Should I do EBS w/ plate amp? *rumble filter*

Discussion in 'Home Theater Projects' started by Scott Simonian, Dec 7, 2004.

  1. Scott Simonian

    Scott Simonian Screenwriter

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    Hey guys.

    Situation. I have a 214liter vented Tempest and was considering adding a second. I have an extra 250w plate amp from PE I got on sale and want to put it to use. The plate amp I have now is the same thing except it is the Adire brand. I know that both have a built-in rumble at about 18hz.

    Now, I was thinking of ditching the 214 liter cab for two (2) 320 liter cabs, for an EBS alignment. I have been playing with Unibox and like the extra SPL in the teens. But if there are the rumble filters in place will I lose the SPL gained from the new alignment? Is it worth it?

    I was thinking of e-mailing Dan Wiggins direct but I don't want to intrude on him. I am sure he is very busy. And I bet someone here should know.

    BTW- I am finally going to get a BFD. I am so excited! Can anyone recommend what cables I should get? If so, from Parts Express. I have no idea what cable I should buy.

    Cannot wait til Christmas!
     
  2. DanWiggins

    DanWiggins Second Unit

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    You won't really lose SPL - you'll lose some extension, but not too much. I'd say give it a shot and see what you think, since it's pretty easy to change the rumble filters on the amp.

    Dan Wiggins
    Adire Audio
     
  3. Scott Simonian

    Scott Simonian Screenwriter

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    Sure. Thanks, Dan! You are so helpful. Are the plans to change the the rumble filter on the ADA250 the same as the ones for the Parts Express amp? I know the ADA250 has about 1db of boost in the 25hz area and the PE amp that I bought was the one with no boost. It would be great if I could get the rumble to start working just under 16hz. It really isn't super important but that would be cool if the subs were flat to 16hz.

    What I am woried about is if I will lose the shelf in the
     
  4. GrahamT

    GrahamT Supporting Actor

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    Scott,

    I have the EBS with the ADA250 and BFD and it is flat to 15. Rather than monkey-ing with the amp you can add some boost with the BFD. I still have plenty of headroom too.
     
  5. Scott Simonian

    Scott Simonian Screenwriter

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    Hey, Graham. I just took a measurement of my room. I haven't mearsured the room I have my HT in yet. I found that the response trails down below 25hz. Just like the sims show the vented Adire alignment at. I am a little disappointed that the room gain didn't flatten the response down there.

    Do you think when I make the switch to the EBS alignment I might gain the extra 2-3 decibel between 16hz and 25hz?
     
  6. GrahamT

    GrahamT Supporting Actor

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    I dont know for sure. My sub is about the same volume at 20 as it is at 70-100 Hz. From 30 to 70 it is a mess because of room problems(pre EQ).

    If you get the BFD you can add EQ to the bottom end on the Tempest. The sub is very efficient.

    I found that modelling in LSPcad came pretty close to the general response of the EBS in room.
     
  7. Scott Simonian

    Scott Simonian Screenwriter

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    I re-measured my sub tonight. This time I turned the cab one-hundred eighty degrees. It is corner loaded but now the ports are closest to the walls and not the driver. The response went up about a decibel or two below 25hz. Good to know. Also, when I posted my last comment I was not getting measurable output below 16hz. Now I am. Measurable to 10hz. Great. Now I just have to wait it out till Christmas. Then I'll have my BFD and (hopefully) a second Tempest.
     
  8. Scott Simonian

    Scott Simonian Screenwriter

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    Not sure if anyone is still going to reading this post but I have a question about the EBS Tempest design and I thought it would be appropriate if I didn't start an additional thread about it.

    I am going to build the EBS Tempest design to Adire spec except for one thing. I wasn't happy with the amount of air movement in the vents. Even with 4" flared ports the air speed seems high. I am using Unibox and I modeled the same cab size and with 250 watts. I tried a 6" vent and I liked the way it modeled. It isn't too big either, only 3 or 4 inches longer than the 4" flared ports.

    Will I have to resize the cab for this approach? I figure I could save some money by using PVC pipe instead of spending $50 for four 4" flared ports.
     
  9. GrahamT

    GrahamT Supporting Actor

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    Since I have built two EBS's maybe I can help. There is NO port noise at all with this design, that is why I chose it. Personally, I would be worried about chuffing (because of the edges) with the straight port but I haven't tried a 6". It will fit in the same location and probably has the same cutout as the flared 4" so you could probably switch later.
     
  10. Scott Simonian

    Scott Simonian Screenwriter

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    No chuffing, huh? I figured that much but when I would model the alignment in Unibox the air speed is about as fast as the air speed for the Adire alignment that uses two three inch flared ports. But if you say so I would believe it. How hard do you drive your sub?

    BTW- I am only considering this option because I could save some money. I really do not think that port air speed or any "chuffing" will be noticable. If I have to purchase two pairs of 4" flared ports from PE it will run a good $50. Just for the ports! That is why I am considering using PVC. If it isn't worth it or I am better off with the flared kit, then so be it.
     
  11. GrahamT

    GrahamT Supporting Actor

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    I drive it to about 110 dB peaks during movies but I have gotten over 120 at the listening position.

    At the deep frequencies there is no chuffing at all, and I hate chuffing. What is noticeable is that the driver reaches it's limits at about 30 Hz I guess. I haven't bottomed it but you can tell that it is straining without the support from the vents. This is only noticeable at painfully loud levels though. At more sane levels with 105-108 dB peaks the is no sign of stress at all.

    Those ports do get expensive. I would fire off an email to Adire and see what they say about the straight port. Maybe it will work fine.

    I hope you have a strong back because this sub is berry heavy. Make sure the legs are very strong.
     
  12. Scott Simonian

    Scott Simonian Screenwriter

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    Oh? Unfortunatly this sub will probably weigh more than I do. I am skinny I guess. :b I have to pick up a whole one and stack it on top of the other. Oh boy! I'll bring some friends over for a hand. [​IMG]
     
  13. GrahamT

    GrahamT Supporting Actor

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    Yes bring friends, you will need 4-6 people to lift it straight up because it is akward. If you make the sub out of BB ply it will save some weight. Ever tried to pick up a 4X8 sheet of 3/4" MDF? Damn Heavy. I used two full sheets and then add 30 pounds for the driver and amp. Make the legs integral like the ones here.
    http://quicksitebuilder.cnet.com/ima...target=tlx_new
     

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