svs ultra 16-20 hz ??

Discussion in 'Archived Threads 2001-2004' started by ShaneH, Jul 27, 2001.

  1. ShaneH

    ShaneH Stunt Coordinator

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    What is the ultra tuned too? if it is 20 hz is there going to be a 16 hz version (Ron,Tom)? Also just wondering if you can hit reference bass with dual 16 hz subs , which i think you can in most rooms with svs, why do most ppl prefer the 20-39's ? I know the 20-39's play a little louder. Is it just a personal preference, lack of under 20 hz material , or that the 16-46's are a shade under reference. Or that some ppls reference is louder than others, you know who you are.
     
  2. Tom Vodhanel

    Tom Vodhanel Cinematographer

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    >>>What is the ultra tuned too? if it is 20 hz is there going to be a 16 hz version (Ron,Tom)?> Also just wondering if you can hit reference bass with dual 16 hz subs , which i think you can in most rooms with svs, why do most ppl prefer the 20-39's ?
     
  3. John Gates

    John Gates Second Unit

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    Shane,
    I bought dual 20-39's, and for me it was a cost issue. If cost was equal, I probably would've gone with the 16-46's, but I was betting I'd get most everything for lower cost with the 20-39's, so that's the route I took.
    John
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  4. ShaneH

    ShaneH Stunt Coordinator

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    Wow those plugs sound like the way to go, thats an aewsome idea. I've been subless since I bought my system, making due with towers (34 hz), and would have bought one of your subs a long time ago if it wasnt for the hideous canadian dollar. I think I'm gonna have to try a cheap diy project over a few months , and look into a ultra and samson long term. Thx for the info and quick response Tom, continued success.
     
  5. John_P

    John_P Agent

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    ShaneH,
    If you are trying to decide between the 20-39 or the 16-46, I have to agree with Tom, reviews (published and unpublished), have swayed more people to the 20-39's. I had purchased dual 16-46's with the samson amp and always wondered if the 20-39's would have been a better choice. So, I purchased 2 20hz custom ports from Tom. Now understanding that I am no expert and didn't take any actual readings, but when I listened to the subs with the custom ports, the bass didn't seem as full or enveloping as with the standard 16-46 ports. I had a friend listen as well, and he immediatly could tell the difference. We were listening to the opening of Lost in Space. Now like I said, this was not a scientific test, but I now have 2 custom 20hz ports sitting in a closet. Just thought I'd chime in.
     
  6. Jack Gilvey

    Jack Gilvey Producer

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    Not to be nitpicky, but a 16-46 custom-tuned with a shorter port to 20Hz will not have the same response as a 20-39. It will actually have a less flat response, with a hump at tuning due to the larger box.
    This is quite different from the "port-plugging" method Tom mentioned above. The Ultra is already tuned flat with 3 ports. Plugging one or two merely lowers the tuning point, creating a shallower rolloff toward the new Fb, and lowering the "Q" of the enclosure (a good thing). I believe this is similar to what Dr. Hsu does with the VTF-2, but I'm not sure what the tuning points are.
    [Edited last by Jack Gilvey on July 27, 2001 at 02:28 PM]
     
  7. John_P

    John_P Agent

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    Jack,
    Please explain.
     
  8. Tom Vodhanel

    Tom Vodhanel Cinematographer

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    Jack's saying a 16-46 tuned to 20hz, won't have the exact same frequency response as a 20-39 tuned to 20hz. The overall response signature will be very close though. Put it this way...if you try out a 16-46cs tuned to 20hz..and you prefer the stock 16hz tuning...there's about a 99.9% chance you'd prefer the stock 16-46 to a 20-39cs [​IMG]
    On most source material...trying to tell a 20hz tuned 16-46 to a 20-39 could be very tough.
    TV
     
  9. John_P

    John_P Agent

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    Tom,
    Like I said to Shane, It was a very un-scientific test, but it was well worth the 50 or so dollars spent. It did confirm, in my mind anyway, that the 16-46's were for me. The only problem now is that I watch too many crappy movies because they seem to have the best sound!
     
  10. Jack Gilvey

    Jack Gilvey Producer

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    This is really DIY forum stuff, but basically, a certain enclosure volume has an optimal tuning point for "maximum flatness". Each of the three SVS models have been carefully tuned with a specific volume and length of port to achieve flatness (-3db, maybe) to their respective Fb's, or tuning point of the box. By increasing enclosure volume for a given tuning point, or just raising the tuning point (putting a 20Hz port in the 16Hz box), you actually increase sensitivity at tuning, causing an increase in output around tuning.
    [​IMG]
    Here, I approximated (very approximate)what the graphs for theoretical subs with similar tunings models might look like. The actual responses of the models are flatter, I think, and, as a result, the hump might be a bit more pronounced. You see a 5.1 cu.ft box tuned to 16Hz, the same box tuned to 20hz, and then a 3.75 cu.ft. box tuned to 20Hz. The hump in the response, and the sharper "knee" in the curve, in #2 is generally regarded as undesireable. #3 would probably have better transient response.
    You can also see, however, how the custom tuning would benefit someone who feels there's not enough output at 20-30Hz with the 16Hz tune: 2-3 more db in that range with just a change of port. Again, these are just my approximations based on generic boxes with certain tuning points. Actual differences are not necessarily represented.
    My whole point is that an actual 20-39 will probably sound better than a custom-tuned one, and that Tom knows what he's doing with these things!
    [Edited last by Jack Gilvey on July 27, 2001 at 03:28 PM]
     
  11. Jack Gilvey

    Jack Gilvey Producer

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  12. Dzung Pham

    Dzung Pham Second Unit

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    Well my dual 20-39PCs are down -4 dB at 17.5 Hz and -12 dB at 15 Hz. However, these are UNCORRECTED values off my Radio Shack digital SPL meter. If the correction charts are correct for my meter, this equates to being flat out to 15Hz. So because my room is fairly small (although it opens up to a rather large area), I definitely still hear/feel most Sub 20 Hz material without having to use the larger models.
     
  13. Thomas_Berg

    Thomas_Berg Screenwriter

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    the anonymous quasi-newbie silently asks, "What's SPL?"
     
  14. John Geelan

    John Geelan Screenwriter

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    Sound Pressure Level
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  15. Ron Stimpson

    Ron Stimpson Stunt Coordinator

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    Since I'm sure the next question will be: "What compensation chart?"
    I post the following. There are several versions of this but the bottom line is (as indicated above) the Radio Shack SPL meter is a great tool but rapidly loses sensitivity down low.
    Use these figures to determine what your sub is really doing in your room. As you can see, some folks with a sub "only" rated to 20Hz are able to get response far below that with good room placement.
    10Hz add 20
    12.5Hz add 16.5
    16Hz add 11.5
    20Hz add 7.5
    25Hz add 5
    31.5Hz add 3
    40Hz add 2.5
    50Hz add 1.5
    63Hz add 1.5
    80Hz add 1.5
    100Hz add 2
    125Hz add .5
    So Dzung, other than the covers you are pretty pleased with this performance? That's about as flat as flat gets. Crank them up and feel what 15Hz is like. Toy Story 2 goes there and then some. That logo flyover during the intro is just plain astounding.
    Ron
    [Edited last by Ron Stimpson on July 27, 2001 at 10:06 PM]
     

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