Sub Output

Discussion in 'Speakers' started by Chris Huber, Jun 17, 2005.

  1. Chris Huber

    Chris Huber Second Unit

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    I am in the midst of testing out a 20-39 PC+ from SVS. I guess I need to understand bass. This sub is plenty loud enough... Are loudness and tactile related in the fact that and increase in one = and increase in the other?

    So, if you had a PC+ and a PB12/isd 2 playing at the same SPL, they would still both have the same tactile feel. correct? So, in my case, increasing to 2 woofers would not do anything since I already think it's loud enough with 1 woofer at 1/2 gain.

    Heres another question: 20-39PC+ vs 25-31PC+... I know that the latter would have more SPL, but if I already have the 20-39 as loud as I like, there would be no SPL gain with going 25-31, correct?
     
  2. John_RO

    John_RO Stunt Coordinator

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    I think you need to e-mail Tom V. at SVS. My humble opinion is that the more air you move (ie. more surface area with two woofs), the more SPL and tactile feel you get. I think it's that simple. But you would probably want to check with Tom for the definitive answer. In a 12/25 room on a concrete slab, my 25-31PCi moves enough air to rattle my windows at 100db. Nuff said.
     
  3. billybob_jcv

    billybob_jcv Stunt Coordinator

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    Isn't the biggest difference in the low-end extension? I think I understand what you mean - assuming you have the 25-31 & 20-39 tuned to the same point, then if the 25-31 is generating the SPL you want, I don't think you would gain anything by going to the 20-39.

    But - I'm just a neophyte - I would also email SVS! [​IMG]
     
  4. BrianWoerndle

    BrianWoerndle Supporting Actor

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    "Are loudness and tactile related in the fact that and increase in one = and increase in the other?"

    For the most part yes. It takes a certian amount of air to create 20hz at xxdb. It doesn't matter is 1 woofers does all the work, or 2 each do half the work. The only thing 2 woofers really gains you is the ability to go louder. But if you will never really go that loud, the 2nd woofer will be mostly wasted.

    ...But extension also plays a big part in tactile feel. The deeper notes (< 20hz) are more easily felt. The bigger and/or dual subs will play the deeper notes in addition to the aformentiond 20hz example, therefore sounding louder/more tactile.

    "Heres another question: 20-39PC+ vs 25-31PC+... I know that the latter would have more SPL, but if I already have the 20-39 as loud as I like, there would be no SPL gain with going 25-31, correct? "

    Correct. The 20-39 gives up a little bit at the loudest volumes, but if you never get that loud then the 20-39 is better for you because it goes deeper.

    In reality, if you are not pushing the 20-39PC+ to its limits, then you are fine with that. I was pushing my 20-39CS to its limits, so I upgraded to dual 16-49CS+s Now I can have my cake, and eat it too.
     
  5. steve nn

    steve nn Cinematographer

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    There would be a slight 1-2dB gain around the 25Hz tuning point of the 25-31 ..... In going with the 20-39, you would realise as much as 10-13dB increase and better around the 20Hz tuning point and lower.
     
  6. Chris Huber

    Chris Huber Second Unit

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    Remember the scene in Matrix: Reloaded, where Neo stops the machines with his hand and then falls over? Well, another ship comes to pick them up on the ground. When that thing flys over, does it hurt anyones ears a little bit? There are parts in movies with Heavy Special effects, like Matrix and Star Wars 1-3 that are almost to loud. It's SPLed right, and I can't turn it down because I'll lose that smaller bass hits durning punches and gunfire that are really nice.

    Any suggestions?
     

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