ScanSpeak Ellipticor
A50-II
Copyright 2022 © Troels Gravesen
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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
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)
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.
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.
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!
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.
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
BACK TO INDEX
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.
