OK, you asked for it.
I’ve now had enough time on the Sierra-2s to have something (hopefully) coherent to say.
I’ll first note that when I upgraded from regular Sierra-1s to the NrT version, I had a very specific goal in mind: I wanted more overall crispness on the high end, and the NrT upgrade delivered that. I was super happy with them and still think the Sierra-1 NrT is a fantastic speaker for the money. As far as I’m concerned, the Sierra-1 NrT is the secret weapon of the Sierra line. There’s no hype or description or measurements or anything on the main Ascend site (unless you dig into the forums), just a checkbox that says “NrT Upgrade” on the Sierra-1 page—pure stealth. I love these speakers. So the bar is pretty high, but I took the plunge anyway.
I managed to have the house to myself for a few hours since I did the upgrade so I could turn them up and really let them shine, but also have had them in the frankly much more frequent constant run at more moderate volume while I work.
So, what are the differences between the two? I hear three primary differences:
2) Detail recovery
Each one in turn:
The single most impressive thing about the S2s is how quiet they are. Not in the sense of not being loud, but in the sense that there’s just no decay time on anything. When a note stops, it stops. Feels instantaneous. It’s sort of like having blacker blacks on a TV—you don’t notice how important it is to really have nothing when you’re supposed to have nothing, until you see what true black actually looks like. This is what really good transient response does for you. The snap on these speakers is just excellent.Crunchy guitars are even crunchier. Well-recorded cymbals (especially Paiste cymbals), in particular, are amazing; the attack is so fast, but there’s no carryover from anything else going on.
A related strength of these speakers is that detail recovery is outstanding. The NrTs are very good at this, but the S2s are just in another class. No matter how close things are in time, there’s never any “smearing” of one sound into another. I’ve heard things I’ve never heard before in recordings I’ve listened to many times over. I don’t find the difference between the two speakers nearly as big for solo music, but for quartets or other music with a relatively small instrument count the ability to really separate the details of each instrument from one another is quite impressive. When I’m really listening, I like to listen with my eyes closed and I’ve never heard a speaker that made me visualize the performers quite like these. The detail recovery is so good that in my mind’s eye I see the bowstring sliding across the violin. I’ve never heard speakers in this price range that make a recording of a violin sound more like being in a room with an actual violin. I don’t just hear the violin, I hear the violin being played, if that makes any sense at all. I don’t just hear cymbals, I hear a cymbal being struck—I hear the stick.
Overall, the effect is somewhat less impressive for full orchestras because the goal there isn’t usually to pick up individual instruments anyway. Really well-mastered rock is also terrific, but I will admit I now want to have conversations with a few recording engineers to figure out what on earth they were doing and why. The S2s don’t really punish bad recordings, but they bring out good recordings in a way that makes me wish more recordings were better. If you listen to a lot of well-recorded and well-mastered quartet or chamber music, you want speakers like these. More of my music is rock or something sonically similar, which doesn’t quite take as good advantage of this as classical music, but no question that everything still sounds great.
The third place where the S2s beat the NrTs is imaging/soundstaging. This isn’t really a surprise, since the off-axis FR graphs for the S2s vs. the S1s shows appreciably better off-axis response above 10 kHz for the S2s (my guess is the NrTs are in between the two here, but that’s a guess since I’ve not seen an off-axis graph for the NrTs). This shows up in the sonic image projected by the two. The S2 has a much wider presentation with instruments located even more precisely in that space. I think the audio reviewer term of at here is “air”; it just sounds like there’s more air in between the instruments. When I don’t have them cranked up and just kind of on in the background this is the thing I notice most relative to the NrTs.
Another place where they’re just a little bit different, without it being worse or better, is that the S2s seem to me a little less forward than the NrTs. The NrTs are a bit more forward than the base S1s, and I’d put the S2s somewhere in between the two, which is kind of a hair-splitting exercise—it’s only rarely a noticeable difference, depending on the music.
Is there anything the S2s do worse? I kind of expected there to be, as audio is usually a world of tradeoffs. So I’m kind of surprised (in a good way) to report that no, there really isn’t. I turned off the subwoofer for most of this and the overall bass extension of the S2 is a smidge worse than the NrTs (though the S2s are slightly cleaner-sounding in the lows before the response falls off). Again, this is pretty clear in the specs and it is audible but it’s not a big difference. Because I normally run with a small sub to kind of fill in the bottom of the low end anyway, when the sub is on the difference is immaterial.
Oh, and aesthetics—that’s one place where I think the traditional Sierra-1 (including the NrT) is superior. I prefer having the grilles off with the NrTs, but I might put them back on with the S2s. I frankly find the RAAL tweeter kind of ugly (I think it’s the sawtooth on the sides of the ribbon area) and the material in the Curv woofer is shiny and variegated in a not particularly aesthetic way. I’m sure some people like the look of the S2s better but it’s not for me. Obviously with the grilles on there’s no difference.
So, the $64,000 question (for you youngsters, that means “the big final question”): are they worth it? As noted, outside of grilles-off appearance, the S2s are better in pretty much every way. For a lot of people in audio, that’s it—better speakers cost more, and that’s the price of admission. If you’re thinking about buying a pair of NrTs vs. a pair of S2s, yes, I’d say the S2s are clearly worth the price difference—unless you’re using a sub. Then in all honesty unless you’re in a big room I’d actually probably get a pair of Sierra Lunas for about the same as the regular price on the NrTs. (Plus the Lunas are front-ported and so less finicky about placement.) Make sure your sub does transients well or smooth integration might be an issue (I now have a little of this problem; probably time to buy another Rythmik). But for 2.0 work I do think the S2s justify the price difference relative to the NrTs.
What about the cost of an upgrade? If you own base S1s (not NrTs) then this is easily a justifiable upgrade, and of course the math works out pretty close anyway (that is, S1s not on sale are about $800 + $800 for the upgrade is not that much more than just buying S2s outright)—super nice it works out like that.
Now, if you already own a pair of NrTs, are the S2s $840 better? That’s a harder one. For current NrT owners it’s a close call and probably depends on what you listen to and how much you care about getting more detail and the soundstage. It works out for me because the S2 upgrade means I now have spare NrT parts I can use to upgrade the base S1s I have at work, so I get a double upgrade out of it—that’s easily worth it, but I don’t think many are in that boat. It just depends on what you care about and how price-sensitive you are, which is utterly generic and applies pretty widely in the audio world, but it’s true in many places and here as well.
OK, this is a long post so unless you really want the minutiae, you should stop here. These last two sections are only for people who want a deep dive…
I was originally trained as an engineer and while I’m not one now (nor was my training in speakers or acoustics), I do enjoy a bit of wild speculating from an engineering perspective. I’ll be the fist to admit I’m not really qualified here, but when has that ever stopped anyone on the internet?
First, while the RAAL tweeter is what gets all the attention, the woofer on the S2s has to be one of the hardest-working drivers I’ve ever heard. It has to cover a much wider frequency range than the S1 woofer and does so with tremendous speed and control. It’s brilliant and I bet Dave had to spend a monstrous amount of effort to get it right.
Based on this, I now grok why the Sierra Luna is a thing, which I admit is a product that kind of puzzled me until now. It has to be a great deal easier to engineer a woofer that goes with the RAAL but isn’t also trying to go sub-65Hz. Now the Luna makes perfect sense to me.
The RAAL really comes across as a tweeter that’d be easier to work with in a 3-way design if you’re trying for more full-range performance, and the fact that Dave managed a woofer than pairs with it in a 2-way design is just super impressive.
This probably explains why Salk uses transmission line cabinets for their 2-way designs that feature a RAAL tweeter—it’d be hard to get a ported woofer to go low enough to still meet up with the higher mids needed to pair with the RAAL. This is also probably a part of why Dennis Murphy’s BMR design gets such accolades from people who have heard that speaker; you need a good crossover design and the right kind of midrange driver to really get the most out of the RAAL. I remember the first time I heard real ribbons in the late 1990s (can’t remember the speakers) and clearly the engineers just slapped the ribbons in for domes and didn’t do much else, which left a really terrible hole in the upper mids. This is now clearly a solved problem. Yay, progress.
One last engineering-oriented bit of commentary. The upgrade is pretty easy to do, and Ascend provides great instructions with videos and everything. It’s like these speakers were designed from the outset to be upgraded. Does anyone else but Ascend do that? Crazy. Also, nothing like being inside the speaker to remind one how these things are built. No skimping on bracing and the amount of damping material inside the cabinet is nuts. I got all this when I upgraded to NrTs, but always a nice reminder.
Saved until the end since the post is long enough already. I first bought the Sierra-1s back in 2010 (here
are my initial thoughts on those) and then upgraded them to the NrT version a little less than a year later (I did a review
of that, too).
Since I love my Sierra-1 NrTs, why do the upgrade at all? For the Mount Everest reason: because it’s there. Because I have very little experience with the RAAL tweeter and I wanted to hear for myself. Because I could. Because I’m thinking about Sierra Towers as mains for my HT and I wanted to see if the difference between the NrT and the RAAL is really a big deal. Because my 50th birthday is coming up and it’s my present to myself. If it sounds like I’m reaching you’re reading this correctly.
None of these are really great reasons; I have to admit I don’t really have a compelling explanation for why I took the plunge. The S2s were introduced in (I think) 2013 and it took me six years to upgrade because $840 is rather a lot when you don’t have a strong reason—you can buy a new pair of S1s for that. Nobody tell my wife, OK?