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.
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Showing 3 responses by magic44ken

@bdp24: Thanks for the sub suggestion. I will put it in my wishlist. Now I need to email Danny to see if anyone close to San Francisco, California for demo.
What are the sound different between the NX-OTICA and Super Mini since some use a woofer for the mid and Bass while the other uses planar? I'm debating either than NX-OTICA MTM or Super Image if it works in my room.

My room is not symmetrical. The left side mostly window with a fireplace on corner sticking out. On the right is an opening to the dinning room. Will open baffle works in this case?
Thanks Jaytor and brewmasterdon for the detail reply. I'm currently researching for a list of potential speakers to upgrade by the end of the year.

I'm for better image, so Super Mini definitely in my top 5 list. I'm hoping the bass module will be smaller than 15". Do you know if there will be 8"servo sub? I'm not looing for full range. More under 40Hz or so fine with me.

I just read Danny's reply to my questions in the AudioCircle forum. He confirm the minimum distance is from the front baffle to the front wall. In my living room I have a max length of 3 feet because i have an open right wall to the kitchen. So I hope the soundstage will siund decent.

May I ask what is the dimension for sub section that you submit to Danny? Will he offer an active version of the bass module?