6 & 7.5 inch mid-woofer test

The 6/7" Mid-woofer

We will test several 6/7.5" Mid-woofer in this article:

SbAcoustics SB17NBAC-4
SbAcoustics SB17CAC-4
SbAcoustics MW16-TX-8
SbAcoustics MW19-TX-8
ScanSpeak 18W4434G00
Sica 6.5H1.5CP
STX W.18.200.MCX_v2
STX W.18.140.8.MCX

All drivers are EQ flat to be compared, at 95 dB SPL.

Discalified mid-woofers

There is too many woofers to have readable charts in overlay so severals has been disqualified, there is the reason why:

STX: Both STX have a hollow about 6 or 8dB in plain midrange, even without EQ we see abnormal distortion then after have EQ it flat, it’s of course worse, letting this hollow will not allow to use theses mid-woofer, so they are in fact not usable.
Sica 6.5H1.5CP: It’s not a bad driver but other are excellents (without air inductor), it was a good Q/P ratio driver before, now his price has risen so he lost his interest, However it’s a driver that rise up in frequency and love to be linearize with a 1.7mH air inductor, resulting a very good driver in active filtering thanks to this trick (as seen in speaker breakup article).
ScanSpeak 18W4434G00: Not a bad driver either, the best of the four, it rises a little bit too much in distortion after 800/900hz but very good in low medium.

Top 4

We will take a look of order that show a difference between each drivers, some order are “far” but they are outside of mask effect and in audible range (depending of their %) as seen in masking effect and audibility article.

Due to their surface and directivity match none of this driver should be crossed above 2/2.5khz, almost all have their breakup begining at 4.5/5kHz.

H3:

H4:

H5:

H7:

H9:

IMD

Here we take the two better and try to find a difference in IMD, with a multitone 4 IMD test at 95 dB SPL.

Here we see IMD but THD is also present in the chart so it’s hard to separate the two, we can just say that the MW19-TX looks like better but as he is better in THD too.

Temporal measurement on midwoofer

When we do it with a compression driver and a horn we measure in fact the couple, for the woofer we don’t want to have the box and the way the woofer is integrated with it.

If we measure CSD or Burst Decay at 25/32cm we measure the woofer with his very close environment (even if we gate the measurement).

If we measure the woofer at 2cm we will only have the woofer alone, and we will see that at breakup his temporal measurement is not good. The rest will be perfect, for all.

So avoid being close to breakup, anyway distortion will dissuade you to go near to it, all drivers perform perfectly in temporal measurement in usable range here.

Conclusion

STX does a great performance in the 8inch driver test, but here we can see that they have both the same issue between 700 hz and 1.2khz, without EQ there is a huge hollow, and EQ we excite the conception problem.

The MW19TX is a perfect companion for a 2 voices speaker, cross arround 1600hz with a tweeter waveguide like ReShape, not too big, and without the need of a midrange voice, at the cost of his huge price of course.

The SB17CAC under perform compared to NBAC/NAC.

The MW16TX is a little bit stuck, stuck between the MW19TX and the SB17NBAC and by its price, moreover the frequency raw response of the MW16TX is a little bit accidented after 1khz when the MW19TX is not.

There are two winners, the SB17NBAC and the MW19-TX, both have linear response in bonus.