Now it really has been more than three years since I finished building my first construction model, when I promised a sound review of the Exotic F8 from Seas that had just come out. In the meantime, there were plenty of other things to do, which gave me the welcome mental excuse that I couldn’t start building the cabinet just yet. As a halfway honest person, though, I have to admit that my procrastination had more to do with the fact that I didn’t have a mental image of the right cabinet for the high standards of the Exotic. The Q values indicated that a reflex box might work, but the necessary capacity of 200 or more liters told a different story. I also couldn’t really get excited about a closed cabinet with -3dB at just under 60 Hz and a volume of 80 liters. Then what would be the point of the open-air resonance under 35 Hz? On top of all that, I had really liked the F8, which I only had one of, even in mono during a random listening test on my measuring wall. Putting it into an open two-meter-wide baffle board, which would be totally incompatible with home listening conditions, just because of the sound I had heard conflicted with my desire to sell the thing at some point.
The print media had no such problems with it – they accepted the chassis very quickly. Since they mainly sell publications and generate their revenue from advertising, the issue of whether or not a construction plan is marketable is understandably less important. They get the reader’s attention with unusual assemblies whose pros and cons are then discussed in detail in the relevant forums. So in one case the F8 was put into a tube that had already been successful with other equipment; another time it turned up in a closed block with a front was unnecessarily wide, structurally speaking, and would have looked very out of place in a living room, but it gave the editors plenty of space to add their own signatures. Later there was another universal tube whose name clearly showed that it had by no means been developed for this specific chassis. Instead, it relied on easily exchanging the drivers, so it wasn’t a good fit with the F8’s special tonal features. I can’t make any statements about the sound quality of these structures, since I neither built them myself nor listened to them.
I also can’t offer those kinds of boxes in this magazine – as you know, we aren’t financed by selling our articles or any associated ads. Leaving aside the few strong-principled followers of closed wide boxes, hardly anyone would voluntarily set up something like that in the living room and give up on the bass range. Even tube constructions, however exciting they may be, are more popular with younger do-it-yourselfers who are very unlikely to buy a high-priced driver. Seventeen interior boards with various angles on two sides that have to be sawn by hand, with weeks of detail work, are no project for a fifty-year-old audiophile who ultimately just wants to listen to his records in peace. The right cabinet for the F8 needs to be easily built and small enough, but with a powerful bass. Otherwise it won’t find a home with its target group, something that Seas already properly took into consideration in developing the chassis. I spent a long time looking for a brilliant way to house this old-style wide-range speaker in a way that meets the needs of potential do-it-yourselfers.
If I have learned anything in almost three decades of working in speaker construction, it’s that you can’t force things. Ideas need time to ripen and to combine with new experiences, which eventually creates a meaningful whole. An unexpected idea came from the Cyborg needle that was performing so well in our Dayton RS 100-4. Then came the Quickly AX-5 and Holly’s AX-08 TQWT, which gradually began to open my eyes to a completely new concept that would certainly be interesting for the Exotic, too. With this construction type, you can more or less ignore the chassis parameters; like a transmission line, the membrane area and the lower frequency limit are included in the calculations. In addition, it establishes a diffusion area at the end of the line. After some fancy calculations, I found an assembly in less than an hour that was not only simple to build, but also promised deep bass notes. Sometimes things just go quickly once the idea is hatched. Even the name of the new construction plan was easy: Simply Exotic.
So I decided it would be a TQWT, working with just under 90 liters and two interior boards, that would house the four-ohm version of the F8. Since this version of the Exotic has not yet been introduced in the magazine, it’s time to bring it out to take the usual bow: .
Item No: 1381071
Price: 599 Euro
Measurements as a Zip-file
|Membran:||Pappe/ Papyrus||Air gap height:||12 mm|
|Seal:||Gummi||Linear height:||4,2 mm|
|Pole-piece hole:||yes||Mounting holes:||6|
|Centering:||raised flat spider||Outside diameter:||221 mm|
|Short-circuit ring:||yes||Installation opening:||188 mm|
|Voice coil:||26||Milling depth:||5,5 mm|
|Bracket:||fiberglass||Installation depth:||110 mm|
|Frequency response and phase||Impedance||Frequency response under 0/ 30/ 60°|
|Distortion for 90 dB||Step response||Waterfall|
I used the calculated specifications to design a cabinet for the F8 that is hard to overlook (120 cm tall, 30 cm wide and 34 cm deep), but still makes a slender visual impression. The use of beech plywood and black-dyed MDF gave it a handsome style – I seem to be acquiring a taste for both of those materials. The contrast between the wood and the paint helps the eye see beyond just the square box, which is important for a TQWT because of its rich inner values. Even though you are probably seeing this for the two-hundredth time, I couldn’t help quickly documenting the gluing process in a series of photos. There are way too many people out there in the real world who still don’t believe that building cabinets is really very simple.
We have the construction plan for you too: it’s available as a jpg and as a zipped Sketchup-file.
On the back side is the connection box, and the interior of the box features five bags of Sonofil, which needs to be inserted into the back section before the second side panel is glued on. It’s not a bad idea to countersink the cutouts for the chassis and the terminal in advance and run the interior cable. I use a rolled product 1.6 meters high, cut to a width of 25 cm and folded in half once; it is then pulled into the boxes once they are completely finished.
After sanding, countersinking the cutouts and painting the boxes, the F8-4 was connected to the outside world via the terminal and placed in its new home for the first time. Up to now, only the first part of its name had fit; now came the exotic part. As a rule, even a speaker box with only one chassis needs a correction network in order to make the choppy frequency response more linear. This is particularly true for the high range, where the emissions are more and more precisely directed, which necessarily raises the volume level very quickly. Since the increase is very even in the F8, Seas initially suggested a simple, frequency-dependent volume regulator for it using a small coil and an overlaid resistor. It’s a very simple trick, because the coil is essentially open at the bottom; only at higher frequencies does the resistance continuously increase. In order to make sure that it doesn’t wipe out the whole upper range, only smoothes out the exaggeration, you add a resistor to it that sets an upper limit. I tried it out right away, and it wasn’t bad at all. Okay, so there were narrow peaks at 800 Hz – 3 and 8 kHz are manageable for a wide-range speaker. But I wasn’t so happy with the measurement under 15 degrees, despite the reduction in spikes. The volume drops by 5 dB between 3 and 7 kHz, and above 8 kHz it falls sharply.
It needed to be better than that. After all, we’re not dealing with a pocket-change chassis here. I didn’t abandon the idea of L and R volume regulators, but I changed the values. In the next step, three suction circuits took care of the peaks before I turned the frequency-dependent pre-resistor into a voltage divider using a parallel C and a downstream R.
In terms of the measurements, the gain from the eleven additional components is not exactly dramatic overall – except below 15 degrees. Also noteworthy is the impedance curve, whose response is guaranteed to warm the heart of any tube owner with its increase in LCRs.
It may be unnecessary to say this, but I avoided taking shortcuts with the relatively low-value components. Even so, that didn’t mean pulling any silver, gold or other precious metals out of the bank vaults. The Audyn Q4 capacitors guaranteed long-term stability, and durability came from the exclusive use of 10-watt MOX resistors. For the voltage divider, I used a 1.4 mm²-thick air coil, while the suction circuits used an equalizer coil, one air coil with 1 mm² wire and one that was 0.71 mm² thick.
Once again, installing the components in the boxes was completely simple. But since there are often questions about the procedure, I took pictures and provided captions for them.
From the photo studio, I packed up the Exotics and sent them straight to my listening studio – funny names for my very simple quarters, which Olaf described in his reader’s review as being very “personal.” Slightly angled toward the chair but not pointing directly at it is the ideal setup for the wide-range speakers, which – it should be said right away – are not designed to provide even sound to a sofa with three seats side by side. I connected them to my type-appropriate eXperience KT 88 and didn’t waste a moment plugging in the CD player. The record player was what I needed, probably the main course for every potential do-it-yourselfer. But what do you play when you only have 2000 discs from every musical genre except for German Schlager singers at your fingertips and you want to test out a wide-range device? I started out with something easy – a man with a guitar, or rather two men with guitars: Friday Night in San Francisco. Pure goosebump material, because it’s just two men playing their guitars for their audience. Clearly they have nothing to do with a couple of wooden boxes standing around in a room completely without motivation. When the notes crash into the room like fireworks, with at least 37 notes per second per man and without a single hesitation, there’s only one thing to do: close your eyes and forge ahead. The only shame was that “Mediterranean Sundance” was over after a much-too-short eleven and a half minutes.
Okay, so full-range speakers should be able to reproduce the mid-range without any problems. Providing a clean bass and high range at the same time is a much bigger challenge when they need to come out of a single chassis.Still cautious, I tried out another jazz classic, Oscar Peterson’s “We get requests,” which at least involved one more man. Bass foundation? What had I been so worried about? At the same time, the bow strokes and then the plucking of the strings on Ray Brown’s upright bass weren’t overshadowed by any undefined rumbling tones. Everything was in harmony, no worse than a box with three specialized speakers in it. In all the excitement, let’s not forget about Ed Thigpen’s cymbals – describing them as silvery would be completely off base. The four plates are clearly made from brass, and the ear is not fooled for a second. I should also mention the piano, which is centered but slightly to the back of the stage, more than living up to its name as a pianoforte with its range of loud and soft notes.
A few more men (and women) found plenty of room on the imaginary stage when I opened up the classical section of my record cabinet, which is actually more of an overgrown shelf a couple of meters wide. Strings in the front, woodwinds and brass behind them, and the kettledrum right at the top – all of the musicians had plenty of elbow room and a good distance from their neighbors, so they never ran into each other and they were able to make their music harmoniously and completely without stress. Just listening to it was a pleasure, regardless of whether it was Mendelssohn’s “Italian” or Haydn’s “Londoner” filling the room behind the boxes. Now, to make sure that no one feels left out by my somewhat one-sided music selection, I have to admit that Prince, Peter Gabriel, Rammstein and Peter Fox are also among the artists whose records made it off the shelf for a listening test. Sometimes my musical tastes are Simply Exotic too, and with these boxes it’s not a problem. I finished up with wide-range blues at its best: Stevie Ray Vaughn and Double Trouble transported me to “Tin Pan Alley.” Anyone who can lean back motionless in an armchair while listening to that is probably a lost cause when it comes to music.
|Chassis||Seas Exotic F8-4||Wood list in 19 mm MDF per box|
|120,0 x 34,0 (2x) sides|
|Sales||Intertechnik, Kerpen||26,0 x 34,0 (2x) lid/floor|
|Construction||Udo Wohlgemuth||26,0 x 116,2 (1x) back wall|
|26,0 x 114,0 (1x) front|
|Functional principle||TQWT||26.0 x 100,1 (1x) diagonal board|
|Nominal impedance||4 Ohm||26,0 x 11,0 (1x) channel board|
|Insulation||5 bags Sonofil|
|F8-4: 5,5 mm|
|Cost per box:|
|Assembly kit:||685 euros||Wood cutting: 30 euros|
|Frequency response and phase||Impedance||Frequency response 0/15/30/60°°|
|Distortion for 90 dB||Step response||Waterfall|
The Simply Exotic can be purchased from Intertechnik