X-over for Acoustic Visions Tumult sub?

Discussion in 'Home Theater Projects' started by Jeffrey Stanton, Oct 14, 2003.

  1. Jeffrey Stanton

    Jeffrey Stanton Stunt Coordinator

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    I am getting ready to BFD my custom Acoustic Visions Denali. Well, it's basically a Denali. 24" Acoustic Visions cube with two 18"/2200 gm PRs, Tumult driver. It differs from the "stock" Denali in that I had Kyle leave off the Keiga plate amp and am using a Mackie 1400i pro amp instead. I am not quite ready to BFD it as I still need to get a balance box to correct for the -4 dBu to +10dBv difference between the pro and home units...

    Since I'm going to be running the sub with Klipschorns, I think it might be a good idea to use a 50 Hz low-pass FMOD to feed the LFE to the BFD. My reasoning is that the 50 Hz low-pass will allow the sub to deal only with that last octave and 1/3 (16-50 Hz) where the k-horns are rolled off.

    It was suggested that a 50 Hz FMOD would "create a gap" between 50 Hz and the 90 Hz Yamaha LFE X-over point. However, I think that may be exactly what's needed, as I do not necessarily WANT the sub outputting anything which will interfere with the K-horns bass output, and possibly complicate EQing (BTW, I'm running all speakers set to LARGE, including rear surrounds...KLF-30s).

    One alternative, of course, is to run the LFE unfiltered to the BFD, and use the BFD to tailor the room response and tame the K-horn/sub bass interactions. Which seems less straight forward and more complicated, to me anyway...

    So my idea would be to use the sub with the 50 Hz low-pass for the lowest octave only and let the K-horns take care of themselves.

    Does this sound like a workable way to set-up the sub? Would anyone have any suggestions as to how to do this better? [​IMG]
     
  2. Dave Milne

    Dave Milne Supporting Actor

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    Jeffrey,
     
  3. Scott Simonian

    Scott Simonian Screenwriter

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    I think some Yammy's have an option of adding the LFE to the mains. It something like "Main+LFE", or something like that.

    Jeffrey - Are you using a menu selection like this in your bass managment? If you are, you should set it to LFE only.
     
  4. Kyle Richardson

    Kyle Richardson Screenwriter

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    Skip the FMOD and use the receiver to manage the bass.
     
  5. Brian-K-Owens

    Brian-K-Owens Stunt Coordinator

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    You can also use a couple of bands of the BFD if you go ahead and get it. . . .

    I use 2 bands to further the shape of my 100Hz LP LFE output. Works GREAT!!!

    Brian
     
  6. Jeffrey Stanton

    Jeffrey Stanton Stunt Coordinator

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    Dave, Scott, & Kyle:

    One very important thing I forgot to mention in the above description of my planned sub set-up: I'm sending LFE to the K-horns ALSO. Thus with the 50 Hz low-pass FMOD I would not be creating a "gap" between 50 Hz and the 90 Hz Yamaha LFE x-over point, because the K-horns would be handling LFE also. I pretty sure K-horns are good to 50 Hz! My idea is to let the K-Horns handle LFE also (the "BOTH" setting in Yamaha bass management) and to only use the sub to achieve a flat response as the K-horns roll-off, from 50 Hz to 16 Hz.

    Can somebody tell me why this is not a good idea (or if it is??). It sounds completely logical to me, but I am no expert and am still learning, which is why I'm asking for opinions from more knowledgeable folks.

    So my question is why shouldn't I send LFE to the mains (with LARGE setting) and use the sub to achieve flat response from the roll-off point of the K-horns on down to 16 Hz...

    I'm already added a subwoofer for my center channel and running it LARGE, and like the results. I also plan on running my Klipsch KLF-30s LARGE and adding subwoofers to them also. See what I'm getting at? Instead of the usual "set 'em all to SMALL and LFE to sub only" routine, I am hoping to get a fuller sound by having subwoofers on the surrounds and center channels. The Denali would be used for deep bottom trolling only, to pick up the LFE the other speakers aren't as adept at. [​IMG]

    Thanks,

    Jeff S.
     
  7. Dan Hine

    Dan Hine Screenwriter

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  8. Scott Simonian

    Scott Simonian Screenwriter

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    I think if you slapped the LFE on the main channels (along with their bass) you would lose a significant amount of headroom. Those Klipschhorns will be working [rant]very[/rant] hard. IMO, this doesn't sound good at all.

    Jeffrey, I am also someone who enjoys full-range all around. Who doesn't? I don't beleive in the, "set all speakers to small and let the sub do all the work." I always thought that was a bad idea.(Bass quality-wise)

    I wish I could replace all my shitty KLH speakers for some sealed 281's each crossed over with their own Adire 75L DPL12. That would be a cool full range setup!
     
  9. Jeffrey Stanton

    Jeffrey Stanton Stunt Coordinator

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    HI Scott:

    Scott Simonian: "I think if you slapped the LFE on the main channels (along with their bass) you would lose a significant amount of headroom. Those Klipschhorns will be working very hard. IMO, this doesn't sound good at all."


    Actually, I have thought about that angle, using small settings AND NOT sending LFE to the sub in order to make it easier on the main amolifier. However, I've got an honest 130 watts/channel to power 104 dB sensitive speakers (the Klipschs). With any other speaker I'd say "yeah that's probably the case."

    But it hardly takes anything to drive those Klipschorns to intolerable volume...for movies I can't turn it up past the 9 o'clock position before things get painful (and hence the phrase "Klipsch'll hurt you before you can hurt them")...in other words, I think I've got the headroom to spare with 130 watts/channel.

    thanks for your response and I will keep that in mind. I have not heard any positive response yet towards this sort of set-up (which is kind of what I expected) BUT I did find someone on the Klipsch Forum who does the EXACT same thing I am proposing to do, and says it works great for his system. So I am not the only heretic out there it seems.

    But even the builder of the sub is recommending the "Standard Approach", so I will probably try it both ways onces I get my Stryke Bass Zone CD. I will see what sounds best from empirical evidence, as all this so far is pure conjecture. What sounds good for one system does not go for every other system.

    The last thing I want to do is use some settings just because every one else is....

    Thanks,

    Jeff S.
     
  10. Kyle Richardson

    Kyle Richardson Screenwriter

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    Jeff, your last post hit the nail on the head. Try several ways and see which sounds the best. We can only speculate on the forum, but the real tests comes from actually experimenting with your setup.

    As others have pointed out, making your Klipsch's run full range will put more strain on your amp but you counter with a good argument about using a quality amplifier with very effiecient speakers. The only thing that has not been mentioned is bass cancellations with bass eminating from so many sources and that is something you can test for when you receive the test CD and using an SPL meter.

    Try it and let us know which way works best.
     
  11. Brian-K-Owens

    Brian-K-Owens Stunt Coordinator

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    "The only thing that has not been mentioned is bass cancellations with bass eminating from so many sources"

    Another good point Kyle. I learned this from the Madisound forum. I was running my Rhythm's as "large" with my 1803 sub, but quickly learned that the bass was actually a ton better when I removed the bass from the rhythm's and let the 1803 take over by itself.

    I actually sealed my Rhtyhms (per George's instruction), and use a 50 Hz HP F-Mod instead of the "small" setting on the processor.

    Works great and sounds great to me!!!
    Brian
     
  12. Jeffrey Stanton

    Jeffrey Stanton Stunt Coordinator

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    Brian-K-Owens: "The only thing that has not been mentioned is bass cancellations with bass eminating from so many sources"


    Hey there Brian:

    I know there are potential cancellation problems once you have more than one subwoofer in more than one place in the room...that's where I was hoping to use the BFD on the Denali, to correct for any such peaks generated by those multiple subwoofers.

    Since the Denali will be by far the most potent sub of the lot, it seems reasonable to me that with the BFD on it I should be able to smooth out any room peaks generated from multiple subs PLUS contributions to peaks from any LFE sent to the mains as well...

    Does this sound reasonable??

    BTW, I've already got the BFD, but haven't found a way to use it yet...used my amp's internal test tones on the Denali, from 35 Hz to 100 Hz and FOUND NO PEAKS!!!...98 db, uncorrected, +/- 2dB or better, all the way).

    need stryke bass zone test disk....(say like Homer S.)

    Thanks,

    Jeff S.
     

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