Quote Originally Posted by Mag_Neato View Post
Ok, I'm going to put this out there.

With all the focus lately on the new Sierra Towers and Center speaker, let us not forget that some of us do not have the budget, and some do not have the space needed to jump onto the tower bandwagon!

So, what if us Sierra-1 NrT owners desire some of the midrange goodness offered by the towers? Would a replacement driver for the Sierra-1 woofer be something possible? Say, more of a mid driver with less emphasis on the low bass, which is usually handled by a sub. Perhaps something similar to the tower mid driver with the required crossover modification. This way we can have more of the mids that the tower produces?

What do you think, Dave? Sound like something possible?
OK -- here we go

Since work began on the towers, must be at least 3 years ago now --- I have seriously challenged myself on coming up with an affordable bookshelf speaker that uses the mid from the tower and the NrT dome. I have built several prototypes and have had this same conversation during several open house listening sessions with both Ascend owners and non-Ascend owners.

The issue that I continually run into is that to deliver the type of midrange detail and quick transients, the tower mid uses an extremely lightweight cone and the overall suspension / motor system is also very low mass. This mid has the lowest MMS of any 5 1/4" "cone" based woofer I have ever come across and the moving mass of this woofer is actually less than half that of the Sierra-1 woofer. It is the reason why it is capable of delivering tremendous levels of detail with very quick and accurate transients.

Having this low of an MMS comes at price, the mid has a natural roll off that starts in the 180Hz range. I could design a ported version and possibly extend the low end to be -3dB at about 100Hz, but a ported version will not provide the same great transient accuracy and I am not fond of high crossover points to a subwoofer (100Hz etc.)

With that in mind, I built a prototype using this mid, one Sierra-1 woofer and the NrT dome. The problem with this is that there is a significant difference in efficiency between the two different woofers and both the tweeter and the mid have to be padded down by at least 4-5 dB. This 3-way bookshelf speaker, or LCR, would only be slightly less expensive than our Sierra Tower and I was simply not able to get the performance I would have liked. The beauty in the Sierra Tower is that the sensitivity of the dual 5 1/4" woofers match the mid and that matches the NrT dome (and even the RAAL, which has a custom impedance / sensitivity profile for us). There is almost zero padding on any of the transducers in the Sierra Tower which means the efficiency on all the components is maximized.

Keeping the bass response of the Sierra-1 intact is important to me, a very large percentage of our customers use these in 2-way systems without a subwoofer. So, how do we keep the bass response and yet provide even more midrange detail? The NrT upgrade does a good job of this as we cross a bit lower so more midrange detail comes from the tweeter, which is quite robust and can handle it with ease.

Along this same line of thought, I have built a custom Sierra-1 with our RAAL 70-20XR. With this particular ribbon, I can cross even lower and just as important, the slope of the high pass can be shallower. This allows less of the upper mids (the critical area where detail is sensed) to be reproduced by the woofer and instead is reproduced by the most detailed transducer I know of, the RAAL... The results of this combination is exceptional and while not as detailed as our Sierra Tower, for a 2-way bookshelf speaker it has to be amongst the best out there. The problem with this is the expense After completing the BOM, the price of our RAAL Sierra-1 will come out to be $1798/pair. Certainly not high for anything with a RAAL tweeter, especially a 70-20XR with AM core -- but, I just don't know if this would be marketable and it will not be possible to "upgrade" existing Sierra-1.

So here is where I look to forum feedback -- at $1798 / pair, would there be demand for a RAAL Sierra-1?