Up for test is the Seas H1397 tweeter. A commonly used tweeter in the car audio world and home audio world due to its compact size (outer diameter is only 53mm; approximately 2 inches) and relatively low cost. Manufacturer’s information can be found here.
Thiele-Small Parameters and Impedance
|Re||3.03||Ohm||electrical voice coil resistance at DC|
|Krm||0.001||Ohm||WRIGHT inductance model|
|Erm||0.53||WRIGHT inductance model|
|Kxm||0.0002||Ohm||WRIGHT inductance model|
|Exm||0.83||WRIGHT inductance model|
|Cmes||246||µF||electrical capacitance representing moving mass|
|Lces||0.07||mH||electrical inductance representing driver compliance|
|Res||1.05||Ohm||resistance due to mechanical losses|
|fs||1212.6||Hz||driver resonance frequency|
|Qtp||1.479||total Q-factor considering all losses|
|Qms||1.974||mechanical Q-factor of driver in free air considering Rms only|
|Qes||5.68||electrical Q-factor of driver in free air considering Re only|
|Qts||1.465||total Q-factor considering Re and Rms only|
2.83v/1m, Nearfield and farfield merged at 1300hz.
Mic placed in the nearfield and measurements performed at an SPL equal to a farfield level of 90dB/1m.
Output increased to represent 96dB/1m.
The Fs isn’t terribly low and this can be misleading as most will shop by this spec only. However, when viewing the other aspects of this driver it looks to be quite a value. The response is (-)3dB from 0 degrees to 30 degrees at 10khz while down 10dB from 0 to 60 degrees. The frequency response has a rise on-axis but a smooth, flat 30 degree response averaging about 85dB at 2.83v/1m. This means the tweeter may be better suited for an off-axis type install, however some seem to prefer a heightened top end. Use your own judgement here and experiment with placement, depending on environment (home or car).
At high output, the HD is fairly low above 2khz, dominated by almost solely 2nd order distortion. 3rd order and subsequent odd order distortion components are at most 0.33% (3rd order; 2250hz) in the 96dB testing. At a moderate output of 90dB/1m, the distortion is pretty much below 1% above 1.5khz with a rising trend above 5.5khz, but again comprised of 2nd order distortion. It’s interesting to note the higher order distortion components essentially stay the same above 2khz as the output is increased while only 2nd order distortion rises.
- Small and very compact.
- $42 price tag (as of this writing) is attractive.
- Very nice off-axis performance, though you may not like the on-axis rise.
- Well controlled high frequency dispersion.
- Crossed at 2khz with a LR4 this driver should be able to provide some hearty output levels.