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ScanSpeak Ellipticor A50-II
Copyright 2022 © Troels Gravesen 

   Go to on this page:
DRIVERS   CROSSOVER   CABINET   MEASUREMENTS   SPEAKER-KIT   CROSSOVER LAYOUT   WORKSHOP PICS

Finishing the Ellipticor-A50, I had a version planned for myself, a smaller pyramid version, better suited in size for our living room - and with a smaller 28W woofer. So, a mockup was made and from measurements and simulations it soon became very clear it just didn't work. The D8404 on a narrow baffle had some + 4 dB @ 1 kHz and there was no way I was going to spoil the simplicity of the A50 crossover by equalising in this area, in particular for this key driver covering some four octaves.
What I had planned - and did work - was having the bass driver driven from a Hypex FA251 plate-amp/DSP, thus eliminating the passive bass crossover of the A50-I. I had this tested with the A50-I, but the ScanSpeak people wanted a fully passive version, which I fully understand having a simple set-up for shows, etc. I also have to say the passive version plays wonderful with the Gryphon amps in Videbaek.

All the drivers are obviously the same as Ellipticor-A50. The crossovers for 21WE/D8404/D2404 are the same, thus an open file as was the request from ScanSpeak, when we signed the NDA papers in February 2020. The Hypex software can be downloaded from this page as well. All free.

For my own version I also wanted an even more classic design, thus 25 mm Baltic birch.


Sound? Read Ellipticor-A50. And please remember that what I hear - is not what you will hear. Please read here.

Basics:
4-driver speaker, 3½-way configuration.
Dimensions: 45 x 45 x 105 cm, WxDxH. H + base panel and feet.
System sensitivity: 91-92 dB/2.8V/1 meter.
Impedance: 4-8 Ohms for MMT section.
Point of crossover: 80, 340 and 4000 Hz.
Power requirement: 20+ watts/channel.
Power handling: 200 watts. Please also read: http://www.troelsgravesen.dk/power-handling.htm, and remember any burned driver is a misused driver.

Useful links (Please read before writing!):
http://www.troelsgravesen.dk/tips.htm
http://www.troelsgravesen.dk/crossovers.htm
http://www.troelsgravesen.dk/LCR-RC.htm
http://www.troelsgravesen.dk/Inverted-Polarity.htm

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.
http://www.troelsgravesen.dk/crossovers.htm
http://www.troelsgravesen.dk/choices.htm



DRIVERS
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D2404/552000.


D8404/552000

 


21WE/8542T00

 


38WE/8582T00
Click images to view large


Download driver specs:  D2404/552000    D8404/552000    21WE/8542-T00     38WE/8582T00


The Hypex modules

 
The Hypex FUSION  FA251 module.
If you can't live with the FA251, ask for FA501.  The FA251 is more than enough for driving the 38WE bass.
The Hypex version allows bass lift of 4-5 dB @ 40 Hz for preset 2 and 3. Preset 1 is flat.
In general the Hypex version allows infinite room adaption.
Also incorporated in file is a high-pass filter @ 20 Hz for vinyl aficionados.

Go to Hypex page here.

Download software here (zip file)


CROSSOVER
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The Hypex version to the left. Like the ATELL-3 and Ellipticor-3, there is no high-pass filter to the 21WE midrange cone driver. This driver can handle a lot of power and with its relatively small closed cabinet, it has a natural 1st order roll-off below 80 Hz, where the 38WE takes over run by the Hypex module.


CABINET
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Click image to view large.
Cabinets were made from 15, 20 and 25 mm Baltic birch.
Use 12-15 mm for the Hypex box. I used 12 mm.


Placement of crossovers on rear panel. Mount though D8404 hole.

 


Port. See images below in workshop pics.

 



Workshop images


I started making the midrange cabinet/braces. Rear panel of midrange cabinet glued in place while placed in cabinet to make a sure fit.


Routing for drivers. Chamfer 21WE hole slightly.

Sometimes I have glued the whole thing in one operation, but a cabinet large as this is enormously stressful as we only have less than 15 minutes to get it all inplace. This time I started gluing the left side panel and rear panel, making absolutely sure it is 90 deg. Next I glued the braces/midrange cabinet in place. After this the top panel followed by the bottom panel. At this stage I glued the port panels/fillets in place, only leaving the right side panel and front panel to be glued in one operation.


Testing drivers on front panel. Right: Gluing upper panel.

 
Sometimes a rectangular box like this may be slightly skewed when you have glued rear, braces top and bottom panel and you need to pull the whole structure to make the front panel fit exactly. Fortunately we have driver holes to add pressure.

 
Making all the felt sheets needed. Gluing the right side panel and front panel in one operation.


View video of felt damping.


Making the Hypex enclosure from 12 mm plywood.

 


Two frames of 450 x 450 mm were made from 30 mm solid oak.
Adjustable feet, read here.

Further damping:


Left: Bass section, add acoustilux. Fasten with staples or dots of glue.
Right: Fill midrange (21WE) cabinet with 200 grams of sheeps wool.


Top cabinet: Fold a piece of 150 x 50 cm acoustilux and cover rear panel (over the crossover) and on top of cabinet.
Not shown: Add a piece of acoustilux on rear panel behind midrange (21WE) cabinet.


Workshop test during crossover development.


Here the final speakers.

 

Some thoughts on mounting Ellipticor mid-dome and tweeters:


Using countersunk screws will eventually skew the drivers a tiny bit and if you have to press the decor ring into place - you are never going to get it up again!
So, add some foil around the driver when fastening the screws. This way you will leave some 0.1-0.2 mm space between decor ring and cabinet. Removing the decor ring by rotating until it slips the magnets and lift with another small neo magnet. The tweeter decor ring pops up by itself. The D84 doesn't.
When routing for the D24 and D84, make the rebate diameter +0.5 mm.


Left: Decor rings in place.
Right: BTW: The D84 is a nice driver for gently soldering the wires to the terminals as the shape of the rear chamber lets it rest nicely in the driver hole. Nice feature - because the D84 is seriously heavy!



MEASUREMENTS

A few comments on MEASUREMENTS before you start interpreting the readings.
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.


Impedance of 21WE/D84/D24 section (both speakers). Tube amps just love it!


Frequency response merged with nearfield responses of 21WE and 38WE drivers at 225 and 80 Hz. In this way we can have a reasonable idea of bass extension. Port is not included here, which will further extend the lower bass area.
The intrinsic increase in on-axis response the D2404 tweeter in the 10-20 kHz range was left as is. For those who can hear the upper octave, this may add just a little more airiness to the soundstage. 


Horizontal dispersion at 0, 10, 20, 30 and 40 deg. off-axis.


For those interested, near-field response of 21WE and 38WE drivers, driven from crossover and Hypex module.
As predicted the 21WE, not having a high-pass filter, does roll off smoothly below ~80 Hz due to the small closed cabinet.

 


SPEAKER-KIT
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 All kit and component prices may be subject to change and are always to be confirmed by Jantzen Audio Denmark.

Download Complete Kit Sale Presentations: to come

Preliminary kit prices ex. VAT, add local VAT:

Passive + Drivers: €12538
Semi-Active + Drivers + Hypex: €12827

Semi-Active + Drivers - No Hypex: €12269
Passive – No drivers: €2668
Semi-Active - No drivers + Hypex: €2957
Semi-Active - No drivers - No Hypex: €2399

 

All technical questions to troels.gravesen@hotmail.com

All questions regarding purchase of kits, please mail Jantzen Audio at contact@jantzen-audio.com


CROSSOVER-LAYOUT
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Crossover layout for 21WE and D2404 drivers.
R8 is made from 2 x 22 Ohm resistors, stacked.
Click images to view large.

 

Crossover layout for D8404 driver.
Click image to view large.


Speaker wiring

Crossover pics


Crossover for 21WE and D24 drivers.
At the time I made the 21WE crossover, Premium ELKOs were still available (C8). Now replaced by CrossCap.
Click image to view large.

 


Crossover for D84 driver.
Click image to view large.


The input wire goes to the 21WE/D24 board and from here to the D84 board.
To the right the crossovers placed on rear panel in cabinet.