[Tyson]

To answer question #4, as you know, OB bass gets you best real world performance in a room.  OB mids and highs get you best imaging and soundstaging in a room.  However, OB speakers present sound in a different way than box speakers.  Compared to an OB, box speakers have very little depth.  So with an OB, a LOT more of the space behind the speakers "fill in" and have acoustic events happening behind the speakers, and not just in front of the speakers. 

In addition, mids lose their boxy coloration when you go OB.  Box speakers tend to make the mids sound chesty and like everyone has a slight cold.  OB speakers are free of that particular coloration. 

[Sonicjoy]

And of course they avoid the bass boom that box speakers almost all generate in rooms. I have found (like mentioned by others) that they avoid most of the room interaction problems. The bass is the best I have ever heard.

My speakers are Emerald Physics EP 2.7's that Danny upgraded the crossovers on. I will never go back to box speakers after owning these. Just Awesome!

[dayneger]

The amps are "plate style"  because they were designed as plate amps. For many sub configurations that works and is the easiest, most economical path. I'll bet they could be configured in some other form but I suspect the potential market determines that. It's a small part of a small market. From the perspective of product marketing only, I'd venture adding a boxed variant wouldn't increase sales much if at all, but would increase cost of production and also double inventory requirements.

Absolutely agree, and wasn't intending to suggest Rythmik should offer a different form factor.  I've developed products in roles across the "mechanical engineering--industrial design--product management--brand strategy--brand experience" spectrum for 25 years and am painfully aware of the choices that have to be made!  Plate amps work great for what they were designed for.

It's just a bit of a head scratcher with open baffle subs... they're open, so where do you put the darn amps?  If distance weren't an issue I'd just stick them on the rack with the rest of the electronics, but apparently the lead lengths shouldn't get too long (not sure why).  At the moment I'm considering burying it in the base, mounted on a short slide/drawer for when you need to access the panel.  Maybe.

Concerning concrete as you casting medium. I'm no acoustic engineer, but experience tells me concrete, especially with the size of aggregate in typical sack mix, rings. Tap a concrete stepping stone not in contact with the earth with a hammer..."tink"!. Tap the same mass made from MDF or plywood and..."thud". I'm guessing  at the effect of such a structure on sound reproduction, but there would be reasons to think resonance would be a factor to contend with.

Thanks for the comments about concrete!  It's curious, I've read everything from "it rings" to "it's one of the most inert materials around."  Others have pointed out that, at least for subs (usually meaning box subs) stiffness is the goal, not resonance, due to the long wavelengths.  So if concrete's fairly non-resonant, that attribute would actually be more interesting for higher frequencies.  Concrete L-panel anyone?   

I'm not totally sold on concrete, but it's certainly fun to learn more about it and think through what the sculptural freedom could mean.  Flat panels are major imagination limiters.

...OB mids and highs get you best imaging and soundstaging in a room.   

That definitely has my attention!  Why then are OB mids and highs not more popular?  Does closed convey some other kind of advantage?

[Hobbsmeerkat]

OB mids/highs arent more popular because they need space to breathe, often 3+ feet at an absolute minimum. And many people dont have that amount of space to work with without having to move them around every time you want to listen to them.

The NX studio can get away with close-wall placement it by redirecting the rear wave upwards, and softening it's reflection thanks to the norez, allowing it to still sound spacious, even with the sealed woofer.

[Tyson]

That definitely has my attention!  Why then are OB mids and highs not more popular?  Does closed convey some other kind of advantage?

Because most people are sheep and can't get their heads around alternate approaches, even when those alternate approaches are better. 

[sunnydaze]

Concerning concrete as you casting medium. I'm no acoustic engineer, but experience tells me concrete, especially with the size of aggregate in typical sack mix, rings. Tap a concrete stepping stone not in contact with the earth with a hammer..."tink"!. Tap the same mass made from MDF or plywood and..."thud". I'm guessing  at the effect of such a structure on sound reproduction, but there would be reasons to think resonance would be a factor to contend with.

Is that really the test?       

I'm surely no authority but I know this......

Years ago I owned a pair of Gallo Nucleus Reference 2's and being aluminum spheres I guarantee there was mucho mucho "tink-tinking" going on when you tapped em with a hammer.   No idea what kindof resonance existed when they played, but they sounded fantastic.  And anyone I spoke to that heard or owned them felt the same.

[Sonicjoy]

Because most people are sheep and can't get their heads around alternate approaches, even when those alternate approaches are better.

LOL! So true. I see people disregard things all the time just because they are not in the main stream.

[Hobbsmeerkat]

LOL! So true. I see people disregard things all the time just because they are not in the main stream.

Cables, DACs, amps, etc. If you never look at your options or experiment with them, you'll never know. But also many people just buy based on brand recognition.. Bose, Beats, Klipsch, Apple, Intel, ASUS, Macallan, BMW, etc. Etc.
Marketing is a v powerful tool, & can make even the most mediocre products sell faster than you can blink.

And depending on what you know beforehand, you might be impressed, or you might be disappointed.

Sometimes a lack of product success is just as much about it's WAF, as it is marketing, or lack thereof.

Danny & Ron will praise OB day & night, but Paul McGowen prefers sealed/ported Dipoles.

People in the 80s largely rejected Laserdisc due to a lack of understanding, despite being a vastly superior format to VHS/Betamax. It wasnt until the late 90s when DVDs caught on cuz by then, people already understood the conveniences of CDs. (Rent a movie & NOT need to rewind it?! Where do i sign up??)

[Peter J]

Is that really the test?       

I'm surely no authority but I know this......

Years ago I owned a pair of Gallo Nucleus Reference 2's and being aluminum spheres I guarantee there was mucho mucho "tink-tinking" going on when you tapped em with a hammer.   No idea what kindof resonance existed when they played, but they sounded fantastic.  And anyone I spoke to that heard or owned them felt the same.

Sunny, I didn't assert it was THE test, but it is a rudimentary demonstration of resonant frequency difference between materials.

 To your example; If  I remember right, Gallo's claim to fame was spherical housings. As I understand it, this was thought to mitigate any internal standing waves created from parallel sides. I'd venture a guess there was some damping inside,  which would change resonant frequency of the aluminum housing, but I've only seen them in photos.

 The conversation I was replying to concerned subwoofers, which would excite lower frequencies than the Gallos were ever designed to produce. As stated, I don't know the effect on loudspeakers, but it seems to me the assumption that concrete would make a good housing is based on a notion that's not necessarily factual.

[opnly bafld]

Try the knuckle test on concrete. 
I have been in cars that play bass notes above 150 dBs, never felt like a hammer hitting me. 

 

[mlundy57]

Another potential reason for lack of popularity is that not all OB designs are created equal. Add to that the tendency for people to think they are, if their first experience with OB is with poor design and or poor setup with resulting poor performance, the tendency is to say all OB is bad.

[Hobbsmeerkat]

I remember reading a story about a guy who was selling his Maggies cuz he didn't like the way they sounded. Then when someone came by to listen to them, the buyer asked to pull them away from the wall to demo them, and the owner finally heard what he was missing the whole time, and was now upset at himself that we was selling them. lmao

[dayneger]

I remember reading a story about a guy who was selling his Maggies cuz he didn't like the way they sounded. Then when someone came by to listen to them, the buyer asked to pull them away from the wall to demo them...

I actually had this exact same kind of experience, although in this case I pulled a friend's 'stats away from the wall.  He was also rather chagrined (and also delighted).

Regarding resonance and material choice, there's also the combination of said material and the form/shape that material is in.  And... if a given object rings at a high pitch, that might indicate that it'd be completely dead to low frequencies?  Anyway, if I had lots of spare time and funds it would be cool to do some scientific experimentation.  Big if, though.  All things said, I've seen a couple of very nicely executed concrete designs that are quite striking (not that I have any pretense of matching those levels, just nice to see).

Sunny, thanks for sharing the example of the Gallo Reference 2s!  I've never had the potential pleasure of listening to anything from Gallo's work but often have read things that made me expect I'd like them.  Inspired by your post, I did a quick scan about what others said about them.  A nice sound bite in a customer review:

"One thing is for sure, practically every box speaker sounds like a damn box after listening to the Gallos."

Without knowing the Gallos, one might expect them to be OB rather than a "non-box-based enclosure" speaker.

As I said in my first post, I kind of "intuit" that OBs should do some things more naturally and not sound like little boxes playing music.  For the lowest frequencies/longest wavelengths this thread has definitely helped me understand the dipole interaction with normal rooms better--the long wavelengths turn almost every other enclosure style into a monopole.  However, how do OBs compare to the strongest non-box speaker designs across mids and highs?

[Tyson]

Box speakers, no matter how good the box, cannot portray soundstage depth like a good OB speaker can.  Just the nature of the design.

[dayneger]

I've been searching around the forum for comparisons between the NX-Otica plus subs vs the Otica MTM on subs and it's a bit hard to imagine what the difference is.... what exactly those extra 4 drivers per side bring.  A little more visceral impact in the mid to upper bass?

Just trying to understand what happens given that those twin dual servo subs should be pretty competent!

Or conversely... could the impact of those 4 per side be replaced by a single 8" OB servo sub mounted under the MTM (assuming that I could find a pair of drivers)?

[jn316]

https://www.audiocircle.com/index.php?topic=153391.0

[dayneger]

Perfect, thanks!  I like your line of questioning. 

Not sure how I missed that one, it was in my search results but I managed to click on 30 other possible threads and jumped right over the most pertinent one. 

[jn316]

Decisions, decisions. 

[mlundy57]

The NX-Otica with triple servo subs was the original design. The MTM/dual servo sub version came about later for the sole purpose of getting as close to the sound of the NX-Otica's/triple subs as possible in a room that is too small for the full 'Oticas/triple subs. From the beginning the MTM/dual subs was a compromised design compared to the NX-Oticas/ triple subs for a specific application.

This in no way means the MTM/dual sub is flawed, it just doesn't give you as much as the 'Otica/triple four tower combo. There are two ways you can look at the MTM/dual sub version 1) as a scaled down NX-Otica/triple sub combo and 2) as a Super 7 with different midrange drivers and I doubt you will be able to find anybody who would even consider describing the Super 7 as flawed.

[Hobbsmeerkat]

Yeah the Otica MTM is a compromise in size.
But from my estimation very little is lost, aside from maybe imaging in the bass region along with some scale.

But where space is tight, I'd imagine the trade off is worth it.