One Subwoofer vs 2: Questions

Discussion in 'Speakers & Subwoofers' started by Shane Martin, Jun 6, 2005.

  1. Shane Martin

    Shane Martin Producer

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    Real soon I plan to pull the trigger on a subwoofer setup for my growing home theater.

    The room is 4,300 cubic feet with 2 openings one of which I can close off with a door. The subwoofer(s) have only one spot in the room for placement that works and that is the front left corner. The opposite corner has a room mode that is a problem so I avoid placement there.

    When I do listen to movies it is near reference so I require more of a subwoofer than most.

    Budget: ~$2k.

    My friend bought a dual SVS 25-31CS+ package. He went that route to maximize the 25hz output as many agreed that 25hz was where the majority of movies tend to be in terms of low end output. He suggests I do the same. I however want more down low.

    Questions:
    For this amount I am considering Dual SVS CS Ultras, Dual PC Ultras or 1 PB12Ultra/2. If I get the final veto on the tubes(unlikely) I'll have to step up to the Pb12Ultra and get 2 of them.

    1. SVS wise: am I on the right Track?
    2. Am I sacrificing that much or at all in the 25hz region to gain more in the 16-20 range? If so would it be that noticable or is it a case of me forgetting about it because it is already good enough and the lower end will make up for it?
    3. Do I need 2 subs? I figured since the dual cs/pc ultras have more port area and a little more power I'd gain more output?
    4. If I go the dual pc ultra route, how would I calibrate that given both have the EQ?
    5. Is a BFD or similar device necessary or will the EQ in the SVS suffice you think?
     
  2. SteveMetcalf

    SteveMetcalf Agent

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    Did you know that you can't just have a room mode problem in the corner? It may be most apparent to you there, but if you walk around the room and listen you'll find it exists along even divisions of the rooms dimensions. If you like, post the dimensions, and I'll figure out the axial modes and maybe make some suggestions as to how they can be fixed. This is really the answer to all your problems if you're serious about bass.(or sound for that matter)

    ;D
     
  3. BrianWoerndle

    BrianWoerndle Supporting Actor

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    I have dual 16-46CS+s in a 12' x 13' room, and it just gives me enough bass when I watch movies at reference levels. A single sub could not give me the subsonics and SPL that I wanted.

    1 driver just can't move enough air. As long as you pick a SVS with 2 drivers (either dual cylinders or a PB12../2) you will be fine. And the Ultra driver you are looking at is an amazing woofer.
     
  4. Arthur S

    Arthur S Cinematographer

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    Shane

    1) You are quite familiar with the SVS line-up so apparently you have ruled out the 4+, therefore, I guess you are on the right track.

    2) Knowing as much as you do and already saying you "want more down low" you are correctly steering away from anything that can't handle 16-20Hz ably. If you get something than can't handle that range, you are always going to wonder what you are missing.

    3) If you get 2 subs and co-locate them you should gain 6 db. This is considerable added output. Since you want reference levels, 2 subs would be the way to go. There is also the matter of headroom. In your big room at reference level, you may not want to be pushing a sub to close to its limit. That extra 6db should take care of that nicely. However, you could get 1 PC-Ultra and try it and get another if 1 is not enough.

    4) I would think that you would calibrate the 2nd PC-Ultra almost exactly the same as the first since they are co-located.

    5) Depends on what kind of FR you end up with after using the PEQ on the SVS and how demanding you are on flat FR. The BFD is only $100. You could try it and if it doesn't make a significant difference sell it and not lose much.

    My vote: 2 PC-Ultra. Try it without BFD, if happy, stop there, if real curious try a BFD.

    I think you will find 2 PCU to be killer. FLAT in-room to 17Hz.
     
  5. Shane Martin

    Shane Martin Producer

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    The B4 just isn't fiscally feasible which is why I ruled it out.

    Am I giving up that much in terms of output in the 25 on up region by going with the PCU or PB12/Ultra or ULtra/2 which are all tuned to 20(last I looked)?
     
  6. Arthur S

    Arthur S Cinematographer

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    Shane

    It seems like you want it both ways. You don't want to give up SPL in the 25 on up range, but you "want more down low". In the $2,000 price range there will be some trade off. If you want to do the 17Hz-25 Hz range with authority you will be giving up some SPL in the 25Hz plus range. Never the less, 2 PC Ultra co-located will deliver a ton of performance all the way around.

    First, find out for sure if you have the OK to go with cylinders. If not that eliminates several important choices. Including the 16-46, and the PC Ultra. This also means that none of the other SVS is natively tuned below 20Hz.

    It is hard to imagine that 2 PC Ultra won't give you more than you need. They are also a less expensive option than 2 PB Ultra, which seem to have captured the fancy of several folks who have gone through numerous subs including the PB Ultra/2. Two PC Ultra is also probably less conspicuous than 2 PB Ultra.

    You seem to be a pretty reasonable guy. I don't see you turning around after 6 weeks and saying 2 PC Ultra isn't quite enough. Even if you did, what other choices are there that would make much of a difference? 2 PB Ultra: not much difference. 1 PB Ultra/2: not much difference.

    That is why I mentioned 4+. That thing will give you a noticable difference at less cost than most other
     
  7. MikeLi

    MikeLi Supporting Actor

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    Go with the PB12/+2Ultra... I have the PB2+ with upgraded dual drivers which is the older version... I love it. I love to be able to feel the tactical presence in movies not just hear good low bass. This one definantly delivers both.
     
  8. steve nn

    steve nn Cinematographer

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    Depends on how bad your room is. I don't require ruler-flat, but admittedly I have the ART-351 on the way with my next purchase. The price was right[​IMG]

    I really think you would like the dual colocated option (if you go that rout?) in that size room and listening preference.
     
  9. Shane Martin

    Shane Martin Producer

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    Steve & Arthur,
    Much appreciated.
    She hasn't balked yet. Considering how dark my room is, the black cylinders will dissapear there and I don't have to worry about kids or cats.
     
  10. SteveMetcalf

    SteveMetcalf Agent

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    Shane, you wrote:
    Quote:
    "No but moving my sub to the opposite corner fixed the lack of bass issue I was having. It was very apparant that my bass level dropped considerably when I moved my sub to that corner."
    If this is the case, then there is a reason for it other than the room modes. There are 3 types of room mode: Axial, which is a product of one set of paralell walls, tangential; which is a product of two, and oblique; inludes commonalities in frequency response for length height and width. If you deal with the source frequencies for each, you will eliminate all.
    You also wrote:
    "I understand that aspect but I think you realize what I was trying to say in that I'm considering one big svs vs 2 cylinders or boxes. Same # of woofers, just it appears there is more port area and a little more power. That should translate into alot more SPL right?"
    No. In order to increase 3db spl, you need to double the output power. To do this you need to; (a)Double the wattage, or (b)add twice as many speakers.
    Your ear will percieve an increas of 10db spl as double the volume level, therefore a 3db increase is noticible but not drastic. The biggest improvement you could experience for this room is by correcting acoustic interference from the room. After this, any other changes you make will have a greater effect.
     
  11. steve nn

    steve nn Cinematographer

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    It's the combination of both, but mostly the third aspect of optimal enclosure volume. If the PB12-Ultra/2 or the PB12-Plus/2 enclosure were the optimal size, then it would translate out differently. As it is, they are both a little undersized for what they could achieve. Can you imagen the enclosures being even larger?[​IMG] Maybe a compromise, but most would consider the 2 driver enclosures large enough? I would think SVS felt they needed to draw the line somewhere.

    My PB12-Ultra's will be arriving today Shane and I'll give you a good idea of the gain in performance going from 1 to 2 units. I'll also show you how close a PB12-Ultra will perform to a PB12-Ultra/2 on it's own because of the enclosure size I brought up earlier. Don't get me wrong> The PB12-Ultra/2 is a incredible sub to be sure and the best I have ever listened to. It's just that I have the space (a sacrifice many cant/wont make) and a rather lousy room. I admittedly might consider the +3 +5dB gain/headroom in the 16-25Hz range more of a advantage than what some others would merit.
     

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