OFFICIAL Hsu MBM-12 thread - Page 13

While everyone's telling you how to set up MBMs (including linking to my setup/calibration guide ), do you even need them?

I say no, you don't. Not with that setup. Set the crossover for your mains and center at 80Hz (you can experiment) not 40Hz, so your crazy subs are playing all that bass. The subs can hit 60Hz a lot harder than the speakers. It will also save distortion and headroom on the speakers so they can play cleaner and louder.

You can experiment with the phase setting on the subs and sub distance setting in your receiver to bring down the hump around 100-150Hz. There's no reason those subs shouldn't be kicking your arse with bass - except if you don't have them playing bass which is what you have now with that 40Hz crossover.

If it werent for the fact that my subs are playing from 100Hz and lower, and my Mains are playing from 40-60Hz and upward your argument would be true, they are all in perfect(or atleast so much as i can adust them) in phase.

The ting im missing in my system is the "in tha chest" bass, the tactile frequencys are so pronound that they shake my ordinary recliner chair more than my frinds masage chairs when i crank them.The reason i was thinking of some MBM-12's is that i feel that the Monitor Audio GS20's fal short when it comes to performance on the midbass erea. Not to say that the GS20's sound awful, they realy are great speakers, but for movies it seems like they lack some punch. I realy don't want to change the main speakers, as i feel thet the GS20's are almost unbeatable when it comes to musicality for the price. And again, im sorry for missprints, english isn't my native language and im drunk ATM.

You could try experimenting with the sub distance setting in your receiver, as I mentioned, and get that hump at 100-150Hz down.

Here is a graph of my sub and mains playing together, with the only difference between the measurements being a different sub distance setting in the receiver.


Try that out, and turn your sub level up a few more dB (how do you have it calibrated now? even? 2-3dB hot (so "even" on the SPL meter)?. That mid-bass you're looking for is in that 60-90Hz range that is the lowest part of your graph

Thanks for the reply again, its dificult to messiure the exact distance since the sub's have a amplifier that adds some delay on the signal. I have tried to change it, but always find that the settings Audyssey MultEQ TX find is the best for my system, the straightest graphs after a REW run. OFC i adjust the crossovers and boost the subs aprox 3-4 db's. Audyssey somewhat adjustthe subs alittle low acording to the Radioshack(i have the correctiontable in mind when i say this).

What I'm saying is, the hump on your graph from 100-150Hz looks like the dark blue line on my graph. If you manually change the distance in the receiver and re-run the sweep, you may find that you can bring that hump down. That hump makes the other bass frequencies sound less powerful in comparison. To take all of those measurements in the graph above, I just changed the distance setting between 3'6" and 8' at 1~2 foot intervals.

My sub is right behind my couch, and I think with the phase setting at 180 on the sub, 3'6" or so worked best. With phase set to 0 on the sub, a 6 foot setting gave me the smoothest response.




Also, I think you might not understand what the crossover settings in the receiver are doing.

Unless you have changed your settings since you posted it, this is what you have:
Mains : 40hz
Sub LPF: 100hz
center: 50hz
Surrounds: 60hz

Basically, the sub plays A) the .1 LFE signal, which can go up to 120Hz, and B) re-routed bass from the other channels. You could have bass down to <20Hz play through the front three speakers and the LFE in an explosion, and you want all of that massive bass energy to be played by the most capable components, the sub(s).

I suggest you up your LPF for the sub to 120Hz.

And wherever the crossover for the other speakers is set to, it sends bass below that to the sub (at a slope to mix the output of the sub and the speakers). So if there is an explosion, and bass goes to the LFE channel, plus left + center + right, the sub is playing the LFE channel and the speakers are reproducing most of the bass because they are crossed at 40~50Hz. The sub should be playing that mid-bass, and it's not if you really have those xo settings right now.

If you still have the crossovers set to 40~60Hz, I suggest you up these to 80Hz and see how that sounds. No matter how flat your graph is at 80dB, your subs will play the 40-80Hz content from the speaker channels with much more authority and power than your speakers ever could, especially with peaks at 90-110dB. I think this is what you're missing. Your massive subs will play 40-80Hz with much more authority than the mains. That should bring back that chest thump you are missing.


Just change the crossover for all of your speakers to 80Hz in the receiver and see if that gives you what you're missing.


Even if you got 1 or 2 MBMs, if you were to run them off of the subwoofer output on the receiver, you'd have the same exact problem. I think your subwoofers are currently only playing LFE + sub-40Hz bass from the mains. The MBMs play 50Hz up to about 120Hz~150Hz. If you don't change your speaker crossover settings, even with MBMs your speakers would be playing all of that mid-bass in the 40-100Hz range (except for the LFE channel), and you would have the same exact problem.

One more thing to check... Do you have any crossovers on your subwoofers engaged? Any Low Pass Filters? If you do have any crossovers engaged on your subs, you are filtering out a lot of bass and a lot of SPL. Turn them off.

As an example, here is my subwoofer without the mains. But it's running through the left+right channels so the receiver's 70Hz crossover slope for the subwoofer is tapering off the bass above 70Hz. The red line is what it's supposed to be. The blue line is what happens to that bass when I turn on the sub's internal crossover at the max 90Hz setting. You can see how much bass energy it cuts out from the re-routed bass (basically double-filtering the bass), not to mention what that does to the bass in the LFE channel that can go up to 120Hz. Everything between the two lines would be the missing bass volume.





Lesson: Turn off or bypass any crossovers in your subwoofers.

i have actually decided to get 2 of these and skip buying an additional ULS. I cant wait to be a part of this club and get the "punch" i am looking for.

has anyone with a Pioneer Elite receiver ever run 2 MBMs with their mains and a true subwoofer connected??? How would that be done????

I read on a page back HSU explaining how to set up the MBM.. However that set up appears to be manual not using Audyssey.. So how would one go about setting up 2 ULS15's and 1 MBM using Audyssey?

If your receiver has a single sub pre-out, then simply split the signal from the sub pre-out to feed any number of MBM's and/or true subwoofers. So you will need two y-splitters. You just need to feed one low level (rca) input on each MBM and each ULS.

Sincerely,

One can still use Audyssey when using MBM + true subwoofer(s). Audyssey will attempt to smooth out the mid-bass response (from the MBM) and the deep bass response (from the true subwoofers).

Sincerely,

Ok so what am I doing as far as hook up? Split the ULS's off SW 1 output and the MBM out of SW 2 output on receiver?

What's your room config look like? I actually like that idea... seems like that real home theater pop is in the mid-to-high bass range. There may be method to this madness.

Yes, that's right.

I had run dual 3.3's with dual MBM's in a 6000+ cu ft room from one sub output on the reciever. Sweet SQ!

Pete, with all due respect and my very limited knowledge of audio theory, I think it would be a bit different to what you are suggesting. Because if i use a y splitter and set the crossover in the AVR to (let's say) 80Hz, both the MBMs and the ULS will be crossing over at 80HZ which is defeating "my" purpose.

I heard bsoko2 mention how he had (correct me if i am wrong bsoko2) his dual MBMs connected to his mains crossed over at 150Hz and then his sub(s) crossed over at 45Hz which is exactly what I am trying to get.

So could anyone please explain to me how that could be done.

Thanks

Hi Kimwyn,

The crossover switch on the true subwoofer(s) should be set to 'In', and crossover knob set ~ 50Hz. Even though the MBM's and the ULS's are getting the same signal output from the receiver, the internal crossover on the ULS amplifier will filter out higher frequencies going to that woofer. The crossover switch on the MBM's should be set to 'Out'. The MBM's naturally roll off below 50Hz (combination of acoustic + electrical rolloff), so no need to do anything special to filter out deeper bass going to the MBM's.

Sincerely,

Thanks Pete, i think that is what is was looking for (thinking to myself) but i am not as versed as you guys in the audio department. Thanks again.

So then that means i set the crossover in the receiver to 150Hz, correct?

Yes, in the location where you plan to put the MBM's (ie. flanking the left/right mains), you should get good results when setting crossover to 150Hz on the receiver...

Can someone in here post a pic of the back of their MBM mid bass module please? it would be much appreciated.

I'm about to list my MBM on Audiogon.

Here is a JPEG of the back of the original MBM-12. This was included as a Quick Set-up Guide.

I cannot find any photos of the MBM-12 MK2.

Thanks WTF. appreciate it.

Does it matter which way the sub is facing? Does the port have to face the listening position?

Since my query is specifically about the Mk2 MBM, I thought I'd post my questions here first before maybe opening it up to a wider audience by starting a new thread in either the DYI or the audio theory forums.
The new MBM12 is designed to be used as either ported or sealed with the amp tuning (via switch) used to compensate for the port/sealed configuration change, all the while the driver characteristics and the enclosure size remains exactly the same. I think that is an amazing feat. I have an older model MBM which has the amp modified for sealed use only but just yesterday I purchased a (used) Mk2... so I got to thinking about damping materials. When I first got my the sealed (Mk1?) MBM I had an amp issue (it was dead) and had to replace it, when I looked inside I saw very little damping material. IIRC it consisted of a few smaller (than the sub's inner dimensions) cut sheets of damping material attached to the open surfaces... I believe the purpose of these were to dampen enclosure resonances since there is no mid-wall internal bracing in there... but then it may have also been meant to damp internal standing waves or mid-bass reflections but I didn't look closely enough to determine the construction of the damping material? I guess I need to go back in there to see if its a laminate and if so, what's in the layers. Anyway, last night I got to searching on the Internet for articles, discussions, marketing jibber-jabber, etc, anything on damping materials for subs I could find that would enlighten me on the subject and I came across a lot of info that leads me to believe ported and sealed enclosures have different requirements in how they are damped that will also affect enclosure tuning. So I'm wondering how does this work within the MBM12 being as how it has this dual use capability. A while back I actually physically blocked the port on the 'sealed only' MBM with an MDF block since it will never and can never be used in the ported configuration (evidently the amp will blow out the driver with the port open) and I put a some polyfil in there while I was at it and I believe the sound was actually improved. However I'm wondering if more damping material or different damping material would improve the sound further or simply change it (or the tuning) to something less desirable. (BTW, the other MBM, once I get it, will also only see sealed-duty in my system however I won't permanently block the port since I might sell it someday to someone who'll want to use it in the ported configuration.) PS... I'm hoping Pete will chime in here with some enlightenment for me.


EDIT: 12/29 - Okay, I got the 'new' MBM in last night and trying to integrate it with the other drove me just nutz. I could set each one up easily enough and got decent in-room frequency response (using REW and RS meter) in their locations (just 2-feet apart) but when I tried both together that would suddenly create several seriously deep nulls... it was just crazy. The more I played with it the more frustrated I got. At one point I opened the first MBM and removed the polyfil I'd stuck in there way back when and it was at this point I made note of what it looked like... and all the refelective surfaces are FULLY lined with ~1.5" rigid fiberglass glued down. Finally after more than an hour of futzing around with these subs I decided to just take simple SPL readings of each MBM (using the AVR's pink noise)... I had their gains set so I got 75dBs on each sub separately but when I ran both together it the meter actually DROP to 70-71dB?!!! On a hunch, I flipped the phasing to 180 on one of the MBMs and TADA! everything fell right into place... the MBM's summed up properly, the bizarre nulls disappeared. So evidently one of these MBMs is wired in reverse because they are spaced only two feet apart to begin with and yet they must be in opposite phasings to combine properly? Anyway they now sound awesome and just I might put some polyfil into both of them later but for now I'm very happy.

i had the same issue...when I had them at seperate phases...all was great.

if anyone has a mk2 version of the mbm please pm me as im looking to buy one or two. thanks!

Little help guys, please. I'm more of an end user than science guy

I'm looking at replacing my mains and am considering going with bookshelfs. I'm already running dual subs for HT purposes, (Outlaw EX's) and it just seems foolish to buy floorstanders when everything below 80hz I'm sending to the subs anyway.

So. Question 1) 1 MBM, or 2. Room is 18 by 24 by 8

2) My receiver has only one sub out, which I currently split with a y adapter to both subs. I assume I would just split it again to send to the MBM's as well?

3) As far as setup is concerned, I assume I allow Audussey to do it's thing with both subs and both MBM's on, then one by one level match them with my RS meter?

4) I've read Pete's earlier posts about where to set the crossovers, I assume I set ALL of the speakers to cross to the MBM's at 150, not just the L/R?

5) In my current setup the subs are nearfield, and the MBM's would have to be placed farfield, basically flanking the L/R speakers. No other real option for me. I know the MBM's are meant to be placed nearfield, does this mean the MBM's are not a good solution for me?

6) These are the options I"m considering: Mirage OMD-28's as floorstanders, http://www.vanns.com/shop/servlet/it...md-28-rosewood, Mirage OMD-15's as floorstanders, http://www.vanns.com/shop/servlet/it...omd15-rosewood, or Mirage OMD-5's paired with the MBM's. http://www.vanns.com/shop/servlet/it...-omd5-rosewood

Would the OMD-5/MBM combination outperform the OMD-15's in the midbass area? Pricewise, the two are about the same. What about the OMD-28's which would set me back considerably more.

Last thing, I'm primarily concerned with HT. Listening is probably 75% HT, 25% music.

Lots of questions I know, but anyone that can help a non science person out, thanks!!

In my opinion, the MBM-12 can be a very challenging, but rewarding piece of equipment. It will require, in most cases, patience and effort to properly integrate into your room and your system.

Hope this helps.

It does, thank you I realize theOmd-28s were probably in a different environment under different conditions, but what was your impression of tem in comparison to your setup of the 15's with the mbm's, if any? I am considering that setup as well but it brings me closer to the price of the 28's themselves

Totally different environment and difficult to really compare. The 28s I listened to were part of a dedicated 2.0 system. My impression was that the OMD-28s had good bass extension and LF output. Although, I'm pretty sure they would not have as much mid-bass slam or extension as a properly integrated OMD-15, MBM-12, true subwoofer set-up.

FWIW.