I think these documents are written to describe only part of the audio interface issue. Up to now, nobody has shown any other interconnect measurements that tell a different story. If I don't see the impedance measurements, all talk is just meaningless. Yes, I do read a lot, but I am not about to attack each report and theory. After nearly 40 years as an audiophile, I see audio technology going in circles in terms of sound quality. So you just have to choose what you prioritize and find a new approach. You can choose not to accept what I say. But if you are doing the things the same old way, you are not going to come up with anything new. Up to now, I have not even seen any anyone say how THAT chips compare against other designs in audio listening. This to me just does not link technology with audio experience. I really wonder why? There must be a lost link somewhere.
You need to understand as well as read. I think that is your problem. For domestic interconnects they can be modeled as simple lumped parameters. No magic, but plenty of confusion spread by the snake oil salesman. A balanced interconnect using a THAT receiver has 30,000 times the interference rejection of a single ended interconnect (to the pedants I know, but it sounds good). CMRR is measurable, differential pickup effects are measurable and can be prevented.
The only thing new is that very few people do signal transfer properly in domestic audio. Doing it correctly and following unfashionable pro methods as were used to produce your music in the first place may feel wrong to the audiophool but it removes another few layers of potential problems and the delta cost is cheaper than 1pr of gold star winning magic bull interconnects from the shiny shiny brigade
The only thing new is that very few people do signal transfer properly in domestic audio. Doing it correctly and following unfashionable pro methods as were used to produce your music in the first place may feel wrong to the audiophool but it removes another few layers of potential problems and the delta cost is cheaper than 1pr of gold star winning magic bull interconnects from the shiny shiny brigade
An externally hosted image should be here but it was not working when we last tested it.
Well said. So, soong, what does that curve represent? How was it measured? What are the units on the Y-axis? Ohm? How many ohm per division? What explains the upward shift of one curve compared to the others?
I bet what you're actually measuring is your sound card. In particular the sharp peak up and dramatic drop-off near 40 kHz looks a lot like the response of an anti-aliasing filter.
You say you back up your claims with measurements. Are you going to explain your measurements so we can have a rational discussion or is that a lost cause at this point?
Tom
And after nearly 40 years as an audiophile, I've seen a lot of snake oil.
There's that burning desire again. Go with it! Set up the double-blind ABX experiment and get some perceived sound quality data on the THAT1200. What are you waiting for? It seems unlikely that you'd believe a review that doesn't support your preconceived bias, so it seems a bit naive to wait for others to do the work for you. You have the skills. You have the burning desire to get the listening test results. Just do it! Go with your passion.
Tom
Now, to get back on topic: There are many mini reviews and comments of the Modulus-86 scattered both in this thread and in the build thread. It seems builders agree that the Modulus-86 is the most transparent amplifier they've ever heard. That does not surprise me a bit. After all, the measurements say that the amplifier's contributions to the output are well below - orders of magnitude below - the threshold of audibility.
Tom
Tom
No. I suggest that you show what the heck it is that you're measuring. "Impedance" you say. Great. The impedance of what? The characteristic impedance of the cable? I doubt that. You can't measure that with sound card. Need a TDR or network analyzer for that.
I saw a mention that the Y-axis should be labeled with 0 Ω at the bottom and 100 Ω at the top. Correct? So why is the cable a short circuit beyond 40 kHz? That's what you're saying your graph shows, right?
I think you have a measurement error. If you start a separate thread for it, perhaps in the test & measurement forum, I'll be happy to help you sort it out to the extent my time allows. This thread is for the fact-based discussion of the Modulus-86 and Parallel-86. Let's get back to that, shall we?
Tom
Modulus-86: Composite amplifier achieving <0.0004 % THD+N.
Tom, I never said the top of the impedance axis can be 100 Ohm. Perhaps you should just calm down and read carefully. You are letting your negativite emotions get the better of you.
Where the plot drop suddenly where the sampling rate is limiting. I normally just read data up to 20KHz. The measurement is the load impedance over the audio spectrum. I never said it was characteristic impedance. Measurement is donee the same way you measure loudspeaker impedance. Others I have explained before and I do not intend to repeat myself.
Tom, I never said the top of the impedance axis can be 100 Ohm. Perhaps you should just calm down and read carefully. You are letting your negativite emotions get the better of you.
Where the plot drop suddenly where the sampling rate is limiting. I normally just read data up to 20KHz. The measurement is the load impedance over the audio spectrum. I never said it was characteristic impedance. Measurement is donee the same way you measure loudspeaker impedance. Others I have explained before and I do not intend to repeat myself.
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I thank that the burden of proof remains on the person making a very poorly documented claim.
Soongsc,
I propose that you revise your diagram by giving it a title, an ordinate scale, unit designators, graph labels and a written interpretation (together with a description of your methodology).
User benb already explained it above.
I don't think anyone else will do it for you and you might by now have recognised that yours is not an accepted way to present a result in support of your argument.
Very soon your half-hearted textual explanation will vanish in the history of this thread. What stays is the incomprehensible diagram and the fact that you defend it.
(In engineering school, handing in a diagram like this will make the teacher let you fail – no matter how valid your result.
)
I propose that you revise your diagram by giving it a title, an ordinate scale, unit designators, graph labels and a written interpretation (together with a description of your methodology).
User benb already explained it above.
I don't think anyone else will do it for you and you might by now have recognised that yours is not an accepted way to present a result in support of your argument.
Very soon your half-hearted textual explanation will vanish in the history of this thread. What stays is the incomprehensible diagram and the fact that you defend it.
(In engineering school, handing in a diagram like this will make the teacher let you fail – no matter how valid your result.
)
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Sek, I am not looking to get flying colors, as a mater of fact I had to flunk a few graduate students because they could not even turn in reports.
I just wanted to raise some issues and see show people would respond. Obviously nobody here had personally hands on studied this before, but feel uncomfortable to admit it. Thus try to bash the originator first.
Since I just did some investigation on my own after reading a Sumiko OCOS report, which lots of people are going to question anyway, and I believe I already had mentioned it in earlier discussions, I could care less about what people here think. I just do not feel the true interest to know, so why would I want to spend more time formatting all this? Lots of people know how to do impedance measurements out there, I am surprise that nobody has posted any here. Really not a big deal.
I just wanted to raise some issues and see show people would respond. Obviously nobody here had personally hands on studied this before, but feel uncomfortable to admit it. Thus try to bash the originator first.
Since I just did some investigation on my own after reading a Sumiko OCOS report, which lots of people are going to question anyway, and I believe I already had mentioned it in earlier discussions, I could care less about what people here think. I just do not feel the true interest to know, so why would I want to spend more time formatting all this? Lots of people know how to do impedance measurements out there, I am surprise that nobody has posted any here. Really not a big deal.
Soong, if you would like your message to get across clearly, you need to present your data in a manner that allows them to be interpreted and reproduced by others. That's the scientific method. You have failed to do so. You have presented a plot with no labels and no description of what is being measured. You are leaving it for the rest of us to guess what's being measured and when we guess wrong, as I apparently did in Post #2045, you chastise the viewer, as you did to me in Post #2050. This is completely unreasonable. We are several people now who have requested that you describe your data and your measurement setup. This is a reasonable request. I would like to see the following from you:
These are the exact same requirements as I impose on myself. It would take you about 10 minutes to type this up. It would benefit the DIY community as a whole and probably you as well. Please write this up and attach the graph in one post. The burden of proof rests on you.
Be honest. Hiding behind obscurity will get you nowhere.
Tom
- A consise verbal description of exactly what was measured and why.
- A schematic of your measurement setup.
- A graph with scale, labels, units, and variables measured indicated on X- and Y-axis.
- Your interpretation of your data and discussion of the shortcomings of your measurement (you mentioned the sampling frequency of your equipment, for example).
These are the exact same requirements as I impose on myself. It would take you about 10 minutes to type this up. It would benefit the DIY community as a whole and probably you as well. Please write this up and attach the graph in one post. The burden of proof rests on you.
Be honest. Hiding behind obscurity will get you nowhere.
Tom
Tom, I did impedance measurements the same way one would measure loudspeaker impedance, that should be very common knowledge and easy for most DIYers. I gues I cannot understand the need to explain more. You are welcome to measure cable impedance the way you find fit and we can discuss the differences. You also will not provide me data that I was looking for, and you are now telling me what I should do? Funny logic.
Since I am not doing work on cables now, and do not expect to do so in at least two years, I am just not going to spend extra time on this unless someone does their own work and shows something worth investigating.
Since I am not doing work on cables now, and do not expect to do so in at least two years, I am just not going to spend extra time on this unless someone does their own work and shows something worth investigating.
You still haven't described your measurement setup or which parameter you're measuring. "Cable impedance" is meaningless. My four requests of Post #2054 still stand. As I said, hiding behind obscurity, or, in this case, "you should know better", will get you nowhere.
Forgive me, but I'm beginning to think that the emperor is attending, clothing optional, here. Maybe H.C. Andersen was onto something.
Tom
Forgive me, but I'm beginning to think that the emperor is attending, clothing optional, here. Maybe H.C. Andersen was onto something.
Tom
Where I'm coming from this is considered trolling.
Seriously Soongc, the time you spent and the amount of words you've made here in order to justify your actions have by now surpassed any effort that would have been necessary in order to prepare a full blown article on audio cable impedance measurement.
Modulus-86: Composite amplifier achieving <0.0004 % THD+N.
Sek, if the expertise here cannot catch on to the explanation here, it would take a full week's work to write something complete enough to where it would pass my own review. Doing the engineering work is a lot simpler that doing engineering documentation, to quote a saying in Taiwan "I don't have the American time" to do that. I really can't understand why people think it is so difficult. There are lots of info out there to read about loudspeaker impedance measurement, the only difference is that you use line level output to drive the load instead of a power amplifier.
Sek, if the expertise here cannot catch on to the explanation here, it would take a full week's work to write something complete enough to where it would pass my own review. Doing the engineering work is a lot simpler that doing engineering documentation, to quote a saying in Taiwan "I don't have the American time" to do that. I really can't understand why people think it is so difficult. There are lots of info out there to read about loudspeaker impedance measurement, the only difference is that you use line level output to drive the load instead of a power amplifier.
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As Sek has pointed out, it would have taken you less time to draw a schematic and write a paragraph or two to document your experiment than you've spent fighting the issue here. You refuse to even put numbers and units on your graph axis. We're not expecting much here. A cellphone picture of a hand-drawn schematic, a couple of lines of text, and proper graph annotation is really all that's required. You'd rather hide behind obscurity and blow hot air. That's rather unfortunate, but that's your choice.
Tom
Tom