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Sealed dual LMS 18" 5400 build - Page 6

post #151 of 176
Thread Starter 
Quote:
Originally Posted by nube View Post

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.
post #152 of 176
Thread Starter 
First time using REW, and man the acoustics in my room stink!

post #153 of 176
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.
post #154 of 176
Thread Starter 


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?
post #155 of 176
Thread Starter 
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...
post #156 of 176
Thread Starter 
EQ differences:

post #157 of 176
Quote:
Originally Posted by lukeamdman View Post



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.
post #158 of 176
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.
post #159 of 176
Thread Starter 
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?
post #160 of 176
Thread Starter 
I assume the loop test is:

Sound card output -> miniDSP -> Sound card input?
post #161 of 176
Quote:
Originally Posted by lukeamdman View Post

I assume the loop test is:

Sound card output -> miniDSP -> Sound card input?

Yes, this is correct.
post #162 of 176
Make sure you're running the latest plugin. If you're still having the issues, you're basically running into the same problems I did with the 2x8. No fun there.
post #163 of 176
Thread Starter 
Quote:
Originally Posted by notnyt View Post

Make sure you're running the latest plugin. If you're still having the issues, you're basically running into the same problems I did with the 2x8. No fun there.

I just checked and the release date on the plugin is 2/17/11, and I bought the miniDSP around September I think. File name is also the same.

How did you get around your issues with the 2x8?
post #164 of 176
Quote:
Originally Posted by lukeamdman View Post

I just checked and the release date on the plugin is 2/17/11, and I bought the miniDSP around September I think. File name is also the same.

How did you get around your issues with the 2x8?

They published a newer plugin that had fixes in it and a different filter type for low end EQ. Go update your plugin to one that's newer, as I believe they have published newer ones since then.
post #165 of 176
Thread Starter 
Using OC 703 I put bass traps in all four corners of the room. Red line is before, black line is after:



Since it changed the response I had to re-EQ, but music sounds a lot better without that nasty 51hz null I had before.
post #166 of 176
Read this thread all the way from the beginning. Awesome job!
post #167 of 176
Thread Starter 
Quote:
Originally Posted by pokekevin View Post

Read this thread all the way from the beginning. Awesome job!

Thanks!

And in case anyone was wondering, yes, I still have my tiny TV!

post #168 of 176
Quote:
Originally Posted by lukeamdman View Post

Using OC 703 I put bass traps in all four corners of the room. Red line is before, black line is after:



Since it changed the response I had to re-EQ, but music sounds a lot better without that nasty 51hz null I had before.

Great build! Congrats!

 

Just curious...is this your preferred curve for your listening tastes (as opposed to flat)? I'm guessing yes, as the minidsp would give you the flexibility to eq to your preference?

post #169 of 176
Thread Starter 
Quote:
Originally Posted by dominguez1 View Post

Great build! Congrats!

Just curious...is this your preferred curve for your listening tastes (as opposed to flat)? I'm guessing yes, as the minidsp would give you the flexibility to eq to your preference?

I've done more EQ since then, but I think I only brought down the 37hz peak a little more. Trying to raise 65hz does nothing, so it's just wasted amp.

I've heard theaters that were EQ'd to completely flat, but didn't like it. Probably because our own ears don't have a flat response, which really throws a wrench into "flat" since everyone hears something different.
post #170 of 176
Quote:
Originally Posted by lukeamdman View Post


I've done more EQ since then, but I think I only brought down the 37hz peak a little more. Trying to raise 65hz does nothing, so it's just wasted amp.
I've heard theaters that were EQ'd to completely flat, but didn't like it. Probably because our own ears don't have a flat response, which really throws a wrench into "flat" since everyone hears something different.

Do you have a variable phase for each sub? Adjusting that mix between the subs may help out the 65hz...or at least your ability to raise it.

post #171 of 176
Thread Starter 
Quote:
Originally Posted by dominguez1 View Post

Do you have a variable phase for each sub? Adjusting that mix between the subs may help out the 65hz...or at least your ability to raise it.

The phase between the two is slightly different, since the sub on the right is further from the LP. I looked up my graphs and EQ settings, and the sub on the right didn't have as much of a dip, and I did EQ that sub to have a slight gain at that point.
post #172 of 176
Quote:
Originally Posted by lukeamdman View Post


The phase between the two is slightly different, since the sub on the right is further from the LP. I looked up my graphs and EQ settings, and the sub on the right didn't have as much of a dip, and I did EQ that sub to have a slight gain at that point.

Do you have the equipment to adjust each sub's phase anywhere from 0-180? In my experience, playing with the phase has resulted in drastically different FRs, as well as your ability to EQ your response. 

post #173 of 176
Thread Starter 
Quote:
Originally Posted by dominguez1 View Post

Do you have the equipment to adjust each sub's phase anywhere from 0-180? In my experience, playing with the phase has resulted in drastically different FRs, as well as your ability to EQ your response. 

Yes, I can adjust the phase of each.

Getting a sweep from each cabinet individually, the responses look very similar, and playing them together doesn't cause any voids. Both by themselves still have a void at 65hz, it's just that one has less of a void than the other, but it's only 2-3db difference.
post #174 of 176
Do you have any sweeps with the mains and the subs together>? When running the sweep, were the amps on for the main speakers? Try re-running the sweep with the speaker wires for the mains disconnected from the amplifier end, and shorted.
Edited by michael hurd - 12/24/12 at 9:09pm
post #175 of 176
Thread Starter 
Quote:
Originally Posted by michael hurd View Post

Do you have any sweeps with the mains and the subs together>? When running the sweep, were the amps on for the main speakers? Try re-running the sweep with the speaker wires for the mains disconnected from the amplifier end, and shorted.

I'll politely ask you guys to ignore those graphs for now:)

Those are pretty old and don't apply much now since I've changed a lot in the system since then.

Within the next couple months i'm going to be completely remodeling my basement, and my theater room is moving to a different area. Right now it's in an 11x29 space, and it's new home will be 12x25.
post #176 of 176
Quote:
Originally Posted by lukeamdman View Post

Thanks!
And in case anyone was wondering, yes, I still have my tiny TV!

nice
you should tell people that that is a normal and you just have giant speakers biggrin.gif
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