subwoofers with dual opposed drivers

[buzwork]

Recently picked up a 2nd baby SVS 3000 Micro. Running them stacked and holy cow. Was relatively easy finding the sweet spot for my first 3Km. Adding a second was as simple as plopping on top of the first. As expected, stacking increased output significantly. I'm using a Martin Logan Unison pre-amp with Anthem Room Correction. It did a pretty good job on it's own, but I still had to tweak gains on both subs manually to dial in integration with my Revel M105s. Sounds excellent and extension is much improved. Couldn't be happier. Eventually I'm going to pick up a MiniDSP and take a stab at REW. Was lucky enough to get the pair for under $1200 (one Electronics Express open box, which was clearly never opened, presumably to get around MAP, and one SVS blemished that is impossible to distinguish from new as the blemishes were on the amp board and underside).

Once again, WAF was easy. She didn't even notice the first sub and also didn't notice the second until I pointed it out two weeks later So small and easy to hide.

Dual opposed driver implementation by SVS is fantastic. One was pretty good. Two of them elevated my personal rating to excellent. I don't think there is a better solution for my situation... this is a living room two channel listening set up and a larger 15"-18" sub was not going to fly, per the lady. Amplifiers for M105s are one Outlaw Audio M2200 per speaker. Overkill but lots of head room.

I had considered the KC62 but the pricing I was able to get for the pair of SVS 3Km removed the Kef from consideration.

 

[Head_Unit]

What I'll toss in here is that I was really pretty shocked one day how much our sub cabinet was shaking. Shouldn't have been a big surprise, as once upon a time a smart guy named Newton postulated that each action has an equal and opposite reaction. How audible is that? Interesting question...I'm trying to picture if a distortion test should catch that...seems like it should...

 

[Chromatischism]

What I'll toss in here is that I was really pretty shocked one day how much our sub cabinet was shaking. Shouldn't have been a big surprise, as once upon a time a smart guy named Newton postulated that each action has an equal and opposite reaction. How audible is that? Interesting question...I'm trying to picture if a distortion test should catch that...seems like it should...

It won't register. You'll need to measure physical vibration of the floor and surrounding areas, as that is where the energy is going, unless the sub is decoupled. Now if those materials rattle, then sure, that will be measurable.

 

[Vacceo]

It depends on your goals. For home theater or theatrical-type music it is not the kind of sub I would use unless I had no choice but to keep things under control for roommates/neighbors.

Dual opposed vented is an interesting idea that I haven't seen done commercially yet.

So if I'm understanding you well, you'd rather go to a design like the Perlisten subs instead of a KEF sub (two easy examples) due to SPL and frequency extension, right?

Bothering the neightbours is a good extra in my book, too bad I cannot afford a pair of Gothams.

 

[Chromatischism]

Yeah. These days I'm really preferring low-tuned vented subs, after trying sealed in single and dual opposed alignments. If you know how to set up and tame your subs, you shouldn't lose anything, but gain lots of low end efficiency and power.

 

[Vacceo]

Yeah. These days I'm really preferring low-tuned vented subs, after trying sealed in single and dual opposed alignments. If you know how to set up and tame your subs, you shouldn't lose anything, but gain lots of low end efficiency and power.

Back when I started, all you had was the phase knob, the crossover settings, and subwoofer crawl. Those are still valid today, but EQ software has made things a loooooooot easier.

Size-wise, there are some vented subs that are not much, much bigger than dual sealed. Extra question: design wise, which style has the capacity to reach infrasonics better?

 

[Willem]

Recently picked up a 2nd baby SVS 3000 Micro. Running them stacked and holy cow

Did you try to use them in two different locations rather than stacked? It would give you somewhat less spl, but a smoother response over a wider area.

 

[Chromatischism]

Yeah. If I bought really small subs, it would be because I want to spread them around.

 

[Chromatischism]

Back when I started, all you had was the phase knob, the crossover settings, and subwoofer crawl. Those are still valid today, but EQ software has made things a loooooooot easier.

Size-wise, there are some vented subs that are not much, much bigger than dual sealed. Extra question: design wise, which style has the capacity to reach infrasonics better?

Sealed will do better in the single digits, however vented will give you a lot more output from 15-25 Hz, which is what really matters.

 

[Vacceo]

Sealed will do better in the single digits, however vented will give you a lot more output from 15-25 Hz, which is what really matters.

Would you mind explaining a bit more? Infrasonics are both 15 Hz and 5 Hz, so why does it matter more?

For 20 to 25 it's evident, but below that, you just feel (and I love that feeling!), not hear; so what is the reason?

 

[Chromatischism]

Would you mind explaining a bit more? Infrasonics are both 15 Hz and 5 Hz, so why does it matter more?

For 20 to 25 it's evident, but below that, you just feel (and I love that feeling!), not hear; so what is the reason?

IME output below 10 Hz is not really even felt, let alone heard. I don't think the resonant frequencies of most materials are in that range. I had way more output at 5 Hz with sealed subs and the vented still provide a better experience.

 

[Vacceo]

IME output below 10 Hz is not really even felt, let alone heard. I don't think the resonant frequencies of most materials are in that range. I had way more output at 5 Hz with sealed subs and the vented still provide a better experience.

Thanks for the answer! Now some listed specs from manufacturers make a bit more sense (both performance and comercial-wise). I have always wondered why is it so rare that manufacturers show the extension of their subwoofers only at 10hz or more (typically 20hz and up): it is measureable but hardly noticeable.

So esentially, the materials of our bodies (yeah, water most of them) resonate at 10 to 20 hz, hence why we feel it and thus, if you want "tactile" subsonics, it´s a good idea to concentrate on subs that deliver on those frequencies.

 

[Chromatischism]

Thanks for the answer! Now some listed specs from manufacturers make a bit more sense (both performance and comercial-wise). I have always wondered why is it so rare that manufacturers show the extension of their subwoofers only at 10hz or more (typically 20hz and up): it is measureable but hardly noticeable.

Well, generally speaking, there are no mass-market subwoofers that achieve even a -6 dB that low.

So esentially, the materials of our bodies (yeah, water most of them) resonate at 10 to 20 hz, hence why we feel it and thus, if you want "tactile" subsonics, it´s a good idea to concentrate on subs that deliver on those frequencies.

Depends on the body part and material, but yeah. 10-20 Hz is mostly floors and walls and not felt in my body - I feel the chair vibrating from the floor. That happens around 20-30 Hz. The walls react more around 15 Hz.

The bass you will feel in your body will be from 30 Hz and up.

 

[Jukka]

Two drivers in one cabinet double power handling where a single cabinet/amplifier is wanted. If they were on the same side, cabinet would be a lot larger and shake more. The only other T/S parameter that changes when adding another identical driver on the same line is VAS, but that's not relevant on this thread.

2-driver sub can be configured to play stereo sound, if electronics allow (with stereo/differential-mono input).

Never forget (watch the end):

With single woofer or all woofers on same side, you get this:

 

[Head_Unit]

It won't register. You'll need to measure physical vibration of the floor and surrounding areas, as that is where the energy is going, unless the sub is decoupled. Now if those materials rattle, then sure, that will be measurable.

Well the shaking back and forth is moving some air, making sound. But I concur probably very low in SPL. That location, the floor is concrete slab, little vibration.

 

[Nobleman]

Subwoofers with dual opposed drivers are increasingly popular, witness B&W, Kef and now also SVS. I have two subwoofers, one a B&W PV1d with dual opposed 8 inch drivers and the other a more recently prurchased and much cheaper KEF Kube8b with one 8 inch driver. Not surprisingly the PV1d goes quite a bit deeper, but its output is also rather better defined/cleaner etc. Admittedly, the price difference was large, but I wondered if there are also sonic benefits from the dual opposed driver design that could be responsible for this.

These are called Isobaric design subwoofers. They are designed to cancel each drivers resonance frequency by creating two opposite waves of the same frequency and amplitude to cancel each other which stabilizes both drivers and make it possible to reach low frequencies at higher db levels. Isobaric s are like Class A amps I.e a bit too much. A properly designed sealed or a bandpass design sub can be more economical and space saving.

 

[sigbergaudio]

These are called Isobaric design subwoofers. They are designed to cancel each drivers resonance frequency by creating two opposite waves of the same frequency and amplitude to cancel each other which stabilizes both drivers and make it possible to reach low frequencies at higher db levels. Isobaric s are like Class A amps I.e a bit too much. A properly designed sealed or a bandpass design sub can be more economical and space saving.

I think you made up most of this. Either way it's mostly wrong. Dual opposed is not the same as isobaric and it does not extend low end response. And a single sealed sub is not more space saving.

 

[Nobleman]

I think you made up most of this. Either way it's mostly wrong. Dual opposed is not the same as isobaric and it does not extend low end response. And a single sealed sub is not more space saving.

Ok,judging by your signature obviously you seem to know lot more than me.I only shared what I believe to be true. I am not in audio business. This was my understanding.

 

[Chromatischism]

The thread is not about isobaric subs.

 

[Head_Unit]

Isobaric

Dual opposed is not the same as isobaric and it does not extend low end response. And a single sealed sub is not more space saving.

I think @Chromatischism is correct, I don't think that isobaric is what the OP meant. I think the thread is about having woofers on opposites sides of the enclosure, pushing/pulling at the same time. In this way the physics reaction forces cancel out for less vibration. An isobaric has two drivers connected...a cone facing outside, and more or less right behind it another cone, which then vents into the big part of the box. They won't force cancel unless my brain is failing me (full disclosure: that HAS been know to happen ha ha). As for low end and space saving either is possible (at the expense of lower sensitivity) but really it depends on the particulars.