[BrandonB]

After reading Hobbs's remarks about the 8 inch subs going down to 30hz. I looked up what actually goes below 30hz.  I found that very little if any music goes that low.  I also read that some explosions in movies may go below 30hz.  I don't have any open baffle subs at this moment but I have read on the forum it is good to have a sealed sub for home theater. 

[BrandonB]

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.

So are you saying the triples 12's open baffle with the triple 8's in the speaker?  That leads to another question.  How does the 8in servo subs compare to the 165BNQ woofer if they are playing up in the range that the NQ's usually play?

[dayneger]

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.
Ed

Thanks for sharing, Ed. That's an interesting thought.  Longer leads than Danny recommends, but very useful to hear that it's working for you.

Any new degree (or partial degree) of design freedom is always good news! 

[dayneger]

After reading Hobbs's remarks about the 8 inch subs going down to 30hz. I looked up what actually goes below 30hz.  I found that very little if any music goes that low.  I also read that some explosions in movies may go below 30hz.  I don't have any open baffle subs at this moment but I have read on the forum it is good to have a sealed sub for home theater.

No need to debate "is there anything to hear down there" in this particular thread if you don't mind. 

For some (lucky) people, systems with an f3 of 55 Hz or whatever are awesome and they're completely content.  For others, systems that can easily go below 30 Hz generate a much more impactful musical experience.  It's a personal thing, and unfortunately I know without a shadow of a doubt that I need deep bass reproduction in my rig.

Now, for HT it's easier to generalize--turn off the sub and half of the movie experience is gone.

[dayneger]

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.

Would you be willing to post a couple of images of your design?  I'm really glad to hear your box is solid, and thanks for posting!  I had anticipated that force cancellation of the dual-opposed drivers would be as important--or possibly more important--than the enhanced pressure differential front to back.

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?

I wish I could help you here.  I'd always assumed that the NoRez was mostly there to reduce the tendency of the H-frame enclosure to sing along off tune... which if I had a facetious streak (clearly not the case  )... from being a buzz box.

[dayneger]

Here's a slightly different formal study to continue the exploration.  In the vertical orientation like this, I'm not sure I'm liking the effect of the big gulp sub opening.  It might work on its side, though.



Since I didn't change the back, but reduced the depth of the front zone, the amp would need a little shaved off the front corners to avoid having it stick out past the sidewalls (or ditch the amp, like Ed suggested). It also needed to grow an inch or two in height.

The other consequence of the front to back compression is that I lost some of the "wing" zone.  The other versions I've shown so far have the far corner of the wing at a 10 degree angle to the baffle and about 15-16" wide.  First, is that the right dimension range for the wing? 

How much would be compromised if it were reduced to around 12.5", which is what this one has?  I'm leaning against reducing it, but it could help make the speaker smaller.

[dayneger]

What would the acoustic impact be of having the amp on the inside of the wing?

This could also bring the overall height down to the 41-42" range (which it also would be with the amps externally).

[dayneger]

Standalone subs aren't my current design intent, but in case someone finds it interesting to visualize--on the CAD journey to explore Tyson's suggestion of putting the sub part on its side I tried out what the ripole section could look like on its own.

This is 21.8" high as shown.  Most of the exterior curvy stuff could be replaced with flat panels, of course.

[Tyson]

IME, having subs facing up or toward the floor lost some physicality in the bass response.  When the woofers face you and the bass wave hits, there's more of a percussive effect that upward and downward facing subs tend to lack.  I’m not saying you shouldn’t do it but it is something to keep in mind.

[dayneger]

IME, having subs facing up or toward the floor lost some physicality in the bass response.  When the woofers face you and the bass wave hits, there's more of a percussive effect that upward and downward facing subs tend to lack.  I’m not saying you shouldn’t do it but it is something to keep in mind.

What you're suggesting makes total sense.  Although it might be visually interesting to point the woofer opening downward, it seems that some of the physical energy would get lost.

Here's another thought experiment where the ripole sub section is placed on its side (what I thought you'd meant earlier).  While the whole thing would get rather wide at 21-22" at the bottom, the speaker could be a chunky runt at like 30" high... presumably too short.  I trimmed the upper part to typical Otica flat panel proportions (at least as far as I understand them), which makes getting the amp in there a bit challenging.  Maybe it could be tucked in on the side sort of as illustrated.  For kicks, I then added 2 of the Otica woofers down low, which would put this at approximately 47" tall.  Or they could be deleted and the amp and crossover could live below the MTM section.

Definitely a little funky, but there are probably (hopefully) weirder things out there.   

[Tyson]

Instead of turning the ripole on it's side, I'd suggest turning the H-frame on it's side. 

But of all the designs you've had with the ripole, I like this last one the best (with the extra midwoofers for more bass impact).

As you can probably tell, I really like bass 

[walkern]

When I built my first GR servo sub (single 12", sealed box) I vaguely recall asking Danny if mounting the driver facing downward was okay, and if memory serves, he did not think that was advisable.  I believe his concern was that gravity would be working against the servo control (in terms of restoring the woofer cone ASAP).  Just a thought.

[dayneger]

As you can probably tell, I really like bass 

I would certainly never fault you for that!   

In your honor... introducing the Tyson Tower.  A 66" tall stack of OB goodness.  2 amps, 4x 12" drivers.  Who needs those wimpy little midwoofers when you can double down?   




In theory the upper set could also be the 8" servo drivers.  Too tall (and $) for my main room, but fun to dream about anyway.

[Tyson]

The Tyson Tower, that's pretty awesome, thanks man

I do run full NX-Oticas with bass towers, and visually they are not too bad if you stack them one in front of the other, like this:





Also, you might have better luck with a compact version of the NX-Otica if you use the NX-Studio as the top part of the speaker instead of the MTM mini-Otica.  The NX-Studio is a more natural fit on top of a pair of H-Frame subs, IMO, and should give you decent mid-bass punch because the mids are sealed.  They also extend lower (70hz vs 120hz), so integration sonically would be a snap.

[dayneger]

I do run full NX-Oticas with bass towers, and visually they are not too bad if you stack them one in front of the other.

Your system looks great!

Also, you might have better luck with a compact version of the NX-Otica if you use the NX-Studio as the top part of the speaker instead of the MTM mini-Otica.  The NX-Studio is a more natural fit on top of a pair of H-Frame subs, IMO, and should give you decent mid-bass punch because the mids are sealed.  They also extend lower (70hz vs 120hz), so integration sonically would be a snap.

That's a really interesting suggestion.  What does one lose not being OB from 70 or 100 Hz through wherever the tweeter crosses in?

[Tyson]

Your system looks great!

That's a really interesting suggestion.  What does one lose not being OB from 70 or 100 Hz through wherever the tweeter crosses in?

I heard that exact setup at Danny’s and the answer is “very little” in this case.  The NX-Studio is a minor miracle.

[Rikard Ekval]

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.

Hi
But if you use a RiPol solution (2x12” servo subs) like the picture?
It’s compact and have ports forward and backwards.
The amp on top and the rest of the Oticas as previous cad.


Lost of different versions to find on Pinterest.
 

[dayneger]

I've been wondering how much open area to the sides of the baskets needs to be retained? 

With these high excursion drivers I was concerned that if I reduced the cross-section too much by sinking in the magnets and/or trimming the angle down, that there would be noise--whistling, chuffing, whatever--past the basket and other driver features.

Here's an image showing what I was describing... what's the limit to how much the area can be reduced?



Are people using some sealant around the magnets in the ripoles like in the photo?

[dayneger]

I heard that exact setup at Danny’s and the answer is “very little” in this case.  The NX-Studio is a minor miracle.

In my mind I was thinking oh cool, lots more room to play with.  Then I looked up the dimensions... 18" H x 8.5" W x 15.5" D.     Not an implied criticism of it, just a bit of a reality check... that's not a small monitor!

On the other hand, maybe it means that a variant based on the Studio could play better closer to the wall when I can't have the speakers out where I'd like them to be?  That would also be helpful.

[nlitworld]

Yes, the NX-Studio is not a small monitor at all. About the size of a mid-sized tower pc, and weighs about 35lbs each when they're done. Jay's flatpacks are slightly shorter height and slightly deeper (17"hx16"d) but they are still quite good sized. The speaker does play very well up against the walls but obviously sacrifices some soundstage depth in doing so. Having some markings on the floor for intensive listening position and back against the wall for casual listening would be a very easy thing to do.