Nearfield Ported MBM for Increased Mid-Bass Tactile Response
In the ULF thread and @coolrda 's Vibsensor thread, we've been discussing how different sub designs (sealed, ported, horn, etc.) can produce different tactile responses. When placed nearfield, these differences become more pronounced. Our focus has been largely from a ULF tactile response (TR) standpoint.
One of the theories is that ported produces more TR than sealed around the tune. I first demonstrated this in the ULF thread in this post:
Ported vs Sealed in my room
Recently, others have also done similar tests, but used a far more accurate measuring system with VibSensor:
His martysub is tuned to 20hz, and you can see in the above (scales were adjusted on images so that you can directly compare) that 20hz is much higher compare to his sealed Marty (plugged vents).
MK ported his IB setup, putting him at around a 7hz tune. You can see from the above how much the 10hz TR changed, even when he was running his sealed setup much hotter.
Within the spoiler below, I put together a much more detailed analysis of MK's example above:
If we assume that around the port tune there is more Tactile Response, then you could apply the same approach for LF frequencies, and more specifically mid-bass frequencies.
The reason I created this thread was to try out an MBM nearfield in support of this theory. :cool:
Based on the above, it appears that this mid-bass "chest slam" or "shortness of breath" effect is in the 50-100hz range.
I know HSU has an MBM offering and it's tuned to 50hz. But the problem with that design IMO is that the driver is downfiring. In order to get max Tactile Response, the driver and port should be facing the main LP. I've heard great things about the HSU though, I just think there might be a better solution.
I searched google, and really couldn't find anyone else that makes MBMs....BUT, if you think about it, an MBM is just a high tuned sub. Most PA subs have high tunes as they are geared toward music. With that being said, this opens up a lot more possibilities!
For my HT, I don't have a lot of space behind my seats as I already have two FV15HPs behind me as well as a second row.
So I do have size restrictions as well when thinking about this sub...it pretty much has to be no bigger (and preferably smaller) than the FV15HP...
So I found this $299 gem:
It doesn't specify tune, but the FR is 60hz to 130hz. The frequency range is 45hz to 180hz (-10), although I'm not sure what that means...
It's only a 12in driver, but it claims to push 122db at 1m. This will be placed nearfield, so I'm not really concerned about it keeping up.
Also, I'm really doing it to see if it can be an improvement...I'm not currently lacking in mid-bass today by any means (2 FTW21s, 2 FV15HPs nearfield, Fusion 12 LCR, and Volt 10 for surrounds).
Thoughts? Any other subs or MBMs come to mind? Is this a solve for max mid-bass slam?
Testing Update 6-1-16: FV15HP vs 1200D
Rythmik FV15HP - 15in Driver w/12hz tune
Behringer 1200D - 12in Driver, w/65hz tune
10.5in behind the Main Listening Position
47hz Sine Wave
LG G5 running VibSensor 2.0.0
Each sub was placed in the exact same location, and each was calibrated to 88db. I placed the LG G5 at the MLP and ran the tests.
The results are in....
As you can see, the 1200D has almost 2X the PSD and acceleration as the FV15HP at the same frequency and the same SPL.
Additionally, I don't believe this is at the tune of the 1200D. If VS was able to measure around 55hz, I believe the difference would be even larger... :eek:
VibSensor does not lie...no subjectivity, just the data. Another example that "at or around port tune", there is more TR in the nearfield because of the increased Sound Intensity.
The below graph (data points extracted from hornresp) show that the ported box produced much more PVL (10 TIMES more) compared to sealed around tune . And it looks as though the elevated PVL continues to about an octave over the sealed.
Given this, it's no wonder why all the examples above demonstrate that ported subs are more tactile around tune. :cool:
Research on Near Field and Sound Intensity
There's a lot of good discussion with regards to the near field and its benefits. I wanted to take a moment and define it based on what I've researched. Caveat: I'm an enthusiast not a scientist. :)
I originally talked about the nearfield almost 4 years ago in this post.
I will try and summarize it below and use the ISO 12001 definition of near field:
First defining Sound Intensity:
Sound Intensity (SIL) = pressure (SPL) * particle velocity (PVL)
Sound intensity has a direction as particle velocity is a vector quantity. This means it has a magnitude and direction. Pressure is a scalar quantity and has a magnitude, but no direction.
Sound Energy is a form of energy associated with the vibration of matter.
Sound Intensity is sound energy per unit time per unit area.
Sound Intensity is how we 'feel' sound on our bodies.
While bass waves are said to be omnidirectional (meaning we cannot locate the sound with our ears), the intensity of those waves are directional. This means we can feel where the waves are coming from in the right conditions. (e.g. Feel a NF sub with the driver pointed directly at your LP and then turn it 180 degrees away and see if you can feel the difference; the answer is yes.).
Now, on to Sound Fields...
Sound travels through various Sound Fields.
What does this all mean in practice...
The majority of sub frequencies in our HT's exist in the near field. This means that just understanding SPL is not enough to understand Intensity, or how we 'feel' sound.
Sound intensity is dependent on distance. The closer to the source, the more intensity you will have. It is also directional.
In the Very Near Field, the physics starts to enter fluid dynamics and starts to behave differently than the near field. It is said that this has high levels of PVL in this field relative to SPL.
To optimize (have the highest levels) Intensity:
Measuring Sound Intensity:
1st - Microflown Acoustic Camera
2nd - Sound Intensity Mapping of a Speaker
3rd - Low Frequency Mapping of Sound Intensity of Speaker/Subwoofer
Commercial and AIY MBM options
@Marc Alexander produced the below close mic response with the different configuration settings for the 1200D:
As you can see, it looks like the tune is around 65hz. Adjusting the 10db boost will change F3 depending on what frequency you set it at.
Yamaha DSR118W Review by @giftedmd $999 street price
PartExpress Assemble it yourself option
This box can be paired with this driver. It will also need an external amp.
Nearfield MBMs in the Wild
Thanks to @Brazle for sourcing these:
AVS member eng-399 built some MBM to go behind his second roll of seats. Next month I will demo them at the local gtg. He may be someone to talk to if you are interested in a cheap build. I think the drivers were around $ 60 for the Infinity 1260. Space was also an issue for eng-399. https://www.avsforum.com/forum/member...6-eng-399.html
Is it cheating to use some TT's for the mid bass slam, lol.
@dominguez1 - I'm currently experimenting with "MBM's" in my 8 x ported setup (4 x 11ft^3/17hz with HST18's, 4 x 7ft^3 avg/18hz-20hz with HT18's nearfield) and Fusion-15's in 4.6ft^3 towers for my LCR's on crown xls1500's. I recently built 2 x 6.5ft^3/30hz cabs and used the Dayton PA-460 with 325w rms/driver... I've set them up farfield with the hst18's, 12' from MLP and my setup is as follows:
General XO 120hz
hst18's, hpf 17hz, lpf 50hz
ht18's, hpf 25hz, lpf 80hz (anything higher caused localization)
pa460's, hpf 30hz
My system has never sounded and felt this amazing. I gave up 2 x hst18's for the pa460's as I didn't have enough space... they're that good in what they do.
I still plan on trying the pa460's on the lower tuned nearfield boxes ala VBSS. It's in the center of the room and is in a 20hz deep null, so I have them hpf at 25hz to save amp power.
@rhodesj has already modelled the 3 drivers in a 6ft^3/25hz box. "Red is PA460 with 400W, blue is the HT18D4 with 900W, and green the HT18D2 with 900W."
Above 40hz, you should see 2-5db more in output with the PA460's. $90 for the driver + $50 for the box and a $160 inuke1000dsp for both.
My only concern with the B1200D is the limited bandwidth as a nearfield sub... unless you plan on integrating it like a true MBM
I'm sure those are killer...but they are sealed. Need to try the ported variety for this test. :)
TT's for mid bass slam? Maybe...do you have the hooked up behind your back? That may work!
I'm not a DIY'r unfortunately...don't have the time. But the PA460s do sound amazing. Was there a huge difference compared to the HSTs for mid-bass?
In terms of midbass output on pa460's vs hst-18's (on inuke6000's), the latter has more output at 50-80hz. What compelled me to try these mbm's is when I experimented crossing my mains over to 40hz; my system sounded better... reminded me of subM's. With the pa460's xo'd all the way to 120hz, I've gained 4db from 80-120hz over my f-15's with the added benefit of having a snappier sound from 40-80hz.
I guess using a MBM is an individual thing after hours of listening to your system. First, what is your goal? MBM is rough 50-250 Hz but, could cover 35-600 Hz. There can be holes caused by room modes. Also, subs tuned low will suffer the higher up you go in the passband. Two questions come to mind, how well is auto EQ at correcting these problems and how are the rest of the speakers in the HT doing in the midbass region?
TT's are not intended for midbass but, I mentioned them since the ULF thread has a major focus on TR.:) Are there benefits to a MBM, sure. Dom mention using a ported enclosures in the nearfield in keeping with the TR focus. The trick is to integrate all of these different XO regions. The goal as I see it is to for more dynamic and a certain bit of headroom. That is one thing that suffers using large subs nearfield. The proximity of the low bass can muddy the midbass. Hopefully we will have some MBM at the upcoming gtg to evaluate.
I have not given much consideration to MBM and space is a problem. This is just another reason for running speakers set to small in the HT is good for. It increase headroom for the midbass from the other speakers in the HT. In the end, the rabbit hole keeps getting deeper, lol.:eek:
When I had only 1 fv15hp, I had it directly behind the main lp. The slam was incredible...when I got a second fv15hp, I decided to flank both sides of the couch with them to get more even TR distribution across the seats. It still slams, but not like it did with it directly behind the main lp.
I'm hoping that adding this mbm back in will get me that and more since the port tune is much higher than the fv15hp. As you and mk have experienced, around port tune there is more TR, so that as well being placed behind the lp i would think would have max TR.
dom don't you live in cinci...?
I have one of these B1200D subs you are welcome to borrow...
see what u think
What did you think of that sub?
Are you in Dayton?
I bought it for mid-bass punch as well but did not use it nearfield. took a bit of work to integrate but liked the effect.
not in my system at the moment so you're welcome to give it a go.
meet you in Middletown...?
Too late...Amazon moves fast!
Appreciate the offer though...
Did it keep up in your system?
for a while...added a PSA s3600i so don't use it at the moment
edit: sorry I was at work and read this too quick...read it as "did u keep it in your system"
yeah it wasn't primo but but I liked the effect.
anxious to hear your impressions...
@dominguez1 Just to add a little info about the HSU MBM, I had one for a while and it most definitely had awesome mid bass - sharp, fast and punchy. I currently run a FV15HP with driver as close as possible to my back and is spectacular for mid bass slam IMO. I tried an MBM and used it the same way with the driver facing right into my back (pretty much touching the back of the couch). The FV and the MBM felt almost identical in that 50-80hz region (my crossover is set to 80) with the difference of the FV continuing to play on down to 12 hz or so.
It looks like you already ordered the other, but you may want to give the MBM a try and all you would be out is shipping if you didn't like it or just wanted to test. Keep in mind that you can take the spike feet off and lay it on its side to get the driver facing into the couch and as close as you want it. Also you can plug the port to seal it as well. That might be real handy as well to do your testing :)
That was my experience with the fv right behind my lp as well. My hope is that because this behringer 1200d is ported and tuned around 50-60hz, that it will even have more slam than the fv.
I looked at the hsu, and was really looking for a solution where both the port and the driver were facing the same direction. Its my belief that the sound intensity generated around port tune is greater than the sound intensity generated from the driver alone. That's why we've seen more tactile response from the ported vs sealed tests I cited in the first post.
Additionally, ported vs sealed aside, what a great alternative to the hsu mbm if it works. I think the hsu runs at 599, whereas this 1200D is only 299. Quite a bargain to me if your focused on this narrow band 45-150 or so. Perhaps a cheap and very effective solution for those craving the mid bass slam.
We shall see!
I decided that I wasn't going to touch my existing FR, and just add the 1200D into the fold...and hope for the best. :eek:
Reason being, I wanted to be able to do some AB testing to determine if I liked it or not.
It always takes quite a bit of time to integrate my FV15HPs, FTW21s, and Audessey. My EQ system is a pair of 2 band PEQs from elemental designs (eQ.2). They are effective especially with audyssey doing the majority of the work, but it takes time to integrate them to my liking (I want certain frequencies amplified by the nearfield FVs and certain ones by the FTWs).
My FV15HPs are tuned to 12hz, the 1200D is tuned to 50-60hz, and then I have my sealed FTW21s.
I wasn't expecting them to integrate all together by leaving everything as is, but this was more about Tactile Response that a better FR. If I like the TR better, than I'd go back to the drawing board and try and integrate all 5 subwoofers.
Here's where I landed just by inserting the 1200D, and adjusting the setting on that and keeping my other EQ settings the same:
Red is my FR before, and blue is it after.... :cool:
Who knew! It literally integrated right in! :D It probably helped that I had a rising house curve before, and this flattened it out, but still...no phase problems at tune, it just filled the gap to make it flat. This probably saved me a half day of EQ'ing all these together.
I haven't done an AB comparisons yet, but first impressions are WOW! Lots more slam and TR! It certainly reminds me of when I had my FV15HP directly behind me. I'm amazed that this little 12in sub can keep up, but it definitely can...even with it's tiny footprint (14x17x16).
More to come, but so far I'm impressed...
You should pick up a growler [emoji33]
I watched In the Heart of the Sea last night with the 1200D as an MBM. Definitely makes a huge difference in Tactile Response! In fact, it might be too much! :eek::eek: I can definitely feel it in the chest more...at some points sort makes your heart race a bit it seems.
It definitely added a new dimension to my HT, and seemed to blend very well from a TR standpoint with what my FVs were doing. I also did some AB testing, and while my FVs can get close to replicating the TR (remember they are not right behind the LP), they can't quite replicate the TR with the 1200D right behind me.
I've also got all new vibrations I need to take care of in the room because of this little MBM...that was also a bit distracting when watching the movie.
It's funny, I've been so focused on ULF that past 3 years, it's interesting to try and maximize LF! :cool:
The true test is to watch a movie that really not action based, and see how it handles that. A pet peeve of mine is to have too much LF or ULF mated to screen action that's not really calling for that; for example, a door slamming or bass guitar riff, etc.
I'm gonna hafta try mine nearfield now...!
just curious how close to your seat did u place the 1200 and at what gain position...?
did u experiment with the "boost" option...?
IE.. -? receiver dual sub out to dual PEQ,
-set LPF to 45 HPF to 80 for 1200D,
-set HPF to ? for FTW 21
-set HPF to ? for FV 15HP
-Settings on each sub set to ?
-1200D placed right behind MLP
-FTWs placed in front corners?
-FV15HPs placed in rear corners/ nearfield
Hey Dom, so you bumped up 25-125hz roughly using this mbm and you are gaining increased tactile response?
Can I ask why you didn't just eq this range with your existing setup?
These are the dials I used to get them integrated the best without touching current eq settings.
Its funny, compared to my other subs this could be classified as "cute"...but it really packs some heat! I can't believe it keeps up.
And for 299, it's a steal for a compact mbm.
I do not have any HPFs or LPFs other than the ones naturally set by the vented subs themselves as part of the design.
With the FTWs and FVs, I get as flat as possible using my PEQs, and then run Audessey. After Audessey, I may tweak each PEQ a bit depending on how the Audessey curve looks like.
When I integrated the 1200D (directly behind the MLP), I just plugged it into the existing FR, and dialed it in using the settings on the back of the 1200D.
The real question (which I do plan to test) is if there is more TR from this MBM compared to the FV at the MBMs tune around 50-60hz...more to come on that, but will probably be a couple weeks until I perform that test because of a busy non-avs schedule. :)
Right now, all I can say is that this 1200D is a very effective and crazy affordable MBM that works well in my setup. I still need to determine if it's more effective that the FV in the same position.
I can also attest to the benefits of a MBM. I have been running an HST-18 and HT-18 in 4ft^3 sealed cabs and recently sold the HT-18 to upgrade to the UM-18, but it is out of stock for several months. So I ordered a PA-460 pro audio driver for $89 that is 98 dB efficient. Dropped it right in to the 4ft^3 sealed cab which is too large i.e. not ideal and powered it with one channel of my Inuke6k with no filter, just running it full range. It integrated will with my HST-18 and added very substantial mid bass kick. In fact, I demo'd it for my wife at reference level with music and she made me turn it down. She had an anxiety attack and said she did not like it. That it was too "sharp". I was like, huh? So she rephrased: "It's too punchy, feels like I am being kicked in the chest". Victory. Seriously though, the mad bass slam was too much for her and she became very distressed....took about 15 minutes for her to relax or calm down from it. So music volume limit with her is now about -15, but alone, reference level rocks hard. I think this combination will be very difficult to beat, but at this point I still have the UM-18 on order. I am considering building a 4 ft^3 dual opposed sealed cab for PA-460's to use permanently as my 2nd sub. Can only accommodate two total in my room, and the HST is very solid by itself down low in my room.
I can tell you that the PA-460 produced sine wave sweeps up to +10 dB above reference running hot with no compression above 40 Hz. When I get time I would like to compare sweeps between it and the HST with the power I have available.
The poor wives have to put up with us bass heads, lol.
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