Ellipticor-1824

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ScanSpeak Ellipticor-1824
Copyright 2024 © Troels Gravesen

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DRIVERS CROSSOVER CABINET WORKSHOP PICS MEASUREMENTS SPEAKER-KIT CROSSOVER LAYOUT

The very first speaker I made from the then new Ellipticor drivers was the Ellipticor-1 with the D3404 tweeter and it was on display at the Munich High-End Show in 2017 (.....has it really been that long?).
Since then we have sold quite a few kits being an introduction to the Ellipticor range of drivers - or for good for those who prefer/have to live with a smaller standmount.
Later the Ellipticor 18WE/8542T00 (8 Ohm version) and not least, the tweeter D2404/552000 was introduced and I have used the smaller tweeter in my Ellipticor-A50 speakers and my Ellipticor-2F8 construction. I liked the latter so much I soon wanted to implement the basics in an Ellipticor-1-mkII construction.
The new speaker will be Ellipticor-1824, and it will be presented with both 4 Ohm and 8 Ohm 18WE driver, should you have either at hand. They sound the same, but obviously the 4 Ohm version will play louder for the same volume setting of your amplifier. Efficiency is the same, but sensitivity is not the same. Lower impedance may let you think a speaker is more efficient, in fact it just draws more current from your amplifier. Your amplifier may have a specified max watt @ 8 Ohm, but this does in no way make it unsuitable for a 4 Ohm speaker. I have these questions...
Next objective was to make a much easier cabinet as the faceting of the original might have put a few potential customers off, hence a simple sloped baffle like the Ellipticor-2F8.

Setting up the 4 Ohm version first with a prototype crossover I was again struck by the dynamic headroom of these drivers. The ease with which they handle all kinds of music - and quite a credible bass despite its modest size. Well, time to move on and make the final crossovers and also for the 8 Ohm version. This is the fun part.

Basics:
2-driver speaker.
Dimensions: 22 x 29 x 40 cm, WxDxH.
System sensitivity: ~89 dB/2.8V/1 meter, 4 Ohm version. 86 dB/2.8V/1m for 8 ohm version.
Impedance: 4-8 Ohms.
Power requirement: 20+ watts/channel.

Useful links (Please follow all links before e-mailing!):
http://www.troelsgravesen.dk/tips.htm
http://www.troelsgravesen.dk/tips.htm#CONSTRUCTION_OF_CROSSOVERS
http://www.troelsgravesen.dk/crossovers.htm
http://www.troelsgravesen.dk/LCR-RC.htm
http://www.troelsgravesen.dk/Inverted-Polarity.htm
http://www.troelsgravesen.dk/choices.htm
http://www.troelsgravesen.dk/Placement-of-ports.htm

DRIVERS
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Download specs here: D2404/552000 18WE/8542T00 18WE/4542T00

CROSSOVER
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Crossover display a simple LR2 topology and is the same for the 4 and 8 Ohm version of the 18WE driver, but obviously all values are different. The Kit Instruction will contain parts' list for both versions.

CABINET
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Cabinets were made from 20.5 mm Baltic birch. Dimension of brace depends on actual panel thickness, so adjust to local conditions. Cabinet materials, read here. And please go trough the entire "tips" page.
Chamfering of the front panel is optional. I did 45 deg to around 10 mm depth.
The optimal listening height is somewhere between the two drivers. If this is not acceptable to you, you may tilt the front panel further, like 24 cm depth at top and 30 cm depth at bottom. Obviously this all depends on the height of your stands. And don't think this is of paramount importance, when listening at 3+ meter distance. What we measure at given height is not necessarily what we hear.

Workshop pics
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These cabs are almost as easy as it gets, so only a few workshop pics.

Cabs sanded and ready for felt damping.

Cabs ready for gluing front panels.

Gluing front panel. Cabinet ready for final sanding and lacquer.

For 1 cabinet:
Left: Cut 1 pcs 20 x 45 cm acoustilux and add to top/sides.
Right: Cut 1 pcs 18 x 50 and add to rear panel/sides, covering crossover board.
Cut 1 pcs 15 x 50 cm, fold and add to bottom of cabinet.

Use thin spacers when mounting Ellipticor drivers. See Ellipticor-A50-mkII for further info.
If not, you won't be able to remove the decor ring once mounted if touching the rebate rim.

Job done!

Intermezzo:

My wife's grandson started an interest in vinyl and had bought a terrible old Luxor "radio-gramophone", that even had a turnable cartridge stylus (!) and I suggested he never put a new record on that one! He had also bought an old pair of Beovox S75, that measured terribly - but sounded quit nice nevertheless. So, we agreed I help him put together a system that would allow him to better explore the world of vinyl recordings.
First of all I bought a 2nd hand Pioneer PL512X turntable with a worn Shure M75. I had a PL-something back in early 80'ies. This is a no-nonsense belt-driven turntable from the 80'ies, and had been lubricated and had a new belt. I replaced the cartridge with a new Ortofon 2M Red. 100€ for the turntable and 100€ for the cartridge. So far, so good. Next I bought a 2nd hand Luxman 2040 integrated, again 100€. This was a dirty old bastard, but after some cleaning everything worked as intended. A little trouble with the input switch, but some massage and contact cleaner, it worked again. Connecting my Kuzma/4P9/2M Black LVB, this amp proved well worth the money. For fun I also bought a new NAD 316BEE, v2 integrated with phono stage, just to hear what had happened since the legendary NAD 3020 some 40+ years ago.
So, these systems were driving my Ellipticor-1824s, speakers that would cost 10+ times that of the whole setup.

Now, you would probably pic some other speakers for this system, but just to say that we can have a lot of fun from modest 2nd hand/modest priced equipment without spending fortunes. I guess a pair of Discovery 3WC-mkII or Discovery 18W-mkII would do well here. BTW, this NAD amp, 360€, does it all damned well for the money. Decent phono stage and very organised interior, pretty much the opposite of the Luxman, which looks like a bird's nest inside - I realise a good FM tuner takes space and is complicated but the overall layout is sloppy - but it works very well.
Anyway, back to the Ellipticor-1824...

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.

4 Ohm version. SPL normalised for 2.8V/1 meter.

4 Ohm version. Horizontal dispersion @ 0, 10, 20 and 30 deg. off-axis.

4 Ohm version. Final system impedance.

8 Ohm version:

8 Ohm version. SPL normalised for 2.8V/1 meter.

8 Ohm version. Horizontal dispersion @ 0, 10, 20 and 30 deg. off-axis.

8 Ohm version. Final system impedance.

And don't even try figuring out which version sounds the best, because you cannot. These graphs tell nothing about the sound we hear. If you have a smaller tube amp, choose the 8 Ohm version. My EAR-861 drives both versions equally well, but this is a great tube amp. For any solid state, it doesn't matter. Even for the 4 Ohm version the impedance doesn't go below 4.5 Ohm.

SPEAKER-KIT
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Parst list is the same for both versions, but values for inductors, resistors and capacitors are different.