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Wow four of those must be a blast. I really cant even imagine 8 of those like Not's. Someday maybe someone around me will have a pair so I can have a listen.
 

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Lots of shaking going on!!
 

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Discussion Starter #143
Got all four in slow motion

http://www.youtube.com/watch?v=diwXHF3HrWw


The drivers in the right cabinet appear to be perfectly in sync, but in the left cabinet, the top driver seems to have a little more loose suspension?
 

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Discussion Starter #144

Quote:
Originally Posted by edoggrc51 /forum/post/21327028


Quick question for ya, how inert are those cabinets??

There's 9lb's of polyfill in each cabinet, and I can't hear any noise/resonances from the cabinets at all.


In terms of cabinet vibration, you can obviously feel it if you crank it up, but it's MUCH less than any commercial sub I've ever had. My DD-18 had WAY more flex in the cabinet.
 

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Quote:
Originally Posted by lukeamdman /forum/post/21328477


There's 9lb's of polyfill in each cabinet, and I can't hear any noise/resonances from the cabinets at all.


In terms of cabinet vibration, you can obviously feel it if you crank it up, but it's MUCH less than any commercial sub I've ever had. My DD-18 had WAY more flex in the cabinet.

Thanks for the info.



Btw, that slow-mo of all 4 drivers pumping looks WAAAAAY COOL!
 

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What camera did you use for the slow-mo shots and what frame rate?
 

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Discussion Starter #147

Quote:
Originally Posted by Looneybomber /forum/post/21328998


What camera did you use for the slow-mo shots and what frame rate?

Canon 300 HS. The mode is called "super slow motion" and is 240fps.
 

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Cool stuff, they appear in phase to me.


It would be quite interesting to catch the manner in which the surrounds de-form, which I've seen in not's vids. At gig excursions, they pull in asymmetrically.


Always neat to see vids, especially the super slo-motion. So thanks for that.
 

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No doubt your system sounds great, Luke. Thanks for the vids.


I do have a comment on the most recent slomo video of all four subs. I think it may be optical illusion, but depending on where I focus during the video, I find different things. I've thought the top two drivers were equally out of phase with the bottom two drivers, but in phase with each other, when looking at the top of the center speaker. I've thought the top left driver was out of phase with all the others when staring at the midpoint between the two drivers on the right. I've though the bottom right was out of phase with all the others, and significantly, when focusing on the light reflection on the top right driver.


Maybe I'm crazy, but try it for yourself. If it's of serious concern to you, a good way to see would be a direct-on camera view (from the front, equidistant from the stacks) with strong side lighting.
 

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Discussion Starter #151

Quote:
Originally Posted by nube /forum/post/21336389


No doubt your system sounds great, Luke. Thanks for the vids.


I do have a comment on the most recent slomo video of all four subs. I think it may be optical illusion, but depending on where I focus during the video, I find different things. I've thought the top two drivers were equally out of phase with the bottom two drivers, but in phase with each other, when looking at the top of the center speaker. I've thought the top left driver was out of phase with all the others when staring at the midpoint between the two drivers on the right. I've though the bottom right was out of phase with all the others, and significantly, when focusing on the light reflection on the top right driver.


Maybe I'm crazy, but try it for yourself. If it's of serious concern to you, a good way to see would be a direct-on camera view (from the front, equidistant from the stacks) with strong side lighting.

Interesting.


I'm going to put the cabinets side by side and really get the drivers moving.


From what I've seen so far I'm thinking I might have to RMA one of the baskets in the left cabinet.
 

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Not so bad. With only one cut around 38hz and you have a nice curve into the teens. You have the headroom to pull everything down to get it pretty flat into single digits if you want.
 

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Discussion Starter #154




Looks like the HPF was causing that dip around 13hz.


The red line is all HP filters bypassed on the miniDSP.


The green line is a 10hz 48db BW.


The blue line is a 16hz 48db BW.



Why would the 10hz filter cause such a massive drop at 13hz?
 

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Discussion Starter #155
So here's where I am now. The blue line was the 10hz 48db I was blindly running before. The black line is a 10hz 24db LR with EQ in place for 38hz, 52hz, and 64hz.




Who would have thought that such minor changes to the HPF would cause such dramatic changes in the frequency response...
 

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Quote:
Originally Posted by lukeamdman /forum/post/21423762




Looks like the HPF was causing that dip around 13hz.


The red line is all HP filters bypassed on the miniDSP.


The green line is a 10hz 48db BW.


The blue line is a 16hz 48db BW.



Why would the 10hz filter cause such a massive drop at 13hz?

Did you do a loop-through the MiniDSP to verify the results of the filter? It's always a good idea to check to see if the results match the software, or if there is an error in the math.
 

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What version of the MiniDSP are you using and what plugin? This is like what I was seeing on the 2x8, which they seemed to have mostly fixed in newer plugins. However, I didn't see these issues with HPF filters. Only parametric EQ settings.


Something isn't right here. You should do some loopback readings straight through the MiniDSP and see if something is actually going on, or if you're having some measurement artifacts.


The best part is, when I brought this up to MiniDSP, certain members of this community jumped all over me saying how nobody uses MiniDSP for this stuff. Oh well.


Also, if you're making changes, you may run into phase issues if you're only making them to one sub, and not to both. I'm not sure how your setup is.
 

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Discussion Starter #159
I have the balanced 2x4 with the 4-way advanced plugin.


It is strange, since moving the crossover setting up or down by 1hz dramatically changes the curve, and the result makes no logical sense. The parametric EQ appears to work flawlessly though.


I have a XLR going from the one of the sub outputs on my AV7005 to the miniDSP. Output 1 on the miniDSP is going to one amp, and output 4 is going to another. Whenever I make any XO changes I do both at the same time.


I can re-create the same curve with any XO, and even doing one sub at a time has the same result.


How do I go about the loop test you mention?
 
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