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<blockquote data-quote="John_E_Janowitz" data-source="post: 6119041" data-attributes="member: 550657"><p>I find it funny that now not only are my woofers being criticized, now the Theil Small parameters and electrical modeling that has been around since 1954 is being criticized as well. You can believe that they are not accurate if you wish and just give over everything to chance. I wish you luck witht he results. However, years and years of physics and electrical circuit modeling has proven the validity of these models. There is however a saying in engineering that "garbage in = garbage out". If you don't have accurate parameters to model what is going on, then you won't get valid results.</p><p></p><p>The primary parameters for a driver are the following. They are physical values that can be easily measured and verified both at small signal levels and at higher excursions.</p><p></p><p>* Sd - Projected area of the driver diaphragm, in square metres.</p><p></p><p>* Mms - Mass of the diaphragm, including acoustic load, in kilograms.</p><p></p><p>* Cms - Compliance of the driver's suspension, in metres per newton (the reciprocal of its 'stiffness').</p><p></p><p>* Rms - The mechanical resistance of a driver's suspension (ie, 'lossiness') in N·s/m</p><p></p><p>* Le - Voice coil inductance measured in millihenries (mH) (Frequency dependent, usually measured at 1 kHz).</p><p></p><p>* Re - DC resistance of the voice coil, measured in ohms.</p><p></p><p>* Bl - The product of magnet field strength in the voice coil gap and the length of wire in the magnetic field, in tesla-metres (T·m).</p><p></p><p>If you have accurately measured parameters and you know how the BL and Cms curves affect things at higher excursions you can model things very accurately both at low and high power. Now, that doesn't mean that you can just take what the modeling program shows for SPL in a box alone, stick it in a car and add the cabin gain to it and get that exact result. There are other variables introduced by the car. Just because you have 30dB of gain at low levels doesn't mean the transfer function is identical as the cabin begins to pressurize, panels begin to flex, etc. Any accurate model has to account for variables.</p><p></p><p>Then the best way is always to verify what you are modeling by measuring the results. The Scientific Method:</p><p></p><p>1. Define the question</p><p></p><p>2. Gather information and resources (observe)</p><p></p><p>3. Form hypothesis</p><p></p><p>4. Perform experiment and collect data</p><p></p><p>5. Analyze data</p><p></p><p>6. Interpret data and draw conclusions that serve as a starting point for new hypothesis</p><p></p><p>7. Publish results</p><p></p><p>8. Retest (frequently done by other scientists)</p><p></p><p>John</p></blockquote><p></p>
[QUOTE="John_E_Janowitz, post: 6119041, member: 550657"] I find it funny that now not only are my woofers being criticized, now the Theil Small parameters and electrical modeling that has been around since 1954 is being criticized as well. You can believe that they are not accurate if you wish and just give over everything to chance. I wish you luck witht he results. However, years and years of physics and electrical circuit modeling has proven the validity of these models. There is however a saying in engineering that "garbage in = garbage out". If you don't have accurate parameters to model what is going on, then you won't get valid results. The primary parameters for a driver are the following. They are physical values that can be easily measured and verified both at small signal levels and at higher excursions. * Sd - Projected area of the driver diaphragm, in square metres. * Mms - Mass of the diaphragm, including acoustic load, in kilograms. * Cms - Compliance of the driver's suspension, in metres per newton (the reciprocal of its 'stiffness'). * Rms - The mechanical resistance of a driver's suspension (ie, 'lossiness') in N·s/m * Le - Voice coil inductance measured in millihenries (mH) (Frequency dependent, usually measured at 1 kHz). * Re - DC resistance of the voice coil, measured in ohms. * Bl - The product of magnet field strength in the voice coil gap and the length of wire in the magnetic field, in tesla-metres (T·m). If you have accurately measured parameters and you know how the BL and Cms curves affect things at higher excursions you can model things very accurately both at low and high power. Now, that doesn't mean that you can just take what the modeling program shows for SPL in a box alone, stick it in a car and add the cabin gain to it and get that exact result. There are other variables introduced by the car. Just because you have 30dB of gain at low levels doesn't mean the transfer function is identical as the cabin begins to pressurize, panels begin to flex, etc. Any accurate model has to account for variables. Then the best way is always to verify what you are modeling by measuring the results. The Scientific Method: 1. Define the question 2. Gather information and resources (observe) 3. Form hypothesis 4. Perform experiment and collect data 5. Analyze data 6. Interpret data and draw conclusions that serve as a starting point for new hypothesis 7. Publish results 8. Retest (frequently done by other scientists) John [/QUOTE]
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