[LewinskiH01]

Hello!

I wanted to ask experienced users about this in light of might system/situation: I run a 4-way active system with dipole speakers including one 18" naked (no baffle) midbass per side from 65 to 275Hz, and two Rythmik F12 sealed subs (in heavy DIY boxes). My room has a significant mode at 35Hz (5m x 5m...) despite significant room treatments including Helmholtz resonators, so also see a dip at 70Hz.

I'm more than sold on the articulation delivered by dipole bass. However I'm not sure that articulation is significant below 70Hz and if it's worth switching to OB subs or sticking with sealed and add a couple more to get a distributed bass array. FWIW, my Rythmiks have the A370PEQ plate amp, same used for GR Research OB subs.

Subs placement is also of consideration. Right now both are stuck into the front corners, and if adding a couple more they would be on the back wall, about 1/3 of the width each. If going with OB subs I might get away with 3 feet spacing from the front wall, but not more.

Would you recommend going OB or expanding sealed?

Thank you!

[sledwards]

LewinskiH01:

I followed a similar path to achieving the bass response I desired. I initially built NX-Oticas with 2- triple OB subs (see photos). The subs are flanking the mains and are about 3 feet out of the corners. I love the sound of OB subs... speed and articulation as you mentioned. However, what I was missing was the "punch in the gut" as many call it.  I decided to supplement the OB subs with 2, 15-in sealed Power Sound Audio subs.  They are positioned on the sidewalls, slightly behind the MLP.  I use a MiniDSP 4x10 to actively control all 4 subs. After experimenting with position of the two sealed subs and setting appropriate crossover frequencies and amplitudes, I was able to achieve my goal.  Feel free to PM me to discuss the details if you wish.

Steve

[hawkeyejw]

Steve that setup looks amazing. Do your PSA subs have the new B&C woofers? I have them on my list for theater upgrades in a few years. What frequency do you cross to them from the OB subs?

[sledwards]

Hawkeyejw:

Thank you for the compliment. No, purchased my subs before the change. I have attached 2 plots. First one is subs after some PEQ and xover selection. Settings were imported into MiniDSP from REW output. Cross over frequencies worked out to be about 90 Hz. While it may seem a bit high, the mains in my large listening room (16 x 32 x 10) just don't play down to typical 50 Hz. The second curve is psycho acoustic plot generated in Acourate.  I run Acourate to generate convolution filters for use in HQPlayer.  It really does a good job.

[subsonic1050]

I have had sort of the opposite experience from sledwards. I started with 2 sealed subs (massive Paradigm Defiance x15 subwoofers) and then built the triple servo subs. What I was expecting was that the servos would have more speed and detail, but I thought that the sealed subs would have more punch. In my experience, that was not the case. To me, the servos have just as much punch as the sealed subs, if not more. What is different is the pressure wave in the room. It's not so much a difference in how it feels, but I can hear it... in my walls. My sealed subs shake the house, and I can hear the drywall shifting around when the bass is loud. The servo subs don't do that nearly as much as the sealed subs.

My opinion, after hearing the difference in my room, is that adding a sealed sub or subs, would only muddy the bass. I have done a bunch of AB testing with the paradigm subs and the servos, and on all songs the bass is dramatically better - in every way (apart from the "punch", which in my opinion is about the same) and now there are a bunch of songs that I never used to like that now I find amazing. Switching back to the paradigms it sounds so absolutely atrocious that I can't listen to it.

What I'm not sure about is you don't have a normal sealed sub - you have sealed servo subs. What I would try is listening to a song that has incredibly fast bass - like Thundercat "Uh Uh". If you hear separation in the bass notes then you're doing well, if it sounds at all muddy or smeared, you are only going to make the bass worse by leaving those subs in your system after adding the open baffle servos. Just my opinion.

[mlundy57]

The way Danny has set up at shows before is with the open baffle servo subs in the front of the room and sealed servo subs in the rear running out of phase.

As for frequency, I run my open baffle H-frame subs down to 14Hz as full range main speakers. I have a sealed servo sub in the rear as the subwoofer for home theater LFE content. Unlike Danny’s setup, in my case the sealed servo sub doesn’t play with music. It only plays when there is something on the .1 LFE channel

[poseidonsvoice]

I have had sort of the opposite experience from sledwards. I started with 2 sealed subs (massive Paradigm Defiance x15 subwoofers) and then built the triple servo subs. What I was expecting was that the servos would have more speed and detail, but I thought that the sealed subs would have more punch. In my experience, that was not the case. To me, the servos have just as much punch as the sealed subs, if not more. What is different is the pressure wave in the room. It's not so much a difference in how it feels, but I can hear it... in my walls. My sealed subs shake the house, and I can hear the drywall shifting around when the bass is loud. The servo subs don't do that nearly as much as the sealed subs.

My opinion, after hearing the difference in my room, is that adding a sealed sub or subs, would only muddy the bass. I have done a bunch of AB testing with the paradigm subs and the servos, and on all songs the bass is dramatically better - in every way (apart from the "punch", which in my opinion is about the same) and now there are a bunch of songs that I never used to like that now I find amazing. Switching back to the paradigms it sounds so absolutely atrocious that I can't listen to it.

What I'm not sure about is you don't have a normal sealed sub - you have sealed servo subs. What I would try is listening to a song that has incredibly fast bass - like Thundercat "Uh Uh". If you hear separation in the bass notes then you're doing well, if it sounds at all muddy or smeared, you are only going to make the bass worse by leaving those subs in your system after adding the open baffle servos. Just my opinion.

subsonic,

Having listened to sledwards' setup numerous times with just the OB sub implementation and then the OB sub plus sealed sub (asymmetrically distributed swarm), I will say, that subjectively, the second setup is much better than just the OB subs.

It's a near impossibility to do this without good, repeatable, didactic measurements. I was involved in the setup remotely and I am happy to say it has definitely paid off as I just recently listened to his setup about 2-3 weeks ago (he went on this quest to complete a multisub setup after listening to my system a few years back).

The quality of the design as well as the implementation of said design counts. So I will take your comments with some grains of salt. Moreover, I will say in my own setup with involves (4) sealed subs, asymmetrically distributed, no one has ever complained that it was boomy or not delineated. In fact, they were curious if I had open baffle subs and where the subs were in the room. The speed is remarkable and it starts/stops with remarkable accuracy if you can put that into words.

I hate to say it fellas and beat a dead horse, but setup and measurements whether with OB subs or multisubs is king.

Best,
Anand.

[hawkeyejw]

Interesting experiences from you guys, thanks for sharing. Mostly academic for me, I don’t have space to try the OB subs in a theater environment as my home theater is also the family room and there’s just not space. I do plan to build a couple for 2 channel down the road though which will replace a couple DIY tapped horn subs with 7” drivers that play flat down to 25 hz. Will be cool to see the difference when I get there.

[Vince in TX]

The way Danny has set up at shows before is with the open baffle servo subs in the front of the room and sealed servo subs in the rear running out of phase.

This is exactly what I'm planning.   I'm still building my servo subs, but I have a pair of SVS SB-2000 Pro subs on the system at the moment to serve as placeholders.   Once I add the servo subs, I'm moving the sealed subs into the side walls (they are open to the attic, so I will build a box and embed them in the walls).   They will be positioned right between the first and second row seats.

[Early B.]

My opinion, after hearing the difference in my room, is that adding a sealed sub or subs, would only muddy the bass.

That's been my experience, as well. At one point, I had dual OB subs and tried to integrate a sealed sub and ended up with muddy bass. I eventually added a third OB sub and it was delightful. 

Let's face it -- OB subs sound very different than sealed subs. The main reason for using OB subs is cleaner, more authentic bass, so why mix OB with sealed?

OB subs don't have the same slam as sealed subs, but you gotta ask yourself -- is this slam authentically musical? Sure, the slam can be impressive, but most of the time, it's not what real bass sounds like. 

[Vince in TX]

That's been my experience, as well. At one point, I had dual OB subs and tried to integrate a sealed sub and ended up with muddy bass. I eventually added a third OB sub and it was delightful. 

Let's face it -- OB subs sound very different than sealed subs. The main reason for using OB subs is cleaner, more authentic bass, so why mix OB with sealed?

OB subs don't have the same slam as sealed subs, but you gotta ask yourself -- is this slam authentically musical? Sure, the slam can be impressive, but most of the time, it's not what real bass sounds like.

For music, I can definitely see that being the case.   But I'm hearing the opposite for movies.   I guess I'll find out soon enough.   

[poseidonsvoice]

I will say that some of the differing opinions (even with good measurements in room) regarding OB bass versus monopole bass or mix of both has a lot do with the genre of music that is being played. Generally, classical music enthusiasts tend to appreciate OB bass more versus other genres.  And I listen to all sorts of jazz, metal, choral, classical, small group ensembles, etc...in large group classical, I would give the nod to OB bass but that's about the only area.

Both require tons of space in the room, so the space argument falls on its face.

As is obvious, I think answer is...it depends... but I wouldn't knock one for the other.

Best,
Anand.

[WGH]

At one of the RMAF's I attended sometime between 2009 - 2014 GR Research had a big room and used a sealed servo sub in the front of the room behind the curtain to augment the OB subs and add the last bit of slam. It worked very well and the room had the best bass in the show.

[Early B.]

At one of the RMAF's I attended sometime between 2009 - 2014 GR Research had a big room and used a sealed servo sub in the front of the room behind the curtain to augment the OB subs and add the last bit of slam. It worked very well and the room had the best bass in the show.

Does anyone know if Danny augments the OB bass with a sealed sub in his personal setup?

[subsonic1050]

I think maybe the key is that the sealed subs are also servo subs. Mine are just traditional drivers. I have only AB tested them, I haven't tried to marry the 2 types of subs together, but from my AB tests I cannot imagine my sealed subs doing anything but making things worse. However, a sealed servo sub is a different animal - one that I haven't heard. It may very well be (and sounds like it probably is) that some sealed servo subs would help to augment the OB servo subs. I'd like to hear that system.

[Early B.]

I think maybe the key is that the sealed subs are also servo subs. Mine are just traditional drivers. I have only AB tested them, I haven't tried to marry the 2 types of subs together, but from my AB tests I cannot imagine my sealed subs doing anything but making things worse. However, a sealed servo sub is a different animal - one that I haven't heard. It may very well be (and sounds like it probably is) that some sealed servo subs would help to augment the OB servo subs. I'd like to hear that system.

My friend had a sealed servo sub. Just sounds less boomy than a typical box sub, but they're not on the level of an OB sub. Nevertheless, if you're gonna use an OB/sealed sub combo for music, it's probably best to use a sealed servo sub.
 

[Hobbsmeerkat]

Does anyone know if Danny augments the OB bass with a sealed sub in his personal setup?

Nope, in his current setup, it's just the OB subs.

He talked about this in the Livestream with Ron lastnight.

At shows, sealed subs were added in the back of the room and run out of phase from the OB subs. It was done to reduce the boominess at the very back of the room, namely for those waiting their turn to hear the setup. It helped to balance the sound in the room as a whole.

[LewinskiH01]

Thank you!!

Excellent insights.
Some more info about where I'm coming from: this is a system for music only, I listen to wide variety of genres from metal to small-size unamplified bands, and a little orchestral. I also use Acourate for 4-way digital crossovers, time alignment of drivers and room correction.

Anand: your 4 sealed subs in distributed bass array are servo subs? Seems you have heard sledwards' system and you are happy with your setup. This would be the shortest path for me: adding two sealed servo subs.

Sledwards: what an amazing system, and room. Lots of room! Mine is the living room, so not nearly as much leeway as you have positioning speakers/subs.

Over at Audiogon someone mentioned Danny uses dual Rythmik F12 in the back of the room to 40Hz and F12G (OBs of course) in the front. Don't know how high he crosses over.

Sounds like either way could work well: adding two sealed servos in the back, or moving the ones I have to the back and playing them from 40Hz or so and above them run GR Research OB subs. Not sure I can get them allowed to be 3 feet from the wall though.

Thank you!