Different factories, different ways of writing, sometimes I'm confused about the xmax in their specs.
Of course I mean linearly xmas, not damagingly.
See if I screw...
SB Acoustics SB34NRX75-6
This is the clearest, xmax p-p
Peerless SLS 830669
The most common expression, xmax, nothing else.
Defaultly, if they didn't mention anything else, just xmax, it ain't no p-p right?
Accuton S280-6-282
I guess +/- 6mm means p-p?
Scan 26W/8861
And ± 9mm also = p-p?
Beyma 15P1200Nd/N
And Vd = Sd * xmax, in this situation, does xmas mean no p-p, only one way?
Of course I mean linearly xmas, not damagingly.
See if I screw...
SB Acoustics SB34NRX75-6
This is the clearest, xmax p-p
Peerless SLS 830669
The most common expression, xmax, nothing else.
Defaultly, if they didn't mention anything else, just xmax, it ain't no p-p right?
Accuton S280-6-282
I guess +/- 6mm means p-p?
Scan 26W/8861
And ± 9mm also = p-p?
Beyma 15P1200Nd/N
And Vd = Sd * xmax, in this situation, does xmas mean no p-p, only one way?
+/- is what it means only "more or less" nothing else. In this case, if only one way it's fine. Beyma makes a classic case of the good use of (parameters) standards and lab testing, that's where they come from (not China, hehe).
mtoc, yes there's the Xmax parameter and the Xmech where in the first formula() is the max cone movement/power and the Xmech the mechanical where it represents a constraint for damage.
Different configurations of drivers ie. short voice coils, PA drivers, have different formulas but generally when testing in lab it represents 10% distortion, that most manufacturers don't do, they use approximation formulas that are more convenient.
Xmax can be derived from data that is given by most manufacturers.
Xmax=(winding hight - gap height)/2
That is not perfectly accurate because magnetic field goes a milimeter or so beyond gap but it is pretty good sign of what to expect from it
When they write +/-9mm that means that Xmax peak to peak is 18mm. Forward movement being + and backward -
Xmax is movement in one direction unless marked otherwise.
Xmax=(winding hight - gap height)/2
That is not perfectly accurate because magnetic field goes a milimeter or so beyond gap but it is pretty good sign of what to expect from it
When they write +/-9mm that means that Xmax peak to peak is 18mm. Forward movement being + and backward -
Xmax is movement in one direction unless marked otherwise.
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I guess my memory was not the best. I must acknowledge. This was my mistake. These formulas are empirical any way. There a few different ones more appropriate to substitute the distortion that is not always used because of the necessity of a measuring chamber and the low frequencies. The formulas give a very close result that at this frequencies is only a mechanical dependent vs. sonic parameter. The typology of the driver and the power used/aloud might justify different formulas for the same parameter.
A short coil that is entirely within the gap is how you get a high BL at the expense of X-max. For high sensitivity midranges, the theoretical x-max is often zero or close to it.
Another possibility is to have the coil be shorter than the gap - many neo motors are built this way (underhung coil). In that case the x-max is when the coil starts to leave the gap.
Another possibility is to have the coil be shorter than the gap - many neo motors are built this way (underhung coil). In that case the x-max is when the coil starts to leave the gap.
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