Conceptually, I could see the speaker at zero voltage having more compliance magnetically, which could lower the phase margin.John, bursts at peaks I manage quite often.
Bursts at low levels and stable at peaks was the rarity.
I wonder if it was a combination of wire layout and decouplers, and the load just sent it over?
That would be interesting..
jn
Accelerometers are used a lot and semiconductor pressure transducers can be in gauge or absolute mode so they can respond to DC in some cases. Ed your post seems a little hasty, just saying.
It is interesting that people are questioning points that I have made and yet do not realise that others are making these points to me. So fine if you feel you disagree with me, I get that, but it's a bit more deeper than that.
I have been talking about this topic for years and engaging many in it, but online it is far more difficult, and that is kinda sad. Yes, this is social media right here, even if some here would like to think otherwise.
I have dished cherished ideas, not easy, but ultimately more satisfying in the end. I don't mind being wrong, just as long as we get ahead. I don't believe this is a topic where everything has been seen and heard and settled up like a convenient bundle. My discussions with so many simply shows this is not the case. But that is also what makes the topic so interesting... and will continue to be.
Suggestions are welcome, but the spirit in which they are made will determine whether they have value or not. Nobody reacts positively to negativity, right?
I have been talking about this topic for years and engaging many in it, but online it is far more difficult, and that is kinda sad. Yes, this is social media right here, even if some here would like to think otherwise.
I have dished cherished ideas, not easy, but ultimately more satisfying in the end. I don't mind being wrong, just as long as we get ahead. I don't believe this is a topic where everything has been seen and heard and settled up like a convenient bundle. My discussions with so many simply shows this is not the case. But that is also what makes the topic so interesting... and will continue to be.
Suggestions are welcome, but the spirit in which they are made will determine whether they have value or not. Nobody reacts positively to negativity, right?
I don't care who is making the points. You stated them.
As such, you are expected to answer questions and comments intelligently.
It is not lost on me that your last several posts to me have been a combination of "I'm too stupid to understand" and "woes me the social media is against me".
While my signature line claims a cabbage is smarter than me, I will certainly bet that it's perhaps only 50 percent of the cabbages out there.
You could at least sprinkle some technical sounding words in amongst your posts. You're "look it's a squirrel Schtick isn't floating my boat.
W/r to social media... I post on this specific forum and no others because there are many here I look up to with admiration of their experience, understanding, and intellect.
If you come here presenting some new theory, expect questions and comments from that large knowledge pool. Don't go crying "social media is bad".
If you do not have the understanding to answer those questions, Just say so.
Jn
Thanks gpapag.
Re the feedback thing jn, I assume you are up on adaptive feedback schemes - there should be plenty of scholarly papers on the subject if you google.
Digitally controlled adaptive feedback systems appeared in SMPSU’s about 20 years ago and also used in motor control where you tune the plant response dynamically to the load requirements.
Bit like self tuning PID controllers, but the control schemes are more complex and orders of magnitude faster.
Re the feedback thing jn, I assume you are up on adaptive feedback schemes - there should be plenty of scholarly papers on the subject if you google.
Digitally controlled adaptive feedback systems appeared in SMPSU’s about 20 years ago and also used in motor control where you tune the plant response dynamically to the load requirements.
Bit like self tuning PID controllers, but the control schemes are more complex and orders of magnitude faster.
Etc, etc, etc. You just made my point perfectly. Yes, I recognise social media and the attitude it engenders when I see it. This combative style you have adopted, you aren't hiding it.
I definitely prefer the complimentary output stage... I love free stuff!
(Sorry, I couldn´t resist it... BTW I don´t have as much knowledge as you do about analog!)
(Sorry, I couldn´t resist it... BTW I don´t have as much knowledge as you do about analog!)
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Having some rudimentary knowledge of amps, motion control, magnetics, audio, I see the disconnect between multiple disciplines, I do like posting here because I learn.
I've been researching for a bit. thanks for the hints, good stuff.
Jn
Your point being what? That every time I ask a technical question, you divert?
It is not combative to ask technical questions and expect technical responses.
Your diversionary tactics will not work here, the posters are just too smart.
Sorry.
Now, answer the question. How does the transition between class A and B suddenly make voltage and current temporally correct?
Jn
Edit: do you even understand what I am asking??
Dumb question time. If we are considering smarter drive, should we consider smarter speakers? At the moment they are not like motors as the restoring force of the suspension doesn't allow you to put them in one place and for them to stay there. So you are fighting a whole load of sources of inaccuracy that you don't need to. Pig meet lipstick.
Joe,
You do understand, I respond to you because I see something there, right?
If I thought differently, you would be on my ignore list.
There is only one human on my ignore list. One person that I consider so irrelevant that I do not even believe it worthwhile to read what he writes. That is not you.
Jn
You do understand, I respond to you because I see something there, right?
If I thought differently, you would be on my ignore list.
There is only one human on my ignore list. One person that I consider so irrelevant that I do not even believe it worthwhile to read what he writes. That is not you.
Jn
I was actually thinking about the possibility of having the open loop gain dependent on the output current. It can't be abrupt, as the output can saturate. But gentle, that may work.
Jn
Oh, edit: I'm not thinking of suspension non linearities, but magnetic force/acceleration non linearities.
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Second Harmonic Distortion
This is a late reply on the topic above (sorry). First I have to say I fully agree with the excellent post by Scott. The musical art has to be respected and it is a job for an EE to solve the problem of recreating it (trying to aproximate neutrality). One of the criteria is low harmonic distortion certainly. So I think I agree with most fellows here I want to take the EE route (even though I have previously liked simple SE circuits). Not to mention I am an EE or at least am trying to be one
All that being said, I read the latest articles by Mr. Pass, then I read the recent posts here and nobody mentioned that second harmonic distortion has a phase.
FIRST WATT
"H2 generator" and "Korg Nutube Preamp". Excellent read, thanks Mr. Pass! I will also watch the presentation at BA 2017 here: YouTube
Cancellation of second harmonic distortion is mentioned, and the context is not a single circuit but separate boxes. Cancelling the 2nd in a SET amp by preceding it with the H2 generator.
Then I recalled the late Eduardo de Lima who wrote articles about distortion cancellation happening when he took into account the speakers. Personally I wouldn´t use an expensive tube amp to try to cancel some of my speaker distortion, I´d prefer something at the preamp level.
At this point I think I have to look at circuit analysis and the math for this stuff, try to better understand it. So I conclude this post with my thought, looking at all of this: audio really is complex (imho).
Thanks,
Alex
This is a late reply on the topic above (sorry). First I have to say I fully agree with the excellent post by Scott. The musical art has to be respected and it is a job for an EE to solve the problem of recreating it (trying to aproximate neutrality). One of the criteria is low harmonic distortion certainly. So I think I agree with most fellows here
I want to take the EE route (even though I have previously liked simple SE circuits). Not to mention I am an EE or at least am trying to be one All that being said, I read the latest articles by Mr. Pass, then I read the recent posts here and nobody mentioned that second harmonic distortion has a phase.
FIRST WATT
"H2 generator" and "Korg Nutube Preamp". Excellent read, thanks Mr. Pass! I will also watch the presentation at BA 2017 here: YouTube
Cancellation of second harmonic distortion is mentioned, and the context is not a single circuit but separate boxes. Cancelling the 2nd in a SET amp by preceding it with the H2 generator.
Then I recalled the late Eduardo de Lima who wrote articles about distortion cancellation happening when he took into account the speakers. Personally I wouldn´t use an expensive tube amp to try to cancel some of my speaker distortion, I´d prefer something at the preamp level.
At this point I think I have to look at circuit analysis and the math for this stuff, try to better understand it. So I conclude this post with my thought, looking at all of this: audio really is complex (imho).
Thanks,
Alex
JN,
You asked what the voltage to the loudspeaker represented. Thus the mention of the input transducers.
Most commonly we record variations in sound pressure level. But not always.
The next question is how do humans perceive sound.
As the input transducer does not match a human's receptor does this affect the entire sound reproduction chain?
One model holds that if we record two time varying pressure modulations and reproduce these using human head spacing for both that is adequate. Anything else looses accuracy.
Now in ear transducers are affected by individual ear parameters. So that model may imply that perfect reproduction transducers just outside ones ears are best. Some call such a device "headphones." (Open air variety which are often considered at some conditions to be velocity transducers.)
Now extending this to a larger scale with loudspeakers introduces much more channel distortions. The practice of using multiple microphones to make the recordings completely changes the implementation of the model.
This is then done by "Artistic taste" to recreate an impression of the event. Technical accuracy becomes more of an amusing concept.
You asked what the voltage to the loudspeaker represented. Thus the mention of the input transducers.
Most commonly we record variations in sound pressure level. But not always.
The next question is how do humans perceive sound.
As the input transducer does not match a human's receptor does this affect the entire sound reproduction chain?
One model holds that if we record two time varying pressure modulations and reproduce these using human head spacing for both that is adequate. Anything else looses accuracy.
Now in ear transducers are affected by individual ear parameters. So that model may imply that perfect reproduction transducers just outside ones ears are best. Some call such a device "headphones." (Open air variety which are often considered at some conditions to be velocity transducers.)
Now extending this to a larger scale with loudspeakers introduces much more channel distortions. The practice of using multiple microphones to make the recordings completely changes the implementation of the model.
This is then done by "Artistic taste" to recreate an impression of the event. Technical accuracy becomes more of an amusing concept.
And on a totally so far off the topic item. My nephew got married and the couple collects Lord of the Ring swords! So I made a copy of Frodo's Barrow knife from Damascus steel. Just got the email it is being shipped back from the tempering house. I dropped it off in person in Meadville PA where their knife specialist complemented me on the piece. They have 2,500 or so knife accounts and process 25,000 or so a month!
So not only are there weirder folks than audio, but apparently a lot of them.
(Most of the knives are from real cutlery manufacturers.)
So not only are there weirder folks than audio, but apparently a lot of them.
(Most of the knives are from real cutlery manufacturers.)
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JN,
Haven't you been paying attention? Some folks have found lots more to worry about. The good news is so far no one has complained about trolls sleeping in their giant horn loudspeakers.
It wan't my claim, but one I understand. If you wish, contact Hans van Maanen via the Temporal Coherence website. His use of the 'temporal' word is his, not mine. But basically when the amp transitions from Class A (both devices 'on') and Class B (one device goes 'off') and the voltage and current (the current phase angle no longer matches the voltage) are no longer 'temporal' time wise, his claim is that the feedback loop will respond in such a way that you will get high order distortions and I believe he claims he had not only examined the mechanism and used measurements to prove it. He is an amplifier designer primarily, as I see it, and does a tri-amped speaker system (active) and so the crossover is done at the line level. But he still uses passive components between the amplifier and the driver, he EQ's the current phase angle flat to treat the above problem and claims (and others have concurred with him) that you can hear a difference. I am inclined to believe him, based on not the exact same work, but similarly EQ the current that a loudspeaker draws.
I am not all against stuff online that has been posted and somebody linked earlier here a link to show that there is a reduction of distortion when the voltage of the amplifier is compared to the current captured by a 1 Ohm series resistor. There is a marked reduction in distortion from current drive. I am NOT disputing that.
What I am pointing out is that (and the idea is getting traction) is that the reduction in distortion under current drive is because the amplifier cannot produce reactive current. But under voltage drive, the amplifier readily produces reactive current. So the increased distortion we see (and the measurement can easily be repeated) is due to amplifier reactive current drawn by the back-EMF impedance of the driver. EQ the current and it should suppress the same distortions as current drive. Do you see what I mean.
I don't think I am diverting at all. Where would the benefit be in doing that?
Joe,
Thank you. And sorry if I misunderstood anything.
There is a test that is being devised, it should show up if the same suppress of distortion products (based on a 100 Hertz measurement) when using current drive, that this same suppression will occur with using voltage drive and the current being EQ'd can be shown to achieve that too. Now that would be really something. But let us not get ahead of ourselves, if it proves to be a dud, then back to... wherever. But I got a kind of Feynman intuition that it will prove at least something. The thinking behind this test is a bit complex to do, a jig has to be set up. A theory of a reconstructing the Vre voltage that represents accurately to within 2% the current and voltage of the Re of the VC. The earlier test used 1 Ohm and that is way to high (10-20% accuracy that makes the test less revealing), but using 0R1 current sense resistor will have greater resolution.
I only have a good feeling, but the 1R test is rough and ready, yet it points the way. So time, please, and more than one person will be doing the test, that is the idea, and reach consensus.
Cheers, Joe
PS: Below is really interesting, it points to something alright, but the mechanism behind the comparison between the two is not explained, but comparing the voltage (distortion) of the amplifier and comparing the current (distortion) of the amplifier does show the way, but a more advanced test is required.
There sure is something going on here. The above is a good start, but not enough.
The current revealed by the sense resistor is the real input to the speaker that we hear coming out of the speaker, garbage in, garbage out.
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There are far more important things to worry about.
Family is far above all else.
I feel for the recent losses. I hope you are well.
Jn
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