Another Newbie SVS Question(kinda long)

Discussion in 'Speakers' started by Ryan_F, Jan 10, 2004.

  1. Ryan_F

    Ryan_F Auditioning

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    Hey everyone, this may be a question for the people at SVS but you guys seem very knowledgable so I'm open to any comments here first. I'm looking to buy a good sub and am totally convinced that SVS is the way to go but I'm a little confused about the differences between a couple of the different models. I can't honestly say what size room my theater will be in because i'm a student that moves around alot but lets just say that it won't be bigger than 20'x20'x10'. I know this is vague and that room acoustics play a big role in how any sub will sound but i'm interested in any suggestions that would have the potential to do a good job. I watch movies and listen to music at fairly high levels and want something that will be capable in these situations but at the same time not be incredibly overpowering should it be placed in a smaller room.

    I've been trying to decide between the 20-39PC+ and the PB2-ISD for around the same price but am not totally against either the new PC-ULTRA or the PB2-PLUS if it would be worth it. What is confusing me when trying to decide between these models is the extent to which the driver type makes a difference. For example, will the 2 ISD drivers in the PB2-ISD outperform the 1 Plus driver in the 20-39PC+ and likewise, would 2 Plus drivers in the PB2-PLUS outperform the one ultra driver in the PC-ULTRA. I don't expect a difinitive answer from anyone but any suggestions or comments that might help me decide would be greatly appreciated. Thanks.

    Ryan
     
  2. John F. Palacio

    John F. Palacio Supporting Actor

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    If you have the money (and the space), you cannot buy a sub that will be "too much" for a certain room.

    The biggest, most powerful sub (whatever that is) can be adjusted (positioned and calibrated in level) to sound great even in a "small" room.

    The folks at SVS will steer you in the right direction, but don't be afraid of getting a sub that will "overpower" a small room.

    Happy Subwoofing!
     
  3. Edward J M

    Edward J M Cinematographer

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    A PB2-ISD will have the edge over a 20-39PC+ when both are set to 20 Hz mode. From about 16-25 Hz it would be close, but the PB2-ISD will edge out the PC+. Above 25 Hz, the advantage grows to the 3-4dB range. So if you can live with the larger PB2-ISD enclosure, it represents a better performance value over the PC+.

    All three PB2 models will have the same extension capabilities. Going from the PB2-ISD to the PB2+ will give you a 2-4 dB jump. Going from the PB2+ to the PB2 Ultra will give you another 1-2 dB jump. So going from the PB2-ISD to the PB2-Ultra will give you a jump in the 3-6 dB range.

    With both set to 20 Hz extension, the PB-2+ will have a 4-5dB edge on the single PC-Ultra in the 25-100 Hz range. In the 16-25 Hz range it would be a lot closer, with the PB-2+ still holding a slight advantage.

    Finally, a PC-Ultra will have an approximately 1.5 dB advantage over a 20-39PC+ across the operating bandwidth.

    Regards,

    Ed
     
  4. Ryan_F

    Ryan_F Auditioning

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    Thanks John and Edward for the responses, that is some good information and was just the kind of stuff I wanted to hear. I had been leaning towards the PB2-ISD since I learned it existed because it looked to be a nice compromise between the 20-39PC+ and the PB2-PLUS and was right around my price range but I didn't want to be dissapointed by the limitations of the ISD driver(if there are any limitations) in the long run and was willing to go the extra mile to the PB2-plus if i would see a huge difference and if it would satisfy me for longer. Also, not that the size of the box subs bothered me but I liked the idea of the PC-ULTRA for positioning reasons if it would yield the same performance at around the same price as the PB2-PLUS. Does this sound like good or bad reasoning? Has anyone heard the PB2-ISD and the PB2-PLUS side by side? Thanks again, any thoughts are welcome.

    Ryan
     
  5. Zack_R

    Zack_R Stunt Coordinator

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    Since you will likely end up keeping what you order, I say go with your gut instinct. Assuming it's price is within your comfort zone.

    I must say I am suprised that a 600 watt PB2-ISD with a port plugged and tuned to 20 hz would have an output advantage over a 525 watt stock tune 2039 plus below ~32 hz. I don't know all the science behind dual versus single drivers but I do understand watts and the impact port plugging has on a sub.

    From personal experience and reading of other's experience, anytime a port is plugged you will lose ~3 dbs of output in a given area of frequency response if no eq adjustment is applied. This defeceit usally starts around 5-6 hz (it's probably octave based, but I think the numbers are pretty close) above the point of the native tune and recovers itself about 2 hz above the new tune point.

    So by my reasoning, the PB2 ISD, tuned to 20 hz would approximately lose ~3dbs from 22 to 33 or so hertz. It also has less port area per driver. You would then need to bump the sub output up 2-3dbs. So any advantage a 600 watt amp gives over a 525 watt amp is lost below the ~32 hz point. Since we are talking 600 watts total power versus 525 watts total power, the PC+ seems to have the advantage in this range to me. Now if the ISD woofers are more effecient with power then I can see how the ISD could be louder. I've never read anything to indicate this was the case though.

    But if we assume similiar efficiencies between the plus and ISD drivers and we assume negligible output differences between 600 watts and 525 watts and we assume three 3 inch ports for one driver is better than two three inch ports for two drivers, then how does the PB2-ISD have an advantage? Or better yet what am I over looking or not taking into account?

    On another note, the SVS subs are so loud to the average person that port plugging and subsequent bumping of the sub level is not going to be detrimental as there is more than enough headroom in the amps to accomodate. If truth be told most of us when watching movies (not demoing) are probably not using more than 100 - 150 watts or so of the amp any way[​IMG].
     
  6. Edward J M

    Edward J M Cinematographer

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    Zack, all of my above "bench racing" comparisons were taken verbatim from Tom V posts.

    With that said, your analysis and critical thought process is (as always) excellent. If I didn't know better from Tom, I would tend to agree. The only thing you might be "overlooking or not taking into account" would be the coupling effect resulting when two drivers are placed in close proximity to each other.
     
  7. Zack_R

    Zack_R Stunt Coordinator

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    Thanks for the feedback Ed. And also thanks to WayneO from a previous thread where he mentioned the info came from Tom V also.

    I was deducing from the frequent question of how a 2531PC+ tuned to 20 hz would compare to a 2039PC+ in stock tune. In this scenario the 2039PC+ was always given the nod around 25 hz and below.

    One nice advantage the box subs offer is easy tuning since you don't have to fiddle with the grill removal. I think if you are considering a cylinder it is more important to get the tune you are most interested in since it's a little more trouble to tune lower on the occasion you would choose to do so.

    The dual box subs are also nice from the standpoint of really giving you headroom to spare so you can tune lower if you desire. I would guesstimate that it would take a 20% increase in box volume to drop the tune 5 hz in order to get a native tune of 20 hz. I think most people would prefer the current size and tune lower as necessary.
     
  8. Philip>L

    Philip>L Stunt Coordinator

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    Just for a point of reference, it takes about 3 seconds to remove the grill on a 20-39 PC+.
     
  9. steve nn

    steve nn Cinematographer

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    Thats a good assessment Zack. Just tuned my 25-31CS+'s to 20 hz for UNDERWORLD. I could tell right away this movie deserves the 20 hz tune imo. Took me about a minute to do so and that is three 25-31+'s. Headroom and options can be a very good thing if it isn't to $$/difficult.
     
  10. WayneO

    WayneO Supporting Actor

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    I'm not very educated on technical aspects, but I would think the excursion of the two drivers vs. the one would be one of the advantanges of a PB2 over a single cylinder.
     

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