How to start measurements when you have multiple subs

[thsmith]

REW is working for me now and no more manual measurements, yahooooo!

My room (Living room)as most everyone elses is challenging, 4200cf, 8' to 12' sloping ceiling, hardwood floors, fireplace is 10' wide and 12' high. 6' frech door, all windows have heavy drapes and large opening in back of the room to the right from sitting position.

I have a HSU VTF3-MK3 Turbo in front left corner and HSU MBM-12s behind each main.

When I start my measuring I know I need to remove the mains, should I also turn off the MBMs and focus on just the 3 3 T and then turn off 3 3 T and turn on 1 MBM at a time to find best location for subs ?

3 3 T XO is in set at 55hz
MBMs XO out (50hz-150hz)
AVR (Denon 2808) XO set to 120hz

Thanks

[thsmith]

ANyone with past experience doing testing with multiple subs ?

Thanks

[weverb]

Mine was done with one Outlaw EX and one MBM-12. Here is one post I did where I compared the three different scenarios.

http://www.hometheatershack.com/forums/rew-forum/12622-rew-noob-3.html#post113906

[brucek]

ANyone with past experience doing testing with multiple subs ?

Your situation is not considered multiple subs. You have a low sub and a couple mid subs.

It's a very difficult job to properly integrate this arrangement into a set of mains, given the obvious time and phase hurdles that have to be overcome.

I would test each sub individually at first, simply to get an idea of how their position is interacting with the room, but I wouldn't get too crazy about trying to get a perfect response at this stage, because you're going to have to get them to play in concert eventually and they will more than likely not react in your favour.

Your low will have to be average phased with the two mid subs, since they're not co-located. Then the phase of each mid will have to be phased with the mains. Since you have them close to each main (and not beside your couch where it is recommended), then this will work in your favour for phasing. You may want to isolate a measure between a mid and its associated main to set the initial phase of each mid.

brucek

[thsmith]

Thanks Weverb, I have been following that thread.

After more thought I think I will raise my AVR XO to max

Then with measure just the 3 3 T on and XO out do a measurement

Then do the same for each MBM

and see where I have overlap and gaps.

Once I get to a happy place I want to read more about applying filters to see the changes, I think that is what you did before buying an BFD.

[thsmith]

Thanks Bruce, many things to consider and try. For some reason I always seem to do things the hard way.

I tried the MBM in nearfield and did not like it, most likely the large opening to the right and behind me.

The really cool thing is that REW makes taking measurements so much more accurate, fast and easy as opposed to the way I have been doing it with RS meter, Freq cd and Excel.

[weverb]

thsmith wrote:

Thanks Weverb, I have been following that thread.

After more thought I think I will raise my AVR XO to max

Then with measure just the 3 3 T on and XO out do a measurement

Then do the same for each MBM

and see where I have overlap and gaps.

Once I get to a happy place I want to read more about applying filters to see the changes, I think that is what you did before buying an BFD.

Let me know if I can help. Have you done the typical pink noise/RS meter 75dB calibration of...

1. Main sub to highs.
2. One MBM to highs.
3. Other MBM to highs.
4. Both MBM's to highs.
5. All subs to highs.

One of your previous graphs looked like your 3.3 was playing really low compared to the MBM mid-bass. You are going to have a lot of fun playing. You have different positions to try out, with and without turbo to try, and max output versus max extension to try. Good luck.

[weverb]

thsmith wrote:

TAfter more thought I think I will raise my AVR XO to max

I would probably not go past 120Hz. There are are a few on the avsforum that have had good luck/response with this setting.

[thsmith]

weverb wrote:

Let me know if I can help. Have you done the typical pink noise/RS meter 75dB calibration of...

1. Main sub to highs.
2. One MBM to highs.
3. Other MBM to highs.
4. Both MBM's to highs.
5. All subs to highs.

One of your previous graphs looked like your 3.3 was playing really low compared to the MBM mid-bass. You are going to have a lot of fun playing. You have different positions to try out, with and without turbo to try, and max output versus max extension to try. Good luck.

If you are referring to balancing the subs with the mains using RS SPL meter, yes I have.

The 3 3 T looks low because I have not applied the SPL meter calibration/compensation file yet. Plan to do that tonight.

I will certainly be picking your brain on setting filters to predict what a BFD can do for me.

Thanks again.

[thsmith]

Bruce, I see what you mean about the sub and MBMs not playing well together. With all 3 on I have a bad suck out at 50hz but individually they look good in that area.

1st graph with 3 3 T and both MBMs on
2nd graph with just 3 3 T on
3rd graph just MBMs on
4th graph just left MBM on
5th graph just left MBM on