Copyright 2018 © Troels Gravesen

   Go to on this page:

Ever since the launch of Ellipticor-1, I've been waiting to set up these two drivers in a larger system and hear what they really can do. Despite the phenomenal dynamic headroom, there are limits to how much air a 6" driver can move. Size matters.

My ATS4-HE prototype bass bins have been in the attic since launch and suitable for a wide range of four-way systems, only waiting for the right midrange-tweeter combinations. The cabs were taken to my workshop for an overhaul and fitted with 12" BMS bass driver, the Hypex PSC2.400d plate-amp/DSP, and the new kid on the block is the 18 Sound 10NW650 10" bass driver. A powerful high-efficiency midbass driver delivering 96 dB and very suitable for handling the 80-200 Hz range. The 10NW650 has been used as a midrange driver in a larger system with a 18" bass driver and did really well up to 1300 Hz target point of crossover, but it was really bought for supplementing the 12" BMS bass driver, and it does extremely well here. It delivers the dry punch of a closed system combined with the deep bass of the 12" BMS. You may object to the look of the 10NW650, but do you want good sound or good looks? Add a front grille or make a ring from black MDF to cover the gasket rim like the Ellipticors. It may not have the expensive "hifi" look of the AT 10C77, but the 10NW650 does just as well for one-forth of the price and you badly need the money for the best capacitors available. And it actually has a slightly larger radiating area compared to 10C77.

In all honesty I had not expected a serious competitor to my ATS4-HE reference. Maybe naive, but this speaker is at least on par with the ATS4-HE. Same sensitivity, same dynamic bass - for obvious reasons. What I had not expected was the ScanSpeak guys to come up with two radical new drivers supplementing each other so well. The Ellipticor-1 gave a good hunch of what's to come, but this 4-way set-up exceeded my expectations by a comfortable margin, or maybe I should say uncomfortable - because these drivers mean work!

Ear-friendly is a dubious term. It may be taken for being forgiving on troublesome recordings. The Ell-4 is anything but forgiving, but I can't help thinking ear-friendly. The mid-tweeter integration works particularly well here, and not just because we have a perfect LR2 profile far beyond point of crossover, but - I think - these two drivers just make a remarkable couple. We can have "the best" of midranges and tweeters in the world, but to make a coherent sound, each supplementing the other in the best possible way, is up to trial'n error. We can't tell from specs - and we can't even tell from experience. Each combination must be tried and evaluated  from various baffle and crossover designs.
Should you think Be domes is the final answer to good treble, try D3404. The D3404 delivers the resolution of good compression drivers when it comes to e.g. cymbals and the ability to reproduce the sound of applause from a live audience, the latter often heard as smeared noise. I've never heard better treble from any dome, regardless of diaphragm material. And I'm aware this is also a result of the integration of mid-tweeter as the 18WE handles the lower part of the treble range.

I've been talking about far-field ambience in my comments to phono-stages, pre-amps and power amplifiers. Obviously the same issue goes with associated speakers and crossovers and their ability to deliver resolution and not smearing details. In a 6+1" set-up my main suspicion has been leaning towards the tweeter's ability of not smearing detail, but the 18WE has made me consider the two drivers equally important, because this 6" driver does things.  

Do the ATS4-HE and Ell-4 sound the same? They do not, and I cannot tell you how they differ, because what I hear is not what you will hear. Please do not try to engage me in any decision making.

Due to time constraints, I shall not immediately make the final Baltic birch cabinets for this construction, so you'll have to deal with the prototype images. I very well know this is a turn-off, but so be it. People buy speakers with their eyes as much as their ears.
The design is fully finished and I have no more to add to the construction except for the finish. Obviously you can make the cabinets similar to the ATS4-HE as long you you stick to front panel dimensions given below.

As always: Any change to front panel design and drivers' placement and you need a new crossover and I can't help. Please read here:


4-way speaker from 12" bass, 10" upper bass, 6" midrange + 34 mm dome tweeter.
System sensitivity: 92 dB/2.8V/1 meter.
Impedance: 8 Ohms, minimum 5.6 Ohms at 500 Hz.
Point of crossover: 80 Hz, 220 Hz and 2500 Hz.
Power requirement: 20+ watts/channel.
Power handling: A lot! But please also read this: http://www.troelsgravesen.dk/power-handling.htm, and remember any burned driver is a misused driver.
All drivers will set you back ~3400 EUR.

Useful links:

To the left the prototype cabinets. Finished crossover to the right.


Download specs here:

ScanSpeak: D3404/552000 4 Ohm
ScanSpeak 18WE/8542T00, 8 Ohm
18 SOUND: 10NW650 8 Ohm
BMS: 12N630 8 Ohm

The 18WE above is the 4 Ohm version. The speaker here features the 8 Ohm version, 18WE/8542T00.

18 Sound 10NW650 and BMS 12N630.
Click images to view large



Above the very simple 2nd order passive crossover for the midrange and tweeter. Thanks to drivers' inherent frequency response and careful design of baffles, we can get along with as little as this. The low-pass filters for the 10" and 12" bass drivers i given by the Hypex module and the program comes on a memory stick from purchase of the kit from Jantzen Audio.


Above the drivers' response up against target LR2. Doesn't get much better.


Cabinets to be made from 20 mm Baltic birch or similar materials. Only the mid-cab front panel is made from 30 mm laminate. It can be reduced to 25 mm to facilitate the chamfering. The volume of the midrange cabinet is approx. 15 litres. +/- 1 litre works fine. Not critical.
Cabinet damping: Please look the ATS4-HE for guidance.

A few comments on the mid cab. If you choose to add the side bars like the ATS4-HE and others, I suggest reducing the overall width of the mid-cab to 314 mm and having the side bars 2 mm at the bottom. It's very tricky to make then less than 2 mm. Stick to the 9 deg. tilt of the mid-cab sides. The slightly reduced width doesn't impact performance. You need to have some 1 mm clearance between mid-cab and bass cab extensions.
This assumes you have the extended side panels of the bass cabinet like the ATS4-HE. If you do not have these you can increase the mid-cab side bars to fit the width of the bass cab, depending on the thickness of the panels you use here.

More bass cab details. Click image to view large.

Bracing for midrange cabinet. Place in middle of cabinet. The mid-cab port is stuffed with a roll of 10 x 20 cm acoustilux to make an aperiodic tuning.

Workshop images

Cuts piling up for the bass cabinet. As before, maple fillets.
Having some 27 mm Baltic birch left from The Loudspeaker, I decided to mostly use this for the bass cabs.
This extends the width to 374 mm.

Routing for drivers in Baltic birch is trouble. Start lowering the router 0.1-0.2 mm and rotate the router slowly.
Sand the panel before proceeding. Next you can start lowering the router ~1 mm per rotation.

Left: The 10N650 is given some 6 mm extra, allowing a front grille of ~10 mm thickness. With the front panel being 27 mm thick, there's still some 11 mm left for mounting screws. More than enough for bass driver with 8 mounting screws.
Right: All holes in bracings made incl. hole for port and front bass driver. Someone asked if I really make the holes in the braces with the router, and yes I do. It takes about 60-90 sec. to make one hole. To me the easiest and quickest way.

Left: Gluing in sections, make absolutely sure panels are 90 deg. Right: Gluing top support brace.

Above and below the bitumen pads.

Bitumen pads hardly necessary with 27 mm panels, but doesn't take long, so her we go.
I used 5 sheets 50x50 cm for the bass cabs.

Bass cabs ready for sanding and lacquer.

A 5 mm strip of mahogany was inserted on front.
The chamfering of the side panel fillets and insertion of mahogany fillets are meant to slim the visual appearance of the bass cabinet - and it works. The maple fillets are 27 x 50 mm and chamfering to the middle and 40 mm depth. It has no impact on speaker performance but is crucial in making the cabinets look more elegant. 

Damping of bass cabinet. 8 mm felt on all internal panels.
I use vinyl glue to adhere the felt to the smooth bitumen pads.

Preparing for the adjustable feet. The bolt is fastened with epoxy glue. Fill a syringe with epoxy and inject around bolt.


-  more to come  -



Above the frequency response of the 4 Ohm and 8 Ohm versions of the 18WE driver. No crossover attached.
Green = 8 Ohm version. Honestly, it does not get better than this!

SPL of midrange and tweeter. Looks like a 1st order filter, but it actually is a 2nd order LR.

Impedance (red) of mid-tweeter section. Minimum 5.6 Ohm @ 420 Hz. Green = electrical phase.



18 Sound and BMS drivers available from LEAN, UK. Very reliable source.

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):

All technical questions to troels.gravesen@hotmail.com

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


Click image to view large