Woo Hoo! Tempest first aid paid off!

Discussion in 'Archived Threads 2001-2004' started by Darren_T, Jul 12, 2002.

  1. Darren_T

    Darren_T Second Unit

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    Used the closed cell foam tape under the driver and ports, replaced the missing allen bolt on the driver and double checked the wiring which was fine. Just the simple foam tape and missing bolt made a HUGE difference. The sub will crank with the amp gain up all the way without reaching xmax...of course I turned it down to half after experimenting. Many much boom boom. This, of course, was before calibrating since I wanted to see what the sub would do.

    Only one problem. When I calibrate my system it takes all the bass out. Very little LFE on The Matrix. Basically once calibrated there is less or the same amount from my 10" sub as there is in the Tempest. Am I calibrating wrong? I'm setting the receiver sub level to 0 and adjusting the sub amp so that at reference level it is putting out 75db and am doing the same for the rest of the speakers...of course I had to adjust some of them on the receiver level adjustments to get them balanced perfectly.

    Basically, when I play the HT at -5 which is quite loud the LFE doesn't shake anything, it's quite subdued...probably as it is meant to be but I like a little thump with my effect. If I crank it up a bit it becomes too aparent.

    Any help with calibration is greatly appreciated so I can judge this thing appropriately. BTW, I have it as a front firing sub, not down firing. I will have detachable legs for using it as a down firing sub later when I have the space for it.

    Darren
     
  2. Griff

    Griff Stunt Coordinator

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    Are you testing the Matrix on Chapter 26? The scene where they enter the building and shoot everything. The proppellar heads song in the background is all bass, if your house isnt shaking, then there is something wrong.

    Have you got your dvd set to outputting to the LFE channel?

    I dont suppose you have a Sony amp, i had the same trouble with some dvds.

    Check the bass settings on the actual amp.

    What is the high pass frequency set too?
     
  3. Pete Mazz

    Pete Mazz Supporting Actor

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    Did you remember to reset your LFE level setting in your processor? It should be set to 0 dB, if not.

    Under "normal" circumstances, if both subs were calibrated, you should not here much difference until a really low bass scene is playing. The Tempest will go down deeper, with more authority. You'll here and feel things you never knew existed in the soundtrack. On the other hand, if your old sub was booming at a certain freq, then you might be hearing the differences there.

    Pete
     
  4. Darren_T

    Darren_T Second Unit

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    Haven't tested chapter 26 yet. I tested the gatlin gun scene in the Helicopter, and the helicopter crash into the building...very little effects with that one btw. I also tested the subway scene where Neo gets thrown up against the walls. No real thunder there either. With my velodyne I got a hit you in the chest feeling with little sound. I expected the Tempest to really kick on that but it did very little with it. Is that as it should be? I'm getting good bass with it turned up but not a ton of SPL. I was expecting chest thumping SPL but might have a poor room for it.

    My LFE is set to 0 and all speakers to small.

    I have heard things I didn't know where there though but thought certain scenes would have it that didn't. It just might be that I'm hearing a more accurate reproduction but I think there still might be some tuning that needs to be done.

    Darren
     
  5. Griff

    Griff Stunt Coordinator

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    What size is your cabinet for your tempest? What is its tuning frequency?
     
  6. Pete Mazz

    Pete Mazz Supporting Actor

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    Was your old sub in the same location in your room as the new one?

    Pete
     
  7. Darren_T

    Darren_T Second Unit

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    I built the Adire vented alignment. The cabinet dimensions are slightly different but I kept the volume to the same 214L taking into account the Polyfil. The dimensions are 22" wide X 24.5" tall X 30" long.

    The subs were tested in the same spot which isn't optimal but is the only place I have...left rear beside the couch.

    Oh, I believe the tuning frequency is 15.4hz.

    Darren
     
  8. Griff

    Griff Stunt Coordinator

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    Your velodyne gave you chest slapping bass, typically the 30+Hz range, whereas your new tempest is pumping out "sub-bass", 15-25Hz range. This is the bass that you can feel but not hear. My suggestion, cut the box in half. Most people want a sub that is as low as possible, when in most cases that it not desired. I am building a 35litre Shiva currently and know that i will get this chest slapping bass due to the cabinet and tuning.

    Anothing option would be to build a low pass filter and have the tempest only abour say 25 Hz.
     
  9. Pete Mazz

    Pete Mazz Supporting Actor

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    Are you using a plate amp?

    If so, you can mod it pretty easily for boost at ~30 Hz.

    Personally, I would live with it for a while to get used to the more accurate bass before changing it. If you raise the tuning to get more "impact", you'll likely bottom it out on those torture scenes.

    Pete
     
  10. Darren_T

    Darren_T Second Unit

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    Yup, I'm using a plate amp. I'll give the sub a chance and try and dial it in a little better. I won't rush into changing anything quite yet. I may build a smaller sealed enclosure also to see how I like that for fun.

    Darren
     
  11. Patrick Sun

    Patrick Sun Moderator
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    I would set the volume level on the plate amp to 1/3 (10 o'clock position), and then use the sub output level from the receiver to calibrate the subwoofer SPL for the room.
     
  12. Jeff Rosz

    Jeff Rosz Second Unit

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    how much polyfill is in your sub?
     
  13. Darren_T

    Darren_T Second Unit

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    I put 64 ounces as the Adire plans called for...

    Darren
     
  14. Griff

    Griff Stunt Coordinator

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    Its your cabinet i tells ya.

    I have had previous experience with this exact problem with tempests.
     
  15. Jeff Rosz

    Jeff Rosz Second Unit

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    i think i read in another of your posts where you used the matt type poly. so did you line the walls with it or just stuff it in there?
     
  16. Darren_T

    Darren_T Second Unit

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    I used the mat type and kind of circled it around the ports then stuffed some of the other kind inside the mat type. I did this for each of the two chamber that have the ports in them. I then placed the remainder of the mat type over the ports loosely. The other two chambers just over the driver are completely bare.

    Darren
     
  17. Robin Smith

    Robin Smith Stunt Coordinator

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    Darren,

    I think we are both experiencing the same kind of feelings. Check my thread that's on a similar subject. Its called:
    "Bass boost disabled and I'm less impressed"

    Basically, I have a 214L sonotube-based tempest sub with the MCM 250W plate amp. The amp originally came with a 4db bass boost at 30hz. I had it that way for four days or so and was mighty impressed with its kick.

    Then I had the resistors changed to mod it for no boost. Over the past few days I have been demoing various movies and am actually less impressed with it now as the kick is gone. It defintely goes lower (which I like), and it is an improvement over my "no sub" situation of before.

    Also, it is more to be "accurately" reproducing the bass, however, there is less of the "exciting" thump I experienced with the bass boost.

    My dilemna has been, I liked the kick of the boost, but want the most accurate sound reproduction. Which should I go for. I am going to guess you are in the same position.

    I just watched Training Day and the sub performed admirably and added a good thump to the various LFE sounds (shotguns in particular).

    I am going to leave it unboosted for the weekend and try to listen to as much stuff as I can. Then I may play around with a 1 or 2 db boost in the low 20's range as a compromise.

    Also, I am trying to find the best way for me to graph its response, so I can see on paper how it is performing.

    Good luck!

    Robin
     
  18. Jeff Rosz

    Jeff Rosz Second Unit

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    try just lining the top, back and one side of the sub. also while calibrating to a reference level, give the sub a couple more dB's.
     
  19. Robert_Gaither

    Robert_Gaither Screenwriter

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    I would buy a freq sweep disc (check Stryke's site it's cheap) and run it to see if your subs are placed such that you have nulls in the 40-60 range. You might need to treat your room, eq, or even relocate your sub. Trust me unless your rooms very large, listening at unreasonable levels, or the subs defective you shouldn't be dissatisfied with it's performance.
     
  20. Darren_T

    Darren_T Second Unit

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    Wow, ok I just set my sub up in a down firing configuration (I built it so I could use it either way) and boy did the SPL increase. I'm now feeling much of what I thought I was missing. Sealing the leaks did a bunch to fix my xmax problem and then adding the feet and setting it up as down firing brought a lot of tactile sensations to the experience. Now, on the Terminator 2 DVD when the gun is fired in the intro it hits me in the chest as it should!

    I wonder if it's just my room or if the Adire Tempest Vented alignment is happier with the floor load of a down firing configuration?

    Darren
     

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