Sierra-2 Development Thread

[RicardoJoa]

I have two thoughts on this new woofer, and why no pics yet. Option one is it looks unremarkable, or just like the Sierra 1 driver, or two there is something revolutionary enough that Ascend, or Seas has some proprietary tech in this thing and are reluctant to unveil this amazing piece. Well I suppose that there is one more option, that being the curiosity is driving me mad. Pretty please with sugar on top, can we please, please, please, see the new woofer?

Jay

Yeah, cant wait for the pics of the woofer and the usual info of the overall construction.

[FirstReflect]

So, I'll ask what seems like the obvious question to me:

looking at the spectral decay graphs, it appears as though the new Sierra-2 woofer (with its fancy new cast magnesium construction ) is actually producing faster decay times and faster transient response than even the Sierra Tower mid-range driver!

Now, from what I understand, that Tower mid-range driver still holds the advantage in overall power handling and sheer output capability. But I have to wonder: the Sierra-2's woofer is using newer technology and newer manufacturing methods.

Does this potentially mean an even more amazing Tower mid-range driver could be developed?

I mean, we've sort of seen the progression:

- the NrT tweeter gets developed as somewhat of a response to the Tower mid-range driver so that there is a tweeter that can keep up. That NrT tweeter then becomes an optional upgrade for the Sierra-1.

- The RAAL ribbon 70-20XR tweeter comes along, and it is so good, and capable of so much output, that it doesn't really make sense to put it in a bookshelf speaker along with the Sierra-1's woofer.

- So a smaller RAAL ribbon gets developed, but it demands a new woofer for proper crossover integration and to keep up with its performance.

- Now that new woofer appears to outpace the Tower mid-range that started it all!

So we've come full circle! haha

Could we potentially be witnessing the birth of a Sierra Tower 2.0? One that comes standard with the RAAL 70-20XR ribbon tweeter plus an all new mid-range driver that expands upon the materials and technology used in the new Sierra-2 woofer?

The RAAL 70-20XR upgrade for the Towers is not a "drop-in" solution that customers can perform themselves. It requires a different shaped cut out in the cabinet. So there would be no restrictions on making a potential, new Sierra Tower 2.0 mid-range driver. What I mean is, it wouldn't necessarily have to use the exact same cut out dimensions as the current mid-range driver -- although 5.25" diameter drivers are pretty common, and I can easily envision sticking with that same size. It WOULD simplify the cabinet construction, and nothing would actually change on that end if this hypothetical Sierra Tower 2.0 mid-range driver were to exist as a drop-in replacement for the Sierra Tower mid-range driver. The cabinet maker would still just be making Sierra Tower and Sierra Tower RAAL cabinets, so that would likely make the most sense.

Anywho, no sooner has Dave delivered this new Sierra-2, I'm already asking if it has spawned the next project! haha.

Truthfully though, I'd love for Dave F. to set me straight on this: does the new Sierra-2 woofer actually outperform the Sierra Tower mid-range driver in some respects? That's wild if it does. But it makes sense as the technology keeps advancing.

Heck, if the RAAL 70-20XR is not using its absolute maximum output capabilities in the current Sierra Tower RAAL design, perhaps an even higher output Tower could be made! Larger woofers, or 3 5.25" woofers, perhaps? Along with a new, cast magnesium construction, super high output mid-range driver? There are always people anxious for even more output capabilities.

It could become an entirely new, flagship line for Ascend! I'd vote to call them the Ascend Andes . I think that's just the logical name after the Sierra series

[JustABrah]

He just finished up a big Sierra-2 project and a few weeks before the holidays and we're already planning the tower 2.0 project for Dave hahaha poor guy won't get any rest with this forum.

[JustABrah]

I wonder if we're still getting the pics and info tonight?

[FirstReflect]

He just finished up a big Sierra-2 project and a few weeks before the holidays and we're already planning the tower 2.0 project for Dave hahaha poor guy won't get any rest with this forum.

But...but...there's a chance -- however slim -- that an even better mid-range driver could be made!

!!!

Does this possibility not encourage, nay, demand for Dave to investigate? And, if need be, to alter the laws of time and space so as to create enough opportunity for him to do so?



In all seriousness, though, Dave needs to take a vacation! Poor guy probably doesn't even get to listen to any music or movies on his own speakers unless it's as part of an evaluation or listening test! No rest for the super busy and successful, though, eh?

Also in all seriousness, I'd much sooner see some Ascend on-wall speakers as Dave's next, big project. We've already established that a Sierra-0.5 doesn't make any financial sense, as it would require new 4" drivers to be developed, and the laminated bamboo cabinet would have to be an entirely new, and fairly expensive design. So a Sierra series speaker that looks exactly like the HTM-200SE has already been ruled out.

But a speaker that is about 6 or 6.5 inches deep from front to back, and that has a front mounted port, or a bottom or top mounted port, and that uses the exact same Sierra-1, Sierra-1 NrT, and Sierra-2 drivers. That is what I have in mind! It would end up being fairly tall (or wide, as the case may be), in order to maintain the same internal volume of air as the Sierra-1/2 cabinet. But I'm pretty sure it can be done. And with its larger fascia, a price that is equal to, or slightly higher than the Sierra-1/-1 NrT/-2 would seem completely reasonable to the average customer.

So, there ya go! TWO massive projects for Dave, now that the Sierra-2 is done

By the way, the on-wall speakers could have the name Ascend Sierra Cordillera

[JustABrah]

On wall speakers would be killer, they seem to be very popular to have them as a LCR with the flat screen but if they did that they'd have to get matching for rears. But right now I can't wait for some of those Sierra-2

[davef]

Sierra-2 – The Woofer

After evaluating about a dozen prototype RAAL ribbons with varying ribbon element heights and widths, different size chambers, magnets, and damping amounts – we learned exactly what performance possibilities existed for the RAAL ribbons. From this knowledge we were able to design a specific set of parameters and performance characteristics for our new woofer, with the primary goal being to achieve an ideal synergy with the ribbon tweeter.

This was quite the challenge as we were presented with several difficult hurdles.

Our new ribbon would require a higher crossover point than we typically used for our woofers. Generally speaking, to maintain good high frequency performance, the woofer cone must be quite stiff. The problem with stiff cones is that they tend to suffer from harsher cone breakup modes that need to be compensated for in the crossover. This goes against our original Sierra philosophy of “less is more” so thus began a search for a cone material that was exceptionally stiff but also extremely well damped. The polypropylene we use in the Sierra-1 woofer, while it has good self-damping, is just not stiff enough to provide the upper midrange response thus required for a proper crossover to our new ribbon.

I confronted Olav Arntzen, director of SEAS, with the challenge and he originally recommended we try some of the Excel woofers. While these are, without any doubt, excellent woofers – they too have some harsh break-up modes and this was something I wanted to avoid. Olav then recommended I try something new, something he said might be the future of cone woofer materials – something called CURV. CURV is a woven polypropylene that takes all the great qualities of PP, but makes significant improvements. Stiffness to mass ratio can be precisely controlled and the material is very lightweight but yet extremely stiff – the best quality, however, is that internal damping is simply stunning with little to no cone breakup modes. In fact, I did not measure any cone breakup or resonance modes within our needed bandwidth which meant I would be able to cross this woofer at higher frequencies without trapping out break-up modes in the crossover.

We had found our cone material.

Note: The CURV cone we are using in our woofer is specifically made for SEAS, and to their requested specifications. This is not the same woven PP already being copied in Asia.

The other significant problem we faced was how to at least come close to producing the phenomenal bass response of the Sierra-1 while using a woofer cone that has significantly lower mass, while also maintaining reasonable sensitivity. We simply can’t defy the laws of physics, meaning it would not be possible for the same size cone...

unless.....

The solution to this problem presented itself in an interesting manner – a bit of luck combined with some clever tooling. It turns out that this new CURV cone is technically equivalent to a 6” woofer and provides just a bit over 29% more radiating surface area than the 5 ¼” woofer we use in the Sierra-1. Because of this, we are able to maintain efficiency and bass response, while also using a lower mass cone which reduces inertia and better matches the amazing transient accuracy of the RAAL ribbon. We managed to fit a custom 6” woofer into the 5 ¼” woofer cutout of the Sierra-1, with the cone having significantly less mass yet maintaining excellent bass --- perfect!

In addition to the above, our new 6” woofer also features:

*Long-throw design for high power handling and extended bass

*Small gap spacing combined with a powerful magnet system for quick transients

*Radially reinforced surround reduces surround resonances at higher excursions and provides for better overall damping

*SEAS’s exclusive SpiderRing® technology improves suspension alignment for higher long term reliability, improved power handling and improved mechanical linearity

*Custom cast Magnesium frame for a stiffer and lighter basket frame allowing for less material behind the woofer cone reducing back-wave reflections for enhanced detail, better airflow and less cavity resonance.

* Vented pole-piece and open spider for enhanced air-flow and cooling, minimizing compression artifacts

In summary, I feel this woofer provides the absolute perfect balance of deep bass combined with fast clean transients and the necessary upper midrange response to provide a seamless blend to the Sierra-2 ribbon tweeter. The timing was near perfect for us with the development of woven polypropylene woofer cones as I strongly doubt we would have had a Sierra-2 without it. I must stress that this could not have happened without our wonderful 10 years+ relationship with SEAS. They provided sample after sample, extensive technical expertise, went above and beyond with our required customizations and toolings, and most importantly – provided extensive encouragement towards completing this significant undertaking.

And now for some pics:

[curtis]

Ahhh...nice!

[parimento1]

so when will we be seeing these woofers in the Sierra Tower Series II haha??

[merrymaid520]

so when will we be seeing these woofers in the Sierra Tower Series II haha??

I second that^^^

Very nice woof design Dave. I'm just going to throw it out there, beta tester for the Tower v2 right here!