LT spreadsheet question with Uber15

Discussion in 'Archived Threads 2001-2004' started by Brad Dixon, Aug 5, 2002.

  1. Brad Dixon

    Brad Dixon Stunt Coordinator

    Jan 10, 2002
    Likes Received:
    linktranadv28.11 for excel is the spreadsheet I'm trying to use. I'm confused by the EQ Information box. It asks for "power applied" and the popup says "Enter power applied that will be multiplied by the EQ". What value do I put here? Using a Qsc830(think that's the model) amp as an example for the amp info...
    I enter 800w for amp rated power box and put 200w in the EQ power box. This gives a peak spl 108.61dB for an 80l box with a target Fsc of 15hz and target Qtc of .57. Also enabling subsonic filter at 16hz(Q of .8).
    This gives a max excursion of 17mm at 15.5hz. From reading the data, I think anyway [​IMG].
    Now if I'm looking at this correctly it takes 800w in the power applied box to reach full excursion but an amp capable of handling 3000w? This is assuming all else stays the same in the worksheet.
    Sorry if this seems dumb, I'm just trying to follow along with some of the posts and want to double check that I'm not to confused.
  2. The Rated power box is how much your amp can put out at the specified load (Ohms).

    The applied power is the amount of UNEQ'd power you applied. Let me clarify what this means and it will be all happy=)

    If you want a 3db boost, you must double the power. a 10db boost needs 10x the power. lets say that you design a linkwitz transform that has up to 10db of gain. If have an 800watt amp, you can only apply 80watts in the Applied power box otherwise you will reach max power at the 10db boost area.

    Something to remember is that it is common for the lower frequencies not to be at 0db reference. 5 and 10db below the rest of the disk track is common.

    Hope this info helps clarify everything

    BTW, what Driver and Volume are you modeling?

    Edit:..helps to carefully read the thread title=)
  3. Brad Dixon

    Brad Dixon Stunt Coordinator

    Jan 10, 2002
    Likes Received:

  4. On the Frequency Responce graph, the BLUE line is what is ultimately important for what you are talking about. It is the sum of the subsonic/buffer filter and the LT circuit. All you have to remember is that the more gain you see in this blue line, the lower the ultimate headroom will be. As you mentioned the TARGET Fsc and Qtc will dictate how much gain you will see in the blue line.

    I personally would just use the buffer filter and not addan additional filter. I ESPECIALLY would not want to use a second order filter because of the high group delay it yields. THe added group delay doesn't really show up till 30hz or so, so YMMV.

    HopeI didn't confuse you

    Note: If you plan on stuffing the box, use UNIBOX to model the driver for you and use the resulting QTC and Fb (Fsc) and select measured box in the Box Information box.
  5. It doesn't when I double the # of drivers. Are you just changing the # of drivers, or also the volume and applied power?
  6. Do you have the newest version of the sheet?

    There could be glitches somewhere, but I don't think there are otherwise it would have been broughten up long ago. You may hae an older version.

    ..let me know and we can go from there.

    likewise, just model one driver for the meantime. a66 db for the other half if you are adding another driver in equal volume with equal amplification.
  7. Beta Version 0.9-28.11 - Updated Sept 10th 2001

    is this the one you have?
    kinda confusing with the version being 9-28 and the update on 9-10
  8. Very odd. I have that version recently downloaded. WHen I double the drivers and keep everything else the same, the excursion goes down as predicted. IIRC, the workbook is not protected, so you may have put a value into a critical field and messed the whole thing up. Geez are more trouble than good [​IMG]
    try redownloading it and let me know if the problem is fixed
  9. Jack, any luck with the re-download?
  10. Vd is calculated from the product of the 1-way xmax and the calculated Sd. i wanted to have it so Sd was manually entered instead of calculated from driver diameter, but it didn't happen. You can actually manually enter Sd and erase the simple formula without messing anything else up.
  11. Brian Bunge

    Brian Bunge Producer

    Sep 11, 2000
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    I thought Vd was Sd * Xmax peak-peak. Is that incorrect? I'd think you'd use the full stroke of the driver.


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