There was mention that the automakers would spend a dollar on better oil if it saved them warranty returns. Automakers count parts pricing in 1/10 of a penny increments so I highly doubt that a fluid that offers only a performance advantage would appeal. Especially since that once the said fluid is drained, the advantage is lost.
I am wondering where this great insight comes from regarding automakers and their configuration practices?
Ironically enough, the only time I use that additive anymore is to help with risk reduction when starting expensive motors for the first time.
I would really like to travel to Portugal someday and experience some of the great cheeses, wines too!
I am wondering where this great insight comes from regarding automakers and their configuration practices?
Ironically enough, the only time I use that additive anymore is to help with risk reduction when starting expensive motors for the first time.
I would really like to travel to Portugal someday and experience some of the great cheeses, wines too!
What a strange response.
You know who else does level unmatched sighted listening and uses AP measuring device? John Atkinson of Stereophile along with bunch of other professional reviewers. Guessing RNMarsh to be in the same league as them is somehow viewed as an insult? Wow...
I dont recall seeing you in my listening room. What makes you assume anything about how I listen or measure?
THx-RNMarsh
What is a brake?
Two of my guys stepped out onto the sidewalk after lunch and jumped back in when they saw a Toyota Land Cruiser coming at them on the sidewalk! It was followed by a dozen police cars.
The Toyota got almost another mile on tight city streets before he got wedged between a car and a stone building entrance staircase. Of course he did do some on street driving the wrong way on a one way street before getting stuck on the sidewalk.
Had to believe but a stolen vehicle, a ditched and recovered hand gun and the fellow was wanted for robbery.
A bit of an in city chase and no one injured!
As to those funny British drivers, true story... One of the better known British drivers was scoping out a road race course new to him. Unknown to him as he started out was an American driver was also out on the course driving in the other direction. When they saw each other coming, both pulled over a lane to allow safe passing. The Brit to the left and the American to the right. Not good news.
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I guessed about level unmatched and sighted listening comparison. Was I close?
Looking at the the posts Indra referred to, It seem we can take for granted that driving the moving coil assembly with a current source produce less distortion. Both harmonic and intermodulation. While PMA has not indicated all the conditions of his mesures. (For example, it is clear that the acoustic levels has been equalized between the two mesures of distortions ?)I must admit, I missed that offer. Thank you for your thank you.
I am thinking through a setup....
A cone/vc/spider mounted, a magnetic gap structure on rails to move the gap w/r to the vc.
The ability to measure modulation of Le vs position...
While I never made measurements of this by myself, (reason why I asked the question in a candid way), I still need convincing explanations of the physical phenomena(s) at work.
But distortion at HF is not the only thing to consider.
Also, if one of us could do the following measurements ( I do not have any more good enough measuring instruments to do this study by myself):
- Comparative distortion curves with the frequency beginning an octave below the resonance frequency. Bot on a basse driver and a tweeter.
- Decay time (damping) curves to know the evolution of it and find, if there is, the point where the loss of amortissement is no longer felt, we would know much more.
By anticipating the expected results, what ways could we imagine to move progressively, with an amps, or a combination of two amps in parallel when the frequency increases, from a high damping factor to a current command ?
I think that something very positive could emerge, for once here, from a collaborative study of this subject if we made a team of all our expertise.
What do you thing ?
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I invite you to come in my listening room and have a good drink of what you prefer.
I had double glazed windows installed in it so that we would not be spoiled by outside noise.
We could compare our sighted listening impressions ;-)
PS: Do not forget to bring your collection of stereophile.
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Automakers have (at least) two sources of financial incentive regarding engine lubrication. The source mentioned of warranty expense and its flipside durability reputation is one. Another is the ongoing pressure for greenhouse gas emissions reductions (formerly CAFE). In the second case the general technique used is to evaluate alternative approaches based on the incremental cost of an improvement in overall GHG emissions, for example the cost of reducing the fleet average 0.1 g/mi CO2e.
Options might include reduced rolling resistance tires, aerodynamic improvements, mass reduction, powertrain efficiency improvements like turbocharging or more transmission gearsteps, and on and on. Alternative vehicles like hybrid, plug-in hybrid and battery-electric vehicles also contribute but at comparatively very large costs. Many of these opportunities only present themselves when a platform or powertrain configuration undergoes a major revision, so every 4 to 7 years. Others like tires and oil are more flexible and less disruptive to implement. The current strange times aside (an Administration proposing relief for requirements that disrupt planning and investment long in process) this will continue to drive the industry. If you wish to know the details look here:
https://www.govinfo.gov/content/pkg/FR-2012-10-15/pdf/2012-21972.pdf
Tounesol, I believe what Joe is referring to with "no reactive current" is that with current drive, the current has no phase shift relative to the input signal. You could call it a reactive voltage.
With voltage drive, the output current and the input signal look very different when using a multitone signal.
Depending on the type of drive used, the input signal resembles the output voltage or current. See below.
With voltage drive, the output current and the input signal look very different when using a multitone signal.
Depending on the type of drive used, the input signal resembles the output voltage or current. See below.
Attachments
As a thought experiment.... Two tone..Lf to modulate coil position, Hf tone of interest.
As the vc leaves the gap forward, L drops, eff drops, hf current will increase a bit, so a v drive will attempt to compensate a bit. Backward, L increases, eff drops, current drops, so it doesn't compensate. This modulation is assymetrical to position, second order harmonics.
Under current drive, eff drops symmetrically, third order harmonics.
Suspension also adds third.
A cone spider assembly mounted independent of the magnetics, with the magnetics on a rail system such that coil position can be scanned.. That allows the hf tone to be reproduced at the center of the suspension while the vc can be moved throughout the range of the magnetics.
This allows measurement of the driver hf efficiency through it's Xmax limits unimpeded by suspension compliance.
It would allow measure of magnetics driven distortion of the hf through the range of motion independent of suspension.
It would allow measure of the effectivity and symmetry of a shorting ring at the hf tone.
Anybody think of more tests?
Jn
Clever. I'm sure we will find other tests depending of the results ;-)
Like the ways cones can be broken when the coil id driven with more brutality.
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No setup yet, only a thought exp. I do have some half inch ceramic coated aluminum rails and slide bushings I bought for my wire EDM setup, but the bushings had a .001 inch slop, so I couldn't use them for that. I also have a spare lead screw I can cut down and a pair of nuts I can do an anti backlash thing with.
If I cut the basket at the magnet side after releasing the spider, the spider would need a mount ring that doesn't get in the way of the magnetics as I move it coil near back. As an alternative, disassemble the magnetics, use the pole piece and front plate mounted on an iron E structure with some neo's for flux.
Hmm.
Jn
Seems interesting.
When i said "more brutality, i thought about damping factor. Need to separate the voice coil dynamic position from the cone material defects, as both require different remedies.
As an example, it should be interesting to see, on a bass speaker if the first bump of the impedance curve that indicate the breaking frequency, if there is any change between the two modes (current or voltage drive). Don't have an idea about how to do this comparison.
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I haven’t seen the comprehensive application of any of that by car makers, more likely people falling asleep at their desks, as the as-delivered can vary so much depending on so many variables. The choice of tires changes easily, as you mentioned, often at the dealer.
My apologies for the ot.
As for the instrumented audio testing, is it necessary beyond legitimate product development, is there a competition where these devices are all compared and crowned top dog or something?
Most of the time a product is not changed, but superseded by a new model.
Well, it is diyaudio.
And, this is how the new models are developed.
I've not seen anybody try this particular test of the magnetics, seems a novel approach.
Course, if it has been done, I would think someone here would provide a link.
Jn
Typical driver has the spider attached to the basket. The magnetics are screwed/glued to te back. (Commodty driver)
You could devise a threaded mount for the magnetics that would allow moving the magnet in and out by rotating it.
I'm not sure what you would learn from this. Maybe that underhung is better than overhung?
You might accomplish the same by adding dc to offset the voice coil for testing. Few drivers have perfectly centered voice coils in the first place.
You could devise a threaded mount for the magnetics that would allow moving the magnet in and out by rotating it.
I'm not sure what you would learn from this. Maybe that underhung is better than overhung?
You might accomplish the same by adding dc to offset the voice coil for testing. Few drivers have perfectly centered voice coils in the first place.
I had considered the DC, but that loads the suspension, changes it's spring constant, so directly adds second harmonic.
By moving the gap structure, the suspension remains force free leaving just the magnetic. I had also considered air pressure with a sealed cabinet, but that added two variables.
Jn
Btw, did you get the ppt's? Were they of any use? As I said, they were geared towards a target audience with significantly less expertise than you..
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