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Ekta 2D
Copyright 2019 © Troels Gravesen

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DRIVERS    CABINET    MEASUREMENTS    SPEAKER-KIT

I think the Ekta family deserves some new members and here's a smaller sibling featuring ScanSpeak Classic and Discovery drivers. The tweeter was also used in Ekta mkII, a tweeter that really deserves a better classification. The revised Classic 18W/8542-10 has become one of my favourite 6" drivers as it allows almost any crossover topology.
Now, the drivers here are the same as used in my STUDIO 101 mkII, but this time we're running fully digital and can place the drivers on a flat front panel as we can delay the tweeter in the Hypex DSP section for time-alignment.
The special feature about this speaker is that you can choose between three crossover topologies, 1st order, 2nd order (LR2) and 4th order (LR4) and provides you with a unique opportunity to pick you favourite crossover, maybe one for one kind of music, maybe another for some other musical genre. The Hypex has three pre-sets and all you have to do is press a button to shift between the three presets. If you're in for further convenience you can buy the Hypex remote and sit in your sofa and pick your flavour.


 

Basics:
2-driver speaker
Dimensions: 22 x 34 x 42 cm, WxDxH.
Points of crossover: variable depending on preset choice, 1st, 2nd or 4th order, but in the range 2-2.5 kHz.
Power requirement: Driven by Hypex FA122, 2 x 125 watts.

Useful links:
http://www.troelsgravesen.dk/tips.htm
http://www.troelsgravesen.dk/crossovers.htm

FAQ:
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 used here and please read this file before e-maling: http://www.troelsgravesen.dk/choices.htm
 

DRIVERS
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Click images to view large

  Download specs here:  D2608/913000   18W/8542-10   


CABINET
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The cabinet is the same as STUDIO-101-mkII, here with depth extended by 40 mm to 320 mm + front panel. Please study workshop images at STUDIO-101-mkII. On the back panel we have to make room for the Hypex module, hence the Hypex box as seen on drawing.

Cabinet almost as simple as can be. Rectangular box with one vertical brace. I used 20 mm Baltic birch for the basic cabinet and 27 mm for front panel.
Front panels can be made from 19-30 mm BB/MDF/HDF. You can make the cabs from 19-22 mm BB/HDF/MDF. If you use 22 mm overall increase depth by 10 mm.
Port is Ø68 x 220 mm. Fairly big, but I think 50 mm is too small. Better too big than too small to prevent any port noise. Add 4 mm bitumen pads to sides, top and bottom panels. Se image below. Add 8 mm felt to sides, top and bottom panels. Place a piece of 50 x 15 cm acoustilux against top panel and down on rear panel. Fold a similar piece and place around the port (see image below).

As always: Any change to front panel dimensions or drivers' placement and you need a new Hypex software - and I can't help without having your speakers in my workshop.


Hypex modules, FA122, two channel plate-amp/DSP

Go to website describing installation of software

The actual program for FA122 comes on a memory stick from purchase of the kit from Jantzen Audio.


Workshop images


Hypex box made from 20 mm BB and 10 mm MDF.


Fitting in Hypex module and starting on the front panels.


Routing for drivers.


Hypex modules in place.


Connect drivers: Red (+) and black (-) for tweeter. Blue (+) and grey (-) for midbass.


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.


Above frequency response of left and right speaker from 1st, 2nd and 4th order filters, red, green and orange respectively.
For the other speaker blue, purple and light blue repectively.
SPL recorded with 6 dB difference for the two speakers.
What can be seen is that we have a frequency response of +/- 0.5 dB regardless of crossover topology, which give a good chance of comparing sonic qualities of the various filters.
Measurements were done at ½ meter distance with microphone between tweeter and midbass.


Above the slopes of 1st, 2nd and 4th order filters.


Step response of 1st order filter. Note drivers have same polarity.


Step response of 2d order filter with tweeter connected with inverted polarity.


Step response of 4th order filter with drivers having same polarity.


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 (pdf file):

Hypex software not available separately.

Programming the Hypex module, go here.

All technical questions to troels.gravesen@hotmail.com

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