4th December 2003 

Tweeter - TW3173A (Made in Malaysia)

Mid - W1343H (Made in Malaysia)

These were factory rejects - passed to me by a friend for investigation. The frequency responses looks respectively as: -

The tweeters (yellow and red - namely left and right or speaker 1 or 2) has very smooth response from 900Hz to 6kHz but prematurely dies very quickly after that, which is a shame. The non-spiky response will render this speaker nice, clean and smooth. Not harsh, striking.

This tweeter, because of it's lacking of very high frequencies is categorized as a mid only or a high-mid. Another tweeter needs to be supplemented for the missing frequencies from 6kHz onwards. This will make the system a 3-way.

The mid is also considerably good, considering it is +/-2.5dB from 90Hz to 1kHz. The sudden transition at 450Hz will be a significant reject in human listening test. That is unfortunate. The 1st cone break-up frequency is around 1.2kHz and has to be rolled off by a low pass filter. It is a good thing that the tweeter is able to carry on after that.

The theile-small parameters was not measured. Guessing from the design it is either a ported-box-able mid/woofer or else another pure bass / woofer is required. If so it will become a 4-way system.

Upon measurement it is found to be a good matching pair for home use as floor standing 4-way category.

The 1st choice of design would be

  1. Add a woofer for pure bass and low pass using 12dB/oct at 80Hz. Spot-on -3dB point.
  2. Band-pass the mid from 80Hz to 650Hz, again using 12dB/oct on both ends. It is hoped that the early roll of the mid will render it's sudden fluctuation at 450Hz less prominent. (Don't seem to be though :( )
  3. Band-pass the tweeter (so-called - by the looks of it) from 650Hz to 7kHz, again using 12dB/oct on both ends.
  4. Now the trick is to find a matching pair of pure tweeter, which works effectively from 7kHz onwards.

The frequency response specifications are this tweeter is: -

700Hz to 7kHz +/- 1dB (or 500Hz to 8kHz +/- 2.5dB) realistic

While the mid is: -

100Hz to 400Hz +/-0.1dB (or 90Hz to 1kHz +/- 2.5dB) realistic



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