Nexus 18-1200Eu

Well 2024 is an interesting one indeed with Nexus Audio ( South Africa ) not only bringing back the Eu series which includes the much loved 18-1400Eu but to my surprise a new little brother joined the family - 18-1200Eu.

Big thanks to Nexus as always for sending us speakers to test - we push these products to the absolute point of thermal and mechanical capacity every time & on the odd occasion we see that magic smoke come out of speaker parts & this gives us valuable data and we get sent another until we know everything about the points of failure. This means that when you buy into the brand you can do so with confidence, Nexus puts tons of emphasis on getting even the cheaper speakers right which I wish other brands would offer. Sadly like many competing brands in this segment of the South African market don't have accurate parameters or none what so ever, sadly some of the brands just print out random specifications that represent a premium product but that's not really what you are getting so again this does not help at all.

I must point out that knowing what the parameters are makes a world of difference to someone trying to Diy any enclosure, noticeably the likelihood of poor performance or product failing under use increase's dramatically especially when products are pushed to the limit. Honestly I would like to see brands like Hybrid & Myth - audio start sending us drivers to validate the specifications, these are also great products at various price points and are extremely popular in the market and way to often I see them being used in enclosures they don't belong in and people land up breaking them or saying they are not good when they are excellent Value!

Back to the 18-1200Eu

As we speak I have the driver in free air above my head with way to much power to feel comfortable, why above my head.. easier to put out the fire lol.

The way this process starts is by taking some basic test just using Dayton Audio Dats, let me share the steps with you for the sake of interest.

Testing speakers part & setup

First we do a calibration test on the lead wires as below.

No we do the resistance against the internal 1000ohm resistor which looks as follows:

At this point we are ready to take our first measurement of a brand new speaker!

First sweep and we get back some information and a sneak preview, though this information will change during out testing if it survives and if it dies before the end.. we start over making sure we don't cross that threshold again! 

The information on the right hand side is the technical data we are interested in, this is the basic data we need to model a speaker box to match the performance to the driver. Without proper Ts parameters we would be guessing and in reality this is not good for designing enclosures and so the question is: What parameters make up a good quality speaker? 

1. Qts: Lower is not always better, however a value here between 0.3 to 0.4 is great for a wide range of enclosure designs and Ebp can play a roll in the overall outcome
2. Fs: Lower values often are a great indication of the potential low end we can reach, 15" to 21" sub woofers have an Fs which range from 25hz to 35hz typically with some being higher.
3. Vas: Plays a roll in how big the enclosure might need to be to reach down to the drivers Fs, some drivers have a very large value which can make a box incredibly large and others incredibly small.
4. Xmax: Cone excursion helps to deliver large amounts of displacement, to much displacement can introduce non linear motion and cause distortion though typically 10 to 15mm is a great value
5. Ebp: this helps to indicate what enclosure "might" work best with a low Ebp less than 50 often being good for a closed box and values of 100+ being good for ported, bandpass & horns.

Our first sweep has given us some early indicators to the potential of the driver, the Fs looks good for an 18" speaker and I know we have around 12mm of cone displacement or Xmax to help generate some deep bass, however the Q set of parameters are a little high in value for my liking but these will change. As we "condition" the speaker by cycling high levels of input power the soft parts undergo a major change from being stiff to softening over time, this will effect a large portion of the parameters from our first measurement! almost all the  mechanical parts will alter the overall parameters and things like Fs will become lower in value along with Qms and Qts will all shift down through this process of conditioning. Right now our Ebp is 63.18 which is indicating to us we might be better off in a vented enclosure, we should see and increase in Ebp once we are done with the testing.

My first impressions is visual and we have a really nice looking driver, the frame looks powder coated in a deep gray and the aluminum basket design feels very robust. The 18-1200Eu shares the same motor structure as the 18-1400Eu or so I'm told but I can see super quickly that this might not be the full story but not on visual inspection! Visual inspection looks like that would be 100% correct as the T-yolk. washer and magnet is identical though on our first test sweep the overall parameters electrically are not close at all. We should be seeing a much lower Qes so I suspect that the Voice coil might be slightly different and the D modulation ring could be removed or changed out to reduce the cost to separate the 1400 to the 1200 series which is not a bad approach and could lend itself to other desirable uses over the 1400 series. 

Currently I'm driving 30hz into the speaker at very high voltage and it always makes me nervous, not directly trying to make the speaker fail and reach Xmech and destruct but I'm 100% pushing the boundaries of causing mechanical failure! Even at these levels of mechanical stress the overall motor and parts remain composed and the speaker itself is not mechanically noisy at all, this is a good sign of quality and to enforce this I will do another sweep in 4 hours to see how much has changed overall and if very little changes it often means high quality components are used. 

4 Hours later here is another sweep, keep in mind the ambient temperature has dropped dramatically and this also effects the parameters so lets take it with a pinch of salt. 

What has changed so far, lets compare a handful of data!

FS: Was 37.85Hz to 34.99Hz which is not much change though the overall temperature has dropped from 30C to just shy of 20C

Qms: Was 24.39 to 20.11 again not much change, like with the Fs value I really expected much more of a decrease but again this small drop is not a bad thing in fact its showing a high level of stability. 

Qts: Was 0.58 to 0.52 I really do hope to see this value drop but I have a feeling we are going to land up with a overall high Q driver

Ebp: Was 63.18 to now being 64.79

So far not much change at all, good sign of quality components but secretly I would hope it settles much lower! Right now the overall specifications makes it a popular choice to compare it to a product like the 3rd generation P audio 18-1200 Gst series which is a higher Q driver & from what I see these should be a nice shoot out to compare on paper and will draw down to Vas and Bl strength to see which pokes out ahead in Spl. 

Time to put the speaker back above my head and leave it for another 8 hours and by the magic of how this article is being produced :)

Here are the Parameters gentleman or should I say some of them, will find out the voice coil information in time to come and share it again, complete but for now I know we should have 12mm worth of cone displacement so lets work with that until we have the full info! 

Is it good - well for the price point it's really not bad compared to other low cost drivers. The build quality is great and the parts look like good quality, I most certainly think it has a place in the market for some vented enclosures!

Suggested box volume ranging between 275 to 400 liters tuned to 30 to 35hz, I'm sure you might be wondering how does it compare to the 1400 series?

To be honest it cant be compared to the larger driver which is vastly superior for horn and bandpass designs with its extremely low Qts and high Ebp, the 18-1400Eu in my opinion is vastly under valued in the market and has the capacity to match drivers that cost R8000 and greater brand to brand.

Overall the Nexus 18-1200 is reasonably well balanced and is extremely affordable for a good quality 18" driver, don't forget if you need a design for these we have you covered with our custom workshop!