[wgraft5]

But we all know a GR cabinet will likely be a superior design, and hopefully a slight bit taller than the Rhythmik design. Pop some isolation feet between the two and BAM you got yourself a party.

It's a timing issue, I will be ready to purchase in a few months. It sounds like a sealed 8" sub is not in the works. If one was being developed I would gladly a make deposit or pre order.  I do not want OB subs because of the cost and I like the sound of a boxed sub and the ease of set up.   

[dayneger]

We do currently have a lot of the 8" servo subs in stock for this model.

Thanks, Danny.

- Could one amp drive 4 of these 8" servo sub drivers?

- Any thoughts on the ripole-like arrangements in the CAD studies above?

[Hobbsmeerkat]

Thanks, Danny.

- Could one amp drive 4 of these 8" servo sub drivers?

- Any thoughts on the ripole-like arrangements in the CAD studies above?

Most amps can only drive up to 3 woofers.
You would need the HX800 to drive 4 or 6 8" subs, same as with the 12" subs

[Danny Richie]

Thanks, Danny.

- Could one amp drive 4 of these 8" servo sub drivers?

- Any thoughts on the ripole-like arrangements in the CAD studies above?

The Ripole arrangement can easily become a buzz box do to the larger unbraced panels at the ends and the uneven output curves. I would not recommend it over an H or U shaped design.

[dayneger]

2 more thought experiments in one file here, both under the notion of "carve".

-  First, what if the majority of the extra material/air were removed from the subwoofer zone?  The front opening could be that simple, or a localized feature added around the opening if needed for whatever reason.

-  Second, would the MTM section benefit from shaving away more of the baffle, or does it not really matter?  Or matters so little that the complication wouldn't be worth it? (not super DIY friendly as shown)

I'm not exactly in love with the look of this hacked version here, but with some thought I could probably clean it up a little.  I'd probably not remove so much from the sub section so it doesn't feel so top heavy, and maybe add an inch or two.  I'm finding that big wing beside the MTM challenging to integrate gracefully.

Images are first with the tangents off, then on in the comparison file.

[dayneger]

The Ripole arrangement can easily become a buzz box due to the larger unbraced panels at the ends and the uneven output curves. I would not recommend it over an H or U shaped design.

The buzz box concern means that it would be important to get the design right.  Point taken, and it makes sense as a general rule as well.

To be clearer about the perspective/goals, I'm not targeting (or expecting) superior performance to the H or U-shaped designs.  Rather, I'm hoping to get within, say, 80% of their performance, in a compact and visually clean form factor that could be acceptable to my family right in the middle of our dominant living space. 

What works for my context is unquestionably a subjective personal evaluation... but it's no less real to me as a consequence!    However, I'm willing to tackle the required design and construction issues if the fundamental approach is sound. 

Could a properly designed and implemented ripole servo sub analogous to what's shown get within striking distance of the H-frames?

[ebag4]

I built a single footprint version of the Otica MTM and H frame subs a few years ago.  They still serve me well.  There is a build thread under my user name on Danny’s circle if there is any interest.  Good luck with the build!







Best,
Ed

[mick wolfe]

Beautiful job. If it sounds as good as it looks, your speaker search is over.

[2bigears]

  that is great work , holy moly.  I would love to hear those and I bet my pen would be writing a note to buy them shortly after a tune or two.   That cross-over is unreal. Wowwww.  Fan-tab work.   

[g3rain1]

Isn't the dielectric effect a concern here?

[dayneger]

No question a lot of love and skill went into those speakers, Ed! Definitely inspiring to see.

My definition of single footprint includes the amps on that footprint--I really don't want extra amp boxes kicking around the floor, and I've read that the amp leads unfortunately need to be quite short. And those amps are not exactly petite.

For our context it comes back to size, scale and visual impact. That's why I'm exploring whether something like the one on the right could work, since the one on the left isn't going to fly.  That's not a knock on anyone else, of course. Our needs are all different.

[dayneger]

You would need the HX800 to drive 4 or 6 8" subs, same as with the 12" subs

Ah, I see.  I didn't find an OB version of the HX800, nor the ability to control the output level and crossover frequency separately for the 2 outputs. 

It had occurred to, say, drive one pair of 8s lower and the second higher, but that would apparently require double the amp bulk and expense to achieve.

So, maybe I don't need that missing midbass the full NX-Otica apparently offers with the extra 8 woofers.

What XO frequencies are used for the NX drivers in MTM config vs full config?  Or are they always crossed at 150 Hz and the dual subs are driven to 150 Hz rather than, what, 80 Hz with the full Oticas?

[ebag4]

My definition of single footprint includes the amps on that footprint--I really don't want extra amp boxes kicking around the floor, and I've read that the amp leads unfortunately need to be quite short. And those amps are not exactly petite.

Understood, I had a similar issue, to keep from having separate amp boxes I built my amps into the ends of my rack.  My servo leads are about 6’ each, I have not experienced an issue.  With the rack at about 3’ wide, that allows me to locate the speakers far enough apart to meet my needs.




If I were to do it again I would change a few things such as having the servo connections come from the back of the rack and having the front sides come out further to block the profile of the amps from my sight line.


Best of luck with your build.
Ed

[ebag4]

Isn't the dielectric effect a concern here?

The spacing of the inductors is great enough to keep the fact they are in the same plane from being an issue.  I ran this by Danny during the build and he didn’t see a problem.

Hard to tell from the pic but the size of the area the crossover is located is equivalent to the base of the Otica MTM.


Best,
Ed

[ebag4]

Duplicate

[77SunsetStrip]

The Ripole arrangement can easily become a buzz box do to the larger unbraced panels at the ends and the uneven output curves. I would not recommend it over an H or U shaped design.

Am I correct you are referring to the OP proposed design becoming a buzz box?  My Ripole experiment is a very solid box with no buzz.  Much less room mode excitation.  Much, Much better than previous sealed Sub. 

Curious about damping material with any style of open baffle bass enclosure.  The GR Research H frame recommended construction includes No Rez.  Is that exclusively to control enclosure resonance?  Does damping material change the FR curve or free air resonance of an open baffle bass system?   

[BrandonB]

I'll just throw this out here, I think GR is working on a single cabinet design for the NX-Otica already.  Hobbs posted this a little while back:

So I asked this question in another post but didn't really understand.  How will this speaker sound compared to the otica and two 12in open baffle subs?  I would think that the 8in. subs will cross at a higher point being smaller but will they go down as low as the 12 in subs?

[Hobbsmeerkat]

Very similar if not identical.
The natural roll-off of the M165NQ is around 120Hz.
The main difference will be low end extension. The 12" can hit into the teens, the 8" will be limited to about 30Hz to prevent over excursion.

[dayneger]

Very similar if not identical.
The natural roll-off of the M165NQ is around 120Hz.
The main difference will be low end extension. The 12" can hit into the teens, the 8" will be limited to about 30Hz to prevent over excursion.

That's interesting, I guess I'd assumed that particularly with the 8s, you'd take the load off the NQs at a higher frequency.  I'm also not a speaker designer. 

Given the low bass and venue cues I'd like to have, good to know that I'd better stick with the 12s.

[Tyson]

Another option if you want to keep the H frame and the 12 inch woofers is to orient them side by side instead of on top of each other.  Basically like laying them down on their sides.