Fountek FW168 Sonic Signature
Before I design anything, I will mount a woofer onto a box and listen to it in it’s raw state, that is, without any crossover. It gives me an idea of it’s tonal characteristics. Usually, the woofer sounds terrible.
With this Fountek FW168, I am truly impressed. It is the first time I’ve come across a woofer with the right balance.The first thing to strike me is the bass is as loud as the midrange. But it is more than just loudness. The bass is punchy and has definition. That is exactly the kind of bass I want. The vocals, surprisingly, are clear and transparent. No screeching voices. The treble is the weak spot but that can be addressed. Overall, this woofer has a lot of potential.
Disregard the deep notch at 150Hz in Fig 1. It’s caused by a floor bounce when the mic is 1 meter away from the speaker. What is important are the bass frequencies. From 75Hz to 125Hz, they are almost at 80dB, the same level as the mid-range. This confirms what I heard. At 4kHz, the cone breakup starts. This is followed by a sharp 12dB peak at 8.5kHz.
What I would like to do in designing this speaker is to preserve the response exactly the way it is up to 4kHz. In doing so, the bass and the midrange tonal qualities in the final speaker will be retained.
Crossing the Fountek FW168
Fig 2 is the response of the Fountek with a 12dB Low Pass Filter. The offending peak at 8.5kHz is now lowered by -20dB. It is possible to remove the peak with a conjugate LCR network but since it’s up in the higher frequencies, I doubt it will interfere with the tweeter.
HiVi TN28 Top Mount 1″ Fabric Dome Tweeter
I’m sure some readers are puzzled by the picture at the top of the page. The Peerless XT25 tweeter below the FW168 is not used. I left it there out of convenience. Saved me the trouble of cutting another front panel. The small tweeter sitting on top of the box above the Fountek is the HiVi TN28. This is the tweeter that is used for this speaker.
Some may wonder why I chose this particular tweeter. The answer to that is it is less problematic to work with. Since it is not on a baffle, it doesn’t suffer from baffle edge diffraction, which is a major issue with all dome tweeters.
Mockingbird-TN Frequency Response
The Black plot in Fig 3 is the summed response of the FW168 and the HiVi TN28. Note it is exactly the same as the RAW response of the FW168 up to 4kHz. We can be assured that at least up to 4kHz, it has the same tonal qualities of a raw FW168. Above that, the harshness in the aluminum cone breakup is taken care of by the TN28.
Fig 4 shows the TN28 tweeter wired in reversed phase (Red plot). The deep notch is a good indication that the two drivers are crossing properly. Note the symmetry of the slopes on either side of the center of the notch (3.5kHz).
The Harmonic Distortion of the Mockingbird-TN is quite impressive. From 200Hz to 10kHz, it averages about -55dB below the fundamental. Further to that, the 2nd harmonic (Red plot) is higher than the 3rd harmonic (Violet plot), which is preferable.
Listening to the Mockingbird-TN
I love this speaker. It sounds wonderful. The music is effortless. It is rare when everything falls together naturally.
The all important vocals don’t sound restrained. They are not buried in the music. On the other hand, the vocals don’t overpower the band either. Positioning is just about right in the soundstage. Slightly in front of the band.
The magic is in the bass. I’ve never heard a 6″ woofer, or any for that matter, that sounds a bit like my Tymphany NE265W-04 10″ Woofer. The bass is dynamic, has attack and punch. You can even make out the details in the bass.
Fountek got it right with this woofer. The FW168 is grossly under appreciated. It is on offer now at Madisound for a mere $26. Grab them while you can. Even at the original price of $37, it still outperforms many 6″.
The HiVi TN28 did it’s job fabulously. There are no grating highs in the treble. When the cymbals come on, they don’t assault your ears. And this is from a tweeter that cost less than $20.
Both of these drivers, the FW168 and TN28, are proof that cheap doesn’t always equate with rubbish. Once in a while, there are gems amongst them.
September 26, 2017Projects