Tuning the B4+. Man, I love this thing.

Discussion in 'Speakers & Subwoofers' started by Gabriel_Lam, Mar 21, 2004.

  1. Gabriel_Lam

    Gabriel_Lam Screenwriter

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    I've finally gotten the chance to play with my B4+ a little. I tell you, the wife has a baby, and everything changes.

    A little background:

    I'm in an 18x22 room (about there), with an 8' ceiling, with a big archway on one corner and corner placement. I just redid much of the room, and I think I'm going to stop for now, so that I can actually enjoy it for a bit.

    Here's the front (click for bigger picture):

    [​IMG]

    The center channel speaker is behind the bottom blackdrop area in the screen.

    When I ordered the B4+, I was unsure of what color to get until I found out they can custom colormatch. No question, this is definitely the way to go.

    I sent them one of my surround speakers (Aurum Cantus Leisure 2 Deluxe in Rosewood), and they sent me some samples of what they did. You really have to see it in person to appreciate what a piece of work that subwoofer is. The colormatching was excellent.

    Again, click for full sized picture:

    [​IMG]

    Here is the equipment rack, near the archway (click):

    [​IMG]

    From top to bottom:

    Gefen 4x1 DVI switcher, hidden (from our good friends at BetterCables, a HTF sponsor)
    Voom HDTV box
    Lexicon MC-8 Balanced
    Vinc Bravo D1 DVD player with DVI output
    LiteOn 5001 DVD+R/RW burner
    Behringer Feedback Destroyer (now has 1" feet for some extra room off of the K2)
    Crown K2 Amplifier
    Panamax 4400 20-amp power distribution unit
    Panamax 4400 20-amp power distribution unit
    Panamax 5300 power filter
    Adcom GFA-7807 7-channel amp

    The K2 & BFD finally came and I started tuning. I started with 3 plugs in, but settled on 2 plugs.

    I'm a COMPLETELY n00b at tuning this thing, but after hours of fiddling (and frantic icq messages to a friend), I arrived at this:

    [​IMG]

    It sounds INCREDIBLE. I can't believe what a sub this B4+ is.

    I know there's still more to tune out of it, so if you have suggestions, please chime in! I'd greatly appreciate it.

    I think I have to start strapping stuff down...
     
  2. Mitch Stevens

    Mitch Stevens Supporting Actor

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    Damn!

    I can't wait to get my B4+ which should arrive here either today or tomorrow. I'm going to have so much fun tuning it, just as you are now.

    I have a question though. I thought it only came with TWO port plugs. In the picture, I see 3.

    I thought, that if you plug one port, it tunes it down to 20hz, and another port plugged, it tunes it down to 16hz. A third one, and you should be getting 12hz, but I wasn't aware that the B4+ could go that low.
     
  3. Gabriel_Lam

    Gabriel_Lam Screenwriter

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    Hmm, it comes with 3, or at least mine did.

    They don't mention what the tune is with 3 ports plugged, in the manual. I'm guessing you're right though, since it does say about 4hz per plug.

    You know... my sub is missing the little SVS emblem! I just noticed that. [​IMG]

    [​IMG]
     
  4. Mitch Stevens

    Mitch Stevens Supporting Actor

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    I have a quick question, Gabriel,

    It seems by your chart that you are only getting 100 dB at 16hz. Now, don't get me wrong, that's a lot, but looking at the online B4+ manual, it clearly states that with 2,500 watts (such as the K2 amp that you're using to power it) that it can hit 122 dB at 16hz.
     
  5. JohnSmith

    JohnSmith Supporting Actor

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    The above graph is used for frequency response chart- not extreme SPL's during use.

    Sine wave are used to plot the graph. You don't want to playback sinewaves at loud levels.
     
  6. qualen

    qualen Agent

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    beautiful sub!
     
  7. Dustin B

    Dustin B Producer

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    I typed this and decided not to post it twice already. Sort of picking an arguement, but I just don't get it.

    Why do so many people buy the mighty B4+ and then cripple it by plugging the ports?

    The B4 is underported with no ports plugged (granted the output four 4" ports can produce is sufficient that it simply doesn't matter for 99% of users). However, plugging 2-3 ports basically limits your sub to the output of a PB2+ in the last octave (with the exception of the very bottom of the last octave). I can justifying plugging one port, maybe, but that's it.

    A 25hz tune is sufficient for ~95% of movies. A 20hz tune is sufficient for all movies. A 16hz stock tune is nice for ~1% of movies and some specific music pieces. A 12hz tune has no benefits with any source material I'm aware of.
     
  8. Allen Marshall

    Allen Marshall Supporting Actor

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    howd you make/get that chart. Im startin to get jealious with all these waterfall and frequency charts up down and all around, there cool.
     
  9. Edward J M

    Edward J M Cinematographer

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    Dustin = the voice of reason once again. I agree 100%. Plugging one port on the PB2 series is all I ever needed, and that was for organ music with genuine 16-17 Hz content. Otherwise, let the sub breathe deep.
     
  10. John Doran

    John Doran Screenwriter

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    when i first got my B4+, i tuned it to 20hz, and then a while later threw in another plug to get it to 16hz, and i can tell you without qualification that the 16hz tune gave me what to my ears (and chest) was a much fuller bass sound/experience. there was just no comparison.

    what's more, since i listen to movies at reference and beyond and have never been troubled by (a) port-noise, or (b) bottoming the sub, and, as i've said, actually much prefer the sound of the 16hz tune, i'm not sure how those two plugs can reasonably be considered a "crippling" of my B4+, at least in my circumstances.
     
  11. Gabriel_Lam

    Gabriel_Lam Screenwriter

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    Dustin: Great suggestion. As soon as I get a chance, I'll play around with the 1 plug and 0 plug tunes. Unfortunately, my wife has reached the limit of my tweaking right now.

    My original thought was that since the sub, which most people use in a 6000+ cubic foot room, was going in my 3100 cubic foot room, I didn't need max output, so I could benefit more from extension. Hopefully, I'll be able to experiment with it more.
     
  12. Dustin B

    Dustin B Producer

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  13. Zack_R

    Zack_R Stunt Coordinator

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    Dustin,

    Are those graphs anechoic or do they include room gain?

    If the former with one port plugged your graphs seem to be showing ~107 db at 15 hz. With room gain they'd likely be pushing 117 db or more at 15 hz depending the size of the room. If this is the case, then it would seem that a little equalization (if needed, again depending on gain from the room) should satisfy all properly spec'd movies at reference level.

    I don't disagree with your thinking but in this instance we are not talking about a single driver subwoofer. Most user reports of single driver woofers (myself included), usually don't have enough extra headroom to plug more than one port or even one port. This is the case for my CSU in 7500 cubic feet. Now if I had four CSUs I think I could spare plugging a port for greater extension and still have gobs more output than the single CSU could provide with no ports plugged.[​IMG]
     
  14. Wayne Ernst

    Wayne Ernst Cinematographer

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    Gabriel,

    Your B4 is gorgeous! I love how well SVS was able to match the stain color of your existing speakers.

    Thanks for sharing your home theater progress. In your rack, my eyes were drawn to the Crown K2 amp.
     
  15. Dustin B

    Dustin B Producer

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    It's just a computer model, not real world data. What I did was use the free version of LspCAD Adire has on their site to model 4 Adire Shiva's in a 280L enclosure with four 4" ports tuned to 25hz and enough power to get the drivers excursion up to a little over 40mm (well past a Shiva's limit but about what a db12 driver would be capable of). The different graphs are just changing the number of ports but leaving everything else alone.

    The top graph is the anechoic response and the second graph is the port air speed of the highest output the sub can give. Ideally you want the port air speed to stay under 25m/s. With one port plugged though you're pushing over 40m/s at the bottom of the last octave and EQing that range up won't make the port airspeed any better.

    Doesn't matter how many drivers you have, around tuning output is limited by the porting. And if one or two 4" ports is providing you will enough clean output, the B4 was way more sub than you needed.
     
  16. ArtH

    ArtH Stunt Coordinator

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    Gabriel

    What colour is your B4?? Did you have to pay extra for the custom match??
     
  17. Gabriel_Lam

    Gabriel_Lam Screenwriter

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    ArtH: The color was a red, matched to some rosewood speakers. Click to see the full sized pict:

    [​IMG]

    This might give you a slightly better idea.

    The picture on the left is a Rocket RS750, from AV123. As you can see, it's slightly more orange than the Aurum Cantus in the center. As you can see, the Aurum Cantus has less grain, and a deeper red color. On the right is an Onix Reference 1 monitor in birdseye maple. Click for full sized image.

    [​IMG]

    The color matching is a bit extra, and it does take a little more time, but well worth it. If you're getting a sub of this quality, you may as well get it exactly like you want it.
     
  18. Bhagi Katbamna

    Bhagi Katbamna Supporting Actor

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    Wow, nice finish. On all those speakers.
     
  19. ArtH

    ArtH Stunt Coordinator

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    I love the birds eye maple....Beautifull...
     

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