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GR Research NX-Otica and Servo OB Subs

I am amazed that these speakers (and other models from GR Research) have not garnered more attention on Audiogon. For about $6K, and 40-50 hours of work, I now have a set of speakers that is, by far, the best speakers I've ever owned. And I have owned some fairly good speakers including Tympani IVs with Entec servo subs, Duntech Sovereigns, Revel Ultima Gems with dual Revel Ultima Subs, Revel Studios, among others.

The NX-Otica, along with GR Research's other speaker designs, are DIY designs. I know that scares a lot of people off, but they are really not difficult to build. For the NX-Otica and stereo triple 12" open baffle servo subs that I built, GR Research has teamed up with a woodworking company to produce MDF flatpacks which just need to be glued up to create extremely robust and well constructed cabinets. GR Research provides everything else.

The NX-Otica is an open baffle design with a narrow (~8 inch) front baffle and side wings to reduce dipole cancellation. The driver complement is a planar magnetic NEO 3 tweeter (in a wave guide), two 6 inch midrange drivers with phase plugs in an MTM array. The wave guide allows the tweeter to cross over fairly low, while the midrange phase plugs allow the driver radiation pattern to more closely match the tweeter at the crossover point. Four 6" woofers complete each tower.

The NX-Otica by itself only reaches down to 40-70Hz depending on the room, and are designed to be used with the servo open-baffle subs. I finished the NX-Oticas a couple weeks before the subs, and in my room they didn't really sound that bass shy on most recordings, but the subs really complete the package.

The crossover components supplied by GR Research are stellar quality with a mix of heavy gauge copper coil inductors, copper foil inductors, sonicaps, miflex copper bypass caps. In other words, these crossovers put most crossovers you'd find in sub $20K speakers to shame.

I've never built a DIY speaker before, and I think I jumped into the deep end with these speakers. The large number of drivers and fairly complex crossover make this a somewhat more challenging project than many kit speakers, but they really weren't that hard to build and Danny Ritchie from GR as well as numerous other builders on Audio Circle, are there to help.

There are obvious downsides to this system: You have to spend some time to build them unless you pay someone else to do it for you which ups the cost. Their complex front baffle shape makes them hard to veneer although some builders have veneered the side panels. I decided to just paint the whole speaker. This was by far the most time consuming part. I don't have great painting skills and have never painted anything like this, but they came out fairly nice. I think if you had another couple $K to invest, you could take the built cabinets to a cabinet shop or auto-body shop and have them professional sprayed and could get a much more professional finish.

Open baffle speakers aren't for everyone. They need a fairly large room. I have mine in a 17' x 27' room, with the front of the baffle about 6 1/2' from the front (17') wall. The two cabinet per channel design takes up a lot of space.

And probably the biggest downside is resale. Even if more people knew how good these speakers sound, finish quality is an unknown, so it's unlikely a buyer would be willing to buy them sight unseen.

But the upsides are huge. For a relatively modest investment in time and money, you get a speaker system that sounds amazing. They have the open, airy sound of magnepans with more precise imaging due to the narrow baffle. They have thunderous, fast bass that doesn't energize lateral room modes and transmits a lot less of the bass energy through the walls. They are efficient (93db/w), easy to drive, and very dynamic, with a beautifully smooth and detailed midrange and high end. Vocals - both male and female - sound amazing.

Sorry for the very lengthy post, but it's hard to stop gushing about these speakers. I've only heard a few other speakers that sounded all-around as good to me as these, and they were ~10 times the cost.
128x128jaytor
jaytor's avatar
jaytor OP
765 posts
 
These OB subs are unlike any other subs I have heard. If you've heard the bass from large magneplaners, you'll have some idea of what these sound like, but the GR Research OB subs go much deeper and perhaps with more energy than the large panels. The -3db point in my 17'x27' room is around 14Hz (with the rumble filter off) - not that there is much music that low anyway. 

They are extremely impressive on acoustic instruments like double-bass and large drums. The sound is very deep and powerful without sounding boomy. They don't seem to pressurize the room like a typical sub, but still create a lot of bass energy. Sort of like the bass that is created when a big truck goes by. 

A nice side effect of this type of bass is that it does not energize room modes as much - particularly side to side and floor to ceiling modes - so the bass is much smoother (you can achieve similar results by using 3, 4 or more separate closed-box subs at different locations in the room). Also, you can get a lot of bass energy in the room without the bass transferring through the walls to the rest of your house or your neighbors. 

As I stated in my original post, the downside is that they have to be at least a few feet from the front wall (although they can be placed directly against the side wall - firing front and back). 
optimize
164 posts
 
@jaytor 
Yes I am lucky with the placement options in my upcoming man cave.
I plan to pair those bass with the RP-600m (Waiting for a complete set of point to point cross over kit for them)

As I understand it it is a fast distinct and more "truthful" than a 2nd order conventional bas reflex arrangement.

brewmasterdon
68 posts
 

I had the opportunity to visit Danny a couple weeks back and listen to the new line forces, which were made from a composite material compared to the originals that were made from aluminum (~200lbs), they were outstanding to say the least, it is hard to describe the realism that those speakers portray without actually hearing them, I had their sound in my head for 3 years!! The new version also have a far more expensive x-over network that is truly next level with his new copper capacitors. Danny mentioned that him and I were the only two people to have heard both versions and although the cost of entry is not for everyone, if your able to hear a pair it is something that you will not soon forget!! As for the open baffle subs, I've owned duals, triples and quads, basically the more you have, the fuller the overall bass realism gets and it really depends on the size of the room as to if you overload it or not, the beauty of the system is you can have more or less at the turn of a button.


Jaytor; great write up,

bdp24; the guy in Canada is my partner Jay, quite possibly the most honest guy in audio, and you're right, Danny is a master speaker designer, as well as an all around great guy,


Cheers,


Don

sunshdw's avatar
sunshdw
256 posts
 
Man, I want to try this speaker/sub combo out sooooo bad. I emailed GR and told them about my smallish (11.5W x 14D x 8H) room and Danny's response was " Open baffle speakers like the NX-Otica are more room friendly than a set of mini-monitors." and then followed with " Any open baffle speaker must be pulled at least three feet or more out into the room." The latter answer makes me very nervous since that would put the speaker about 6' apart and about 7' from my chair making them nearly a spendy set of headphones. 

brewmasterdon
68 posts
 

Don't quote me, but I believe that Jay's NX-Otica's played flat down to around 40 with a bit of PEQing in a room that is very similar size wise so it's really about what your willing to live with sub sonically, that said, a pair of OB subs really rounds out the sound.


Don

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