Speaker excursion what causes it ? - Page 2 - AVS Forum | Home Theater Discussions And Reviews
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post #31 of 155 Old 02-13-2017, 05:51 PM
 
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Originally Posted by Bigus View Post
Anyone else find it odd that two members who both just joined happen to misuse commas extensively in the same manner as another member who makes eerily similar wordy and mostly semantic arguments?

Maybe its just me.
See post 11 above - first paragraph nails it.
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post #32 of 155 Old 02-13-2017, 05:56 PM
 
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Originally Posted by Bill Fitzmaurice View Post
Really? Credentials? How about starting with a real name?
There's nothing that you can teach me, and obviously nothing that you aren't cocksure that anyone can teach you, so this relationship ends now. I've better things to do.
What importance is a person name over the content of their assertions?

AMO BRO is asserting the truth, even tho masked behind anonymity; like the mass majority of AVS Members.

Invoking anonymity, doesn't invalid a members posts.
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post #33 of 155 Old 02-13-2017, 06:04 PM
 
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Originally Posted by A9X-308 View Post
Your reading skills are poor: I said it wasn't driven by a current source. Which it's not.
The OP hasn't't introduced current source amplifiers in this thread, he did so in another, perhaps some are crossing/mixing the two accidentally.

It can easily happen.
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post #34 of 155 Old 02-13-2017, 06:43 PM
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Originally Posted by Jady Jenkins View Post
See post 11 above - first paragraph nails it.
What... "theory"? An explanatory framework which is supported by logic and evidence and presumed true until falsified? Yeah, I suppose that fits pretty well. Thanks.
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post #35 of 155 Old 02-13-2017, 06:45 PM
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Originally Posted by Jady Jenkins View Post
The OP hasn't't introduced current source amplifiers in this thread, he did so in another, perhaps some are crossing/mixing the two accidentally.
Of course you didn't. I did, unintentionally really, skirted around a bit by hevi, and here we are.
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post #36 of 155 Old 02-13-2017, 06:56 PM
 
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Originally Posted by AMO BRO View Post
It's all theory sir! The machines that are used for measurement, are running mathematical extrapolations, based on merely two knowns. Namely, Voltage (because its easier than current to measure) and resistance (because it too is easy to measure). The rest is all very much programed theory.

And when actually 'measured', as in at 1m/1w the signal agitation is pink noise, which doesn't output a constant voltage. The sensitivity score is then selected, as being the frequency (or pass band, depending on standard being used) exhibiting the highest SPL @ 1m/1w, or 1w/1m, however, you prefer to express it.

The speaker doesn't have a uniform / linear sensitivity to all frequencies throughout its pass band, that is quite impossible. The spec published is the highest.

They should publish the actual sweep, so we would all have a more informed understanding (but many don't take actual measurements any more, they theorize what the performance is likely to be, and when they do, the scores are always bolstered / higher to the linear tune of 3dB vs real-world measurements), however, one could look to a frequency response sweep (if available), then locate the highest peak, and reasonably assume that is where the Sensitivity spec is based.

Regardless of being measured or purely theoretical, current resides within every volt in a locked relationship, based on load, no exceptions, not even in here!
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Originally Posted by Bigus View Post
I'm not making any argument against the math presented. AFAIK, the reason we reference everything to voltage is because our amplifiers try to maintain voltage source behavior, largely because current source amplification is difficult to do. Feel free to correct me.

And of course that wasn't my point.
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Originally Posted by Jady Jenkins View Post
See post 11 above - first paragraph nails it.
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Originally Posted by Bigus View Post
What... "theory"? An explanatory framework which is supported by logic and evidence and presumed true until falsified? Yeah, I suppose that fits pretty well. Thanks.
Please tie the bold text together... I am correcting you as stated I was free to do so.

AMO BRO is correct, we can use either, but our ability to accurately, and repeatedly take current measurements isn't as stable as taking voltage readings, especially when dealing with higher currents. Therefore, using ohms law, one can and does extrapolate the current measurements, by dividing the voltage by the resistance present...

I agree with him. It's really 6 of one a half dozen of another, so it comes down to ease, accuracy and repeatability. Therefore AMO BRO is correct in this assertion, as well.
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post #37 of 155 Old 02-13-2017, 07:00 PM
 
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Originally Posted by Bigus View Post
Of course you didn't. I did, unintentionally really, skirted around a bit by hevi, and here we are.
I am not the OP, you seem confused.
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post #38 of 155 Old 02-13-2017, 07:40 PM
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Originally Posted by Jady Jenkins View Post
Please tie the bold text together... I am correcting you as stated I was free to do so.
That's fine, but you've misquoted in one of two places. This post #36 of yours makes it look like your post #31 was in response to my post #17. I don't know if that was your intention, but in post #31 you quoted my post #15.

I responded appropriately. It would help if you quoted the posts you intend to. Or, if you did, don't rearrange them later to make it look like the conversation went somewhere it didn't.

In any case, thanks for the correction. Don't confuse me for someone who doesn't understand the relationship between potential and current. I offered the "feel free to correct me" because it was an assumption, and I really didn't care much the reason. I figured it was more convention. You say more measurement convenience. Works for me.
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post #39 of 155 Old 02-13-2017, 07:58 PM
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Originally Posted by Bill Fitzmaurice View Post
Shortly after a similar thread was unceremoniously shut down, with multiple deletions and in all likelihood sanctions. Coincidence?
Is that allowed? And wouldn't that warrant an investigation?
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post #40 of 155 Old 02-13-2017, 08:05 PM
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Not good etiquette at the least. Depends on how much forum members and admins care I suppose. Easy enough to mask your IP if you were so inclined. Since I've thought about changing my username over the years, maybe I should just create an alter ego instead to 'like' all of my posts.
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post #41 of 155 Old 02-13-2017, 08:16 PM
 
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Originally Posted by Bigus View Post
That's fine, but you've misquoted in one of two places.

I offered the "feel free to correct me" because it was an assumption, and I really didn't care much the reason. I figured it was more convention. You say more measurement convenience. Works for me.
Bigus, I personally don't feel like examining the validity of your assertion/accusation. There has been more contention in this thread than production of worthwhile, collaborative fact finding. Nature of the beast perhaps, however, on the better side of the beast, if you will, id prefer not to get caught up in any more minutia, relating to posts which are potentially filled with more conjecture, than on-point technical rebuttals, or agreements.

This being said, there was no intentional perversion towards their respective contexts, by means of their posted sequence. It may or may not exist, and frankly, it isn't that important, as we seem to be on the same page with regards to the prime, initial assertion.
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post #42 of 155 Old 02-13-2017, 08:22 PM
 
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Originally Posted by LFEer View Post
Is that allowed? And wouldn't that warrant an investigation?
I agree!

They should investigate it, and post the findings so we can all get back to discussing the technical content, rather than the probability that someone is a sock puppet or in cahoots with another.

This commentary has become very stale dated, IMO!

It's well past time to move on!
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post #43 of 155 Old 02-13-2017, 08:37 PM
 
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Originally Posted by Jady Jenkins View Post
I agree!

They should investigate it, and post the findings so we can all get back to discussing the technical content, rather than the probability that someone is a sock puppet or in cahoots with another.

This commentary has become very stale dated, IMO!

It's well past time to move on!
Agreed, this is nuts. This has been quite the welcoming. One I didn't expect from a science forum.

Lot's of mudslinging, very little in the way technical rebuttals.
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post #44 of 155 Old 02-13-2017, 08:46 PM
 
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Originally Posted by AMO BRO View Post
Agreed, this is nuts. This has been quite the welcoming. One I didn't expect from a science forum.

Lot's of mudslinging, very little in the way technical rebuttals.
Well, welcome to AVS!

This behaviour will die down, over time. There's a bunch of great people in here, some have a strong hate on for trolls.

Net result, strong personalities get pulled / put into a trial by fire. That is a posting fire from several seasoned members (just like you are going through now).

Net result, many get wrongly persecuted.

Only a few get rightly persecuted.

Cheers!
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post #45 of 155 Old 02-13-2017, 09:13 PM
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This is amusing.
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post #46 of 155 Old 02-13-2017, 09:15 PM
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BTW, what was in need of rebutting? I thought this thread was just a drawn out way of presenting a well known physical relationship.
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post #47 of 155 Old 02-13-2017, 09:17 PM
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But if its a game for the sake of honing your arguing skills, I'll play devils advocate for a moment.

You can have voltage without current, but you cannot have current without voltage.

Which is prime?
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post #48 of 155 Old 02-13-2017, 09:21 PM
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And did "you guys" really both have to use the phrase "technical rebuttals" within minutes of "each other"? If you want to help hold down the speculation... c'mon!
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post #49 of 155 Old 02-13-2017, 09:36 PM - Thread Starter
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Quote:
Originally Posted by Bigus View Post
You can have voltage without current, but you cannot have current without voltage.

Which is prime?
Valid question, not sure one could quantify a given voltage without measuring it? Be it an O-scope or multimeter,etc.

Edit: which requires current
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post #50 of 155 Old 02-13-2017, 11:28 PM - Thread Starter
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Originally Posted by Bill Fitzmaurice View Post
...There's nothing that you can teach me
One can't really "teach" another anything, only help him/her learn. No shame in being wrong...will all stand upon the shoulders of others before us.
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post #51 of 155 Old 02-14-2017, 03:10 AM
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Originally Posted by A9X-308 View Post
And the example given then wasn't driven by a current source either. In the nearly 6 years since, have you come up with anything more convincing?
Something more convincing than the fundamental laws of physics?!? Well, to the best of my knowledge they have not changed a whole lot the last six years so no, I haven't really had any good reason to find "anything more convincing" than that.
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post #52 of 155 Old 02-14-2017, 04:21 AM
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Originally Posted by Bigus View Post
Wow. I know text can misconvey emotion sometimes, but dang dude. What happened, not get enough sleep last night?
It was not my intention to come across as rude. It is basically two reasons I don't want to summarize. The first is that I don't want to clutter this thread with more advanced concepts when some "key contributors" still seem to think that it is voltage that moves the coil and not current. It is simply not meaningful. You can always read my posts in the link I provided and you'll get a pretty good summary of it.

The second reason is that I have explained it twice before and it will do little good to repeat it a third time.
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post #53 of 155 Old 02-14-2017, 05:32 AM
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No problem. I read some of that thread, I'll go through it more fully when I get a chance. Seems famiar, I'm sure I read it at the time. Just a topic that is interesting to me intellectually.
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post #54 of 155 Old 02-14-2017, 05:33 AM
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Originally Posted by Tomas2 View Post
Valid question, not sure one could quantify a given voltage without measuring it? Be it an O-scope or multimeter,etc.

Edit: which requires current
Of course, you have to measure anything to quantify it. But that doesn't necessarily require the creation of a current. You could weigh it.
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post #55 of 155 Old 02-14-2017, 06:06 AM - Thread Starter
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Originally Posted by hevi View Post
It was not my intention to come across as rude. It is basically two reasons I don't want to summarize. The first is that I don't want to clutter this thread with more advanced concepts when some "key contributors" still seem to think that it is voltage that moves the coil and not current. It is simply not meaningful.
Agreed.. another simplified way one could solve this logically would be to think in direct vs inverse products i.e the inverse, projected sound waves moving a speaker diaphragm would produce voltage.

The delicate subject of 'current drive' was tabled inside another thread which Bill referenced to earlier. I would like to hear more discussion (maybe another thread so titled?) on different drive topologies. FWIW I was the forum member who introduced the subject of current drive and transconductance in the other discussion.

Tomas
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post #56 of 155 Old 02-14-2017, 07:07 AM
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Confusion about current source and voltage source that can easily solved by going back to the ee basics.
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post #57 of 155 Old 02-14-2017, 07:21 AM - Thread Starter
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Originally Posted by Frank Derks View Post
Confusion about current source and voltage source that can easily solved by going back to the ee basics.
Seriously!

You and another said PhD EE buttressed the notion that speaker excursion was fundamentally a product voltage, if that is indeed fact ?

Please provide the math

PS: I didn't name the PhD for reasons of anonymity

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post #58 of 155 Old 02-14-2017, 08:13 AM
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Originally Posted by Tomas2 View Post
Seriously!

You and another said PhD EE buttressed the notion that speaker excursion was fundamentally a product voltage, if that is indeed fact ?

Please provide the math

PS: I didn't name the PhD for reasons of anonymity

No you are misinterpreting what is said.
There is no doubt that current is what driving the speaker. What I say is that the current is drawn from an amplifier that acts as a voltage source. You are mistaken in characterizing such amplifiers as 'current sources'. The amount of current flowing is determined by the voltage across the loudspeaker impedance. And this impedance changes over the frequency range.
And so does the current.


Amplifiers that are true current sources always deliver the same current amount into the varying impedances across the frequency range. This means that the voltage at the ls terminals will vary across the frequency range. With the side effect that the spl over the frequency range varies as well.
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post #59 of 155 Old 02-14-2017, 03:55 PM - Thread Starter
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Originally Posted by Frank Derks View Post
No you are misinterpreting what is said.
Then I apologize Frank, IIRC I quoted Bill here:
Quote:
Bill Fitzmaurice
Current does vary with frequency, and by dint of that so does power delivery, but speakers respond to voltage, not current.
and if I'm not mistaken, you validated specifically the underlined premise?
Quote:
Frank DerksThere is no doubt that current is what driving the speaker.
Not sure this align with Bill's?
Quote:
What I say is that the current is drawn from an amplifier that acts as a voltage source .
Again I apologize for the wording or adjectives that I used previously in the other thread.

revised post:

1) a voltage drive amplifier is attempting to be a source of alternating current i.e. current drive

2) and the speaker itself completing a series circuit (pathway from a given reference point) to either +/-supply rails via the output topology

3) and speaker excursion itself being a product current regardless of the voltage present

I also provided some examples (schematics, block diagrams, circuit topology with circuit description) depicting a topology that I believe to be an output stage that is effectively modeling transconductance ? The MOSFET output stage "node' being controlled in essence by a re engineered feedback scheme. Also fundamentally the typology of both the Trans*ana and Trans*nova are included in the Hafler P1000 .pdf I"ve provided here:

http://www.hafler.com/pdf/archive/MA..._P1000_man.pdf

http://www.hafler.com/pdf/the-transnova-topology.pdf

http://www.current-drive.info/9

Thanks !
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post #60 of 155 Old 02-16-2017, 06:50 AM - Thread Starter
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Quote:
Originally Posted by whale-av View Post
Einstein has been dead for a while, and you want to discuss Precambrian physics on this forum? Back to school everybody......

n..n..n..no!
With all due respect whale-av, are you directing this comment towards me, thread title or both?

I'll echo the post made earlier by forum member hevi;

...some "key contributors" still seem to think that it is voltage that moves the coil and not current"

Would you just happen to have other formula(s) for the driving force (F) that sets the diaphragm in motion other than F = BL x I

Thanks in advance !
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