JN, I am interested in what you´re teaching here. As are many others for sure.
I´m bookmarking and highlighting this in order to do the tests when I´m able to.
I´m bookmarking and highlighting this in order to do the tests when I´m able to.
Ummm.
Regarding directional couplers or bridges also with high vswr used in precision and high resolution measurements ......
A trick I was shown 45-50 years ago is to add resistive pads. As long as you can detect/measure the level, the loss does not matter. However, the vswr will be reduced as the reflected signal is attenuated as well. In fact ---
To reduce the reflected signal from the input or output of any device is to place an attenuator before or after the device. The attenuator reduces the reflected signal two times the value of the attenuation, while the transmitted signal receives the nominal attenuation value.
In practice, the padding on the source side seems to work a little better.
I have measured vswr to an Absolute level 1.001 at 1 GHz and 1.002 at 2 GHz this way 45 years ago. Thus, proving the spec of the GR slotted line in the standards lab at LLNL. Used the setup to calibrate precision microwave attenuators over a range of freq and verify an atten still met spec.
THx-RNMarsh
test and measurement junky
Regarding directional couplers or bridges also with high vswr used in precision and high resolution measurements ......
A trick I was shown 45-50 years ago is to add resistive pads. As long as you can detect/measure the level, the loss does not matter. However, the vswr will be reduced as the reflected signal is attenuated as well. In fact ---
To reduce the reflected signal from the input or output of any device is to place an attenuator before or after the device. The attenuator reduces the reflected signal two times the value of the attenuation, while the transmitted signal receives the nominal attenuation value.
In practice, the padding on the source side seems to work a little better.
I have measured vswr to an Absolute level 1.001 at 1 GHz and 1.002 at 2 GHz this way 45 years ago. Thus, proving the spec of the GR slotted line in the standards lab at LLNL. Used the setup to calibrate precision microwave attenuators over a range of freq and verify an atten still met spec.
THx-RNMarsh
test and measurement junky
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JN, don't despair, this is all good input information. It may seem that my and JC's comments are OT but I contend that this is not the case. OK, so collectively we are looking for reasons why amplifier/cable match/mismatch can cause audible sound effect. Pavel's test is with a reasonably 'ideal' or 'perfect' amplifier which is class A and zero loop feedback so expect this amplifier to be 'immune' to return/reflected energies. This is one test condition only and cannot be used to draw universal conclusions.
A more appropriate and representative 'real world' test would be with more typical consumer amplifiers or receivers that are sensitive to loading and induced and stored/delayed energies. My experiments with terminating resistors at each end of speaker cables causing different (improved) sound, and resistor chemistry itself causing further subjective changes indicates that the problem is not simple. Carry on.
Dan.
We are just experiencing a negative peak in the 1/f noise of internet jabber.
In your opinion? OK, fine for your own consumption. However, communicating with others on this matter will not be successful because of "language" barrier. IOW, you have a different view of what hi-fi is in audio electronics. Just of kicks, look up that definition on dictionary or online search site.
Thanks for confirming my suspicion. You should have also done objective listening comparison to confirm if your subjective comparison was just a mistaken identity, operator error or truly dependent on damping factor of amp. BTW, which store bought amplifier today has damping factor so low that it sounds different from... say, Yamaha or Denon stereo receiver in level matched double blind listening test?
I understand why PMA or others are so confident. But you're so confident for reasons unknown to me. Do you think it is possible that you may change your opinion/view at all?
Buy a second hand Aleph3 and change the mosfets with various types of differing trans conductance (still paying attention to the capacitance). But that's not going to change your opinion. So, what is it? How about you create two test files with different DF and i will tell you which one is which?
So it is possible then (if there is proof)? Honestly, to me you look like wanting some input to reinforce or confirm your super firm bias/belief. But if you really want to see how amps can sound different, i think i can help you. Just follow up your own question regarding Yamaha and Denon.
I have made many statements/points. Which one that you don't understand? All? 😀
I stated something about subjective (there's no rule) regarding BORING amp. The word is subjective. A boring amp to you can be not a boring amp to others. Amp is not human, how can it be boring? Sure it can, but we haven't defined the criteria for boring amp, hence the subjectivity.
The 'favorite fruit' was an analogy to this subjectivity. You can define your own criteria, which is not necessarily the same with my criteria. (Your favorite fruit is not necessarily the same with mine).
I was guessing that your favorite fruit was apple. It was an analogy of me trying to guess what a boring amp is to DF/you. My first guess was we have similar criteria. If my guess was wrong, it has nothing to do with my 'weak' logical thinking (in your words: logic is not my strong point) as very little logic has been used in my guessing. As to your favorite food analogy, the only logic I used was: IF 'An Apple A Day Keeps The Doctor Away', it should be the choice of many intelligent people. (You see, as my basic instinct i don't under estimate people).
For me, through a 'good' hifi, a boring music should sound boring, a non boring music shouldn't sound boring. So if the second criteria is not fulfilled (i.e. the amp is boring) I don't think it is a 'good' hifi (the apostrophe is for anyone who insist on dictionary meaning of hifi).
Now, why do i wont consider the boring amp as 'good' hifi? Because i understand some decision mistakes in amp design that will produce a 'boring' sound effect. As i consider this as a mistake, i wont call it good design or good hifi. The point here is not related with any definition of hifi, as it is simply about 'design mistakes'.
Well, to me looks like they've agreed to differ, until JN or someone else gets to make some measurements that show that cable / load interaction can create ITD variations that are audible under real conditions.
Pavel thinks it can't, JN thinks it can, neither likes the other's info.
While I understand JN's frustration that Pavel isn't doing the exact measurements he wants him to do, it's not surprising that Pavel will tend to make measurements that support his POV.
I sort of hate to say this but the normal situation in here is that folk would say JN should provide measurements to show how his theory will work in practice......
Moving quickly on, despite all that the dialogue and technical discussion has been very interesting and thought provoking - I think we are all enjoying it, so both Pavel and JN please do not feel frustrated - it's all good really. Really good! 🙂
As I said, the amplifier damping factor (i.e. output impedance) has to match whatever the speaker designer wants. In addition it has to be reasonably linear. Making the impedance small matches most speakers, and means that linearity is less of an issue. Hence most amps follow this path.johnego said:
I don't want my amplifier to be heard or seen, but merely amplify the music with as little fiddling with it as possible. You might describe this is boring; I call it hi-fi.
No, you have drawn the wrong conclusion from a valid experiment. Basically what you have done is match the amp DF to what the speaker needs for good performance or, perhaps, matched the amp DF to what the speaker needs in order to provide the sound you prefer (which is not necessarily the same). You have not shown that DF is a matter of amp quality; you have shown that DF is a matter of amp-speaker matching. Curiously, this is exactly what theory says it is.
Irrelevant. However, you are good at bringing in irrelevant things which might confuse people; have you ever thought of a career in audio marketing?Max Headroom said:
Record the sound produced by the speaker. With different amp setup. Many ways to vary the DF but in case of mosfet class A i prefer to vary the mosfet. This is how i build my amps. I don't compare Denon with Kenwood but i compare amp A with amp A modified, not side by side even.
That's what I said. The word 'funny' was referring to my mistake. I carried the wrong understanding for quite a long time.
Same policy. More or less. But when you think your amp cannot be heard, i might think it can be heard. Depends on how much more i can hear details other people can't.
And why should i describe that as boring? I don't even know your amplifier. Are you using a known schematic?
Ok, so you mix up with DF the speaker, room, microphone and where the user stands. Next you will be telling us to go on Youtube to audition amps?johnego said:
You do measure the DF after each FET change? Much simpler to add a resistor at the amp output. Then you know that it is DF only which has changed.
No.
My comment is perfectly relevant to the point that JC made.
Like I keep saying different elements and compounds cause different sounds, and this difference is recordable and replayable.
I encourage you to try the experiment of mounting copies of the same circuit (eg DAC) in 'same but different' enclosures, eg steel or aluminium or copper etc and listening to the changes in the outputs.
While you are at it try resistors of differing chemistries wired across your loudspeakers.
Dan.
The question of whether different materials sound different is without debate, it is enough to listen to make the finding. The only interesting and useful thing, on my opinion, is to understand why and not to be mistaken in its assumptions.
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