Christophe; it is culture-dependent, like it or not. A German guy was doing push-ups on the beach, when French guy said, "Your woman left!"
Both were right.
He is a hero to calculate 7 poles (what for?) I am too lazy, I keep things much simpler, Like he did when was not afraid to include the filter into the loop.
But may be let's ask Bruno himself? May be he meant something way different that can help us a lot?
Both were right.
He is a hero to calculate 7 poles (what for?) I am too lazy, I keep things much simpler, Like he did when was not afraid to include the filter into the loop.
But may be let's ask Bruno himself? May be he meant something way different that can help us a lot?
What I heard the big Byrstons on was the Martin Logan CLX, Totem Wind, and the PMC studio speaker Bryston distributes here in North America. They can be impressive dynamically, but they are harsh and undetailed compared to Pass and Parasounds I have heard on 2 of these speakers even using a Bryston preamp and Bryston DaC / CD player. I like other amplifiers and anchovies on pizza - there is a link......
I also have Quad 63's and took the dust covers off them. They hissed every summer. I hand carried them to Huntington in the UK in the late 90's and had them totally rebuilt. Then they were too wide to sit next to the LCD TV and have been in the crawlspace for 15 years...
I also have Quad 63's and took the dust covers off them. They hissed every summer. I hand carried them to Huntington in the UK in the late 90's and had them totally rebuilt. Then they were too wide to sit next to the LCD TV and have been in the crawlspace for 15 years...
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Standard control system theory applications. For ultimate linearity, you keep the OL gain up as high as possible for as long as possible, and then it falls off with, according to Bruno, 100dB/oct. Then (his words again) you put on the breaks just before it gets to unity gain and slow it down to 6dB/oct to keep it stable.
Lots of zeros and poles to juggle, and he does it masterly.
I have seen this kind of thing in for instance missile intercept and attitude control loops, but never in audio.
jan
The French reputation is highly over-evaluated, concerning their interest to women. Lot of them have been married...
Brrr...
http://www.youtube.com/watch?v=ytAYsn__ZZI
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It is the limitation when you fly to the Mars, but amplifying audio? Still I wait for Bruno to explain. Thanks Jan anyway.
The key to the basic UcD is a comparator with "substantially" no hysteresis and just a little delay, which along with the two poles of the basic L-C output filter and overall feedback, gives you the self-oscillation. Unlike many, the patent is fairly open to comprehension.
I think Philips (the patent holder) assumes that you will simply copy the early reference design, down to the last discrete bipolar driver transistor. I gather that BP has gone well beyond that initial design for the Hypex products.
I think Philips (the patent holder) assumes that you will simply copy the early reference design, down to the last discrete bipolar driver transistor. I gather that BP has gone well beyond that initial design for the Hypex products.
Prof. Edward Cherry showed how to do this for simple (?!) amps with his NDFLs. (check out the AES library) His analysis of PA behaviour is a 'must (heavy) read'. But you don't have to go to his lengths to get substantial benefits from his insights.
Some months ago I started playing with Bruno's topology in LTspice, the goal is 2.4kW into 8R, quite doable in fact. No major problems so far, but it's been pushed to the back burner, other enthusiasms and life came along, as is always the way. So, it's a round tuit for the moment ...
Frank
Frank
National Defense Foreign Language ?
Natalie Dufty Family Law (New Zealand) ?
North Dakota Film Library (Fargo, ND) ?
Nuclear Development Field Laboratory ?
CAE (Committee for Acronym's Eradication)
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Nested Differentiating Feedback Loops
AES E-Library Nested Differentiating Feedback Loops in Simple Audio Amplifiers
An anecdote about Ed Cherry: Floyd Toole intended to do graduate electrical engineering study with him and came to the institution where he thought he was at that time.
But it turned out that Professor Cherry was Prof. Edward Colin Cherry: Colin Cherry - Wikipedia, the free encyclopedia
And things changed a lot
But it turned out that Professor Cherry was Prof. Edward Colin Cherry: Colin Cherry - Wikipedia, the free encyclopedia
And things changed a lot
This is the "apparent" dilemma of audio: a system must be able to reproduce the dynamics cleanly, but if it succeeds in doing this then all the deficiencies elsewhere in the chain are ruthlessly exposed. So, you either pull back on the dynamic capabilities, "politise" (what a word!) the sound; or you clean up the whole system. Very different approaches, usually very little overlap
My approach is to get the dynamics happening first, the guts must be there in the reproduction. It will be aggressive, in your face, just another PA sound at first glance. Then, you start refining, you find all the weaknesses, one by one, and eliminate them; when enough of the elements causing the harshness are dealt with, almost as if by magic the sound will gell: the hifi, PA qualitities will fall away and completely natural, full impact, realistic reproduction will take its place.
Frank
Thanks a lot.
We, speaking other languages, with enough efforts to translate and different acronyms for the same things, can understand-it much better that way.
Frank, i vote for you.
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some other things about optical fiber
This just seen: Stanford Researchers Use Synthetic Magnetism to Control Light | News | Product Design & Development
Actually their latest 'specs' are much less outrageous than their original claims. Now about the level of a better than average electret omni.
Maybe they ran out of Unobtainium & virgins
This just seen: Stanford Researchers Use Synthetic Magnetism to Control Light | News | Product Design & Development
So true.
And there is two listening fatigues.
The first one is physical, when a system is very sharp high level and dynamic, with every attack well defined, you cannot listen too long at it. It is some kind of violent pleasure, the one i'm looking for. And the best for 20Th century music, i believe.
When a system is soft and smart, there is a different fatigue. You get tired with your brain's efforts to separate the instruments. The best for classical music, i believe. You can listen longer, but you listen with less attention.
Ferrari or Rolls.
Designing a system, as Frank said, the first situation put you in front of lot of defects to correct, from sources etc. "right in your face".
But, yes, it is more easy to go from this to a more fluent system, than the contrary, and, at the end, more natural and easy.
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But, where I may go in fact a slight step further is that I believe you can get the Ferrari and Rolls at the same time; so what I look for, for example, is replay of classical music with tremendous intensity and bite, the violins should have that a true, luxuriously sizzling edge to them, with no harshness, and a trumpet call should knock you sideways. This is indeed difficult to do, far from being a trivial list of steps to follow to get there, but once experienced anything else is too much of a compromise ...
Frank
It depends on whether there is a dynamic amp which reveals deficiencies elsewhere in the system, or whether an amp may be both dynamic and having a harsh sound to it.
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