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Old 17th December 2011, 02:34 PM   #19341
Previously: Kuei Yang Wang
 
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Hi,

Quote:
Originally Posted by MiiB View Post
much more can be gained by making the driver better, than trying to correct the errors they are born with
How do you sugest to improve Le(i), Re(i) and BL(i)?

Ciao T
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Old 17th December 2011, 03:24 PM   #19342
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I have got a question from "subjective" domain.
Usually we consider interaction between driver stage and output stage (lets suppose both are MOSFETs) in terms of driver stage output impedance (usually resistance R) and gate capacitances of the output stage (some C).
Usually it is supposed, that if in two different designs the RC is close, hence the stage interaction issue is solved similarly.
What I observed subjectively, from listening, one never get similar sound in case if gate capacitances of output stage differ strongly, lets say as 100pF and 1000pF. For the second case, by simply decreasing driver stage output impedance, we could hardly approach the sound at the first case. I suppose, there could be some second order effects, related to interaction of stages. Are there any ideas, what kind of effects could play here?
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Old 17th December 2011, 04:10 PM   #19343
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Quote:
Originally Posted by MiiB View Post
I second Joachim,,, much more can be gained by making the driver better, than trying to correct the errors they are born with, besides any driver that has mechanical damping cant be reversed, as its components are neither linear or amplitude consistent...
Exactly, so, Thorsten, that is why you want drivers with the highest possible Qms. Any mechanical dampening that is not there cannot cause problems. All mechanical dampening that is will.

vac
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Old 17th December 2011, 04:29 PM   #19344
MiiB is online now MiiB  Denmark
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Thorsten, this is just one one the things i recently did on one of my drivers, Increased bl to 2 dB more sensetivity while l maintained Re and reduced Le so much that impecance had just risen to 7,5 ohms at 10 KHz (5,6 ohmmDCR) where it was 15 ohms prior, imagine what that did to performance, but mechanical damping is also what goes on in a mambrane Mwhere it totaly unpridictable and varies with SPL.
Le is horrendous besause it varies up to 50 % vith excurtion amplitude. So getting that out of the driver improves performance quite a bit, maybe not on the direct liniarty/responce of the driver, but for sure when you make it into a system
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Old 17th December 2011, 04:48 PM   #19345
Previously: Kuei Yang Wang
 
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Hi,

Quote:
Originally Posted by vacuphile View Post
Exactly, so, Thorsten, that is why you want drivers with the highest possible Qms. Any mechanical dampening that is not there cannot cause problems. All mechanical dampening that is will.
Proof?

Given the extent of nonllinearity in electrical damping I am not sure mechanical damping done right (e.g. flowresistance integrated in basket) would do so badly by comparison.

Ciao T
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Old 17th December 2011, 04:49 PM   #19346
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Quote:
Originally Posted by VladimirK View Post
I have got a question from "subjective" domain.
Usually we consider interaction between driver stage and output stage (lets suppose both are MOSFETs) in terms of driver stage output impedance (usually resistance R) and gate capacitances of the output stage (some C).
Usually it is supposed, that if in two different designs the RC is close, hence the stage interaction issue is solved similarly.
What I observed subjectively, from listening, one never get similar sound in case if gate capacitances of output stage differ strongly, lets say as 100pF and 1000pF. For the second case, by simply decreasing driver stage output impedance, we could hardly approach the sound at the first case. I suppose, there could be some second order effects, related to interaction of stages. Are there any ideas, what kind of effects could play here?
Could it have any ground an idea, that driver stage Rout - L of wiring - C of gate(s) start to interplay ? For the same L, with larger C and smaller Rout we could allow achieving some ringing conditions at close to or below 100MHz frequencies, that are already recognizable by most active parts.
In case of tube schematics, we usually deal with high Rout and very small C (like few pF).
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Old 17th December 2011, 05:30 PM   #19347
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Quote:
Originally Posted by scott wurcer View Post
That is correct, I question the reversibility of loudspeakers to the degree of getting any useful results, and I don't see any use for doing it with two.
Scott,

We both are looking for the same thing, an easy way to get accurate acoustic measurement results. I have looked at two ways, a hot wire signal source and using loudspeakers bi directionally.

Reciprocity refers to a reciprocal relationship. The microphone standard uses three as a minimum, as it is intended to give converging results. I don't think that is required for a simple is it flat question. It is if you want to know how flat!

As to NIST traceability accuracy that is what a pistonphone and barometer are for. My acoustic standards are better than many local testing labs! That is needed as sound level meter calibrators need to be checked each year. SLM's are checked before each use. The cheapies can drift by several db between uses and operating temperature. The local noise ordinance allows for 5 db calibration error!

ES
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Old 17th December 2011, 05:30 PM   #19348
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Johnloudb, reciprocity is a calibration method that allows absolute calibration in the absence of an absolute reference. The idea is to use the transducers in question as a sender
( loudspeaker ) and receiver ( microphone ).
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Old 17th December 2011, 05:33 PM   #19349
MiiB is online now MiiB  Denmark
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Flow resistance is equally bad. As it is prone to reflections and turbulence which is both unpredictable and impossible to model...At Raidho this has been one of the key drivers to design our magnet structure, which has very litlle compression and reflection from the rear structures in the driver.

http://www.raidho.dk/uploads/Raidho-...ix-Drivers.pdf
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Old 17th December 2011, 05:37 PM   #19350
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Flow resistance turns energy into heat. Unfortunately my ears are no heat sensors.
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