ScanSpeak Illuminator-71
Copyright 2021 © Troels Gravesen

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The Illuminator 71 here is meant to replace the Illuminator Monitor standmount and the Illumina 66 floor-stander, which will be discontinued as kits from Jantzen Audio. The Illuminator Monitor used a rather elaborate all-pass filter to time-align the drivers, and the Illumina 66 a tilted baffle. Here we use a stepped baffle allowing an overall simpler crossover. The Illuminator 71 can be made into a floorstander by extending the cabinet and lifting the bottom panel like seen in the Ekta mkII. You can use the Ekta mkII cabinet by eliminating the 12MU midrange driver and midrange cabinet and make the front panel similar to Illuminator-71 seen from top. I strongly suggest using the 70 mm port used here. Cabinet volume here is around 26 litres. The 7" 18WU has a cone area of no less than 154 cm^2, so quite some bass capability from what would traditionally be classified as a 6" driver, but really is a 7". "18" comes from having a frame diameter of 184 mm.
I have also decided in incorporate two tweeters, the venerable D3004/660000 and the R3004/662000. Being tuned to the same amplitude and roll-off, they sound very much the same, the 6600 being the classic fabric dome, the 6620 the grown up brother of the venerable R2604/832000. The dispersion of the two domes is different, which may count for some of the minor difference in sound and the frequency response will always vary a little. I like them equally well, but I have friends who disagree. Matter of taste and habit. Some just don't like the pointy center plug of the 6620.
I decided to use the large flanged 70 mm port - because this stand-mount can play bass and we don't want any port noise. And it should be on the back because port often leak midrange - and not the good part. Any port can be close to the front wall without jeopardizing the port performance. For some reason many think this is a no go. What near-wall placement will do to the overall sound of the speaker is a completely different matter, but it has nothing to do with placement of the port but counts for all speakers (early reflections).

After finishing the the Illuminator-71 I quickly had an offer I couldn't resist, hence after some months I had to build a 2nd pair for my stock speakers, as an example of what a relatively simple 7+1 can do. Read here.

The finished speakers with the 6600 tweeter.


I wasn't quite prepared for getting the finished speakers into our living room in front of my bridged EAR-861 amps - and the Anna-D cartridge. Tin Pan Alley came through with a deep powerful bass - as should. Vocals, cello and Vestbo Trio - all came trough with a credible power and soundstage thanks to the 7" Illuminator bass driver. My always-first-to-hear friend just couldn't believe the scale and power of Tin Pan Alley when he sat down on the couch to have his first listen. The vocal of Ingram Washington came through with a clear presence and bottom weight his deep voice demands. Female vocals just as well, Diana Krall, etc.
What these sandwich cones also deliver is clean and transparent midrange and I recall a situation at ScanSpeak factory some years ago and engineer Birger Jorgensen asked me what I thought of the Illuminator drivers. I scratched my head and said that my general impression was that I could driver the Illuminator drivers harder than the Revelator drivers before hearing any distortion. That the Illuminators had significantly increased power handling. He smiled and looked happy. Mission accomplished. Well, these paper sandwich cones and their ingenious non-reflective magnet system and underhung voice coils do their thing. As can be seen from the crossover and measurements, easy on crossovers.
The D3004/660000 tweeter? It had been some time since I last heard the 6600 tweeter - and.... like meeting a good old friend! No wonder this tweeter is found in numerous constructions, often with a different faceplate and sometimes with weird looking back chambers. It is hard to find a tweeter with a ruler flat frequency response from ~600 Hz to well above 20000 Hz, very low distortion down to below 700 Hz, a clean waterfall profile, etc. What's not to like? This tweeter does it and can be handled with shallow sloped crossovers.

2-driver speaker.
Dimensions: 24 x 33 x 50 cm, WxDxH.
System sensitivity: 87 dB/2.8V/1 meter.
Impedance: 4-8 Ohms, minimum 4.7 Ohms.
Power requirement: 30+ watts/channel. Depends on how loud you play. If you play it loud - and this speakers can handle it - use 50+ wpc. This speaker works well with my Hypex UcD power amp, 400 wpc (4 Ohms).
Power handling: 100 watts.
Please also read:, and remember any burned driver is a misused driver.

Useful links (Please read before writing!):

FAQ (Please read before writing!):
You cannot change cabinet front panel dimensions and drivers' placement without needing a new crossover - and I cannot help.
You cannot use any other drivers with the crossover specified.





Download specs here:  D3004/660000   R3004/662000   18WU/4741-T00

The two tweeter options.


The crossovers for the two versions are identical except for value of R1. The D3004/660000 is a little more sensitive than R3004/662000. The crossover topology is LR2 with a point of crossover around 2.5 kHz. R4/C2-3/L2 is impedance linearisation to make the high-pass filter work properly. Ideal listening height (most linear response) is between the two drivers. I've use 45 cm stands and tilted the speakers a little to listen on that axis from my favourite chair.
The kit will have resistors for both tweeter options, so "one-fits-all". In the Kit Instruction following the kit, you will find what resistors to use for R1. There will be two more resistors for your favourite treble tuning.


I used 20 mm Baltic birch throughout for the cabinets. Use 19-22 mm MDF if only this is available.
If you use 18 mm BB, add 4 mm bitumen pads to your order.
Bitumen pads are optional. I used it. You don't have to adjust for volume when using bitumen pads. Too little change in port tuning.

Should you prefer a floor-stander, look at bottom of page.

Setting up your speakers


"The room is half the system". An old hifi saying - and as true as the very first time it was said. Room acoustics and speaker placements can turn even the best speaker into mediocrity and visa versa.
In my room I found the speakers doing the best placed on my 45 cm stands and tilted 2-3 deg. to have the on-axis between the two drivers pointing towards my listening position (ear height). This also reduce floor bouncing - good for midrange. The speakers are toed in so that I listen approx. 5 deg. off-axis horizontally. The speakers are 90 cm from the front wall and have 145 and 180 cm to end walls. I have speakers on the long side of the room. See here. Please also read this.

The two tweeter options.

Workshop pics

The procedures here are the same as for the Purifi-6R, so please look here for more details.


Bitumen is optional. If you want to do so, add 3 pcs 50 x 50 xm 4 mm bitumen pads to your order.
Bitumen pads do not have to cover 100%. Make 5-10 mm to nearest edge.

Add felt to the compartment behind tweeter. I forgot - and had more trouble placing it through the large hole in the brace.

Ad felt as seen on photos. No felt on rear panel.

Left: The bass crossover is to be placed on rear panel behind the port. Little space - and we need to be able to remove the straight port tube.
Ad two turns of painters' tape and it will fit tight and reasonably secure. We can't remove the entire port by unscrewing the port flange.
Right: I did the lacquer work on tweeter panel and top of bass panel before gluing the front panel. Use tape to mask off the lower part of the tweeter panel to preserve a good gluing area. Adding lacquer to these parts after gluing the front panel is not easy as I use a roller.

Fold a piece of 23 x 50 cm acoustilux at place at bottom. Fold a piece of 23 x 50 cm acoustilux and place behind tweeter in upper compartment.
Fold a piece of 20 x 50 cm acoustilux and place around the port covering the crossover as seen on photo below.

Acoustilux at top (left) and bottom (right).


Place the crossover on the rear panel and fasten with screws. Fold a piece of 20 x 50 cm acoustilux and place around the port covering the crossover. 


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.

Intrinsic response of drivers on actual baffle. Red = 6600 tweeter. Orange = 6620 tweeter.
Green and yellow the two 18WU drivers.


An example of final system response with 6600 tweeter taken at 0.5 meter distance and merged with near-field response of midbass at 175 Hz. In addition to this comes the port response centered around 37 Hz.


Final system impedance of 6600 version.


Final system impedance of 6620 version. Virtually the same as 6600 option.


Just this to show the nice roll-off of the 18WU driver given its very simple crossover.


Tweeter attenuation of 6620 version with various values of R1. Values come with the kit.


Tweeter attenuation of 6600 version with five different values of R1. Red, green and orange are too hot for tweeter level.
Sometimes half a decibel of too much treble can turn a speaker too harsh on certain recordings.



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Be aware of inverted polarity of tweeter. PLUS from crossover goes to tweeter MINUS!


Crossover pics

Check this out:


Fill up half the center hole of L3 to secure firm attachment to the board.
C2 i gone and replaced by a single C3 MKT Z-cap.

As can be seen, I have two resistors for R1, one for each tweeter. The lower resistor here not connected to C1.
You only need one - or you may place the other resistors coming with the kit to suit your preferred treble level. 

This leaves quite some room at the bottom, but plenty of space for the crossover.