elektroj,
Electrons don't know they are in a piece of audio equipment, they just follow the laws of physics. You can't suspend those laws, they apply everywhere. By that inconvenient truth, Marce's professional experience applies to audio (called base band) frequencies. At least he and others who do have experience understand and recognize what affects the signal. How you hear this signal has everything to do with your prejudiced opinions and nothing to do with the actual truth that defines what happens to that signal. You are welcome to have questions about how things work, but you are in no positions to take anyone who has experience to task by inferring they don't know what the are talking about. This comes down to a lack of respect. As for support, his education and actual work experience qualifies him to offer information to people who are reading along here. Just because Marce does have qualifications and experience doesn't mean you have the right to call those into question just because you have no other argument to offer. His real world experiences do qualify him to the statements he has made here, and this also goes for every other member or reader with similar experience.
Personal attacks are not acceptable here. Please refrain from doing this
-Chris
Your honest opinion is flawed to the point of being silly.
Electrons don't know they are in a piece of audio equipment, they just follow the laws of physics. You can't suspend those laws, they apply everywhere. By that inconvenient truth, Marce's professional experience applies to audio (called base band) frequencies. At least he and others who do have experience understand and recognize what affects the signal. How you hear this signal has everything to do with your prejudiced opinions and nothing to do with the actual truth that defines what happens to that signal. You are welcome to have questions about how things work, but you are in no positions to take anyone who has experience to task by inferring they don't know what the are talking about. This comes down to a lack of respect. As for support, his education and actual work experience qualifies him to offer information to people who are reading along here. Just because Marce does have qualifications and experience doesn't mean you have the right to call those into question just because you have no other argument to offer. His real world experiences do qualify him to the statements he has made here, and this also goes for every other member or reader with similar experience.
What a nice response to give to a person who is attempting to help you. In fact, you have to at least try to take on some information - knowledge here. Otherwise it will be impossible for you to ever learn why things happen and target your funds accurately to solve your problems with any system. Remaining ignorant of the science behind how and why things do what they do means that all you have left is magic to explain these things. If that is the road you wish to take, fine. But do not disrespect more knowledgeable members on the basis of whether you like their message or not.
Personal attacks are not acceptable here. Please refrain from doing this
-Chris
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My experience with Yokogawa TA520 (25pS resolution) was similar. :-(
I was measuring oscillator jitter directly, I have to say, not recovered clock coming from AES receiver IC.
1audio, have you tried setup similar to what these Dutch guys did, i.e. connecting PLL output, if it is accessible, to audio analyzer? I think I've posted the link before:
DAC Overview
This test seemed OK to me for relative playback device jitter comparisions and somewhat similar to tests that Stereoplay did back in 1993 with Remy Fourrer analyzer:
A Transport of Delight: CD Transport Jitter | Stereophile.com
Some lighter fare if I may; played a bit with my vintage QUAD 405-2 this afternoon. You know that this current dumping amp is basically a bridge with 4 elements: 2 resistors, a cap and a coil. Bridge balance would (in theory!) cancel all distortion.
I replaced one of the Rs with a trimmer so that I could balance the bridge, and what do you know, I could cancel the odds to the point that they disappeared in the noise. Isn't that a nice experiment! JC you must love this amp no 5ths, no 7ths!
Jan
I replaced one of the Rs with a trimmer so that I could balance the bridge, and what do you know, I could cancel the odds to the point that they disappeared in the noise. Isn't that a nice experiment! JC you must love this amp no 5ths, no 7ths!
Jan
Attachments
I would cautiously added after "the laws of physics": "to what we know about them". ;-)
That could/might be done. First, it is my own system that I want to measure, as it is used. Also, as with distortion(s), I want to know what I can hear or detect.... what my own jitter threshold is. That way, if I read a spec or a measurement somewhere, I will know its significance to myself. .... and what adding and removing jitter sounds like to identify it when I hear it.
THx-RNMarsh
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Some lighter fare if I may; played a bit with my vintage QUAD 405-2 this afternoon. You know that this current dumping amp is basically a bridge with 4 elements: 2 resistors, a cap and a coil. Bridge balance would (in theory!) cancel all distortion.
I replaced one of the Rs with a trimmer so that I could balance the bridge, and what do you know, I could cancel the odds to the point that they disappeared in the noise. Isn't that a nice experiment! JC you must love this amp no 5ths, no 7ths!
Jan
Very
What do you speculate the values of the coil and cap came from? Quad's speaker? How can you/we modify any existing PA to include this feature??
THx-RNMarsh
Marce, you're not even funny.
Why do you think that, because this is DIY forum, everyone posting here is some noob with 60W soldering iron in hand and desperate for your unasked advice? How do you know who you are talking to here? ;-)
IMHO, you are entitled to criticize others only if you have experience in your field RELATED TO AUDIO, in which case it shouldn't be difficult to provide practical examples of YOUR WORK IN AUDIO field to support your critique.
Telling people here how smart you are, how many space shuttle PCBs you have done and what mega-million dollar company pays your hotel bills is pointless showing off.
As to the links and papers... you know what? I can send you links and provide papers on the subject that will keep you busy reading for weeks.
Your response is rude childish and pathetic, it shows ignorance as well, I am not happy.
Many have appreciated what little help I have been able to give them...I do not understand your vehemence.
I don't wish to shatter your illusions but audio is no different from any other field of electronics, and the basics of digital clocks apply in ALL situations.
elektroj,
Your honest opinion is flawed to the point of being silly.
Electrons don't know they are in a piece of audio equipment, they just follow the laws of physics. You can't suspend those laws, they apply everywhere. By that inconvenient truth, Marce's professional experience applies to audio (called base band) frequencies. At least he and others who do have experience understand and recognize what affects the signal. How you hear this signal has everything to do with your prejudiced opinions and nothing to do with the actual truth that defines what happens to that signal. You are welcome to have questions about how things work, but you are in no positions to take anyone who has experience to task by inferring they don't know what the are talking about. This comes down to a lack of respect. As for support, his education and actual work experience qualifies him to offer information to people who are reading along here. Just because Marce does have qualifications and experience doesn't mean you have the right to call those into question just because you have no other argument to offer. His real world experiences do qualify him to the statements he has made here, and this also goes for every other member or reader with similar experience.
What a nice response to give to a person who is attempting to help you. In fact, you have to at least try to take on some information - knowledge here. Otherwise it will be impossible for you to ever learn why things happen and target your funds accurately to solve your problems with any system. Remaining ignorant of the science behind how and why things do what they do means that all you have left is magic to explain these things. If that is the road you wish to take, fine. But do not disrespect more knowledgeable members on the basis of whether you like their message or not.
Personal attacks are not acceptable here. Please refrain from doing this
-Chris
Sorry Chris, you're just a few thousand pages too late with your no personal attacks here, at some point, that's all we had here. It's all there, in the log. Deplorable, and some of it coming from your fellow moderators, too.
This thread lacks some basic manners at times, which is a great pity, because at the same time, we have some outstanding contributors, so in effect, we end up by wasting valuable time and on occasion, patience. It's only in mathematics that two minuses produce a plus, in social relations two minuses will most likely produce intermodulated minuses which will quickly pile up.
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Very
How can you/we modify any existing PA to include this feature??
THx-RNMarsh
No the bridge values have no direct relation to the load. It's really inherent in the design of the current dumping concept; very smart. When the dumpers come in, it doesn't just change the loop gain but it also changes the feedback factor to compensate for the dumpers gain. That's where the bridge comes from: feedback from the class A main amp and the feedback from the dumpers chain form a bridge-like circuit and when precisely balanced it cancels all changes in loop gain and feedback factor.
Not something you can casually insert in a 'regular' amp.
Jan
In a regular amplifier you can use an input output comparator to generate an error correction signal. This can be applied through a gain reduction resistor via a separate cable to the loudspeaker terminals. Very tricky to properly balance it.
The problem with this and similar approaches is that it is pretty much impossible to maintain the balance over frequency. All kinds of parasitic inductances and capacitances will rear their collective ugly heads. If you read Giovanni Stochino's articles in Linear Audio you'll know that those issues are by far the most difficult - all else is child's play.
The beauty of the current dumping approach is that the bridge has a cap and an L, so with increasing frequency the cap impedance goes down but the L impedance goes up. The bridge is arranged such that the ratio of the two arms (one with the cap, the other with the L) remains constant. Peter Walker was a brilliant designer, the epitome of 'thinking out of the box'.
Edit: attachment from a presentation I once did gives the concept.
Jan
Attachments
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fields and shielding
BTW, Audio Precision learned that their AUX0025 passive lowpass filter box had to be made of non-ferrous material to meet spec. Inductor selection was also critical, as one would expect.
Thanks for these posts regarding fields. Another book that has a very good discussion of fields and shielding is Peter Fish, Electronic Noise and Low Noise Design, 1994, McGraw-Hill, ISBN 0070210047.
BTW, Audio Precision learned that their AUX0025 passive lowpass filter box had to be made of non-ferrous material to meet spec. Inductor selection was also critical, as one would expect.
Rats! It would be more useful at a higher power level. Being able to trim out the distortion would be a plus for DIY'ers.
Why didnt this idea get taken up by other mfr?
THx-RNMarsh
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Hi Dejan,
On June 29th in 2009, I split this thread off from the original one. We had to keep the thread in reasonable lengths for maintenance purposes, and it was hoped that some of the fighting would be interrupted. Didn't work for the latter and the former doesn't seem to be a problem anymore. There is one particular division among our members that is about the most destructive I have ever seen. Some folks use that "argument" time and time again to voice disagreement over some comments. Specifically, to attempt to cancel information from people who actually work with various signals. Everyone loses when this minority is allowed to dump the applecart. My interruption at this time was in response to that exact issue. I saw the first rocks go in this instance and stepped in.
There are a few conversations ongoing right now with great information from various people, and I think this is why people come here to begin with.
-Chris
Yes, but things were going along very smoothly for a bit. I think we are all tired of the other issues being dragged in time after time.
Well, they are just human and try to do their best. We post as normal members, we just have more work to do. Each also has their own personality along with those "hot buttons" like everyone else. Your point is valid and serves as a reminder that the mod team needs to try to keep feelings under wraps. For the most part, I think we do that pretty well.
I couldn't agree with you more! There are some people with excellent reputations that you wouldn't expect would be involved in some of what goes on. But, as I said above, they are just human too. Everyone has buttons that when pushed gets them in a fighting mood.
Given the length of time people have been at it, I would say that you have made a good observation. I have been guilty of these things myself. People playing games is one of my buttons.
On June 29th in 2009, I split this thread off from the original one. We had to keep the thread in reasonable lengths for maintenance purposes, and it was hoped that some of the fighting would be interrupted. Didn't work for the latter and the former doesn't seem to be a problem anymore. There is one particular division among our members that is about the most destructive I have ever seen. Some folks use that "argument" time and time again to voice disagreement over some comments. Specifically, to attempt to cancel information from people who actually work with various signals. Everyone loses when this minority is allowed to dump the applecart. My interruption at this time was in response to that exact issue. I saw the first rocks go in this instance and stepped in.
There are a few conversations ongoing right now with great information from various people, and I think this is why people come here to begin with.
-Chris
One of the reasons was that the original Quad power amp intensly disliked any load below 8 Ohms and was pronouced as current starved. It was believed, in my view wrongly, that the concept is such in total, a point subsequent versions had shown to be all wrong. It just needed evolution, like any other technology.
Actually, Quad were a bit responsible for that themselves, they kept harping that the original 405 was the best choice for driving their electrostatics, which gave the impression that it was good for those speakers only. And it was not cheap in its day, although it could not be called wildly expensive.
From personal experience, the original version would balk when known to be difficult loads speakers, like AR3a Improved, were connected to it. It tonality would shift audibly the instant you asked for 3 dB more than the usual room levels. But when it felt comfortable, it was very good listening to it.
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