Sundown X-Series History leading up to Xv.1 10/12/15/18
This is a historic article about the original Xv.1 subs that launched over a decade ago & I wrote this over a decade ago as well:
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The Sundown X Series : As part of the X-10/12/15/18 line-up of woofers (the X-8 is a separate entity... much like the SA-8 is in that line). The idea for an "X" line began in 2010; a year so after the SA series was launched; to fill the big gap between the SA and the Z / NS series. The first prototypes were very much a bigger SA woofer with 3" coil also based around the 4-spoke basket. They were great -- and many customers that saw my posts were excited. But I didn't feel like it was truly what I wanted from this line so I went back to the drawing board.
It was about this time that I started development on our tooled Sundown frames. The new 10/12/15 frames started out as a big list of numbers on a legal pad (I have shared the photo of this before... as I keep all of my notes on file). From there a 2D computer drawing of the surround landing, spider landing, and frame base was created. After all ; the entire purpose of the new frame was to allow bigger spiders and more excursion. By late 2011 I had all of the measurements completely to my satisfaction for the 10/12/15 frames and also had the plastic adapter ring for the 18" 6-spoke designed to allow a 10" spider (the tooled 18" frame is a separate project that I am working on now).
Throughout 2012 we worked on the 3D drawings of our frames (and their patents) as well as our "mega roll" surrounds to verify 100% that everything was the way I wanted and needed it to be. Our surrounds were mathematically designed to allow excursion all the way up to the limits of the frame in a linear fashion and without fatiguing the material. Around the end of the 3rd quarter of 2012 the first samples of my frames were produced at the factory; that was one of the most exciting days I've ever had at Sundown Audio.
As for the spiders now used on the X, Z v.4, and NS v.3 (they use the same design but different layers and colors) -- the roll geometry of the spiders used on the 10 and 12" were already heavily field tested and proven designs from the Z v.3 -- except that the new 10" design uses the spider from the Z v.3 15" and the new 12" uses the spider from the Z v.3 18"; a massive gain in travel per size. We tooled a new spider in a full 10" diameter to use on the 15 and 18" models.
With all of the soft parts being developed, tested, and theorized about for so long I could FINALLY test the X series that I had wanted since 2010... a truly stand-apart model in our line that wasn't simply a bigger SA series. We received the first prototypes towards the end of 2012 and after some final tweaking of the spider pack (they received a stiffness equal to the Z v.3) and surround stiffness we were able to start pre-ordering around March of 2013. Needless to say I was incredibly excited to offer this speaker to our customers.
The X series motor is very much like a smaller Z v.4 motor; it features a triple stack 190mm diameter magnet with a total height of 66mm, a robust 15mm thick top plate, a hyper-extended pole piece and a bumped back plate -- allowing 4" of p-p travel before physical coil bottom. The coil itself is a high temperature Copper Clad Aluminum 4-layer round wire coil 55mm in length wound on a thick aluminum former. This combination allows for 30mm of linear stroke one-way by 70% BL method; non-linear stroke can reach full motor limits of 50mm one-way. The X features a version of our special voice coil ventilation system that was discussed in the SA series post.
So... why am I so excited about this speaker? What is so special about it, exactly? The X series not only represented a goal of mine for a new line back from 2010 for Sundown Audio -- the new frame and suspension platform that made it possible also represent my dreams for loudspeakers dating back to college in the early 2000s. I had been on a quest for over a decade at this point to be a part of something like this speaker (this platform also made possible the Z v.4, NS v.3, and "Team" designs). A truly high LINEAR excursion platform all of my own that would allow incredible deep-bass performance without sacrificing output OR box size.
Every time that I hear about someone getting a new X series or any other new platform driver and absolutely loving how it sounds... it makes my day. It is truly a very different sound; but a sound that I have been chasing for years. The suspension linearity of the new platform prevents a "traditional" form of distortion over stroke that creates a peaky upper-end the further a woofer moves. In short... "normal" woofers experience a tightening of the suspension almost immediatly as they begin to move; by the time they reach 1 inch or more of travel parameters such as FS and QTS can be *double* their rest value. This creates a massive peak in response on the top-end and a decrease in bottom-end that is often heard as a "punchy" sound. To be honest; some people LIKE this sound -- but there is no getting around the fact that it is distortion.
All of our new platform drivers equipped with the "mega roll" surrounds have almost none of that form of distortion. This generates a HUGE gain in output at the very lowest octaves. Of course... I realize that this sound is not for everyone so I have started development of SPL surrounds (smaller and less linear rolls; a more traditional "high roll" design; but some of the bigger high rolls available) as well as SPL spiders -- so we can build and offer new platform drivers with a bit more traditional sound. Expect these parts to be available in the summer of 2014!