# Average Joe Review: Stereo Integrity BM MKIV



## LaserSVT (Feb 1, 2009)

*fade in*

*fat man that looks like Peter Griffin with a goatee is sitting in a truck with a look of shock on his face*

*a screw falls from the overhead door onto the trucks hood*


*4 days earlier:*

I get a text saying that I have a box at the local FedEx office. I first think I will wait until after work and pick it up. That lasts five minutes as I have no patience. I leave work to get the package. Its my first time at the local FedEx office and am greeted with some wonderful Waco architecture.




I think about putting a sign on the pillar that says "No Fatties" and then laugh at the irony.
There is a large box sitting there and as I pick it up I realize it must not be the subwoofer I thought it was because it is way too lite and figured it must be a customers headlight set I ordered.



I open it up and was pleased and confused to see it was the subwoofer from Stereo Integrity as the box within the box says on its side. (I neglected to open the packing slip on the outside LOL) Pleased because I wanted the sub but confused because I have bought 8" subs that were heavier.



I open that box and find another box.





Well then, I see Nick likes to make sure they are protected. Cool. So I open that box and.....




Okay, now I am thinking Nick has a thing for those Russian dolls. LOL
Alas upon opening the last box I see a rather pleasant looking subwoofer looking up at me.




Here are some pics from SI website:



























The very first thing that strikes me is just how light this thing is. Pretty sure both my mids are the same weight.
Amazing just how light these Neo magnets are.


So a little about what we are playing with here. This is a relatively new subwoofer from the fine folks at Stereo Integrity called the BM MKIV. It is a very shallow mount 12" subwoofer that is tailored for SQ above all else. It is designed for a .5-.6 cubic foot sealed enclosure and the driver itself is only 3.2" deep so anyone should be able to find room to fit this subwoofer. It has an 8 layer DVC 4 ohm voice coil and a 10" spider. Two specs that had shocked me for a shallow mount sub was the 14mm Xmax and the Fs or 19hz. Even though it is an SQ subwoofer it suggests it will have respectable output and be able to play deep with ease. 

Let me repeat this. It is an SQ subwoofer. When you open the box..... well the last box, you are greeted with a paper from Stereo Integrity that states (condensed version) If you want an SPL sub just call them and they will send you a return label to send this one back because you bought the wrong one. But if you value SQ above all else, go and install it and enjoy! Don't blow the coil or we will send out some hired goons.

Anyway, back to the sub. The looks are quite impressive. The black flat aluminum "cone" looks fantastic and reminds me of the days when I had the PPI flat piston subs only these look like they have been to finishing school and cleaned themselves up. 
From the rear it is a different story. No giant double stacked magnet. No giant basket extending out several inches. Just a nice shallow setup that has great detail to attention. Attractive venting around the edge and a nice polished center section for the vented coil. It is almost a shame it will be hidden.

I installed the subwoofer in a .5 cubic foot sealed box with approximately 1/3 lb of poly-fill. Box is a downfire mounted in my rear cab of my truck. It will be powered off a JL Audio 500/1 running at 2 ohms. That should allow up to 320 rms per coil. One day I may clamp the amp to see what it really does but this is average for a V1 500/1 @ 2ohms.




I had about 30 minutes before my next appointment so I took that time to play with the subwoofer a little bit. After some testing I found in my application that 80hz with a 18db slope blended best with my particular midrange drivers. I also have the sub channels attenuated by 5db where as with the two Dayton HOs I had it attenuated 9db.

As I sat there listening to the sub it put a smile on my face almost instantly. The clarity, the bass, the attack and decay.... how can this be from such a lite and thin subwoofer? Without thinking I switched to Korns "Never Never" to hear that opening bass line and had the volume up a bit much and giggled as the truck shook and then I heard a quick "smack" and I shut the system down realizing what I just did. Well there is xmech I suppose. Made a notation to make some adjustments and went back to my day job as a grease monkey.
As I left for the day I get back in the truck and see that at some point I accidentally knocked the bass knob up to max which is why the Korn song "bottomed out" the sub. I was impressed because the Daytons would throw a fit when it was maxed like that and the SI just said "Hey" and that was it. LOL

I spent the next several days breaking the sub in and fine tuning the EQ. To my surprise my eq is now set completely flat below 125hz and I set the bass knob to 50hz and only need a small bump for older classic rock that I want some more "kick" with. After getting it all dialed in I find the sub is able to use apx 75% of what the 500/1 can dish out so that leaves me with a good amount of headroom.

Now to today. I wanted to get this down while it was still fresh. I found a nice shaded area to park the truck where it was quiet and allow me to run the fan on low without melting. August in Texas sucks. I devoted all my attention to just listening to the music.

Started with the songs I know. I once again used a track called "Craziest Drum Solo Ever". I don't know who its by or how I got it but it turned up on a CD one day and I have used it ever since. The track starts off with basic drumming but then switches tempo starting off with a xylophone and then into some very intense and rapid kick drums. Two things jumped out at me. One, that I never knew just how accurately this single sub could reproduce that drum and two, that now it all sounds like it is coming from in front of me. I was a bit slack-jawed. How the heck did I manage that?
The bass kick was intense and just right at the same time. The subwoofer really seemed in its element.
I then switched back to Korns "Never Never" to hear that bass line that rolls in at 18 seconds. This time with it properly tuned I was blown away. As the bass line hit it was felt in my chest with a wonderful growl that never once became muddy.
That caused me to load up several other Korn tracks that I had stopped listening to because my previous subs just did not seem to like Korn at all.
"My Wall" is a demanding track below 100hz due to the constant digital bass line that shifts in frequency often and with most subs it sounds like one long variable note where as with this sub you can hear the start of each bass note clearly. I had only heard that particular track sound like that on higher end home systems.
Next up was Janet Jacksons "Go Deep". Always liked this song and the bass line throughout the song. The MKIV did this song proper justice. Strong reproduction that was very natural sounding. Near the end of the track there is a bass line that simulates a helicopter (I think that's the idea) that any sub can reproduce but few can reproduce while making it sound as if something is about to land on your roof. Well I looked up. LOL

Next up I went for some classic rock not known for bass just to see what would happen. I cued up Yes "I am Waiting" and waited for the bass at the 2:40ish mark. Being a single sub I was not expecting much as it usually takes two 15" subs to make that bass line sound natural. Much to my surprise the little BM reproduced that feeling all be it a bit strained. I think two would resolve that problem.


That brings me to the last of my testing for today. "Bass I Love You" was the closer. Most of us know it. It has a lot going on between 7hz and 17hz that will just punish a subwoofer. I saved it for last as I was worried I may actually damage the subwoofer.
I played it first with the 80PRS volume at 30. The bass was powerfull and deep. I was not expecting this from this little sub but there it was. Then the 7-17hz note hit and I watched my entire dashboard move. Okay, both Daytons could do that with the volume at 33 but no where near as defined.
So I restarted the track and set the volume at 33. This time as the 7-17hz note came in I watched the passenger seat shake on its seat track. Wow. Just wow. 
I again restarted the track and pushed the volume to 36. The bass was impressively strong for any sub, but a shallow SQ sub? It was unnatural. It should not be able to do what it was doing. I heard a faint rattle at this point but reclining the chair I could hear it was not the sub distorting. I put my hand on a side panel thinking it was the culprit and that is when some hardware from my garage door in my shop decided to drop a screw that landed with a "thud" on my hood.
*shock face*
I open the door and find that my entire shop is vibrating. LOL

Well heck, Nick knows how to make a sub!


So here are my impressions:
Pros: They fit in the smallest of boxes and are slim so finding a location should be duck soup. They are incredibly clear and detailed. They play down to frequencies that only really really high dollar 12" subs should hit so cleanly. Somehow they manage to make the bass sound as if it is coming from the front instead of behind you. Not sure of the voodoo going on, but they do. Despite 14mm of xmax and 450 rms power rating they can get impressively loud and still maintain composure.
These are easily one of if not my favorite sounding 12" I ever heard. They remind me of the old Infinity Betas only better. They are smooth and at the same time full of impact. They are allowing me to enjoy some songs I haven't enjoyed for a bit that I thought was due to recording quality issues. Turns out it was just bass imperfections of previous installs.
With 500 watts (rated) it is as loud but cleaner and deeper than 2 Dayton HO 12" subs. That being said you could triple that power to the Daytons and I am sure the scales would slam the other way.

Cons: I should have ordered two.
They are not an SPL subwoofer and due to their high quality they will not distort until they reach xmech with a thud. So be careful. 
I wish the spring terminal holes were a bit larger. For running the coils parallel its hard to jump a 12awg wire into a hole that already has a 12awg wire in it. Running in series would alleviate that issue.
I also would like a SVC version so that a pair would be able to get the most from an amp that can not do a 1 ohm load.



I will add onto this review as I get more time with it. I will also be buying another one and can give some info on how they sound when only sending 150 watts to each coil. 

At $380 they are not cheap subwoofers but I am hard pressed to think of another 12" in that price range that are as clear and detailed. Yes there are many louder ones but SQ wise these are on par (or better) than any of the real big boys.
If you have to have a small box or are limited on depth then really IMHO there is not a better option out there. The beauty of these subwoofers is even if you do have the room for something larger it does not matter if your goal is SQ because these subwoofers sound wonderful. Two thumbs up for Stereo Integrity.


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## bertholomey (Dec 27, 2007)

Thank you very much for your entertaining review. I enjoyed it immensely. I love how you told the 'story' of getting the sub through listening impressions - well done. 

I had very similar impressions with my single BM in the front of my BRZ. This sub played low notes that my dual 12" IB subs couldn't play. I love the tone - the way it effortlessly plays finesse material - stand up bass plucks from Mumford and Sons sound like good home audio. Thank you again for your initial impressions, and I look forward to reading additional comments as you get further acquainted and if you add a second BM.


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## edzyy (Aug 18, 2011)

Lovely review!


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## Electrodynamic (Nov 27, 2007)

Thanks for the review.  Thanks for going in-depth about exactly how it sounds on various tracks. And your second driver awaits if you choose to order again. Simply email me again and we can get a second woofer in your hands for the same price.


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## LaserSVT (Feb 1, 2009)

Oh it will happen. I hope Tuesday to order it.


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## Flinchy (Feb 29, 2012)

LaserSVT for ban please, i didn't need any more encouragement to spend $760 on subs ffs 

nothing about your review seems to suggest that it has anything other than more-than-adequate SPL output too, for any normal listening haha.

very much enjoyed the read!


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## ryyo (Jun 29, 2009)

Yeah, this review has me really contemplating getting two of these


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## casey (Dec 4, 2006)

I have a pair of these and they will put a huge smile on your face. Was able to get a little bit of listening time in this weekend. The output is phenomenal in addition to being extremely detailed and accurate. I couldnt believe how deep they get without straining. 


Ill have to concur with this review and cant say I have any downsides at this point


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## wdemetrius1 (Aug 16, 2007)

Great Review!


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## LaserSVT (Feb 1, 2009)

I pulled in my driveway after work and ended up going through 3 Lorde songs, two Robert Plant and even some Bruce Springsting and just sat there smiling and lost myself in the music. Before I knew it I had been sitting there for almost an hour just lost in the sound. That subwoofer is really something special. It blends so well with the mids it really amazes me.

One of Robert Plants songs called "In The Mood (for a melody)" has this combination bass guitar pluck at the same time the kick drum is smacked and it has been a while since I heard each instrument so clearly defined. I had gotten so used to it sounding as if that particular impact was made only by the drum it really made me smile. 

Just went on a taco run and jammed out to ABACAB and was very impressed how that single sub was able to hang so well with my front stage. My ears are still ringing. LOL


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## Guy (Feb 16, 2006)

edzyy said:


> Lovely review!


 This. I really liked the first pic, nice way to start off.


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## LaserSVT (Feb 1, 2009)

I figured I would give an update after a couple weeks of useage.

I love this sub. It has a sound unlike any other 12" I have ever heard. It plays low so effortlessly you would think it was an 18. Its output is also very impressive. While I have not noticed any change in sound quality or signature now that it has broken in there is a noticeable gain in output ability as I have been able to go higher and higher on the volume without any mechanical noise or that tell tale stench of a burning coil.
While I have not been abusing the subwoofer, I have not been gentle to it. I am on a Blue Man Group kick right now and holy hell does this sub love to make drum sounds! You feel it right in your gut. The attack and decay is impressively fast. I know I have said it before and I will say it again, you would never know it was a shallow mount sub in a tiny box. This thing really goes deep. I get a kick out of watching my dash move with sub 25hz frequencies. The sub plays 10hz with no problem. While you can not hear that it defiantly makes the music more alive because you sure can feel it.

I can say this sub is easily my most favorite 12" of all time. Sure it cant slam the neighborhood like an Illusion C12XL but three can and three are still cheaper than one C12XL. LOL

Not only is a second one going to be ordered for my daily driver but I believe I will order a couple more for backups or just to look at. So pretty.


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## T3mpest (Dec 25, 2005)

LaserSVT said:


> I figured I would give an update after a couple weeks of useage.
> 
> I love this sub. It has a sound unlike any other 12" I have ever heard. It plays low so effortlessly you would think it was an 18. Its output is also very impressive. While I have not noticed any change in sound quality or signature now that it has broken in there is a noticeable gain in output ability as I have been able to go higher and higher on the volume without any mechanical noise or that tell tale stench of a burning coil.
> While I have not been abusing the subwoofer, I have not been gentle to it. I am on a Blue Man Group kick right now and holy hell does this sub love to make drum sounds! You feel it right in your gut. The attack and decay is impressively fast. I know I have said it before and I will say it again, you would never know it was a shallow mount sub in a tiny box. This thing really goes deep. I get a kick out of watching my dash move with sub 25hz frequencies. The sub plays 10hz with no problem. While you can not hear that it defiantly makes the music more alive because you sure can feel it.
> ...


Shouldnt' be that much down in output from a cxl12, xmax is about the same on each and they are both xbl^2 so they should have a similar sound signature. Surely 2 of them outdo a CXL12 and as you said, 3 is STILL cheaper lol. Have you heard both to compare directly?


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## LaserSVT (Feb 1, 2009)

No sir. I only have fellow members impressions of the XL to go off of. I have heard the C12 which is a very nice sounding sub but I prefer the SI BM to it. Granted I only had 20 minutes or so in a car that I wasn't allowed to adjust settings on to sample the C12 but overall I liked it.


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## Audiophilefred (Oct 24, 2012)

Man I'm thinking about getting a pair for the f150 now that they are on sale... Dam good review and update


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## LaserSVT (Feb 1, 2009)




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## casey (Dec 4, 2006)

oh snap


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## LaserSVT (Feb 1, 2009)




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## casey (Dec 4, 2006)

so what do you think now that you have 2?


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## WhiteL02 (Jul 25, 2014)

Looks pretty sweet!


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## LaserSVT (Feb 1, 2009)

casey said:


> so what do you think now that you have 2?


I need a bit of time to give full impressions. Its louder though. LOL


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## LaserSVT (Feb 1, 2009)

Alright, update time! Running two of them dictated a few tuning changes but nothing major. Switched them back in phase with the fronts and had to attenuate them a tad more to blend but that's it.

Sound quality hasn't really changed. Still deep and clean. The difference is now the subs seem much more relaxed at high volumes while maintaining that signature SI sound. Very happy with the pair of them. Trying out the song "Afterglow" really gives a nice bass line at th3 50 second mark that you can feel in your throat.
Pink Floyds live albums are much more realistic as well.
I have thrown classical, classic rock, new rock, pop, R&B, hip hop, rap, dubsteb and everything else I could think of at these subwoofers and nothing seems to trip them up.

I am not a bass head (much) but I find myself looking for songs with subsonic bass just due to how well these things reproduce it.


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## Coppertone (Oct 4, 2011)

Again another reason why people should own one of these.


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## bertholomey (Dec 27, 2007)

Coppertone said:


> Again another reason why people should own one of these.


Or two of these


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## seafish (Aug 1, 2012)

Thanks...NICE review...makes me want to see if I can shoehorn one into my JL Stealthbox...it has the right sealed volume and depth easily, just need to see if I can cutout the opening by an extra 1" (25mm) on the radius and it will slip right in!!


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## LaserSVT (Feb 1, 2009)

Thank You. I am trying to get more reviews done but work has been nuts and with Christmas coming up a few installs I was going to do have been delayed till January. 

I do like these SI subs though and hope to do a review of the 65s soon.


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## tjswarbrick (Nov 27, 2013)

LaserSVT said:


> Thank You. I am trying to get more reviews done but work has been nuts and with Christmas coming up a few installs I was going to do have been delayed till January.
> 
> I do like these SI subs though and hope to do a review of the 65s soon.


Looking forward to the review! Gotta make sure the pre-buy was worth it.
Thanks for the update on going 2x MKIV's. Sounds just perfect.


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## LaserSVT (Feb 1, 2009)

Well these subwoofers have spoiled me. I have been doing more installs lately (not a stereo shop) and I find as I am tuning the systems that I just cant make the bass sound right. My partner tells me they sound great and the customers are happy but I am just so used to the ultra low distortion of the BM that I just cant go back to anything else. I fear it may bias future reviews of subwoofers. LOL The only two installs I was really pleased with were both SI BM subs and both were just singles.

That being said I let a good friend with the proper equipment take my truck yesterday and "fiddle" with my settings and do some testing. Turns out my tune was pretty close to where it needed to be but gains needed a small tweek. He said he clamped the amp, not sure what that means, and its doing 636 rms @ 4ohms and only does 1 watt more at 2 ohms. So each BM is able to take 318rms without any issues at all. I was surprised to find the SPL is 141.8db! Turns out what I thought was loud wasn't even close to what they can do. He showed me just where my signal was starting to clip at and I don't ever come close to turning it up that high. LOL
He was having an issue with his mic though and couldn't get proper readings below 20hz. We were freezing our butts off though so figured I could wait till he comes back to town in the spring and do it again so we can save the files before the laptop crashes again. Don't know if it just didn't like the cold or what.


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## Electrodynamic (Nov 27, 2007)

LaserSVT said:


> Well these subwoofers have spoiled me. I have been doing more installs lately (not a stereo shop) and I find as I am tuning the systems that I just cant make the bass sound right. My partner tells me they sound great and the customers are happy but I am just so used to the ultra low distortion of the BM that I just cant go back to anything else. I fear it may bias future reviews of subwoofers. LOL The only two installs I was really pleased with were both SI BM subs and both were just singles.
> 
> That being said I let a good friend with the proper equipment take my truck yesterday and "fiddle" with my settings and do some testing. Turns out my tune was pretty close to where it needed to be but gains needed a small tweek. He said he clamped the amp, not sure what that means, and its doing 636 rms @ 4ohms and only does 1 watt more at 2 ohms. So each BM is able to take 318rms without any issues at all. *I was surprised to find the SPL is 141.8db!* Turns out what I thought was loud wasn't even close to what they can do. He showed me just where my signal was starting to clip at and I don't ever come close to turning it up that high. LOL
> He was having an issue with his mic though and couldn't get proper readings below 20hz. We were freezing our butts off though so figured I could wait till he comes back to town in the spring and do it again so we can save the files before the laptop crashes again. Don't know if it just didn't like the cold or what.


Hahaha, that is awesome! Not too shabby from low distortion some shallow mount 12's! :beerchug:


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## 00_Lifted (Mar 3, 2015)

I saw Nick recommended using fiberglass vs poly. I planned to use polyfill. What are your thoughts?


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## bbfoto (Aug 28, 2005)

Basically, Fiberglass insulation has a lot more fibers or strands per square inch than Polyfill, so it works better because it's more efficient for the same amount of space taken.

Here's a very good test on the effects of Polyfill in subwoofer enclosures. Unfortunately it doesn't compare Polyfill to Fiberglass or other materials that are commonly used...

http://www.nousaine.com/pdfs/Box%20Stuffing.pdf


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## LaserSVT (Feb 1, 2009)

So here it is several months latter and I am still in love. I have run a few different setups since then just to try things and the Daytons are still my favorite.
Most people I know are bass heads so i always play the obligatory bass heavy songs and people are always blown away. More so when they find out how shallow the sub is and that they are only 12". They play so low so well. Not to mention with a 500 watt (rated) amp they really have impressive output. I am activly seeking another 500/1 or a 1000/1 (both V1) to allow the subs some wiggle room. They can take way more than what i am throwing at them.


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## LaserSVT (Feb 1, 2009)

More updates on this thread.

I have since changed out the 500/1 for a 1000/1 and made some changes to the box. When I bought the box I was told it was .77 per side so I added boards to drop it to .61 and then added a little (1/2 lb) of polyfill per side. Some frequencies were a tad boomy but I attributed that to the truck. Well the truck has been heavily sound deadened and I could hear that i may have made a mistake. I called the manufacturer and discovered the box was exactly .6 per chamber. I removed the wood and it did improve on the boomy issues and smoothened them out quite a bit. What helped even more was removing the polyfill and putting a layer of GTMat on the sub boxes wall behind the drivers.
The bass is very very impressive now. Deep and tight and now I no longer need to adjust the JL bass EQ from song to song.

With the windows down it absolutely rattles my skull. Amazing output for an SQ sub.
I anxiously await the MKV version.


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## LaserSVT (Feb 1, 2009)

I have had many say that the SI cant hit that 7hz note in "Bass I Love You". Granted the truck has a couple hundred square feet of multi layer sound dampening and it is a tiny sealed box but here is a video where you can see what happens when they hit that note. Due to camera quality the audio sounds poor, that also has to do with the volume level. Its not near max as it upsets the neighbors but here you can see the dash move with that low note:


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## Gomer Pilot (Nov 30, 2014)

Anyone who ever said that hasn't heard them. It's ridiculous.


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## EricP72 (Mar 23, 2008)

Bringing this back up. Question. I'm thinking 4 of these might be overkill, but I have a SUV. Would it be better to use a shared chamber or seperate chamber? I know if I'm using separate amps for each sub I need to use individual chambers, but I think im going to use one large mono amp. And would 3 be more than enough and 4 is just crazy?


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## Gomer Pilot (Nov 30, 2014)

Depending on the size of the suv, four would probably be fantastic. I know Bradknob was running three in a Dodge Ram I believe. Really personal taste on if you want to give up that much room, but I'd go for it.


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## Bminus (Sep 24, 2014)

LaserSVT said:


> I have had many say that the SI cant hit that 7hz note in "Bass I Love You". Granted the truck has a couple hundred square feet of multi layer sound dampening and it is a tiny sealed box but here is a video where you can see what happens when they hit that note. Due to camera quality the audio sounds poor, that also has to do with the volume level. Its not near max as it upsets the neighbors but here you can see the dash move with that low note:


Quick Question.
Im looking to get more low end out of my 2 BM MKIVs. I have mine behind the back seat of my Tundra, and while I do have some low end on "Bass I Love YOU" it's not near what you have in the video. Now I realize yours are down firing, which makes a difference.
Im running them on an Arc KS 600.2 so they have more than enough power and I have yet to see how much of it they can take because how clean the bass sounds, plus my back seats rattle pretty bad being up against the sub box. I mediated that a little with some CCF but I believe it needs more. 
My box is closer to the .5 cubic ft per chamber and has a little bit of denim insulation inside each chamber.
Would building a slightly bigger box help? And putting some CLD on the inside of the box instead of the insulation?


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## LaserSVT (Feb 1, 2009)

Down fire make a very large difference. Having over 1000 watts helps too. 

Now that truck was sold and the subs removed. We rechecked the box internal volume and it came out to .608 on one side and .612 on the other. No pollyfill at all.
The new truck will get these subs but only have 600 (never could use all of the 1000 I had) and the box is spec built to .6 on the money with 1" MDF. I will be sure to update how they do. It will still be a downfire configuration.


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## Bminus (Sep 24, 2014)

is the .608 and .612 net or gross volume?


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## LaserSVT (Feb 1, 2009)

No sub


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## Bminus (Sep 24, 2014)

Thanks. So that would put you around .56 per side with subs in. I think I can get that much without building a new box hopefully 


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## EricP72 (Mar 23, 2008)

would love to see some pics of your box LaserSVT


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## LaserSVT (Feb 1, 2009)

Oddly enough I didnt have many pictures of the old box. I have some in the new box with the same displacement. Different amp too but even on 500 watts these things are very impressive. They dig so low and play so well I couldnt imagine ever selling them.


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## Bminus (Sep 24, 2014)

Beautiful setup


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