Sierra-2 Development Thread

[davef]

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?

[GirgleMirt]

while not as detailed as our Sierra Tower, for a 2-way bookshelf speaker it has to be amongst the best out there.

So if I understand correctly, for about 15% more, 300$, you could get an NrT tower which would be more detailed? Or are we talking about the RAAL Sierra tower? If the RAAL, how would the NrT tower compare?

Hard to say without hearing, but I think that if the NrT tower was more detailed in the mids and I wanted a ~2000$ speaker, I'd probably opt for the towers, since 300$ isn't that much more, and you do get towers in the end... Just a question like that, would you go for the RAAL bookshelf instead of the NrT towers? Because I think that could influence possible answers

[curtis]

To me, it seems like you would get better midrange detail than a Sierra-1, but not as good as a Tower, and the treble response of Tower w/RAAL.

I would certainly like to hear it.

And we could call it...the Sierra-R....or maybe not.

[Dark Ranger]

First off, props to Dave for considering and actually working on suggestions from customers.

In my opinion, the towers are a no-brainer with either the NrT or RAAL option. You get the luscious mids and highs in an optimal 3-way design.

However, there are customers who cannot fit a tower into their listening environment. I am one of those customers. A Sierra-1 with RAAL would cater to a niche group including, but not limited to:

- those with no space for full towers
- those who prefer two-way bookshelf designs
- those who prefer high-quality sound in a discrete enclosure

However, I think the lack of upgrade path from Sierra-1 to Sierra/RAAL may cause some folks to back down because of the additional investment. I figured it would be extremely difficult to retool an existing S-1 cabinet for a RAAL upgrade.

One thought I had: a "trade up" program might be attractive for those who already own S-1, but I have no idea how much that would affect Ascend's ROI or resale objectives. There would be a lot of B-Stock going this route, and it will impact Ascend's current inventory turnover.

I do have a soft spot for quality bookshelf monitors. I will definitely stay tuned.


EDIT: Oh, I forgot to mention names. My thought was Sierra-1R. Simple, but descriptive.

[Mag_Neato]

Glad to hear there is experimentation with this concept!
The difference in cost vs. The NrT towers would be the tough choice.
That would be dependent on each persons situation. Having the room for the monitors but not towers..........RAAL vs NrT.......etc.
Space for large speakers is not an issue for me, but cost is. If I could manage $2000 for the towers I'd be sticking with the excellent NrT tweeter. If I wanted the goodness of the ribbon combined with a little better midrange over the Sierra-1 NrT then a Sierra-1R(ribbon) crossed over to my 12" Rythmik would fill the bill.
Tough decision.

[Dark Ranger]

Glad to hear there is experimentation with this concept!
The difference in cost vs. The NrT towers would be the tough choice.
That would be dependent on each persons situation. Having the room for the monitors but not towers..........RAAL vs NrT.......etc.
Space for large speakers is not an issue for me, but cost is. If I could manage $2000 for the towers I'd be sticking with the excellent NrT tweeter. If I wanted the goodness of the ribbon combined with a little better midrange over the Sierra-1 NrT then a Sierra-1R(ribbon) crossed over to my 12" Rythmik would fill the bill.
Tough decision.

I was thinking more about this today.

Dave already has a NrT upgrade kit available for stock Sierras. This takes the original design with excellent sound and refines it in several ways. The great thing about the NrT upgrade is that it does not require reengineering the cabinet, and the kit can be installed by the user. However, nearly everything changes with the RAAL upgrade: new cabinet design, new crossover, new tweeter, etc. It is NOT a drop-in replacement kit.

As far as sound quality, I recall that the NrT and RAAL share similar voicing, although the custom RT for Ascend does provide several key advantages over the excellent NrT.

OK, here's my point: the Sierra-1 with RAAL could be attractive for new customers who want a bookshelf monitor, but desire higher-quality sound than either stock or NrT versions provide. However, for customers who already own Sierra-1 systems, the RAAL upgrade would be harder to justify in my opinion, and it still would not offer as much detail as the full Tower system.

On the other hand, Ascend could offer this "exceptional" bookshelf monitor that would be among the very best two-ways at almost any price point.

Decisions, decisions!

Honestly, I would be extremely interested in seeing measurement data comparing the prototype Sierra-1R (had to plug my suggested name) with the existing stock/NrT versions. Of course, a listening session would be great, but since I'm on the East Coast, I'll have to leave it to others.


Just a few thoughts on this Thursday morning.

[merrymaid520]

Dave,
My thoughts are divided as well. Its tough to justify $1800 for a RAAL bookshelf when the NrT towers with a dedicated mid driver are the same price. On the other hand, if the RAAL bookshelf has an improved mid range presence because of the lower XO point over and above the Nrt sierra-1, then it might be a interesting proposition.

I suppose if someone is after the best tweeter (highs) in a bookshelf, it would be tough to beat.

I suggest letting some folks hear the prototype(if possible) and gauage the feedback. I of course would not mind demoing a pair Had to throw that out!

Just out of pure curiosity while we are on this subject, if there was a possibility to improve upon the Towers (with RAAL) such as better drivers, different cabinet design, etc, what would you do?

Thanks,
Brandon

[parimento1]

would love to see a small 3-way bookshelf : )

[curtis]

would love to see a small 3-way bookshelf : )

What would you consider small? It will have to be bigger than the current Sierra 1/NrT.

[parimento1]

Actually I was thinking of something similar in size to the NHT Classic 3 or the KEF Reference 201/2. Its just my opinion that most 3-way designs sound better than 2-ways, especially in the midrange, while not sacrificing bass as much.

What would you consider small? It will have to be bigger than the current Sierra 1/NrT.