Impedance curves were taken using the LinearX LMS analyzer both in free-air and in a test box using the conventional impedance method for both the QWD 100 and the QWD 160.
Designed for sealed box performance, MB's QWD 160 6.5" woofer will work well in sealed enclosures as small as 0.25 cubic foot and as large as about one cubic foot. For the LEAP computer simulation I used a 0.5 ft3 sealed box that produced an F3 of about 70Hz with a box Q of 0.92, which is should give the woofer a warm sound quality and good power handling (note that my computer simulation included 50 percent fiberglass fill material which is necessary in a two-way design to absorb rear radiation and reflections in the enclosure). Xmax on this driver is on the low side of average for 6.5" woofer at 2.46mm. Loaded in a 0.5 ft3 with a 5.75V input, the woofer will stay linear (not distort noticeably) up to 97dB, which is reasonably good performance for a 6.5" woofer. This SPL number is higher on program material and if you are using a subwoofer with an electronic crossover high-pass, the output capability would be significantly higher.
Frequency response measurement of the combined QSD 210/QSD 164 system (woofer, midrange, tweeter and crossovers) on a large flat baffle (2'x4') with the tweeter/midrange mounted about 12 inches from the woofer, resulted in a system response of +/- 4.48dB with the tweeter in the -3dB from 70Hz-16.4kHz (see Fig. 1). The titanium dome tweeter response extends out to slightly above 23kHz before reaching its breakup mode at nearly 40kHz (you won't hear that). At 30 degrees off-axis (see fig. 1), and with the tweeter set in the -3dB position, the response is nearly the same as on-axis, but with a more even overall response. This is quite good for this kind of component system, especially considering the tweeter response is still out to nearly 15kHz. Good off-axis performance, such as that exhibited by this MB Quart system, is essential for good sound quality in either a home or car audio speaker system.
Crossover between the QWD 100 midrange and the QTD 25 tweeter occurs at 2.6kHz and is reasonable in-phase, which was indicated by the moderate null I measured with the midrange polarity reversed.
Lastly, I checked the system impedance of the QSD 210/QSD 164 combination and found the lowest impedance to be 3.3 ohms at 1.5kHz, a very easy load for any car audio amplifier. Looking at the whole package, MB Quart's QSD 210/QSD 164 is a very attractive package with lots of high quality bells and whistles, and at $1844 it better sound really outstanding. However, I just measure 'em. How does it sound? Ask Eric. -V.D.
Listening
Hey Rodney! (I'd have called him "Wonderboy," but he completely ignores me when I do that, even when we are on the phone.) Waz up! Yeah, Casey's on vacation, and you need me to come and get the latest stuff that I'm testing... All right, I'll be right over!
So I'm thinking, with Casey out, I can have some fun. Or at the very least, Casey will not be around to pressure me to finish the story and turn it in. I mean it's not that Casey is a screamer. No way, that would be way easier to deal with. No, he just applies the pressure gently: "Hey Eric, how's the article coming? Do you think you will be able to get it done, or do you think I'll have to help you?" AGHH!!! And you can just hear the smile in his voice, but not this time.
I arrange to meet Rodney over at the CA&E photo studio, which I have never been to before and was excited to see. He tells me that it's on the third floor of the CA&E tower in beautiful downtown Placentia, Calif. I'm thinking to myself, "Dang, that sounds impressive!" Well, let me tell you, lavish is not the word for it.