Sierra-2 Development Thread

[Mag_Neato]

----> 1/21/2014: Sierra-2 are now available. Please click here for order info <----

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?

[curtis]

We talk about something like this at one of the gatherings at the shop. It definitely would not be the Tower's mid-driver. It can not play low enough to cross to a sub.

How low would you want it to go? It would have to go to at least 60-70hz or so to cross to a sub nicely.

Hopefully Dave can elaborate.

[Funambulistic]

Ed,

Way to throw a monkey wrench into my works! Yes, I have been coveting the new towers and, yes, they are out of my financial reach, but I am totally satisfied with my current system (Arcam DV137, Sony BDP-N460 [only reason for two disc spinners is the Sony plays BluRay but the Arcam plays SCAD, DVD Audio and sounds MUCH better on CDs and the picture and sound on up-converted DVDs is no contest] T+A Power Plant, Ascend Sierra 1 Nrt and my trusty Sunfire True Sub) for the first time since 1997 (Adcom CD player, Audio Alchemy DLC, circa 1978 Marantz amp [a beastly 254wpc] Sony ES SS-M5 speakers [you know, those odd, tetrahedronal units made FOR Sony but not designed BY them] and my trusty Sunfire True Sub). Between 1997 and the present, my system has gone through many changes because of marriage and/or divorce, unemployment, ad nauseum. Suffice to say, aside from intellectual longings, I am done (for now, hehe). There have been a select few speakers that have really lit my fire (Proac 1SC, Ruark, Vandersteen 2CE [oy - those are ugly to this day] the aforementioned Sony's and, now the Sierras). To tamper with small monitor perfection is, shall I say, heresy! I do not know what Dave has up his sleeve (I read the thread on how difficult it would be to incorporate an RALL tweeter) but leave well enough alone! My check book cannot afford it. And to deprive the Sierra of it's bass response with the mid driver from the tower - heck, go for an Axiom M22 (kidding, though I did own a pair).

I hope you find this post in jest, for that is how I intended it. If Dave can come up with something better than the Nrt at a similar price point, I'm all in. Doubtful...

John

[Mag_Neato]

I did not mean this as a replacement for the NrT, but as another enhancement/upgrade like the NrT tweeter was. The goal being a cost-effective method of another performance enhancement.

[curtis]

How much bass are you willing to give up? Also remember, cost effective goes two ways. Dave has to be sure he can sell enough for it to be cost effective on his end, he also has to believe the improvement is cost effective to his customers.

[GirgleMirt]

If you use a crossover (with sub) anyhow, it lowers the 'strain' of the woofer, so that should marginally improve performance, probably not up to the dedicated mid's level, but maybe audible?

I think it was mentioned that the mid woofer wouldn't go low enough... After 25 pages of the "tower thread" and no luck finding the number, I'd say definitely >200hz, maybe even 500hz, which would leave a really big gap between speakers/sub, and maybe even making the mid unusable... Another thing to remember, the Sierra-1 is ported, and the mid has its own sealed cabinet compartment... So again, just 'sticking' it in the Sierra-1 cabinet would probably be all wrong with internal volume and ported vs sealed...

And even if the mid could go down to 200hz, as it was most definitely optimized as a mid and to be crossed over to dual 'bass' woofers, it's performance <200hz (<500 hz or whatever) might not really be viable (not as clean; more distortion; sounds worst) when compared to the Sierra-1 woofer... Making it probably not a good idea as a replacement...

So all of that said, I'd be tremendously surprised if it ended up being a good idea for a Sierra upgrade... Sorry! lol (But I'm not the speaker designer genius though, so hope remains... haha)

[Mag_Neato]

I realize as well as the next guy that it may be an impossible dream, but if you don't ask the answer is always no!

[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.