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ScanSpeak Ellipticor-A50
Copyright 2022 © Troels Gravesen

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ScanSpeak Ellipticor-A50 is a loudspeaker created to celebrate 50 years of service in speaker driver manufacturing. Since 1970 speaker drivers have been produced under the ScanSpeak brand name and countless models, from economy drivers to some of the most sophisticated and expensive transducers the hifi market has seen, has been produced. The ScanSpeak history here by Claus Futtrup.

The construction here is based on further expansion of the Ellipticor series and you will find new models never seen before, like a 15" bass driver with elliptical voice coil, a large elliptical midrange dome with double spider an exceptional flat frequency response - and icing of the cake - a 24 mm elliptical dome ensuring delicate handling of overtone structure. All ingredients for making state of the art speaker constructions - if we do well! The crossover is the heart of any speaker construction and can be tuned to personal taste and specific acoustic conditions, and a four-driver speaker can be put together in countless ways and here's my take on these new and exiting drivers.

What was meant to be a springtime celebration at Munich High End Show, May 2020, was delayed until 2022 due to corona virus and all the things that followed, like delays in shipping, etc. Writing these preliminary lines here in April 2020, where the pandemic has affected almost all parts of the world in ways we haven't seen since the Spanish flu a century ago, is really strange. This is going to impact our lives years ahead, but here and now, the sick must be nursed, children must be taken care of, schools must operate under restrictions, food must be produced - and speakers must be built.
And I have to admit that due to corona, I've had a lot more time to try out a large number of crossovers designs and not necessarily play the safe card, as we sometimes do, when time is limited as an introduction at Munich 2020 would have been.

Most of my regular readers will know I hate describing sound as we will never know how it sounds before we hear it ourselves. If I wrote a book on this speaker - you'd still not know. I've often been thinking all speakers should have a front grill as so many listen with their eyes rather than ears. As soon as our eyes sees something our brains are working overtime to form an opinion. Vision rules! Some thoughts here. This prototype cabinets here do feature a front grill and it impacts performance very little - if anything at all.

When I visited the ScanSpeak factory in February 2020 to sign a NDA, I heard an initial set-up of the 15" bass driver on an open baffle and I was immediately struck by the featherlight and responsive bass. By simulation this 15" doesn't go particularly deep, it's not a subwoofer - but for sure this 15" can play deep bass. I remember my first visitor jumping the seat when I put on my 45 rpm Tin Pan Alley by Stevie Ray Vaughan and turned up the volume. The classic hifi-show LP/track that makes professional reviewers run away. It is chokingly dynamic. Fortunately my first open baffle experience at ScanSpeak was transferable to a vented solution here at home.

Doing measurement on the D8404 mid-dome and seeing how deep it goes, I realised the 21WE didn't have to go very high, actually only handling the ~80-300 Hz range, thus a 3½-way system might be feasible, and this was what I was most excited about with regard to the bass section, when setting up the system. Would this go well? Given the low point of crossover from the 21WE to the D8404 I wasn't happy about having a high-pass filter on the 21WE. Given its limited cabinet volume it makes F3 = 66 Hz, so it really doesn't do deep bass and also given its closed box, has all the advantages of dynamics in handling upper-bass and lower-midrange. The 21WE has phenomenal dynamic headroom and regardless of source material I've never been able to overload the driver from a 3½-way configuration. So, with the 38WE doing deep bass in a vented box, the 21WE adds punch in its closed box. The best of both worlds.

I goes without saying the elliptical midrange dome is the key component in this speaker as it handles the overall most important frequency range, from middle-midrange and lower- to middle-treble, say ~300-5000 Hz, some four octaves. Quite frankly, I had no idea what to expect from such a driver and I was more than exited after some 120 hours of cabinet work to finally put together my initial simulated crossover and hear what it does.
I ran the 21WE/D8404/D2404 from my 32 wpc EAR-861 and had my Hypex UcD400 power amp run the 15" bass driver - and was blown away. Half the night I put on record after record to experience what this mid-dome did, because it does something very differently - and to my ears better than anything I've ever heard. I guess one of the things it does - or does not - is start beaming in the same way any conventional cone driver does, even small drivers will at some point start beaming and it may not sound bad at all, just different and with a certain sonic character. The D8404 allows an unprecedented window to the music and I've never had the spatial information so clear in that sense you do not have to concentrate on listening for that quality, it is just there. It has presence and transparency - and at the same time is smooth on the ear. I'm amazed such a small driver can go so low with such power and lack of distortion - and even from a simple low-pass crossover.
 

2022: Finishing the Ellipticor-A50 called for some celebration and I went to our local vinyl pusher and picked up these records. Not all stellar recordings but featuring artists I have enjoyed for decades. I addition to these records I obviously went through my current selection of records I use for testing loudspeakers. See some of the latest speaker constructions. For some reason I also picked up an old and worn copy of Double Fantasy/John Lennon-Yoko Ono. I mostly know this album from CD and hadn't heard it for many years. I don't think I had ever really heard this album before this speaker. Even Yoko's high pitched voice came through tolerable which is - again - a credit to the D84 dome. Not having a crossover in the region this driver covers pays off. 


 

Basics:
4-driver speaker, 3½-way configuration.
Dimensions: 45 x 45 x 105 cm, WxDxH (+ base support and feet)
System sensitivity: 91-92 dB/2.8V/1 meter.
Impedance: 4-8 Ohms.
Point of crossover: 80, 340 and 4000 Hz.
Power requirement: 50+ watts.
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 follow all links before e-mailing!):
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 follow all links before e-mailing!):
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

 

 


After 5 months of crossover fine-tuning, I took the speakers to the ScanSpeak factory in Videbaek:
"Well, heard worse". I think they liked it!
From here the cabs would be dismantled and shipped to a professional painter for front, top and rear.

Almost one year later I could finally assemble the speakers seen in the intro picture above and set them up in the ScanSpeak demo room. A newly acquired Gryphon Diablo 300 had been installed and the speakers were tested at disco+ levels - so much I got worried from the 3½-way configuration. Would the 21WE takes the heat? It very much did so without loosing grip of the 80-350 Hz range. This driver has dynamic headroom way above what I would ever have thought possible.


DRIVERS
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D2404/552000. Click images to view large.

 

 


D8404/552000 middome.

 

 


21WE/8542T00

 



38WE/8582T00

 

Download spec here: 38WE/8582T00    21WE/8542T00   D8404/552000    D2404/552000


CROSSOVER
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Above the basic crossover topology.

In principle, the A-50 crossover is simple. Basically LR2 topology, except for D8404 high-pass, with 2nd order roll-off on all drivers, both high-pass and low-pass. Now, to make this work we need to linearise the impedance of three drivers for the passive version except the tweeter.
The 38WE driver having a very low point of crossover below 100 Hz, the upper impedance peak caused by the bass reflex tuning would otherwise prohibit low-pass section in working properly, thus R10/C10/L8.
Similarly the 21WE, due to its closed box compartment, needs the impedance peak at ~70 Hz flattened to make the low-pass filter work properly, hence R8/C8/L6.
What may be special here is the 21WE driver not having a high-pass filter and works in a 2½-way fashion with the 38WE. This goes well because the 21WE is quite a capable driver and it's placed in a fairly small closed box, thus limited with regard to cone excursion and furthermore it doesn't go higher than ~340 Hz and only takes care of upper-bass/lower-midrange. This also means we we do not need seriously expensive capacitors for the low-pass filter. With the 21WE LCR circuit we have the flattest impedance profile I have ever produced.
The mid-dome, D8404, has its impedance peak around 300 Hz, thus close to the point of crossover. L4/R6/C5-6 handles the impedance peak here and ensures proper functioning of the high-pass filter. Above ~700 Hz the mid-dome impedance is almost flat, thus no need for any impedance corrections here. Tweaking the D8404 high-pass section I came around to a topology that just sounded very good and from modeling the crossover it turned out to be a 4th order Bessel configuration. These filters have a 1st order roll-off in the transition area slowly progressing to a 4th order roll-off.
The tweeter has its impedance peak way below point of crossover, thus no need for any correction here.


Above the crossover for both versions. To the right the passive version presented on this page. You may connect the two sections and run it from a single amplifier. 50-100 watts recommended. My bridged 64 watts EAR-861 runs it smoothly but more power for the bass is recommended if you want the punch it can deliver.




CABINET
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Click image to view large.

The cabinet drawing shown above is my Ellipticor-A50-II drawing. The images seen below is from my prototype cabinets and the lessons learned from this led to the -II design. The -II cabinet is easier and placing the crossovers a lot easier.
Download large image and open in e.g. MS Paint and 1 pixel = 1 mm.

Prototype cabinets seen below were made from 19 + 9 mm HDF, thus 28 mm panel thickness. For internal bracing 19-21 mm panels were used, either HDF or BB. There are no specific requirements to the materials used for internal panels. I was short of HDF and used some BB instead.
The dimensions of the bracings are based on 28 mm panel thickness. Adjust to actual conditions. I suggest 22 mm panels minimum.
As always: You cannot change the front panel dimensions and driver layout - or you need a new crossover - and I cannot help!


Workshop images

Below the prototype cabinets. Goto A50-II cabinet.

 
Building the cabinets. 


Testing rebate of prototype 38WE drivers and to the right prototype crossover, which often looks like birds' nests.

 


Above testing prototype 38WE and D8404 drivers in cabinet.
To lift the cabinets I made a stretcher and a friend helped whenever needed.
These cabs were seriously heavy!


Left: Preparing the front grill frame. Right: Mockup with side panels and front grill.


Oak fillet inserted into front grill panel.


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.

Below the D8404 domes, for further measurements, go to A50-II


The intrinsic response of four D8404 domes on an "infinite" baffle (80x120 cm).
Driver sensitivity ~93 dB/2.8V/1m.


Waterfall plot of the D8404 driver. 25 dB scaling and showing 300-20000 Hz.


Four D8404 impedances. Fs = ~310 Hz.


Horizontal dispersion of D8404 dome @ 0, 10, 20, 30 and 40 deg. off-oxis.


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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Please read this before mailing about the layout: http://www.troelsgravesen.dk/LCR-RC.htm

In an RC, RL and LCR parallel circuit, the components can be in any order; thus, layout may differ from schematics.

Also please read this: http://www.troelsgravesen.dk/tips.htm#CONSTRUCTION_OF_CROSSOVERS



 



Layout 38WE bass driver.
For the prototype bass crossover I used PREMIUM-ELKOs, which are no longer available, thus CrossCaps instead.
Click image to view large.


The bass crossover, here with discontinued PREMIUM-ELKOs, which have been replaced by CrossCap.

 

 


Layout 21WE mid-bass driver and D2404/552000 tweeter.
R8 is made up from 2 x 22 Ohm in parallel.
Click drawing to view large.


Some PREMIUM-ELKOs still in place.

 

 

Above the layout for the D8404 dome.
C2: 6 x 10 uF Alumen-Z + 1 x 5.6 uF to make 65.6 uF.


D84 crossover.



Placement of crossovers.
Place the MDT section through the D84 hole and fasten with screws to rear panel.
The bass passive crossover is placed on rear panel behind the bass driver.


More crossover pics



Tweeter section.


21WE section.




D84 section.

 


D84 section.


Speaker Wiring



Please note that the mid-dome is connected with inverted (negative) polarity!


 


Having been introduced to the drivers to come, I made the above suggestions to the ScanSpeak folks for introduction of the new drivers.
They decided on the classic version, which should turn out to be fortunate. We never know how drivers will perform on a given baffle before we have made one - and done the measurements and simulations. Much too often design dictates and the consequence may be elaborate crossovers to provide the necessary equalisation.

Please, no future plans for any of the of the above speakers, except the Classic. I'd love to - but time.. Well, maybe the Studio Monitor-C, who knows.