Two Subwoofers

[Greenway54]

I'm thinking of upgrading my present system to two subwoofers. My room (home office) is 9' x 12' with a single listening position. Right now I have two Neumann kh120's with a JL Audio D108 8" subwoofer. I am considering EITHER upgrading the kh120's to kh120ii's and keeping the D108, OR keeping the kh120's and adding another D108. The first option is going to be around $3000 while the second will be around $1500 CDN. I've never even heard a two-subwoofer set-up so I'm not sure what it would do for my listening experience (rock, jazz, blues, folk...no movies)

 

[DVDdoug]

The dips & peaks from standing waves are different at different places in the room. Multiple subs in different locations can help to even-out those variations. And if you are using EQ/room correction doubling the output gives you more to work with when correcting dips/cancelation, but there's only so-much you can do when the direct and reflected waves are canceling each other.

Here's something from Floyd Toole's book:

 

[Keith_W]

Before you spend any money, the first question you should ask is - do you have a problem with your current set-up? And are you sure your problem will be fixed by adding a second sub? Because, the solution may be - finding a better place for your existing sub, or DSP.

Get a microphone (you will need one anyway) and take some measurements.

 

[sigbergaudio]

As @Keith_W is saying it's hard to predict your experience of moving from one to two subs without knowing your current situation and what you're trying to improve on. It could be anything from mindblowing to hardly noticeable.

Do you have DSP/EQ capabilities in your current setup?

 

[Greenway54]

As @Keith_W is saying it's hard to predict your experience of moving from one to two subs without knowing your current situation and what you're trying to improve on. It could be anything from mindblowing to hardly noticeable.

Do you have DSP/EQ capabilities in your current setup?

I don't have DSP/EQ capabilities, although the Neumann kh120ii's would provide that. Basically, where I'm coming from is that I bought the one woofer and liked what it did to my experience of the sound system, so then I am wondering...what would a second one bring to the overall sound? I like what I have, but there's always the thought...one sub brought so much into the sound, so what will another achieve? And what if I place them under the satellites? You don't see that sort of set-up much, but I have seen it occasionally on the net. (I don't have the room to place the subs next to the satellites, on the floor or such.

 

[sigbergaudio]

I don't have DSP/EQ capabilities, although the Neumann kh120ii's would provide that. Basically, where I'm coming from is that I bought the one woofer and liked what it did to my experience of the sound system, so then I am wondering...what would a second one bring to the overall sound? I like what I have, but there's always the thought...one sub brought so much into the sound, so what will another achieve? And what if I place them under the satellites? You don't see that sort of set-up much, but I have seen it occasionally on the net. (I don't have the room to place the subs next to the satellites, on the floor or such.

Well,

The first one gave you deeper bass, the second won't extend the bass further.
The first one gave you more bass, but you now likely don't need a higher level (you could just turn up the gain on the one you have in that case), so the second one won't give you that either.


So the second sub is likely to give you a more even response (even without EQ/DSP), it will potentially give you more headroom (if you need it), and with the setup you are suggesting it might give you stereo bass. All these things are relatively subtle. More even response can be pretty noticeable if you are experiencing uneven bass today. This is easily identified by the experience of some songs having too much bass, others having too little, and possibly some are just perfect - all without any adjustments to the sub.

 

[OldHvyMec]

The more the merrier, and the more you can turn down the gain. The steeper the slope on the XO, the less bloat (or wide extended peaks) you have in that crossover region. I cross at 40-60 Hz into bass columns that cross again at 250-280 Hz, into the mains, both at a 24-48 dB slope. The steeper the slopes, the cleaner the sound, especially in the sub/bass region.

Treat the room with minor room treatment, and you likely won't need anything but tone controls. I have a single notch in the 800-1000Hz region that can drive some people nuts with the SS gear because of the driver's (neo 8 planars) inherent issues. Between a notch with my SS gear, or swapping to valve gear, it is quite manageable with NO DSP. I had a company build the passive notch for the drivers I use in 2005 or so. STI. It was for some SS amps I used (at the time) and liked very much, Threshold

Class Ds (Ncore) don't need the notch, OR my ears are getting worse. It's likely the ears, not the gear.

Placement is VERY important with 1 or 2 subs. Corners don't work for subs, mid wall is a great place on any 2 right-angle walls, and if you can, different distances from the parallel wall.

DOS subs are one of the better ways to get better distribution from a single or double sub. I run the drivers parallel to the wall, whether one driver is active and one is passive, or both are active. If you're using a single driver in a ported or IB, point, the driver (usually) away from the corners and slightly in front or behind the seated position.

Have fun.

Regards

 

[J.M. Noble]

Mo' subs, mo' problems. I'd go with a single sub whenever possible.

Time alignment complexity, room mode interactions, reinforcement/cancellation causing power alleys like we have in sound reinforcement & PA applications, and a bunch of other issues can be avoided by having just one sub (assuming the subs aren't identical and grouped together to effectively create one larger sub through coupling).

 

[sigbergaudio]

Mo' subs, mo' problems. I'd go with a single sub whenever possible.

Time alignment complexity, room mode interactions, reinforcement/cancellation causing power alleys like we have in sound reinforcement & PA applications, and a bunch of other issues can be avoided by having just one sub (assuming the subs aren't identical and grouped together to effectively create one larger sub through coupling).

Interesting (unique?) perspective.

So you feel like you have more problems with room modes wiht two subs rather than one?

 

[Keith_W]

I don't have DSP/EQ capabilities, although the Neumann kh120ii's would provide that. Basically, where I'm coming from is that I bought the one woofer and liked what it did to my experience of the sound system, so then I am wondering...what would a second one bring to the overall sound? I like what I have, but there's always the thought...one sub brought so much into the sound, so what will another achieve? And what if I place them under the satellites? You don't see that sort of set-up much, but I have seen it occasionally on the net. (I don't have the room to place the subs next to the satellites, on the floor or such.

Nobody can answer your question, sorry. Well, they can try, but until we see some measurements, nobody even knows if you have a problem that needs to be solved. Adding a second subwoofer is one potential solution, but there are other solutions that don't cost money, and it could be as simple as adjusting the volume of your subwoofer, or leveraging the DSP capability of whatever hardware you already own.

I forgot to welcome you to ASR in my previous post ... so here it is. Welcome to ASR!

 

[Sokel]

And what if I place them under the satellites? You don't see that sort of set-up much, but I have seen it occasionally on the net. (I don't have the room to place the subs next to the satellites, on the floor or such.

You'll need bass modules for that, not subs.

What you see on the net are people attempting to turn a 2-way to a 3-way.
Can't do that with subs and the complexity is just like building a new speaker unless the bass modules are designed for that like W371A are designed for Genelec for example.

I suggest to follow the advice of proper placement, measurements, etc before you buy another sub.

 

[just1n]

I'm thinking of upgrading my present system to two subwoofers. My room (home office) is 9' x 12' with a single listening position. Right now I have two Neumann kh120's with a JL Audio D108 8" subwoofer. I am considering EITHER upgrading the kh120's to kh120ii's and keeping the D108, OR keeping the kh120's and adding another D108. The first option is going to be around $3000 while the second will be around $1500 CDN. I've never even heard a two-subwoofer set-up so I'm not sure what it would do for my listening experience (rock, jazz, blues, folk...no movies)

What is your source? Preamp, DAC, computer, streaming device?

 

[Greenway54]

What is your source? Preamp, DAC, computer, streaming device?

PC Windows 10 running Audirvana Origin > iFi Galvanic 3.0 > Eversolo DAC-Z8 > Schiit Saga Pre-amp

 

[just1n]

PC Windows 10 running Audirvana Origin > iFi Galvanic 3.0 > Eversolo DAC-Z8 > Schiit Saga Pre-amp

I would suggest using a mic and REW to see what would require attention, then see what improvements can be made with what you have using the Audirvana parametric EQ. Far cheaper and likely more effective use than adding another sub or changing speakers.

 

[Greenway54]

I would suggest using a mic and REW to see what would require attention, then see what improvements can be made with what you have using the Audirvana parametric EQ. Far cheaper and likely more effective use than adding another sub or changing speakers.

So, no subwoofer with your kh120A's?

 

[just1n]

So, no subwoofer with your kh120A's?

Not yet

 

[kemmler3D]

So, I run 2 subs with my genelecs in my office, but they're in the corners and not right under the mains.

I will say that the D108 is not a super great value unless the size constraint is insurmountable. @sweetchaos has put together a pretty comprehensive list of subs and their tested performance here: https://docs.google.com/spreadsheet...6ZL6anVTW2_M/edit?gid=834598950#gid=834598950 - I think you can't really get small, cheap, and high output, but the SVS 3000 Micro is worth a look as an alternative, as they give a deal on a pair of subs, it's slightly smaller than the JL unit, and the output is similar.

I have 2x BIC F12s, I got them used for $250 total, and one of them beats the D108 @ $1K USD. So if you can lose the size constraint somehow, there are deals to be had.

Aside from that, I definitely recommend running EQAPO on your PC, you can EQ the bass to perfection, it's really the best upgrade you can make for small dollars. (EQAPO is free but you'll need a mic.)

 

[just1n]

So, I run 2 subs with my genelecs in my office, but they're in the corners and not right under the mains.

I will say that the D108 is not a super great value unless the size constraint is insurmountable. @sweetchaos has put together a pretty comprehensive list of subs and their tested performance here: https://docs.google.com/spreadsheet...6ZL6anVTW2_M/edit?gid=834598950#gid=834598950 - I think you can't really get small, cheap, and high output, but the SVS 3000 Micro is worth a look as an alternative, as they give a deal on a pair of subs, it's slightly smaller than the JL unit, and the output is similar.

I have 2x BIC F12s, I got them used for $250 total, and one of them beats the D108 @ $1K USD. So if you can lose the size constraint somehow, there are deals to be had.

Aside from that, I definitely recommend running EQAPO on your PC, you can EQ the bass to perfection, it's really the best upgrade you can make for small dollars. (EQAPO is free but you'll need a mic.)

For an office setup near-field the 3000micro may be enough, but give the Kali WS-6.2 some consideration. I’ve had both and the Kali has higher output and lower extension.

 

[J.M. Noble]

Interesting (unique?) perspective.

So you feel like you have more problems with room modes wiht two subs rather than one?

In a sufficiently small room you might just be able to overpower the joint with multiple subs. Maybe.

But in general you're adding another issue besides the added complexity of an additional mode excitation calculation/measurement. If the subs aren't equidistant from the listening position, you will get lobing and such on top of the modes. Put a couple of subs outdoors, to get rid of room mode effects, and walk around. It's educational. I do this a few times a month as a live sound engineer.

 

[sigbergaudio]

In a sufficiently small room you might just be able to overpower the joint with multiple subs. Maybe.

But in general you're adding another issue besides the added complexity of an additional mode excitation calculation/measurement. If the subs aren't equidistant from the listening position, you will get lobing and such on top of the modes. Put a couple of subs outdoors, to get rid of room mode effects, and walk around. It's educational. I do this a few times a month as a live sound engineer.

This goes against both common theory and experience unless I'm severely misunderstanding what you're saying. Typically adding more subs will give you a more even frequency response over a wider area of the room.