CNO-GRANDE

DIY Loudspeakers: HOME INDEX UPDATES RESPONSE WHAT'S NEW

CNO-GRANDE
Copyright 2019-21 © Troels Gravesen

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

20-01-2021: CNO-GRANDE updated with new SEAS W18NX003 and new W12CY006 drivers. See below.

CNO-GRANDE is the third speaker in a range of upgraded and new CNO constructions. First one was CNO-mkIII, the second CNO-25-mkII and here icing of the cake from 2 x W18NX003 + W12CY003-edge-coated + T29CF002.
The virtues of adding a small 4" midrange driver has been discussed in detail in the intro here.
The CNO speakers have been the best selling kits from the SEAS portfolio - and for good reasons. These nextel coated SEAS drivers just sounds great and have found their way into some serious high-end speakers as observed at the Munich High-End Show in recent years.
Some of the writing below is copy-paste from CNO-mkIII and CNO-25-mkII. I apologise should you find this tedious, but using the same drivers the qualities described goes for all.

If you want to change your CNO-25 to CNO-GRANDE, you must make a list of the coils and caps you have. For caps value and brand. For coils value and DCR.
Send this to Jantzen Audio and they'll see what can be taken out of the kit. Be prepared that only a few components can be reused.
All of the new CNO constructions will require new cabinets.

My previous designs featured 4th order series crossovers. I had a crush on series crossovers back then and still don't mind series crossovers at all and sometimes we can find very simple solutions with series crossover like the 8008-CORNER, a crossover that could not have been made as simple from a standard parallel crossover. We never can tell before we have our final cabinets and drivers in place and start modeling and set up test crossovers to see and hear what works and what doesn't.

The Nextel coated drivers can do with a lot less than 4th order crossovers as can be seen here from the SEAS W18NX001 driver mounted on the Jenzen cabinets. The W18NX can be run 1st order by simple means, but whether this sounds good is to be heard. Just because something works technically doesn't automatically produce the best sound. It doesn't work that way. W18NX001* also features a glass fiber voice coil former, ensuring high Qm, i.e. good dynamics.
*: 2021: CNO-GRANDE now updated with the new W18NX003 and W12CY006 drivers. This without any change to crossover.

It's been quite some time since I last heard these Nextel coated drivers - and I'd forgotten how good they are. The updated 18WNX003 very much reminds me of my current Ellipticor 18WE drivers. These SEAS drivers are as easy on crossovers as the Ellipticors.
With default tweeter attenuation these speakers deliver a smooth and balanced presentation with decent bass given their size. I also have to say my front-end is much better than back then. I really didn't hear what these drivers could do when I did my first CNO.
The smooth response of the mid-bass drivers and shallow crossover present a naturalness and ease of listening I have come to appreciate from my reference speaker.

A key component in this study is the edge-coated W12CY003 midrange driver, only available from Janzen Audio. Adding the edge-coating to the W12 drivers makes it the most linear 4" driver I've ever had - and I've had a lot over the years.
In a study presented here, I try digging into the importance of low linear distortion, in particular in the 800-2000 Hz range, where we often have rubber resonances from the surround causing rapid change in amplitude and phase and significantly impacts the sound perceived. In short, the dip in frequency response often seen here causes a rapid change in phase and creates a presence feeling that may be seducing to the ear as it projects the soundstage forward into the room, where in fact, the music should start at the plane of the front panel and extend as deep as possible behind the speaker. BTW: I've always found 4. order filters to have this presence effect, which may be desirable and taste cannot be argued. A study was performed with a 4" midrange driver having a significant dip at 1.5 kHz and where an edge-coating of the rubber surround produced ruler-flat amplitude and phase. The two drivers were tuned to exactly the same amplitude, and basically having the same frequency response, except for the dip and phase shift of one driver, were set up aside and run full-range covered with a front grille. People were invited for a blind test to evaluate the sound and every single person was shocked when he were told what they'd be listening to. But follow the link to learn more. For my self this study has meant I'll never again go into a demo room without thinking what kind of linear distortion I may be subjected to.

My hopes were high on the addition of the ever-so-smooth edge-coated W12CY003 midrange driver. I'd been enjoying the CNO-25-mkII for quite some time and how would this extended version perform? Fortunately I wasn't disappointed. On the contrary, it even exceeded my expectations by a comfortable margin. All drivers perform perfectly in the crossover regions and none of the drivers are asked to do more than half of what they can do in terms of frequency range. The first order crossover to the midrange low-pass section and tweeter high-pass section here provides a seamless integration with an ever so smooth a credible tonal balance and timbre that fully pays tribute to oboe, clarinet, cymbals, tambourine (so tricky to get right), vocals, massed strings - and you name it. Ideally we would have a driver for each frequency, but having a small driver bridging a 6" and a dome helps an awful lot and although not apparent from horizontal dispersion measurements, a 4" driver is an ideal size for mating two drivers of such difference in radiating area as 6" and a 1" dome, although it helps the W18NX001 is not a particular large 6" driver (130 cm^2). All speakers a compromises, but from simple means - and ideal drivers - we can get a long way.

Listening to he phenomenal 45 rpm LP from Vincent Belanger, the cello here comes with a credible low-end weight and midrange-treble as good as any speaker I've had in my room. The overtone structure is truly amazing - and I'm not done with these Nextel coated drivers. Equally well the fabulous Domnérus LP with a portrayal of the cathedral acoustics as good as I have ever heard. I recently bought a bunch of LPs featuring Lars Danielsson and Paolo Fresu and Paolo Fresu lead me to Mare Nostrum and some 45 rpm LPs. Very European music. I love it.

The CNO-GRANDE presents a more powerful bass compared to the CNO-mkIII but similar to CNO-25-mkII. Two mid-bass drivers can obviously move more air compared to a single driver and although it doesn't go deeper - on paper - it feels so. Relieving the W18 for upper- mid obviously means we can push these driver a little harder, thus the -GRANDE can be played louder.
I use the Disque de Demonstration Focal #8 CD a lot for quick testing of some specific parametres like bass extension and Liane Foly's Au Fur Et A Mesure proves the speakers capable of a potent bass as does not least Rachelle Ferrell Sista with its heavy bass line. Give the W18s some heavy beating for break-in and they deliver.
The increased sensitivity compared to the CNO-mkIII is felt too. My 32 wpc EAR-861 has no trouble running these 90 dB speakers higher than they should from their 4-8 Ohms tabs. Here I prefer the 8 Ohms tabs, despite being a4 Ohm speaker. This always have to be tried.
Oh, and I had forgotten what a phenomenal tweeter this Crescendo T29CF002 is. One of the true high-end tweeters. On top of all this, these EXCEL drivers come with an impeccable finish. Lovely pieces of engineering.
It's been more than a year since I had the prototypes of Jantzen Audio's new AMBER-Z copper foil capacitors and I've been using them ever since for evaluation and crossover fine-tuning. The problem with this is that you get used to the very best of capacitors and don't want to use anything else. Fortunately the capacitor for the tweeter here is of rather low value and maybe money allows to squeeze the last bit of information from the Crescendo tweeters. I never enjoyed cymbals more since The Loudspeaker - but that's another story.
Pooling all the Amber-Zs I have I managed to replace also the midrange capacitors, which I shouldn't have done because now I want them to stay. Having a very shallow 1st order filter to the W12CY003 driver, the midrange here mingles well with the tweeter. But price would be prohibitive and the caps would cost almost as much as the entire speaker kit itself, but it's a strong indication of the potential of the W12 midrange driver.

Please note phase plugs will be black with updated drivers.

Basics:
3-way, 4-driver speaker
Dimensions: 22 x 30 x 110 cm, WxDxH, plus feet.
System sensitivity: 91 dB/2.8V/1 meter.
Impedance: 4 Ohms, minimum 3.7 Ohms @ 160 Hz.
Point of crossover: 1000 and 4000 Hz, LR2 and 1st order crossovers.
Power requirement: 20+ watts/channel.
Power handling: 160 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/tips.htm#CONSTRUCTION_OF_CROSSOVERS
http://www.troelsgravesen.dk/crossovers.htm
http://www.troelsgravesen.dk/LCR-RC.htm
http://www.troelsgravesen.dk/Inverted-Polarity.htm
http://www.troelsgravesen.dk/choices.htm
http://www.troelsgravesen.dk/power-handling.htm

DRIVERS
BACK TO INDEX

T29CF002. The finish and build quality of this tweeter is nothing short of magnificent. So is the sound.

Click images to view large

Above the new W12CY006. Click images to view large.
Edge coating and improved magnet system and titanium voice coil former.
More info here.

W18NX003. One of the best midbass drivers I know of. Easy on crossover and no rubber resonance at ~1 kHz as is all too common.
New titanium voice coil former and improved magnet system ensures high mechanical Q and improved dynamics.
Check here: http://www.troelsgravesen.dk/SEAS-W18NX003.htm

Download driver specs: T29CF002 W12CY006 W18NX003

(The W12CY003 data sheet here is not applicable to the driver supplied with the kit. See measuring data below)

CROSSOVER
BACK TO INDEX

The crossover hardly gets less simple than this. A mix of LR2 profile and 1st order filters makes perfect phase integration from the stepped baffle providing proper time-alignment of midrange and tweeter. At the point of crossover between bass and midrange, the wavelength is so long, time-alignment really doesn't matter.
The kit is supplied with two pairs of binding posts for each speaker allowing you to bi-wire the speaker should this be preferred.

CABINET
BACK TO INDEX

The cabinet volume is ~42 litres, giving an F3 = 42 Hz. Two port is tuned to 42 Hz from Ø68 x 70 mm.
Key issue here is having the correct panel width and drivers' placement with regard to the top of the cabinet. The outer front panel sides are chamfered 45 deg. to a depth of 15 mm. Top of outer front panel is chamfered 20°.
Place bass crossover on front panel and mid-tweeter section on bottom panel. If you want to by-wire, add two pairs of binding posts to your order.

Place crossover at bottom of cabinet and attach bottom panel B with screws for access to the crossover.

With the updated drivers, the phase plugs will be black.

Flat pack or finished cabinets can be purchased from EBEL Holztechnik, Germany.

Workshop images

Also check CNO-mkIII and CNO-25-mkII for ideas.

CNO-GRANDE cabinet shaping up. My prototypes had the rear panel attached by screws for any possible modification. I suggest only the bottom panel being attached by screws for access to the crossover as show on drawing.

I used 20 mm panels throughout, not laminated as I often have the question.
What you see is a rebate for the rear panel, not laminated panels.

Chamfering of driver holes is important, please read here: http://www.troelsgravesen.dk/chamfer.htm
Chamfer driver holes to around 5 mm from driver rebate on outer front panel as seen above and turn around.

Mark diameter of chamfer as seen above, route for driver holes on inner front panel and chamfer holes to around 5 mm from driver rebate.
This way drivers have free ventilation from the rear.

Remove the W12CY003 rubber boot. The boot is so large it cannot pass through the driver hole.
Make sure the wire hole is completely sealed from the bass drivers. See here.

The rubber boot looks good but does no good for performance.

Eight layers of acoustilux at bottom of cabinet.

CABINET DAMPING

Cabinet damping:
Add bitumen pad to all internal panels except front panel and only one side of the midrange rear panel.
Add 8 mm felt to all internal panels.
Add 8 layers of acoustilux to bottom of cabinet.
Add 4 layers of acoustilux in cavity behind midrange cabinet.
Add 2 layers of acoustilux behind midbass drivers.
Add 50 grams of sheeps wool to midrange cabinet.

Two layers of acoustilux behind 18W drivers on rear panel.
Midrange cabinet stuffed with 50 grams of wool.

Crossovers in place.

Twin terminals for bi-wiring/amping.

MEASUREMENTS
BACK TO INDEX

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 can be seen the impact of the edge coating before (red) and after (green).
The dip comes at 500 Hz comes from the width of the baffle, 70 cm, equal to the wavelength at this frequency.

W12CY003-EC on actual baffle displaying response from 200-10000 Hz.
Now, one thing is measuring a driver on an "infinite" baffle, another thing is placing it on real-world baffles.
I couldn't be more happy with the result above. This is as good as it gets.

Above the Full Monty, merged with near-field response @ 250 Hz. So far, the best 4" I have ever measured.

W12CY003-EC horizontal dispersion. Very even response up to 3600 Hz from 0-10-20-30-40 deg. off axis.

Measuring a speaker this height and with such shallow crossovers pose quite a problem as I can't measure at proper distance to capture the true integration of all drivers. With 1st order crossover we also have significant crossover lobing, which makes it even more troublesome.
Here's the simulation that better capture what's going on:

Summed response of midrange and tweeter driven from crossover.

Bass drivers' response merged with nearfield response @ 200 Hz, port contribution included.
Red = without crossover, green = with crossover.

Final system impedance. Minimum 3.7 Ohm @ 160 Hz.
Generally this is a very easy load and my 32 wpc tube amp has no trouble running these speakers louder than they should and my 64 wpc bridged tube amps just love them.