public's fancy. One can't have it all - cell phones, tablets, DVD/Blue Ray, PCs, etc, etc, etc.
A cell phone can play music, but an audio system can't call up your friend.
A cell phone can play music, but an audio system can't call up your friend.
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I wonder if sometimes, worrying about PSR (PSRR) creates a problem because it favours a mental picture of the amplifier somehow being a creature that is separate from the power supply and yet it seems those who have spent time in looking at these things find a better sound when the amplifier is considered to include the power supply, warts and all.
some well known publications about the affect of different feedback levels supports this approach. But other reports I remember reading show that any amount of feedback can be a benefit. It appears to depend on the topology and the type of active devices. A square law device in Class A seems to fit the zero or lots model, a BJT push-pull Class AB output seems not to.
where I am today in my journey to learn and understand more about amplifiers I feel it is easier to design without feedback. I think there are people who believe the opposite, that feedback makes life easier. But there are so many nuances to consider when using feedback and it's impact on the sound that I usually just accept the 'sound' I get when I use feedback because I don't understand enough how to optimize it (e.g. short local loops of low impedance with little phase shift and no rf ingress with wide power bandwidth and careful pcb layout to avoid parasitics etc.).
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How does one consider the workings of any amplifier without taking into account its power supply?
No amp I have ever heard of or seen will operate without power supplies. They are, therefore, an integral part of the amplifier itself, even if they are mostly not shown on various schematics, or are shown separately.
I think it's hardly necessary, at least in this company, to expound the virtues of a high quality power supply. A quality power supply will, literally, can make or break an amp.
In my wild and misspent youth, I experimented a few times in the opposite direction, giving generally dull amps a different, much upgraded power supply, only to discover that they were in fact capable of much better results than originally. Since power supplies are not cheap, far too many manufacturers choose to "save" on them, the end result being a product performing below its actual capabilities.
But I honestly don't think there's a soul here which needs to have that explained to him.
No amp I have ever heard of or seen will operate without power supplies. They are, therefore, an integral part of the amplifier itself, even if they are mostly not shown on various schematics, or are shown separately.
I think it's hardly necessary, at least in this company, to expound the virtues of a high quality power supply. A quality power supply will, literally, can make or break an amp.
In my wild and misspent youth, I experimented a few times in the opposite direction, giving generally dull amps a different, much upgraded power supply, only to discover that they were in fact capable of much better results than originally. Since power supplies are not cheap, far too many manufacturers choose to "save" on them, the end result being a product performing below its actual capabilities.
But I honestly don't think there's a soul here which needs to have that explained to him.
Well, there's always a tendency to think about individual bits divorced from the overall picture. PSR is one factor in the overall design, but clearly not the only one. There are excellent designs with simple power supplies and high PSR, but also excellent designs with lousy PSR and elaborate supplies. Many valid approaches; I tend to favor the former, but that's a design esthetic choice, not the One Way to Nirvana.
Perhaps its time to revisit battery power supplies.
It seems a lot of the problems created by trying to convert and filter AC would be eliminated.
Though it may not be practical for commercial companies, for diyAudio it should be doable.
I have wanted to have a battery power supply, even just to compare the effects of filter caps to different frequencies vs. a "true" battery.
Do you think you could here a difference between Lithium and Lead acid?
Buckle up.
It seems a lot of the problems created by trying to convert and filter AC would be eliminated.
Though it may not be practical for commercial companies, for diyAudio it should be doable.
I have wanted to have a battery power supply, even just to compare the effects of filter caps to different frequencies vs. a "true" battery.
Do you think you could here a difference between Lithium and Lead acid?
Buckle up.
No question about, it is doable.
But, ...
Battery power supplies work wonderfully in preamps if assisted with a shunt regulator. Wonderfully! With that setup, I wouldn't buy my own filter.
Unfortunately, batteries are very slow, and will kill stone dead any dynamics of a power amp in a jiffy. You can try it, but I'll bet you'll be back to regular vanilla very quickly.
But, ...
Battery power supplies work wonderfully in preamps if assisted with a shunt regulator. Wonderfully! With that setup, I wouldn't buy my own filter.
Unfortunately, batteries are very slow, and will kill stone dead any dynamics of a power amp in a jiffy. You can try it, but I'll bet you'll be back to regular vanilla very quickly.
Yes, there are advantages to it, but you have to be aware of the relatively high impedance of batteries compared to good regulators. I use batteries in my mike preamps, but the circuit has high PSR so that the several ohms of impedance are rendered moot and the advantages- total isolation for 60/120Hz and portability- can come to the fore.
For high level circuits, I don't quite see the point.
Maybe latter on this weekend I will try measure the internal resistance of some Lithium batteries.
I suppose it (internal resistance) would be less of an issue at higher voltages.
If you are worried about dynamics, capacitors could be used in conjunction with the battery. Certain combinations may compliment each other nicely.
At least the hash would be gone.
My little DIY SS amp runs for tens of seconds after power down, at low volume levels the clarity change is noticeable.
This is an otherwise "silent" amp I will add.
I suppose it (internal resistance) would be less of an issue at higher voltages.
If you are worried about dynamics, capacitors could be used in conjunction with the battery. Certain combinations may compliment each other nicely.
At least the hash would be gone.
My little DIY SS amp runs for tens of seconds after power down, at low volume levels the clarity change is noticeable.
This is an otherwise "silent" amp I will add.
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You would.
After all, the theory of cybernetics is said to have two fathers. One is certainly Norbert Wiener, who established it as science (key work: The Human Use Of Human Beings, cca 1947), and the other one is Oscar Lange, from Poland, who put the science on its mathematical feet (throughout the 50ies).
You would.
After all, the theory of cybernetics is said to have two fathers. One is certainly Norbert Wiener, who established it as science (key work: The Human Use Of Human Beings, cca 1947), and the other one is Oscar Lange, from Poland, who put the science on its mathematical feet (throughout the 50ies).
I have no connections with Poland. I was born and raised in Russia, so I know that steam machine was invented by Polzunov, radio was invented by Popov, filters by Chebyshev, geometry by Lobachevskiy, periodical table by Mendeleev, helicopter by Sikorsky, rocket by Tsiolkovsky.
I have no connections with Poland. I was born and raised in Russia, so I know that steam machine was invented by Polzunov, radio was invented by Popov, filters by Chebyshev, geometry by Lobachevskiy, periodical table by Mendeleev, helicopter by Sikorsky, rocket by Tsiolkovsky.
Ah, so!
Well, actually, the helicopter was first made to work by Sikorski indeed, the only fact left out is that he did this in USA.
Mendeleev did, as far as I know, create the periodic table.
And Chebyshev did come up with some fine filters, a fact that for example Technics made much play of in the late 70ies. They used them. Of course, that's just one type of filter, as there were a few other people involved, for example, a man called Butterworth seemed to be very keen on them, then there were Linkwitz and Riely, and a few other boy scouts.
But if memory serves, the actual first rockets which worked were invented by the Chinese. The Russians did indeed do much work on them, they invented the Katiyusha, which the Germans during WW2 showed surprisingly little appreciation for ...
I saw live what a derivative from a mobile launch platform can do while doing my national servce in 1980/1981 during some war games - man, that is some scary stuff. Turns you into a peacenick in a second.
Make love, not war, speak sopftly but always carry a condom.
What is amazing, is how each country has INVENTED virtually all the major inventions. I was taught in elementary school that Americans invented almost everything.
Later, I found out differently. Still, don't the Germans have their own order of inventors?
The British? The French? Let's compare.
Later, I found out differently. Still, don't the Germans have their own order of inventors?
The British? The French? Let's compare.
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