MBM & True Sub Crossover of 50hz

[bsoko]

Watch the crossover between the true sub/subs and the MBM/MBM's. I found that my true sub crossover had to be set at 45hz in order to get rid of some horrible reverb from the bass at 50hz due to subs adding TOO much mid. I used the HDDVD movie "Miami Vice" and the first scene where the boats are entering the harbor. Ths bass quitar riff tells the story if the crossover is right for you. It took me 2 hours of experimenting to finally get it right with 2 MBM's, 2 3.3's, and 1 15" Dayton sub. If you look at the MBM chart http://www.hometheatershack.com/foru...-mbm-12-a.html (http://www.hometheatershack.com/forums/subwoofer-tests/5760-hsu-mbm-12-a.html) at 45hz and compare to the 3.3 MO chart http://www.hometheatershack.com/foru...um-output.html (http://www.hometheatershack.com/forums/subwoofer-tests/5762-hsu-vtf-3-mk3-maximum-output.html) you see that they crossover at about 45hz and that is the best place for it.

Bill

[mojave]

Hmm, it seems that I've seen "bass quitar" spelled wrong on another forum today, too! :D

Although 45 Hz may be right for your room, it may not be right for everyone. Illka's charts that you linked to have no bearing on where to set the crossover for two reasons. First, the MBM-12 chart does not factor in room interaction. These measurements were taken outside. It will roll of differently in different rooms. Second, the crossover on the VTF 3.3 is variable from 30-90 Hz. However, there is no chart showing the crossover at 45 Hz.

I set my crossover on my VTF 2.3 (actually on my DCX2496) a while ago using Room Equalization Wizard to measure the frequency response. I think I ending up setting mine to 55 Hz, but I'll have to check.

[mojave]

bsoko,

I checked my DCX2496 settings and I did set my VTF 2.3 high pass crossover at 45 Hz and allowed the MBM-12 to roll off naturally. You must be on to something!

[bsoko]

Yes, the audio is cleaner now and I know that I was amazed at the change a few hz could make. When I played the "Miami Vice" movie with all speakers set to "large" the mid bass issue wasn't there as I was not using the MBM's and tru sub to support the mains. When I changed the mains to "small" the issue was there. That's what got me to thinking that something was wrong with the crossover between the MBM and 3.3. A couple of hours of tinkering came up with the 45 hz crossover. I use the Anti Mode 8033 for my room EQ so I have nothing to look at. I use a 15 to 25 hz (4 to 6 spl increase) lift from the Anti Mode to give my low bass a punch and it sounds pretty cool.

Enjoy, Bill

[thsmith]

AFter many hours of moving and measuring I like what I have so far and is probably the best sound achieved so far. Adding the 2nd MBM and setting the xo on the 3 3 T to 45hz helped.

I do not have REW or any other measuring tools or EQ other than a RS SPL and the HSU freq CD. NO room treatments as this is a LR HT.

Below is a room picture and my freq results

Any feedback is appreciated.

Denon is XO at 120hz
MBMs up front (xo out) and positioned to achieve best room gain I could find.
3 3 T behind couch with driver facing away from fireplace. To much thump in couch when driver is facing couch.

[bsoko]

I'm glad that you got it setup the way you want. Nothing to ad except that our setups are similar as far as the room goes.

Bill

[n737nc]

To much thump in couch when driver is facing couch.


I don't understand :confused: :D

[thsmith]

I don't understand :confused: :D

Even at I what I consider lower volume the 3 3 driver facing the couch would make the couch vibrate like mad. With the driver now facing the wall I still have the sound and the couch only vibrates/thumps when the volume is higher.

[n737nc]

Even at I what I consider lower volume the 3 3 driver facing the couch would make the couch vibrate like mad.

I still see no problem :D
People pay extra for that sensation.....butt shakers :D

[thsmith]

I still see no problem :D
People pay extra for that sensation.....butt shakers :D

Understand but it was giving me headaches. If I ever want it back I just have to rotate 90 degrees and have best possible buttkicker.

I am looking for feedback on the graph. It sounds great to me and has the most punch, tight clean sound I have heard so far.

With my room not having any wall treatments and not buying an external eq for now is this pretty good?

Thanks,

[Bori]

What size subdude are you using under your MBM-12? Is it the 15x15? I measured the the MBM-12 and the depth is over 16 inches. Will the 15x15 still work?

[thsmith]

What size subdude are you using under your MBM-12? Is it the 15x15? I measured the the MBM-12 and the depth is over 16 inches. Will the 15x15 still work?


As far as I know the subdude comes in one size 15X15 which is what I have. The Gramma is something like 15x23 and the super Gramma is even larger.

[Bori]

As far as I know the subdude comes in one size 15X15 which is what I have. The Gramma is something like 15x23 and the super Gramma is even larger.


So you have the subdude under your MBM-12 and it fits nicely?

[thsmith]

So you have the subdude under your MBM-12 and it fits nicely?


Yep. I think the feet on the MBM are 14x14. I fits just fine !

[ryan]

Where is the driver on the MBM-12?

All I can see in the pic is a port on the front.

[mojave]

The driver is down firing and is located on the bottom.