Alpine DDC F17A Component Speaker
24th December 2003
The woofer is typical and not studied. Proper study of woofer's behaviour requires other method.
This write up is mainly concern about component sets quality.
The mid is good, purple color curve. True useable frequency from 100Hz to 700Hz +1dB. Cone breakup starts slowly but surely :( This is better than sudden rise of cone breakup.
Applying 24dB/oct low pass filter to this mid at around 800Hz will probably be effective.
However the tweeter is not very good. Lost of frequency (sound) at 6kHz -8dB. The bandwidth is also significant with an highest demand of quality stating it from 4kHz to 12kHz. It also have an extremely fast roll off after 12kHz resonance. This resonance is very peaky and sharp. It will not be welcomed by the ears.
The tweeter also starts very late at 2kHz. This means cross-over point is around 1.6kHz. But the mid is unable to low-pass at 1.6kHz because it has already entered cone breakup region. Compromise will have to be made.
Still, due to the tweeter starting around 1.6kHz therefore the sound stage will be generally high on the dash. Couple with a smooth mid, they will be good. It is a shame that the tweeters suffers a lost of sound quite big chunk :(
The re-surface of a peak at 12kHz only serves to defeat better sound quality because it can be seen from the response that it is fighting with itself to produce sound. Response like this "sudden" or "peaky" always yields harshness to the sound reproduction.
This tweeter is not recommended for purchase because lower cost and better quality speakers has been found. Those are far more easy to setup and optimise.
This mid however will be a good candidate for all scenario. Very good boy, easy to setup as long as low-pass before 800Hz using 24dB/oct. If 12dB/oct then have to be earlier around 650Hz or so. This is to counter-react the rising cone breakup curve.
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