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The Crossover
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The rationale behind the three 10W 6.8 ohm resistors in parallel is to
keep the resistors providing mid attenuation absolutely cool. Maybe overkill, but it's cheap.

The Complete Kit
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All technical questions to troels.gravesen@hotmail.com

Measurements
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A few comments on MEASUREMENTS before you start interpreting the readings below.
First of all, if we think measurements will tell us how a speaker sounds, we're wrong. The perception of sound is way too subjective to be reflected in any measurements we can perform. A loudspeaker system is meant to give us a satisfying idea of an acoustic event and for some people a pair of 5 USD ear-plugs are enough, others spend 200 kUSD on a truly full-range pair of speakers - and the latter may not be happier than the former.
Measurements may give us an idea of tonal balance of a system, i.e. too much or too little energy in certain areas, although dispersion characteristics play a vital role here. A two-way 7+1 and a three-way 7+4+1 may display similar horizontal dispersion, yet sound very different. Measurements may tell us about bass extension if far-field measurements are merged with near-field measurements. In addition to this, ports may contribute to bass extension. Most of we diy'ers do not have access to an anechoic room for full-range measurements from 20-20000 Hz.  
What cannot be seen is what kind of bass performance we get in a given room. Bass performance is highly dependent on in-room placement of your speaker and the same speaker can be boomy in one place and lean in another. Actual SPL level at 1 meter distance and 2.8V input is useful for en estimate of system sensitivity and combined with the impedance profile may give an idea of how powerful an amplifier is needed to drive the speaker to adequate levels.
What measurements do not tell is the very sound of the speaker unless displaying serious linear distortion. The level of transparency, the ability to resolve micro-details, the "speed" of the bass, etc., cannot be derived from these data. Distortion measurements rarely tell much unless seriously bad, and most modern drivers display low distortion within their specified operating range. 
Many people put way too much into these graphs and my comments here are only meant as warning against over-interpretation. There are more to good sound than what can be extracted from a few graphs. Every graph needs interpretation in terms of what it means sonically and how it impacts our choice of mating drivers, cabinet and crossover design.
What measurements certainly do not tell is the sonic signature of the speaker, because speaker cones made from polypropylene, aluminum, Kevlar, paper, glass fiber, carbon fiber, magnesium, ceramics or even diamonds all have their way of adding spices to the stew. Nor do measurements tell what impact the quality of the crossover components add to the sound, from state of the art components to the cheapest of coils and caps, they all measure the same if values are correct, yet sound very different.

Left: Green = combined response from all drivers driven from crossover. Purple = bass + midrange. Blue = tweeter. Red = mid + tweeter.
Right: Point of crossover between mid and tweeter is 3 kHz, where the bass and mid crosses over around 350-400 Hz.

Left: System impedance. Minimum is 3.8 ohm at 150 Hz. To make a long story short: This is an easy speaker to drive and my 20 wpc single ended triodes have no trouble driving this speaker to considerable levels.
Right: SPL of system at 2.8 V, 1 meter. Bass response merged at 350 Hz. Blue = port response.

The above two measurements are not normalised for 1 m/2.8V.
Left: Vertical dispersion @ +/- 10 deg. Right: Horizontal dispersion @ 0, 10, 20 and 30 deg. An overall even response in the treble area over a wide listening area. Above 10 kHz we see a gradual decline in dispersion as can be expected from a classic 1" dome. Only a 19 mm dome like the HIQUPHON OWI can do better above 10 kHz. Or the new SEAS 27TBCD-GB-DXT, but that's another story.

Out of curiosity I tried to overlay my W22NY001 measurement with the SEAS graph from the data sheet and I was pleased to see a good correlation between measurements. Blue = SEAS measurement. Red = my measurement where the response merged with nearfield response at 300 Hz is close to actual and predicted SEAS claims.

SEAS W22NY001 8" bass driver close-up.

 I like this speaker so much I'm going to give the whole system an overhaul: Cabs need sanding and a fresh oil rub and I'm going to finish the rear grille, which has been on the shelf ever since I built the cabs. A new port must be installed and new binding posts as well.

I'm going to use Jantzen Audio Superior Z-cabs for the tweeter and possibly for the mid as well. I mean: The drivers alone are some 1,000 EUR, so they deserve the best in terms of crossover components. First I'll try Cross Caps for the mid on one speaker and Superior Z-caps for the mid on the other and try an AB test.

The crossover layout has to be prepared to 3 x 22 uF Superior Z-caps; takes quite some space, 123 x 106 mm. The bottom panel should leave plenty of room for the mid crossover. The bass crossover will be on the rear panel with the coil upwards to keep distance to mid crossover below. The tweeter crossover will be placed right above the tweeter like the Acapella SEas.

Here are some pics from the work:

New foam has been added to the rear panel and the fillets holding the grille has been painted black.
Tweeter X-over is placed like before, right above tweeter.
2.5 mm^2 Supra mounting cable custom made for Jantzen Audio is used throughout.

Port is installed. 68 x 120 mm.

Crossover layout-
tweeter and bass

Crossover sections for bass and tweeter shaping up.

Left: Bass crossover section. Simple 2nd order.
Right: Tweeter crossover section, 3rd order.

Connection from bass and tweeter crossovers to drivers.

Mid x-over:

Now, this is a temporary set-up. The Superior Z-caps to the right is going to stay in place (1 uF + 8R2 bypassing the series 0.82 mH coil. The 10 uF Superior Z-cap goes to ground. The series 68 uF to the left is the series input capacitor making the high-pass filter together with the 4.5 mH + 4R7 going to ground. For my initial set-up I by-passed the 68 uF Cross-Cap with a 1.5 uF Superior to possibly optimise the performance of the Cross-Cap. So far, so good.

Below to the right you can see a chunky load of paralleled Superior Z-caps making almost 68 uF capacitance. This is going into the other speaker and I'm going to AB-test these two speakers. Quite a challenge I think. Everything is the same except for the chunk of Superior Z-caps for the midrange in one speaker.

Disregard the black colour of the 10 uF Superior Z-cap. This is a test samples I had before the bordeaux red colour was decided.

Left: Mid X-over section seen from above. As can be seen, a lot of space is left open for 3 x 22 uF Superior Z-caps in parallel; black marking on bottom panel.
Right: Mid X-over section with series Superior Z-caps. The bottom panel was given a grey colour, just to look nice for the photoshoot.

Mid crossover layout for Superior Z-caps.

Before fastening the bottom panel, two sheets of MDM3 damping material were folded and placed above mid X-over. Take care not to block vent.
All panels in bass section are damped with 20 mm polyester foam. Use e.g. 20-30 mm egg-crate foam.

Sonic evaluation of mid series capacitor contest

Well, this is difficult! Having set up the two speakers as described above, the fun started. One speaker with Superior Z-caps (SZC) to the mid, the other with Cross-caps (CC). All other things the same. Frequency response was checked and was the same for the two speakers within 0.5 dB. It's hard to get any closer than that. In my workshop I have a connection panel attached to the power amp so that I can switch between two pairs of speakers.

The two speakers certainly didn't sound the same. One brighter than the other. The CC version sounded brighter compared to the SZC, but at the same time, while listening to the SZC version my perception of the sound could swap - and all of a sudden I could hear the Superior Z-cap version being the brightest. Weird!!
The problem is this: With the CC the sound is somewhat more compressed compared to the SZC version. With the CC the midrange appears to be located around the speaker front panel plane, where the SZC has a significant deeper soundstage, thus less presence is perceived, yet it allows you to focus your attention on the bright (treble) parts of the instruments and voices and then - brighter. Quite simple actually. The SZC will allow you to focus on details that standard MKPs simply cannot resolve.

During this exercise I changed the position of the speakers from time to time - left and right. These are dipoles or rather semi-dipole speakers and highly dependent on room position. However, still what is described here followed the speakers no matter what position they had. The SZCs simply reveals details and a depth in the acoustic scenario the CCs are not capable of. The CCs certainly aren't bad, not at all. They very much sound like what we're used to hear from the majority of hifi-speakers. Even if you don't have high-quality front end gear, SZC will improve sense of depth and perspective.

I once borrowed an expensive Parasound pre-poweramp set-up. Mega watts and I've never seen so many transistors and integrated circuits in a preamp. Sound? Nice, smooth - and utterly dull and un-inspiring.
A visitor brought a mega NAD integrated. Sound? Nice, smooth - and seriously lacking dynamics compared to my homemade valve preamp + Rotel RD981 workshop set-up. I was quiet surprised by this, but that's how it was. Sorry NAD. I've stopped reading Michael Fremer reports after his enthusiastic review of the same NAD amp. This guy simply tells us what he's paid for.
Point is: The Supreme Z-caps may not be the only thing that will ruin your budget, so watch out!

I better order 6 x 22 uF SZC. Having bundled my residual stock of Superior Z-caps I now have both running with SZCs and they are in my living room right now, driven from my 20 wpc SET amps. Thank Heaven I didn't get rid of the Acapella cabs during my Autumns sale. 20 wpc do well, even up to considerable levels, but ultimately I recommend 40 wpc really high-quality watts for these 90 dB/2.8V speakers. It will provide a more firm bass and the ability to play really loud too.

What more can I say?
Well, if you have some 10-15 kilo US $ burning in your pocket for a pair of commercial speakers, ask your carpenter what he takes for a pair of Acapella cabs. You may save megabucks in doing so.
OK, OK, I know, but as one of my American colleagues always says: "It ain't bragging if it ain't lying".

Enjoy!

- and here's the final mid Superior Z-caps
- some chunky beasts!

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