Tempest T/S inconsistencies

Discussion in 'Archived Threads 2001-2004' started by Jeremy Stockwell, Aug 10, 2002.

  1. Jeremy Stockwell

    Jeremy Stockwell Supporting Actor

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    OK, I'm new to all of this, but I've been playing around with LspCAD and WinISD trying to fine-tune a sub design. In the process, I was setting the T/S parameters for the Tempest in WinISD since it's not one of their presets (is it? I didn't see it). First, I took the values from LspCAD, but then I was looking at Adire's site and they list different values. Why would this be?
    Such as:
    Re: LspCad says 7.00 ohms, Adire's site says 3.50 ohms
    Le: LspCad says 5.8 mH, Adire's site says 2.9 mH
    Qes: LspCad says .80, Adire's site says .40
    Qts: LspCad says .71, Adire's site says .38
    Xmax: I know that this one is different depending on one way or both ways, but which to I put into WinISD??
    These all seem to be doubled in LspCAD and I'm sure there is a reason for this (??), but I want to make sure I'm putting in the correct parameters into WinISD.
    ***Also*** - This is fair warning to Patrick Sun, Dustin B, Kyle Richardson, Brian Bunge, etc, etc. I'm planning on building a sub very similar to Pat's Sunosub II and will have some questions along the way, I'm sure. But -- trust that I will do my best to search first and bother you guys second. [​IMG]
    Thanks!
    JKS
     
  2. warrick

    warrick Stunt Coordinator

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    Jeremy,

    I'm no expert could one set of values be for a single voice coil and the other for the double voice coils

    Warrick
     
  3. Isaac C

    Isaac C Stunt Coordinator

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    Yup, LspCAD lists the individual voice-coil details while Adire Audio's site presents the parallel voice-coil values.
    [​IMG]
     
  4. Jeremy Stockwell

    Jeremy Stockwell Supporting Actor

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    Thanks for the replys from down under!!

    So does it make any difference which I use in WinISD?

    I'm planning on using an old Pro Logic receiver as an amp to drive the Tempest until I can get something else. It's rated at 100W into 8 ohms, but I'll wire both voice coils of the Tempest in parallel and one channel of the receiver should recognize a 4 ohm load. Sound right?

    JKS
     
  5. Dustin B

    Dustin B Producer

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    I think you'd be better off spliting your sub preout to one of the left and right audio inputs on the prologic receiver (6ch input would be best I would think, but any of the other device inputs should work for this). Then one voice coil off the left main channel and another off the right main channel of your prologic amp. Your driver will get more power and the prologic amp will see a much easier to drive 8ohm load.

    You'll want to use the ones on Adire's website in WinISD.

    And make sure you select seperate sources (VC radio buttons) in the driver config dialog in LspCAD. If you do what I suggest above. If you do what you said, then you'll want to select VC in parallel.
     
  6. Jeremy Stockwell

    Jeremy Stockwell Supporting Actor

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    Dustin,
    I'd really rather do what you suggested, but on the Sonotube link at the top of the DIY section of HTF there a "Wiring FAQ" near the bottom of that page if links that I've read. It says:
    I don't know much about it. Any reason you (or anyone) would disagree with this quote?
    I appreciate your input and answering my question about LspCAD.
    JKS
     
  7. Dustin B

    Dustin B Producer

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    Interesting. I'd email Adire and see what they say. And report it back here.

    I'm not sure why LspCAD would offer seperate sources as an option for the voice coil config if you couldn't do it. And I know I've seen other people on the forum recommend doing so. I don't think I'm wrong, but if I am, better I find out now than go on telling people they can do what they shouldn't.
     
  8. Isaac C

    Isaac C Stunt Coordinator

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    I think that warning was issued under the assumption that some amps are uncomfortable with a load which produces too much opposing current (when no signal is present). I sincerely doubt anyone would purchase less than capable sub amps. Moreover, sub preouts from receivers are mono in nature anyway; unless you'd like to have a stereo sub setup, both channels of your sub amp would be fed with the same signal anyway.
    [​IMG]
     
  9. Chris Carswell

    Chris Carswell Supporting Actor

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    FYI:
    WinISD = you have to load the value in by hand but you get the benefit of the box calculator and vent air speed.

    WinISD Pro= tempest value already loaded for you. No box calculator, port air speed is listed in a graph.
     
  10. Jeremy Stockwell

    Jeremy Stockwell Supporting Actor

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    Dustin,

    I will e-mail Adire and let all know what they say. Thanks!


    Isaac,

    That's a good point about the mono signal. I'll mention that to Adire too.


    Chris,

    That's good to know about WinISD Pro. I'll check it out!


    JKS
     
  11. Patrick Sun

    Patrick Sun Moderator
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    If you're set on using the Tempest, I would not bother with WinISD, just use the Adire version of LspCAD.
     
  12. Dan Wesnor

    Dan Wesnor Second Unit

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    You can run one coil with the other open, one with the other shorted, or both, depnding on which set of T/S parameters you want to work with. Most DVC drivers are meant to be run with both coils inparallel, which increases power handling.

    I would not run each coil from a different amp (or different channels from the same amp). If something damages the voice coil, you run the risk of the coil shorting one amp to the other, which would not be good... Human sacrifice, dogs and cats living together, etc.
     
  13. DanWiggins

    DanWiggins Second Unit

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    Hi all,

    Jeremy, got your e-mail, so I'll answer here...

    The wiring FAQ above is wrong; you can run different signals to different voice coils, and use different amp channels (even different amps) to power each voice coil. Nothing wrong with doing so. Only problem is as Dan Wesnor cautions - catastrophic failure could short the two amps together, but usually what happens is the voice coils open and there's no cross-pollination of amplifier outputs.

    LspCAD lists the T/S parameters of dual voice coil drivers for each individual voice coil. When running both voice coils (whether in parallel to a single amp channel, or seperate to different amp channels), it correctly reduces the proper T/S parameters to account for the wiring method.

    Dan Wiggins
    Adire Audio
     
  14. Jeremy Stockwell

    Jeremy Stockwell Supporting Actor

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    Dan,
    Thanks for your time. That's exactly what I wanted to hear.
    Dustin,
    You were right! Thanks for your help.
    JKS
     

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