The Family12 is the successor to the successful Family 6, which we were continually asked about. Unfortunately, for a long time we could only answer: "Yes, once upon a time ...". In the meantime, no adequate chassis were available for a new design. The problem was construction-related: Not every chassis runs in a bandpass design, including the W 148-4, which would have been the most obvious replacement. Also the computer simulation with other inexpensive 15s from the extensive delivery program promised little success, bandpass chassis are usually just a little more expensive.
Now the tide has turned for the better and we can finally meet the many inquiries about the Family 6 un with a successor model: Instead of the 15-inch chassis used in the Family6, there is now a suitable 18-inch chassis, the W 176-4, which does not even require a larger cabinet. With its ideal Thiele Small parameters, it is excellently suited for the successor in the handy bandpass cabinet.
That was the starting signal to completely redesign the Family, i.e. to choose a new midrange-tweeter lineup. So the question arose about the appropriate mid-high range, especially since tweeters and midrange drivers were also no longer produced in the meantime. From experience, the construction with drivers of one brand is more promising than a mixed assembly, if only because the technical data of a manufacturer are reliably comparable.
So we constructed the Family12 completely with the Gradient Select series, which simplified the So we constructed the Family12 completely with the Gradient Select series, which simplified the selection of the tweeter: The GDT 104 N already makes a good figure in some construction proposals and is virtually unrivaled as far as the use in inexpensive speakers is concerned. The choice of a suitable midrange driver was a bit more difficult: W 148 and W 115 promised to be the best choice, especially since both have 4 ohms.
Even though the W 115 doesn't need a much smaller cabinet, we decided to use the W 115 for optical reasons alone - the surprise effect when decent bass orgies come out of a speaker with such a small chassis is simply overwhelming - and so the tweeter and midrange have almost the same diameter, which looks quite good. So the only decision left was whether to use the W 115 in 4 or in 8 ohms. The four ohm driver is 3 dB louder, but leads to a critical impedance drop below 3 ohms in the crossover area, which is not tolerated by every power amplifier. So we went for the safer eight ohm and finished the chassis selection with it
Now to the design itself: LspCAD determined 5 liters for the closed and 5 liters for the ventilated chamber during the computer simulation of the bandpass enclosure, in which a full-length HP 50 BR bass reflex tube is already taken into account. The W 115-8 requires an additional 2.5 liters of enclosed volume. With this information it was easy to use Sketchup to calculate a reasonable cabinet, which does look a bit more nested than a normal box - pardon - box.
With a bandpass design, however, you have to make sure that the inner boards don't get in the way of either the drivers or themselves. Thus, we allowed the midrange driver its place in front of the closed bandpass chamber and placed the vented chamber below it - which works out quite well, since the bass reflex tube can then also radiate forward like the midrange driver.
The internal subwoofer chassis (or what should we call a bass driver with such a low crossover frequency?) of course needs a mounting hole, which should be placed in the relevant inner board before assembly. And if you don't want to glue the bass in, you also need a mounting frame including a removable base plate, which also pays off if the driver needs to be replaced - otherwise a new cabinet would be due.
Since the assembly is quite simple despite the multi-chamber construction, we have not documented the assembly further photographically, the construction plan should clarify all steps necessary for the assembly.
After cutting the MDF boards to size, we glued them together and then sanded the housings after they had dried. In addition, we traced the cut edges with the shadow gap cutter for design reasons. Blue stain finally provides the final finish.
After the stain had dried, a total of two bags of Sonofil ended up in each box. Then it was time to install the loudspeaker chassis along with the associated cables, which must be soldered on beforehand.
Then we could go to the development of the passive crossover, which is not quite so trivial with a bandpass design, since the bandpass acts more or less as a mechanical filter. The closed chamber limits the frequency response as with a closed box also with 12 dB/Oct. downward and the reflex chamber with the same slope upward. So theoretically only a narrow frequency band should get out of the reflex tube - but in practice this doesn't work out, especially since the impedance response would then also pose a problem. So we tackled the midrange, which whined too loudly without a crossover, with a core coil and a rough audio frequency electrolytic capacitor, which works quite well with a bandpass without choosing higher quality components. This measure then kept the noise a good 20 dB below the useful level.
Since the closed cabinet of the W 115-8 is also a mechanical high pass with 12 dB/oct. and thus already limits the excursion, only a large electrolytic capacitor for an additional 6 dB slope is necessary to not only further limit the excursion, but also to keep the impedance curve uncritical for the amplifier. Moving up, we added a 12 dB/oct. low-pass filter for the midrange driver to allow the tweeter to take over cleanly. The tweeter also received a network with 12 dB/Oct. The GDT 104 N needs an additional voltage divider for level adjustment due to its high efficiency, which increases the power handling as a side effect.
The sum of the individual branches add up to an ideal frequency response curve as long as the woofer is connected out of phase with respect to the mid-high range, which is explained by the internal driver.
Then came the most interesting part of the construction report: The sound test in the listening room. There, the Family12 also had to face the test with different music material. First, Katie Melua landed in the CD player. Her soft, well-emphasized voice was accompanied by a good spatial resolution and lacked any sharpness, which sometimes even expensive domes don't leave out.
Nevertheless, we didn't miss any details, they were definitely discernible, just not as superficial. Compared to the predecessor version, the Family12's low bass even reached a bit further down into the frequency cellar, which makes a subwoofer superfluous even in rooms of 30 m² and more, at least when playing music. The bass guitar sounded clearly bumped behind the singer and the drums next to her struck short and surprisingly dry - despite the bandpass design.
Quiet music with vocals from singer-songwriters, however, is not a real challenge for properly developed speakers with serious drivers. So, we fired up the newcomers with rocky tones, or rather, following Katie Melua, we had Rammstein blasted around our ears, a band that you can only listen to loud, as we all know. It was pleasant during the sound test that even with Rammstein the ears do not have to hurt - although the small ones were very committed and spectacular to work. For this, even amplifier outputs below 100 watts are easily sufficient in not too big rooms. Peter Fox treats our ears a bit more demurely. The Pussycat Dolls, who followed the bard's footsteps, also provided sufficient stomping bass. Madcon also let through that the bass was recorded a bit cheeky during the recording. At the end of the sound session, we simply used the tuner to capture music from the airwaves - or rather, we wanted to, because the news was promptly read out. Clear announcements from the speaker documented world events - there were comprehension problems at most with the world events, less with the articulation.
In any case, the first buyer of the Family12 couldn't help but be amazed during the sound test when the tiny Yello's "Baby" thundered into his auditory canals. In any case, he was unable to describe the sound other than with "want to have".