回復 12730# agic
哦....明白了....{:8_399:}
四方Alnico{:6_181:}
四方Alnico
xover 發表於 2012-5-31 12:05 http://www.post76.com/discuss/images/common/back.gif
{:6_121:} 巧新淨呀.....
回復 12733# beerboy
你地估下呢隻係乜..... {:8_403:}
回復 12734# beerboy
Pass: Well, I suppose everyone, when they settle down to do creative work, likes to think of themselves as artists. In that regard I see myself as primarily a circuit topologist. That's what interests me—it's the basis of my patents, and it forms the central thrust of my design effort. I like very simple topologies—-the simpler you can make an amplifier, the more likely there is be good correspondence between the sonic performance and what you measure on a bench. The more complex, the less likely that is to occur. Having been through other designers' amplifiers for years and years now, I've come to learn that the amplifiers everyone regards as classics—the ones that stand out over the years—if you look at them you find that they were fairly simple topologies. And they were elegant—they are elegant. So I strive for that.
But at the same time there's quite a bit of room for creativity. The dynamic bias was one such example, I think. The Stasis amplifier certainly stands out as probably the premiere example of a simple, creative topology that's done a very good job and stood the test of time. It's my fundamental belief that if the idea is correct, if the topology makes real sense, the amplifier will tend to function right off the drawing board with very little extra work required. So as a rule, we don't spend a lot of time tweaking the individual values of capacitors and such. You certainly have to go in and make all of those adjustments, but I've seen other manufacturers who start out with a design, then tweak it at length in an exhaustive series of adjustments until they finally get what they want. I'm a lot happier with a design if it rapidly converges on proper performance. If it doesn't, I think there's something fundamentally wrong with the approach
回復 12735# beerboy
The notion of simplicity ties in a bit to short- or long-lived trends—I don't want to call them fads—where the emphasis in electronics has been in one area over another. When Threshold first started out, back in the Phase Linear days, high power was the item that was going to deliver the performance that everybody really wanted. The emphasis was on high power. Then, high power and very little distortion, so that static figures—getting those double-0 distortion specs—became very important to everybody. But people still weren't satisfied with that. "How come tubes still sound better?" was a very common refrain.
The focus then shifted to slew rate and TIM—low amounts of feedback and high-speed circuitry—the idea being that high-speed signals would somehow confuse an amplifier. People began building fast amplifiers and, lo and behold, quite a few of those fast amplifiers sounded significantly better. The interesting thing was that in order to achieve that higher speed, they had to make the circuits simpler. I don't think it was actually a cause-and-effect relationship. I think that for the most part the higher-speed circuits sounded better because it took simpler circuits to get high speed with stability.
However, there were some examples of very high-speed circuits out of some companies—who shall remain nameless—where they were doing 1000V/µs but everybody thought they sounded pretty bad. And tube circuits aren't so fast, especially after they get through the output transformer. The notion of measuring slew rate on a tube power amplifier doesn't make a lot of sense because you don't ever get to observe slew as such.
After that, though, the focus shifted to class-A and high current. High current seems to have been the real thing that a lot of people began buying by. In other words, they stopped worrying about what the distortion spec and the slew rate were and simply wanted to know how many amps it would put out. And we, along with other high-end manufacturers involved in the race, have been able to demonstrate how much high current we can deliver. I believe we are the champions of that, and I say that only because we've publicly demonstrated output currents on amplifiers in excess of 200 amps. I haven't seen a similar demonstration elsewhere. But in fact, we do get output currents for brief periods of time that will go up to those levels, with fairly low distortion. I've got some examples of amplifiers where the output current is ±100A sinewave into, say, a 0.1 ohm load, at about 1% distortion. Not bad at all. And there really isn't any limiting built into the amplifiers. In our latest brochure we published the curves of all of our amplifiers at 8, 4, 2, and 1 ohm, and they actually hold up pretty nicely.
There is some reason to do this. Some loads that are out there do go below an ohm. Quite a few of the electrostatic designs have been observed to hit points below an ohm. Some of the woofers from major manufacturers go down below an ohm. And when you start looking at that you can see that there's some merit to having that much current. You can also view it from the standpoint of the engineer's bias. The engineer always says, "Well, if an amplifier is going to be called upon to do say, 10 amperes, then let's just put a 10:1 margin on it." This is a very common thing. I've heard John Curl say it, I've heard other designers say it...Well, 10:1 is pretty good. That sort of thinking was being used also when people were dealing in slew rate. A 1000V/µs slew rate was, at one time, obviously state-of-the-art, but it was also being touted as "you need this!"
回復beerboy
你地估下呢隻係乜.....
beerboy 發表於 2012-5-31 14:12 http://m.post76.com/discuss/images/common/back.gif
如果有，你會唔會入先~~{:1_338:}
如果有，你會唔會入先~~
siukit_siuhan 發表於 2012-5-31 15:19 http://www.post76.com/discuss/images/common/back.gif
唔會。因為對得多會腦缺氧.... {:8_369:}
唔會。因為對得多會腦缺氧....
beerboy 發表於 2012-5-31 03:29 PM http://www.post76.com/discuss/images/common/back.gif
老pass 每格一段時間就玩一D
老pass 每格一段時間就玩一D
xover 發表於 2012-5-31 15:48 http://www.post76.com/discuss/images/common/back.gif
隻speaker有d material係用影印機d料做...對得耐會腦缺氧.....{:8_385:}
