[jmimac351]

I'm wondering if anyone has done any measurement of subwoofer spectral decay (speed), or whether that's even a thing to measure? 

Issue:
I own a pair of SVS SB16-Ultra subwoofers.  They are in a large room and are capable of producing BIG bass.  I've been able to blend them, by ear, to various main speakers... and they please me.  Their quality appears to be very high... I love the app for tuning / selecting different preset settings, etc.  The app allows full DSP control over a wide range. Again... I've done it by ear - no measurement, yet.  As I am considering some Open Baffle speakers, specifically the (mentioned) NX-Otica speaker with Triple-8" OB Servo Sub drivers built into the speaker... I'm wondering about the subs I currently own, and whether they are "good enough" for the very low end fill that I would do with those Otica, or any other OB speaker.  It's made we wonder... "How good are these subs, really, and can I measure it?"  The obvious comparison is to a servo-based sub unit. With those NX-Otica with triple 8" OB servo subs, I'm probably just blending in a bit under 30Hz to fill things out... and I may not even miss them if I didn't bother doing that. 

Other possible speaker candidates include NX-Treme and current NX-Otica. I'm considering whether I "need" to address my current subs for pairing with any of these OB speaker.  I am not excited about the thought of "needing" 2 towers of 3 or 4 OB subs, given my room size, and the feedback I've read from others about the OB sub / room size question.  What's a bit more likely is that I may consider replacing my current subs with sealed servo units... but if it's not OB, is it worth even going to that expense / trouble?  I have not experienced the difference with the servo stuff, so I am aware that I probably don't know what I don't know. What I don't want to happen is going thru that trouble and ending up at "Well... those SVS subs were really good after all... I should have just kept them." The driver in the SVS SB16-Ultra appears to be pretty unique.  Is is great? No idea. I can't test drive this idea and I want to try and make the call with some actual measurement included into the decision.

So, has anyone done any measurement, other than just frequency / room response?  Any other thoughts / experience is certainly welcome. 

[Danny Richie]

One thing that you can use as a guide is to look at moving mass. Simple physics is the more mass put in motion, the harder and longer it takes to settle.

Add servo control and stopping or settling time gets cut significantly.

Also, once you go full open baffle bass, it is hard to go back. By comparison the boxed design pressurizes the room and causes a lot more room boom, while the open baffle bass can hit hard and then there is no trailing boom. It just stops.

[jmimac351]

I'll post a drawing of the room space we're talking about... maybe that will help give an idea of what's viable / needed.

[Tyson]

If it's a combo HT/Music setup I'd use OB subs for the music setup and not use the box subs at all.  With HT I'd use the box sub for the effects channel (it's fine for that).

If it's just a music setup with no HT, then I'd just get the OB subs and sell the box sub.

[Early B.]

If you want the best sound quality, it's OB servo subs. End of story. Those SVS subs will sound boomy comparatively, no matter how much DSP control you have over them. Sell the SVS subs and use the proceeds to invest in OB servo subs.

[rinzzlr]

I’m still on my journey but I can provide some feedback now and more later (soon). I had SB2000’s, 13Ultra’s, SB16’s and PB16’s in my room. All in dual configuration. Currently I have dual Rythmik G25HP’s. I am about to be finished building my Double Troubles so that’s what I mean I can provide more feedback later. My plan is to keep the G25HP’s and the Double Troubles - though yet to be seen when I’ll be using them at the same time. I’m going to attempt to integrate them all but likely will be DT for music and DT+G25HP’s for movies.

Having owned all the stated above I would recommend getting into servo controlled subwoofers vs the SB16’s. As long as you remain in a dual subwoofer configuration when you hear how much more controlled the bass is you won’t miss the SB-16’s sound quality (though you may miss the app).  I don’t have measurements anymore unfortunately but it was big increase in everything I wanted going to dual Rythmiks. My room is probably as small or smaller than yours at 13x11x9 and the major issue with all of the subs even the SB2000’s is the room boom that Danny mentioned. I’ve had to add a lot of bass trapping in the room to reduce the ringing. Rythmiks will get you way closer in taming that room boom because of the integration and damping options available on the Rythmik amps. If waiting for the 8” Otica’s I would probably just plan for those and grab 2x 12” or 2x 15” sealed Rythmiks for the LFE stuff in movies if you want more infrasonics. I say this not having heard DT’s in my space, I’ll chime back in when my DTs are running and see how they do in some movie LFE in my room.

I uploaded a quick video of the first blend attempt I tried with my NX-Otica’s and G25HP’s. I have them high damped at 14hz and crossed over at 55hz and had to turn them way down because they easily over power the clean bass response of the NX-Otica’s. No measurements yet, this was literally just quickly getting them to blend by ear and placement is still up in the air. It sounds really great and questioning if I even needed the DT’s.. we’ll see soon.

https://youtu.be/XlK5iUQt0pU?si=6FbasgAaAzFau1b3

[WGH]

Also, once you go full open baffle bass, it is hard to go back. By comparison the boxed design pressurizes the room and causes a lot more room boom, while the open baffle bass can hit hard and then there is no trailing boom. It just stops.

Tucson Audiophiles has four members that use servo subs including a pair of open baffle and pairs of sealed servo subs. I have heard the subs many times. My friends are also gentle souls that listen at moderate levels so I have never heard their Rythmik servo subs hit hard. They have also learned to never hand me the remote, I see panic in their eyes as I crank the volume.

From my experience REL subs hit harder and pressurize a room better at moderate volumes, the guys in our group all agree Rythmik bass feels softer by design. Admittedly nobody in our group has towers of open baffle subs in a small or moderate size room, the living rooms are shared with their wives and not designed for ultimate sound quality.

One of the guys in our group has two 12" sealed Rythmik servo subs made by Salk Sound to match his Joseph Audio Perspective speakers. The room is big with a high ceiling and the bass is lost, no hard hitting pressurizing here. No way would his wife let him put two 6' tall open baffle towers in their elegant room.


The best advice is to keep the SVS SB16-Ultra subs. You seem to like them so they will be OK for your needs. I would guess you have a budget and if dual tower subs do not excite you then a plan to upgrade to a faster box sub would completely destroy the budget.

I recently bought a REL G1 MkII sub to replace a REL Gibraltar G2. Both subs are fast, I first heard the G2 with a pair of Magnepan 3.7 speakers, integration was seamless with no hint of trailing boom. If the G2 could keep up with the Maggies I knew I had to have one. The G2 is perfect for music but the 10" driver can reach it's limits when used in a home theater system like I have, hence the upgrade to the G1 MkII which has no limits. My room is 326 sq. ft. and the G1 MkII doesn't have any trailing boom either.

The G1 MkII has a 12-inch, long throw (2"), carbon fiber driver, Class-AB 600 Watt amp, throughput time from input to output is four milliseconds, a LED display calibrated in 1 dB steps and a remote.

"REL opted not to include “DSP” or Digital Signal Processing which many subs use specifically for digital room correction. Supposedly, after experimenting with both digital and analog filters, REL decided the extra time for a computer to analyze and apply correction algorithms was not worth it – both from a performance and price standpoint. REL estimates digital correction would add somewhere between five and thirty milliseconds to the signal throughput. Their analog filter’s throughput time is four milliseconds total. REL’s position is they will take overall speed any day."
https://futureaudiophile.com/rel-acoustics-g1-mkii-subwoofer-reviewed/


Even though the SVS SB16-Ultra has more power on paper, Audioholics found that:
"One feature that can be discerned right away is that the SB16-Ultra driver has more to give at 31.5 Hz and up, were the amplifier able to give more power. Above 31.5 Hz, this driver is taking all the juice that the 1,500 watt amp can give and is asking for more. Below 31.5 Hz, the driver can be pushed to its limits..."
Although overall they liked it.
https://www.audioholics.com/subwoofer-reviews/svs-sb16-ultra


Oh yea, that budget thing I mentioned. A pair of REL G1 MkII subs will set you back $8790 + tax.
https://upscaleaudio.com/products/rel-g1-mk-ii-reference-subwoofer-piano-black

That may sound like a lot of money but other options cost way more. The new REL No.31 still has a 12" driver but is also bigger and badder at $7000 each. And if you really want to stay with a 15" driver the REL No.32 are $10,000 each.

I recently posted a REL G1 MkII review
https://www.audiocircle.com/index.php?topic=187300.0


Boy howdy, keeping the SVS sub is looking real sweet right about now.

[Early B.]

Tucson Audiophiles has four members that use servo subs including a pair of open baffle and pairs of sealed servo subs. I have heard the subs many times. My friends are also gentle souls that listen at moderate levels so I have never heard their Rythmik servo subs hit hard. They have also learned to never hand me the remote, I see panic in their eyes as I crank the volume.

One of the drawbacks of servo subs, especially open baffle, is you need more of them - 4 or 6 compared to a single 15" sealed sub IF you want hard-hitting bass for music. The beauty of OB servo technology, in particular, is a more natural sound. "Hard-hitting bass" often has an unnatural sound -- perhaps too much of a good thing. That's when the bass is usually drowning out everything else. It sounds impressive initially, but it ain't musical. Sure, the servo subs can be dialed in to hit hard, but why would you want them to? That's why those four "gentle souls" in Tucson with servo subs listen at moderate levels. If you want to crank up their systems, they would need to change the settings on their subs and they're not gonna do that.   

[Tyson]

It is exactly the sound pressurizing affect with box subs that I don't like.  OB subs are cleaner and faster and don't pressurize the room. 

But, I also realize not everyone feels like I do.  Many people love box bass BECAUSE it pressurizes the room so well.  The bloat and overhang don't bother them as long as they can feel the bass. If you have good EQ and some big bass traps in the corners, you can go a long way toward taming the room, even with box subs.  And if you can manage to get 3 or more subs into your room, you can implement a swarm approach which usually gets you the smoothest bass response possible with box subs.  My buddy Mike does this in his setup and it sounds great. 

Having said all that, I still prefer OB bass.  Especially for music.  And yes, I do listen to bass heavy music some of the time, EDM and hip hop in particular are pretty demanding down low.  But even some modern pop acts have pretty intense bass, like Billy Eilish's last 2 albums.

[WGH]

If a room is consistently pressurized with a box sub then you are doing it all wrong, or you have the wrong sub.

Take the NX-Studio for example, the frequency response is 70Hz-20KHz. The REL G1 MkII I have mentioned would be a horrible sub to use with that speaker, it does not go gracefully up to 70 Hz, it is a sub-bass sub designed to go from mid-30's on down.

A guy in our group made a pair of speakers using two 4.5" SEAS Excel mid-range drivers and a SEAS Excel tweeter with the gold ring in a D'Appolito configuration. The crossover has exotic caps and is in a box that is the same size as the speakers. I have started calling the speakers "Little Screamers" because they are very analytical with no bass. I don't know how low the speakers actually go, I can guess maybe 80 Hz. The Screamers are paired with two 12" down firing servo subs in heavy custom cabinets. The room has plenty of low bass but there is a hole in the upper bass, lower midrange that no amount of tweaking can fix, everyone in our group agrees too. Once again the wrong subs for these speakers although the owner loves the combo.


One thing I have noticed in sub reviews is they never talk about space. But space is the first thing mentioned in a REL review, people write that the room opens up, performers have air around them. Turn off a REL sub and the soundfield collapses. Space is something I rarely hear in other systems. Do other subs create space or just the low notes?


Anyone coming down Tucson way this winter send me a PM and I'll pick up a bottle of Del Bac Single Malt Whiskey and play you some music.

[Tyson]

If a room is consistently pressurized with a box sub then you are doing it all wrong, or you have the wrong sub.

Take the NX-Studio for example, the frequency response is 70Hz-20KHz. The REL G1 MkII I have mentioned would be a horrible sub to use with that speaker, it does not go gracefully up to 70 Hz, it is a sub-bass sub designed to go from mid-30's on down.

A guy in our group made a pair of speakers using two 4.5" SEAS Excel mid-range drivers and a SEAS Excel tweeter with the gold ring in a D'Appolito configuration. The crossover has exotic caps and is in a box that is the same size as the speakers. I have started calling the speakers "Little Screamers" because they are very analytical with no bass. I don't know how low the speakers actually go, I can guess maybe 80 Hz. The Screamers are paired with two 12" down firing servo subs in heavy custom cabinets. The room has plenty of low bass but there is a hole in the upper bass, lower midrange that no amount of tweaking can fix, everyone in our group agrees too. Once again the wrong subs for these speakers although the owner loves the combo.


One thing I have noticed in sub reviews is they never talk about space. But space is the first thing mentioned in a REL review, people write that the room opens up, performers have air around them. Turn off a REL sub and the soundfield collapses. Space is something I rarely hear in other systems. Do other subs create space or just the low notes?


Anyone coming down Tucson way this winter send me a PM and I'll pick up a bottle of Del Bac Single Malt Whiskey and play you some music.

You are right, and I think I wasn't being clear when I was talking about the subs pressurizing the room.  What I meant is that the radiation patterns for box subs are different than the radiation patterns for OB subs, resulting in different room interactions.

A box sub radiates sound like a pulsing sphere (360 degrees).  This means that all 3 room modes are excited, which is floor-to-ceiling and side-to-side and front-to-back.  When I say box bass is boomy, it's not because the sub itself is boomy, but rather the way it interacts with the room excites the greatest number of room modes.  And that's true regardless of the quality of the sub itself. 

OB subs on the other hand, radiate in a figure 8 pattern.  So side-to-side bass nodes are avoided, and I find that floor-to-ceiling are also minimized.  OB subs still excite front-to-back modes, so you still have some 'room boom' with the OB subs but it's WAY less than a box sub. 

[Early B.]

One thing I have noticed in sub reviews is they never talk about space. But space is the first thing mentioned in a REL review, people write that the room opens up, performers have air around them. Turn off a REL sub and the soundfield collapses. Space is something I rarely hear in other systems. Do other subs create space or just the low notes?

"Space" is sort of the whole selling point for OB servo subs.

I think the main reason space isn't mentioned is marketing. Most consumers equate subwoofers with heart-pounding bass, so that's what you sell them. A good-sounding sub is essential for broadening the soundstage, kicking up the dynamics, adding grunt to male vocals, and improving the highs. So when some audiophiles choose not to use a sub, even with floorstanders, they're leaving a lot of meat on the bone.

[VinceT]

I have an old pair of ACI Titans, down firing sealed subs. They don't load or make the room boomy at all and really pair nicely with GR speakers, they are not as good as OB servos; but for a conventional sub sealed is the way to go IMHO

[AlexH]

An off topic reply. My first set of DIY speakers a set of ACI SR2's. I loved those speakers. Best speakers I ever built, until the next set.   No seriously they were very nice sounding. 
Thanks for the memories.

[mkane]

Anyone coming down Tucson way this winter send me a PM and I'll pick up a bottle of Del Bac Single Malt Whiskey and play you some music.

have a favorite?

[WGH]

have a favorite?

The Del Bac Classic is good at a fair price, not of big fan of the mesquite smoked Dorado but then not a big Scotch drinker. Some of the Distillers Cut are tasty but at 103 proof have to be cut with a little water in order to bloom.

KXCI, our local independent radio station celebrated their 40th anniversary last week. In honor of the event, Steve Paul, Del Bac's owner put together a special blend.

The Private Barrel is now my favorite. I don't know if or where it is sold, Plaza Liquors is a couple blocks from my house usually gets a few bottles of Del Bac's extra special blends. Del Bac was selling bottles at the KXCI anniversary party at Che's Lounge for $100 each. I didn't buy one because it would be gone in a week, a few drinks with friends and it would become an empty bottle.

Alice and I did have a shot each at the bar but they were big pours, closer to two ounces. This is what the unopened bottle looked like after the bartender poured us 2 drinks. We agreed it is excellent.

[jmimac351]

Thanks for the all of the feedback!!! 

Here's the room... lots of volume.  Speakers can easily be placed along the front wall with 3' from front baffle to wall.  If I put the speakers on "transfer rollers / casters" on the speakers I could slide them out further, if I wanted to.  This same wall had Magnepan 3.7i speakers, without any front wall treatment. 

[Tyson]

For music, your room will benefit enormously from OB speakers.  Your room is exactly like my last 2 music rooms.  Open on one side and closed off on the other.  IME, box speakers will always sound unbalanced because the right speaker is in a different acoustic space than the left speaker.  I tried for years, rotating among different box speakers as well as spending a ton of money on sophisticated EQ and lots of acoustic treatment and nothing worked. 

Then I tried OB speakers and they solved the issue immediately, no EQ or giant bass traps needed.  I was astonished.  And happy!

[jmimac351]

For music, your room will benefit enormously from OB speakers.  Your room is exactly like my last 2 music rooms.  Open on one side and closed off on the other.  IME, box speakers will always sound unbalanced because the right speaker is in a different acoustic space than the left speaker.  I tried for years, rotating among different box speakers as well as spending a ton of money on sophisticated EQ and lots of acoustic treatment and nothing worked. 

Then I tried OB speakers and they solved the issue immediately, no EQ or giant bass traps needed.  I was astonished.  And happy!

Good to know, thank you!

[jmimac351]

Here would be the "out of the way" placement for one of the subs... I can go taller, for sure.  I suppose a Double cabinet could be on transfer rollers as well, or how would an OB sub sound in this spot?

NX-Treme will also fit vertically... no problem.  You can see the scale relative to Magnepan 3.7i.  I'm married to a Saint... I can treat the front wall behind an OB speaker.