# Review of the Stereo Integrity BM mkIV



## bertholomey

I will be completing a full review of the Stereo Integrity mkIV in the near future once I can get it installed properly. Right now, it is in a temporary box, but I can give some impressions based on what I have heard. 

Information about the sub can be seen on the website (still under construction). Stereo Integrity Home

A little bit of background - I met Nick in 2009 at my first DIYMA meet that took place in Statesville, NC. I found Nick to be cool and very knowledgeable. He had a mkIII woofer and a Mag V4 to look at, and I was able to eventually get the mkIII for a review. Here is a link to the meet thread and my impression thread of the mkIII. 

Meet Thread: Statesville, NC Meet



Nick's Lexus and Jacob's jeep (this jeep was insane!)



Review thread: http://www.diymobileaudio.com/forum...sions-stereo-integrity-mkii-bm-subwoofer.html

The mkIV has been in the works for quite some time, but it is finally in production. Nick contacted me to see if I would want to listen to the driver, and of course I agreed. I placed the box in the floorboard between the JL sub and the passenger seat. Here are a few pics. 




























I have used a variety of subwoofers in my BMW and in the BRZ, but I remembered how much I liked the sound of the Mag V4 that I had in my BMW and the mkIII that I had for a review. 

Once again, I'm very impressed with what Nick has put together. I plan to explain the reasons why I like the sound of this driver. Stay tuned.....


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## Electrodynamic

Nice start to your review.  I'm anxiously awaiting the rest of your listening impressions.


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## captainobvious

This is a great subwoofer. I also got the chance to demo this in Jay's BRZ. I'll wait for his full review before I put in more feedback.

Thanks for posting a review for us Jay.


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## papasin

Sub'd


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## Kevin K

Sub'd


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## Lars Ulriched

subscribed.....


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## saMxp

Had the pleasure to listen to this sub yesterday for a little while in Jason's BRZ. Here are my impressions:

Listener reviews are subjective, so first let me say that what I primarily look for in a subwoofer is to disappear into the sound field as an low frequency extension of that field, fully integrated into the field.
This subwoofer, positioned in the passenger footwell of the BRZ, definitely disappeared into the sound field. I've heard good subwoofer installations before that did a good job at integrating with the soundstage on some music, but then making its presence individually known on other types of music. We listened to a good variety of genres on the sampler disc from blues to rock to folk to dubstep and the music always extended into the lowest octaves cleanly and seamlessly. Now that I think about it, though, I would have liked to hear some more kick drums of various types to hear how it help up in more dynamic situations, as most of the low frequency information we heard was more of a sustained note.
Guess we'll need to do lunch, soon!


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## bertholomey

Thanks Sam for that feedback. I certainly would like to get together to hit some rock / metal to see if it delivers the impact. Hopefully I'll have that voice imaging issue sorted by then


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## 2010hummerguy

Wait does this mean the MKIV's are shipping soon?


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## dgage

I'm subbed for the answer to Architect7's question.  I want my preordered sub!


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## casey

I emailed Nick on Saturday. He said they should be in stock next month


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## rton20s

Subscribed as well.


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## 2010hummerguy

casey said:


> I emailed Nick on Saturday. He said they should be in stock next month


That is great, thanks for checking!


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## Electrodynamic

Yes, they are due in next month.


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## bertholomey

Hey Dudes.......

I had an incredible time with this sub today. From Zac Brown Band 'Different Kind of Fine' - very strong drum kit sound and strong bass guitar sound. 






To Cirez D........at about 1:30.....my mouth dropped wide open while driving down the freeway  = this is exactly what I looked like - the driver beside me must have thought I was crazy. Such incredibly deep, accurate, and tight bass. Bliss!!!!


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## captainobvious

Was just looking at the website. 50% more linear excursion than the TW5? Nice!

Shame I missed the pre-sale! A pair of these would look mighty fine in my Mazda


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## edzyy

My girlfriend want some hatch space back in her x6

Wonder how 4 of these would do..

decisions..decisions..


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## captainobvious

edzyy said:


> My girlfriend want some hatch space back in her x6
> 
> Wonder how 4 of these would do..
> 
> decisions..decisions..


4?? How does that give space back :laugh: Is she a total bass head? If so, this might not be the driver for her. If she's an SQ enthusiast though, 2 of these would be more than enough.


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## bertholomey

One of my all time favorite builds! Slade's STI with two of the MKIII BMs.


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## casey

wow that is a nice looking setup.

i love the look of this sub. its going to be a shame if mark is able to stuff one in the passenger foot area out of sight


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## bertholomey

Another great dual MKIII build - Trevor in his C30 Volvo


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## TOOSTUBBORN2FAIL

captainobvious said:


> Was just looking at the website. 50% more linear excursion than the TW5? Nice!
> 
> Shame I missed the pre-sale! A pair of these would look mighty fine in my Mazda


Klippel tested linear excursion? I know the TW5 was designed with access to a Klippel.

The reason I ask is because going by manufacturer specs, the SI only has 27% more linear excursion, but depending on sd, that could be cancelled out by the tw5's larger size.


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## Electrodynamic

TOOSTUBBORN2FAIL said:


> Klippel tested linear excursion? I know the TW5 was designed with access to a Klippel.
> 
> The reason I ask is because going by manufacturer specs, the SI only has 27% more linear excursion, but depending on sd, that could be cancelled out by the tw5's larger size.


Yes. Topology top plate height and coil height are un-changed from the mkIII. I think the new slim JL woofers are on newer versions since that text was put up but after a quick look the JL TW5 still doesn't have more linear displacement than the BM mkIV. 686 cm^3 compared to 614 cm^3.


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## TOOSTUBBORN2FAIL

Awesome, thanks for the info. I was more curious than anything, but this may be a good option for my wifes new car.


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## rton20s

TOOSTUBBORN2FAIL said:


> Awesome, thanks for the info. I was more curious than anything, but this may be a good option for my wifes new car.


Is it ordered yet?


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## bertholomey

rton20s said:


> Is it ordered yet?




Like!


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## TOOSTUBBORN2FAIL

rton20s said:


> Is it ordered yet?


Yep, the cars ordered. 50-90 days. Maybe sooner if he can trade a slot for one thats ready for production. The boat ride over takes the longest. 

This might be the ticket for her. She doesn't listen as loud as I do, but she likes it to dig all the way down below 20hz.


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## edzyy

captainobvious said:


> 4?? How does that give space back :laugh: Is she a total bass head? If so, this might not be the driver for her. If she's an SQ enthusiast though, 2 of these would be more than enough.


She's a little bit of both 

With their tiny box requirement, 4 should work in 2 cubes, no?


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## rton20s

TOOSTUBBORN2FAIL said:


> This might be the ticket for her. She doesn't listen as loud as I do, but she likes it to dig all the way down below 20hz.


Sounds a lot like my own wife. Especially now that we always have a 2 yr old riding around with us. When you hear, "I don't like this song. It's too loud!" from the back seat, you have to respect it.


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## bertholomey

That's funny - made me think of this exchange I had with my buddy after one of our meets recently: 



bertholomey said:


> Mike - I was talking to your lovely wife at lunch time yesterday, and she said the other day, 'her song' came on, and she turned it to '3'.........last night it hit me........that must mean -3.0 db on the Clarion.........I thought the system was loud at -15.0 db!  The BOOM with no RATTLES!





Velozity said:


> Lol, I just showed her this post. Sadly, when she said "3" she meant the one on the other side of zero (+3.0db!). The damn thing only goes up to +6.0db! Luckily when 'her song' came on she was streaming from iHeart radio and the sensitivity of the aux inputs is lower than the CD level. So my voice coils were spared a meltdown, lol.


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## rton20s

bertholomey said:


> That's funny - made me think of this exchange I had with my buddy after one of our meets recently:


Ha... wimmenz! No offense MrsPapasin... if you happen to be lurking.


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## papasin

rton20s said:


> Ha... wimmenz! No offense MrsPapasin... if you happen to be lurking.



I'll let her know. Lol


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## Electrodynamic

bertholomey said:


> Hey Dudes.......
> 
> I had an incredible time with this sub today. From Zac Brown Band 'Different Kind of Fine' - very strong drum kit sound and strong bass guitar sound.
> 
> *To Cirez D........at about 1:30*.....my mouth dropped wide open while driving down the freeway  = this is exactly what I looked like - the driver beside me must have thought I was crazy. Such incredibly deep, accurate, and tight bass. Bliss!!!!




I just listened to this on my ear monitors on the YouTube link you provided. As son as I get done typing this I'm going to search for the CD on eBay! Holy crap!

Actually, can someone help me find a way to purchase this song or the CD that this song is on (preferably the CD instead of the just the single song download)? I'm having no luck finding it.


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## Coppertone

Sadly that makes two of us as I was also searching for the cd. :-(


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## edzyy

Found it.


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## Electrodynamic

edzyy said:


> Found it.


...Ok, I'll bite.  Where did you find it and/or can you provide a link?


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## rockytophigh

Guys I've narrowed my choice down to these or Illusion Audio. Either way they will be going in a hatchback. Having never had a hatchback, which way would you recommend they be installed? Down firing....up....front. ..back? Thank you for the input!


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## bertholomey

rockytophigh said:


> Guys I've narrowed my choice down to these or Illusion Audio. Either way they will be going in a hatchback. Having never had a hatchback, which way would you recommend they be installed? Down firing....up....front. ..back? Thank you for the input!


All of these methods could potentially sound good (in my opinion and in my experience). The two builds using the mkIII BM's that I clipped photos of above had them firing up in a false floor presentation. I know the one sounded great, and I could imagine Trevor's sounded good in the Volvo. When you weigh out the various compromises - that will likely determine your answer. Space savings, aesthetics, purely best sound, etc.......

Interestingly, I saw this post the other night:

http://www.diymobileaudio.com/forum/2015918-post266.html

Concerning the Cirez D......I haven't found CDs either - I think individual tracks can be downloaded from Beatport, but I haven't used them yet. 

Here is another one that really impressed me on the mkIV BM. The beginning beats don't seem very interesting until the volume is turned up on a good sub system. There is a lot of detail going on there that the BM played flawlessly. I'm sure me previous dual 12" sub install wouldn't have been able to resolve that.


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## casey

im going to have to check some of these songs out. see how it sounds on the sd-2 and the mkIV


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## 2010hummerguy

rockytophigh said:


> Guys I've narrowed my choice down to these or Illusion Audio. Either way they will be going in a hatchback. Having never had a hatchback, which way would you recommend they be installed? Down firing....up....front. ..back? Thank you for the input!


I've owned both Illusion and SI subs, you will be much happier with SI.


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## rockytophigh

Thanks for the reply. I spend hours going through Trevor's Volvo build after you posted the pic the other night. My wife says thanks lol. 

Where are you over in NC. I've been working in Cherokee for the past month....


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## rockytophigh

Architect7 said:


> I've owned both Illusion and SI subs, you will be much happier with SI.


That settles it then. I hope they blend well with the Brax 3way. Anyone know a top notch installer in East TN/Western NC?

I really want to try this myself, but I live on top of a mountain with no garage or tools. Plus, it's a hybrid (Cargina) and honestly it makes me nervous...and let's not kid ourselves, my install skills are crap 

The biggest problem is I'm (soon to be) a single dad and it will be tough for me to leave the car for large periods of time. I literally drive 5+ hours, plus work, every day to make ends meet so this system will really be a blessing to me & little man.


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## edzyy

Electrodynamic said:


> ...Ok, I'll bite.  Where did you find it and/or can you provide a link?


Download 01-Cirez_D__Acki_Kokotos_-_Tomorrow_(Original_Mix).flac from Sendspace.com - send big files the easy way


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## Electrodynamic

edzyy said:


> Download 01-Cirez_D__Acki_Kokotos_-_Tomorrow_(Original_Mix).flac from Sendspace.com - send big files the easy way


Cool. Thanks!


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## bertholomey

Architect7 said:


> I've owned both Illusion and SI subs, you will be much happier with SI.


I prefer the mkIV BM vs the C12 I had. 



rockytophigh said:


> Thanks for the reply. I spend hours going through Trevor's Volvo build after you posted the pic the other night. My wife says thanks lol.
> 
> Where are you over in NC. I've been working in Cherokee for the past month....


It took me a good 20 minutes to skim through his huge thread to get that one picture 

I'm near Greensboro. I travel to Asheville and Boone for work (typically not with the BRZ though ) 



rockytophigh said:


> That settles it then. I hope they blend well with the Brax 3way. Anyone know a top notch installer in East TN/Western NC?
> 
> I really want to try this myself, but I live on top of a mountain with no garage or tools. Plus, it's a hybrid (Cargina) and honestly it makes me nervous...and let's not kid ourselves, my install skills are crap
> 
> The biggest problem is I'm (soon to be) a single dad and it will be tough for me to leave the car for large periods of time. I literally drive 5+ hours, plus work, every day to make ends meet so this system will really be a blessing to me & little man.


Mark is the best installer I know, and he is based out of Hickory. 

http://www.diymobileaudio.com/forum...w-mark-worrell-audiomasters-charlotte-nc.html




edzyy said:


> Download 01-Cirez_D__Acki_Kokotos_-_Tomorrow_(Original_Mix).flac from Sendspace.com - send big files the easy way


Thanks dude!


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## bertholomey

I have received a question about TS parameters and enclosure modeling, so I thought I would address this now. 


When Nick was developing this driver - he had certain performance and sound criteria he was aiming for. The sub + the enclosure type (sealed) + enclosure size (0.5 ft^3 (after speaker displacement) with fiberglass lining the inside sides of the box and light polyfill stuffing) is a system that has a reproducible quality and quantity. That is why I'm hopefully getting the one I have in that kind of box this week so I can evaluate it as it should be. _A consumer can certainly put it in anything they want, but the performance will not be the same as stated by Stereo Integrity. _

According to the things I have read and discussions with home audio manufactures, they will either design a speaker cabinet based on the speaker drivers they want to use, or they will source speaker drivers based on the type of cabinet they are working with. It is a system - the Magico Q7 will likely sound like bullocks if the consumer replaced their drivers with a Scan Speak set of drivers. I remember there was a bit of discussion when the recommendation of 1.0 ft^3 enclosure for the Mag V4 - for the speaker to work as intended - to hit the performance and sound expectations of the system - and I had Ryan build that sized enclosure for my car. 

A good little discussion in a thread that was questioning the enclosure size for the upcoming mkIII BM:

http://www.diymobileaudio.com/forum...067-question-about-upcoming-bm-mkiii-sub.html

For me - that is liberating - I don't have to second guess the manufacturer. If I follow their guidance, and it sounds like ass, then move on to something else. If I don't follow their guidance, and it sounds like ass, is it because of the product or the application of the product. When I was using my 10" Onyx sub - I had no idea what the TS Parameters were, and I never used a woofer tester. In the box my buddy built - it worked perfectly. When I put it in a different enclosure - it constantly bottomed out - guys told me it was blown. I replaced it (fortunately with the Mag V4), and discovered later that it was not blown - just not in the right sized box. 

In summary, it is up to the consumer what they do with the equipment they purchase, but there is a probability that it won't perform as well as it could in the recommended enclosure. For me, I want to provide the best opportunity for the piece of equipment to perform - as I recently did with my tweeters, midrange, and mid bass drivers. I'll follow the manufacturer's recommendation for the mkIV BM.


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## WhereAmEye?

I preordered one of these babies back in November, I regret not getting more than one. Subbed for further reviews.


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## hurrication

Electrodynamic said:


> Cool. Thanks!


Discography: (House, Progressive House, Techno) Cirez D - Discography - 2003- (download torrent) - TPB


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## TOOSTUBBORN2FAIL

Sorry, on my phone, but I still think ts parameters are needed. You cant just build a sub for a certain size box and have it sound good in every car. Every car is different, many of them significantly so. A sub that works well in my car in a 0.5 cube box may not work well in a truck with the same box. Or a convertible.


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## Electrodynamic

TOOSTUBBORN2FAIL said:


> Sorry, on my phone, but I still think ts parameters are needed. You cant just build a sub for a certain size box and have it sound good in every car. Every car is different, many of them significantly so. A sub that works well in my car in a 0.5 cube box may not work well in a truck with the same box. Or a convertible.


For those of you who can't look at a T/S list and look at a few select parameters to see how deep the woofer will play and how it will behave, being able to plug the full list of T/S parameters is nice to have [we have a full T/S list on our forum]. 

Regardless of any speaker that you have it will sound different in different vehicles...especially going from a truck to a convertible! A certain vehicles acoustic signature is not easy to duplicate across multiple types of cars. 

The BM mkIV performs the best in 0.5 ft^3 to 0.6 ft^3 sealed whether you put it in a home, or in a sedan, or in a hatchback, etc. Frequency response, power handling, excursion at power and frequency, etc, are all nicely handled in the enclosure size of what we recommend. Power handling becomes the biggest issue if you try to get the woofer to play lower than it already does by increasing box size.

I definitely see where Jason is coming from. It's refreshing to trust a manufacturer instead of running through multiple enclosures (and maybe burning through multiple woofers) only to find out that the original recommendation was the best overall solution.


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## captainobvious

Without having looked at the SI site for TS parameters or any graphs...Did you have a target roll off curve with the 0.5cu ft enclosure? I know the JL recommended ones for the 10TW3 include a little hump in response. I'm guessing the BM mkIV has a much flatter response from what I heard. It also has significantly better low end response which I was a little surprised by. In fact, I'd say it compared well in that regard to my 13TW5. The JL has more output, but that BM mkIV is very very clean and sounds fantastic. Job well done Nick.


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## bertholomey

Electrodynamic said:


> The BM mkIV performs the best in 0.5 ft^3 to 0.6 ft^3 sealed whether you put it in a home, or in a sedan, or in a hatchback, etc. Frequency response, power handling, excursion at power and frequency, etc, are all nicely handled in the enclosure size of what we recommend. Power handling becomes the biggest issue if you try to get the woofer to play lower than it already does by increasing box size.





captainobvious said:


> Without having looked at the SI site for TS parameters or any graphs...Did you have a target roll off curve with the 0.5cu ft enclosure? I know the JL recommended ones for the 10TW3 include a little hump in response. I'm guessing the BM mkIV has a much flatter response from what I heard. It also has significantly better low end response which I was a little surprised by. In fact, I'd say it compared well in that regard to my 13TW5. The JL has more output, but that BM mkIV is very very clean and sounds fantastic. Job well done Nick.


Thanks Nick and Steve. I got some information on what Nick has said about it playing flat on the low end. I'll post it later when I get time. 


Here are the parameters for the BM mkIV 12" shallow subwoofer:

Re: 6.26
Fs: 19 Hz
Qes: 0.54
Qms: 7.97
Qts: 0.50
Le: 3.97
Sd: 453.7 cm^2
Vas: 71.3 liters
BL: 19.9
Mms: 287.5
Xmax: 14mm
Xsus: 19mm
SPL: 82 dB (1W/1M)


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## captainobvious

I had a feeling it had a very low FS...didn't expect THAT low though for a shallow mount flat-coned 12". Very nice.


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## Kevin K

Specs are nice, thanks for sharing.


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## gsxr1300

anyone have an ETA on the pre-orders?


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## wdemetrius1

bertholomey said:


> One of my all time favorite builds! Slade's STI with two of the MKIII BMs.



^^

I could not agree more. :thumbsup:


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## Electrodynamic

gsxr1300 said:


> anyone have an ETA on the pre-orders?


They will be here around the 27'th of this month. There are a lot of pre-orders so it will take us a little while to get them all tested and shipped out.


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## OgreDave

What's the regular price? Missed the preorders as well. Haven't owned SI since the claw Mag .. might need to check this one out.


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## quality_sound

I really wish I'd pre-ordered now. These would be perfect in my STi. 

Sent from my Moto X using Tapatalk


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## xXTX_ChallengerXx

OgreDave said:


> What's the regular price? Missed the preorders as well. Haven't owned SI since the claw Mag .. might need to check this one out.


^^^^
This....I am on the fence between the SI and 12TW3.


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## bertholomey

Both have excellent performance. I preferred the sound of the SI (not just the greater output and the ability to play lower) than the JL 10TW3. As you can see earlier in this thread.....Captainobvious compared the SI favorably to the JL 13TW5. I haven't heard the 12TW3 yet, so I can't comment on that comparison.


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## xXTX_ChallengerXx

Anyone know the normal purchase price on these and when ordering may start back up? I'm looking at purchasing 2 slim 12's once I get back from deployment and it looks to be between these or the JL TW3. Right now I am leaning towards the SI because at least I have read reviews on them.


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## bertholomey

Sweet, where are you deployed?


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## Electrodynamic

xXTX_ChallengerXx said:


> Anyone know the normal purchase price on these and when ordering may start back up? I'm looking at purchasing 2 slim 12's once I get back from deployment and it looks to be between these or the JL TW3. Right now I am leaning towards the SI because at least I have read reviews on them.


Regular price will be $389 once they are in stock.


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## xXTX_ChallengerXx

bertholomey said:


> Sweet, where are you deployed?


I am a submariner in the Navy and will be deploying to the Mediterranean Sea/Arabian Sea area. I've been in the Navy for 10 years now and have been on two different Western Pacific Deployments. This will be my first deployment in this part of the world and I'm pretty excited about it.



Electrodynamic said:


> Regular price will be $389 once they are in stock.


Thanks!


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## bertholomey

xXTX_ChallengerXx said:


> I am a submariner in the Navy and will be deploying to the Mediterranean Sea/Arabian Sea area. I've been in the Navy for 10 years now and have been on two different Western Pacific Deployments. This will be my first deployment in this part of the world and I'm pretty excited about it.
> 
> 
> 
> 
> 
> Thanks!



That is awesome! Thank You for your service! My wife says 'No Way! Major claustrophobia issues there' ? 

I spent 6 months at Bragg and 1 year in Afghanistan, so I hear ya on getting back and getting things squared away in your car. Have a meaningful and productive deployment!


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## 2010hummerguy

xXTX_ChallengerXx said:


> Anyone know the normal purchase price on these and when ordering may start back up? I'm looking at purchasing 2 slim 12's once I get back from deployment and it looks to be between these or the JL TW3. Right now I am leaning towards the SI because at least I have read reviews on them.


SI over the TW3 every day all day long. You will not be disappointed with a pair of these. I am fiberglassing every last cubic inch under my back seat to squeeze two of these in just because I am addicted to how clean and full these sound, definitely the best sounding car subs I have ever heard, slim or not.


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## Golden Ear

captainobvious said:


> I had a feeling it had a very low FS...didn't expect THAT low though for a shallow mount flat-coned 12". Very nice.


19hz IS pretty amazing! I'd love to hear one of these someday. Looking forward to your review Jason. I'm still very happy with the c12


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## bertholomey

Golden Ear said:


> 19hz IS pretty amazing! I'd love to hear one of these someday. Looking forward to your review Jason. I'm still very happy with the c12


I'm very glad to hear that - the C12 is a wonderful sub!


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## eddieg

Just went over the entire review. 

OK - the SI is now marked as my next B-Day gift for my self :laugh:

Though there is over six months until it happens but it falls directly in to my plans! 

I am now downloading the Criez D - I liked it a lot 

It remindes me of creations by Rob Dougan and as well Juno Reactor (both can be found on the Metrix trilogy OST collections) 

Rob Dougan:






Juno Reactor: 







But I would recommend the two CDs (chronicles) by Trentemoeller at most if you liked Criez D 






Thank you again! 

Eddie (hint - I am pretty sure I loaded Trentemoller on the thumb drive  )


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## mSaLL150

Can't wait for my BM mkIV!


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## bertholomey

mSaLL150 said:


> Can't wait for my BM mkIV!



Marc, I believe you are going to be impressed with the improvements. I'm looking forward to hearing your impressions. 

I finally got mine in the right enclosure, so I'll be concentrating on getting this review done in the coming weeks.


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## wrcrs24

Looking forward to getting mine as well


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## 2010hummerguy

Just saw that Nick announced on Facebook that the subs are due in on the 30th for testing before shipping to customers. Very exciting


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## bertholomey

Life has gotten in the way, so I haven't been able to update this thread. I finally was able to hook up with Mark to have the sub installed in the proper sized enclosure. Net volume comes out to 0.5 cu ft - extremely strong but light enclosure. From my BRZ build thread.

This is the box I received the sub in:










I tried to put it in a similarly sized box that Mark had built, but the basket made it impossible without trimming out the opening of the enclosure. I wanted to get it in this box for when I took the sub down to Erin's G2G this past Fall. 










Just couldn't get it to seat:










So this is how I was doing a lot of my initial listening......sounded like it had a lot of potential to me. Mark had some criticisms about the sound - because of the box size and because it was just firing up into nothing, but he felt it had potential as well. 










This is the first pic that Mark sent me.....with a caption 'Oh My!' This was going to be a challenge to get a 12" subwoofer in a 0.5 cu ft enclosure mounted under the dash that won't take up any more foot space.










Well, this was a hard one to build.....primarily due to the challenges of the recent polar vortex that decided to strike right when I needed to have my subwoofer built.....how dare it! There was some challenges with heating and equipment availability (apparently fiberglass doesn't want to cure at 43F) - Mark was eventually able to overcome these set backs, but it caused some incredibly long, frustrating hours. Here are a couple early pics:


















































































Lined with Road Kill for GP










Stuffed and wired










This is basically what I saw when I arrived on Saturday.......I was pumped!!!




























He asked me to pick it up and carry it over to the other side of the shop to blow it off with the air hose - I nearly threw it to the ceiling - it weighed HALF of what I thought it would weigh. We looked for a scale, but none could be found. We guessed the enclosure + sub was about 25 pounds.....at the most. I think Mark said (please correct me if wrong) he layed up 9 layers of 1.5 ounce mat - the thing is strong!!! From what I remember, it is about half the weight of the JL enclosure - it had a lot more MDF in it's construction. 

Of course.....perfect fit. The total increase in distance from the fire wall (or loss of foot space) was less than 3/4" from what the JL enclosure was - I thought that was amazing!



















Next step was creating the beauty panel. Again, Mark had a concept in his head that he tried to communicate to me.......I didn't get it. Really cool though to see it put together right in front of me. He joined two pieces of wood....fiberglassed the joint for strength.....added some cleats for strength.......and then covered it to match the interior of the vehicle. He did this in about an hour......very cool.





































At one point, he was talking about something, and then he flipped this thing around and I got a look at the front.....I just stopped in mid-sentence 



















I apparently didn't get a pic of the back side - he covered it with carpet, so that the mdf is not seen.

Dirty test fit










Some finished pics I took yesterday after I cleaned up the car. 









































































Last one!


----------



## bertholomey

I also attended a meet in North Carolina this past Saturday, and many of the folks there commented on the quality of the sound, the amount of output from a shallow sub, and the wonderful impact this sub delivers.


----------



## bertholomey

Double post


----------



## casey

glad you like it, im excited to get mine and see if mark can throw one up front or if im just going to do 2 in the trunk


----------



## 1fishman

Hoping i can make this sub fit where my 10" is. I assume the BM MkIV will give good mid bass also, maybe crossed at 120hz. 

Anyone know the outside dia of this sub?


----------



## bertholomey

1fishman said:


> Hoping i can make this sub fit where my 10" is. I assume the BM MkIV will give good mid bass also, maybe crossed at 120hz.
> 
> Anyone know the outside dia of this sub?


I have tried it crossed higher, and I was pleased with the performance. Nick from Stereo Integrity said that he has had the mkIII's crossed up that high with good results as well. When I get my amps back in the car, I'll run it up higher and let you know my impressions. 

This is from SI's website. 

Mounting information
~ all dimensions are in millimeters. ~
All mounting specifications are with the supplied gasket:
Mounting depth: 81.3mm
Cutout diameter: 282mm
Overall diameter: 320mm

Gasket information:
Width per side: 26mm
Edge height: 18.5mm
Bottom thickness: 5mm


----------



## rton20s

Just to help out the mathematically challenged...

All mounting specifications are with the supplied gasket:
Mounting depth: 3.20"
Cutout diameter: 11.10"
Overall diameter: 12.60"

Gasket information:
Width per side: 1.02"
Edge height: 0.73"
Bottom thickness: 0.20"




bertholomey said:


> All mounting specifications are with the supplied gasket:
> Mounting depth: 81.3mm
> Cutout diameter: 282mm
> Overall diameter: 320mm
> 
> Gasket information:
> Width per side: 26mm
> Edge height: 18.5mm
> Bottom thickness: 5mm


----------



## dgage

Bertholomey - I was really looking forward to putting my Mark IV in the front passenger well of my Acura TL but that looks like a large damn enclosure. For some stupid reason, I wasn't thinking a half cu. ft. would be that large. Dammit. So how is it to sit in your passenger seat now?


----------



## bertholomey

dgage said:


> Bertholomey - I was really looking forward to putting my Mark IV in the front passenger well of my Acura TL but that looks like a large damn enclosure. For some stupid reason, I wasn't thinking a half cu. ft. would be that large. Dammit. So how is it to sit in your passenger seat now?


Interesting. This enclosure really isn't any bigger than the enclosure Mark built for the JL 10. I lost a little less than 3/4" of foot space versus the 10" enclosure. You see the flat wall, and then the enclosure has a drastic slant of the footwell. The enclosure is barely bigger than the glove box. I wouldn't call this 'large'. I think you would have no problem putting a 0.5 cu ft box in the footwell of a TL.


----------



## dgage

Thanks for the feedback. When you say not that large, you're coming from the position of your previous enclosure in your footwell. When I say large, I'm coming from not a damn thing in the footwell...and now there's going to be a fairly large thing in the floor. . Queue ideas for selling to the misses. Maybe I'll do a David Letterman style Top 10.


----------



## bertholomey

dgage said:


> Thanks for the feedback. When you say not that large, you're coming from the position of your previous enclosure in your footwell. When I say large, I'm coming from not a damn thing in the footwell...and now there's going to be a fairly large thing in the floor. . Queue ideas for selling to the misses. Maybe I'll do a David Letterman style Top 10.


Ok....I see your perspective....your not saying it is a large enclosure in comparison to the whole world of enclosures.......you are saying that in your mind's eye, you were hoping to add a shallow sub in a small enclosure, and still have space in the footwell for feet (what footwells were designed for ). 

I think this is probably the same as when I try to visualize an amp rack and a bunch of stuff fitting in the trunk of my old BMW or in the BRZ........the trunk seems to be twice as big in my mind as it is in reality......when things start being put in there. 

It is a tough thing.......for short trips - it isn't too bad - for giving demos, it isn't too bad (except your knees are up because your feet are closer to the seat, so there is a little bit of blockage of the door mid bass drivers). I typically never have passengers - I have probably sat in that seat (giving demos) more than anyone else. The other issue may be for those who have a 2 door car where they need to move the seat all the way forward. Where my sub is, I can get the seat all the way forward with the sub in there, others might not be able to get it all the way forward depending how far the sub comes out into the footwell. 

It is hard to sell the misses on the 'need' to do it because it may sound better or you may get better performance....."see honey, this is what it would sound like if the sub is up here....all the bass comes from the front of the car because the thing making the bass is in the front....." I typically get, "Ah, huh.....so you know that I won't ride in this car now.........how much is it going to cost......how long will it take to get it done.......this is it right.....no more changes after this....."


----------



## dgage

Ughh. This is for a daily driver and "it's not too bad" isn't necessarily compatible with my wants for a daily driver. Yep, I didn't think .5 cu. ft. was that big but looking at yours, it is definitely bigger than my mental picture. I'll build a 1/2 cu. ft. box for the MK IV and see how it sounds and go from there. I've got a Morel Ultimo SC 10 to compare it to and I'll use one of those or go all out and separate the trunk from the rest of the car to install an AE SBP 15 in an infinite baffle. Thanks for the pictures and info.


----------



## bertholomey

This question was posed on my install log - thought i would share it here. 



Golden Ear said:


> Very nice! Have you done any tuning yet? Most importantly, how's it sound?! When I see a sub facing up at the glovebox like that I instantly think of the glovebox or it's contents rattling. Is that an issue at all? Where do you hear the bass? Sorry for the 20.questions, just very curious



I haven't passed this over - I've been flying today, so I'll likely answer tomorrow 

Ok - a quick reply 

On the way to Salisbury today, I listened to this entire album, and I was extremely excited by what I was hearing!






I haven't had time to do any tuning on it, but I'm not sure it will need much if anything. I have been trying to lock down the crossover point / slope / polarity - and I think I got it on the drive this morning.......at least for what I could discern while driving at 77mph with this particular album :roll eyes:

The bass was deep, articulate, and authoritative. When I adjusted the crossover, the bass was locked in above the dash - kick drum and bass guitar were very well defined with great impact - in the center of the soundstage. Again, I was absolutely thrilled with the sound. I'm getting a lot better low range than I did with the JL 10" (no surprise), and I believe I'm getting much better low range than I did with the dual 12's IB. 

A few of the differences that I'm experiencing with the new sub install......

1) better sound in every way versus the speaker in the old box sitting in the footwell (not bolted to the car) facing straight up into the cabin 

2) more energy transferred into the floor - seat rails - seat back than with the JL - I guess it isn't necessarily a bad thing......not much that can be done about it......the driver is really working and there is a lot of energy up front - more of a difference than a negative. 

Concerning the glove box - the only thing in there is the big owners manual booklet that came with the car, so there isn't anything inside that would rattle, and the glove box itself is not rattling - so far, so good 

Feedback from a recent meet 



req said:


> phew! it would be a sad sad day if that happened.
> 
> your car sounds brilliant sir. imaging and everything - i was very impressed and wish i could have sat in there for much more time... i know ill get that chance heheh.
> 
> even carly said that it was very technically right.
> 
> its almost like your windshield is a window into the recording studio haha. the mid-window level bass is what really impressed me the most... i just wish that i fit in the car better hahah! i felt like i was in a maita - but im sure that was just your seating position because im like a foot taller than you.
> 
> 
> either way - glad everything is getting taken care of and you (and your car) are ok.
> 
> *knocks on wood*


Several at the meet commented on the solid integration of the sub / mid bass and the ability of the sub to disappear on one hand, but play with such authority on the other. One asked how I was able to get such low notes to play out of my 3's because the image was in the center of the dash. They were being very generous. 

Of course....I have to say.....that I heard a car at the meet (Mike Still's (Tintbox) xB) with two JL TW5 subs in the rear of the car that imaged on the hood


----------



## dgage

What amp and how much power are you driving it with? Thanks.


----------



## bertholomey

dgage said:


> What amp and how much power are you driving it with? Thanks.


I'm using a Mosconi AS200.4 - one side of the amp bridged - the sub wired so the amp sees a 2 ohm load and the amp is rated at 950 watts at 2ohm.


----------



## casey

i thought i was going to give mine headroom at 700 watts :O


----------



## 2010hummerguy

bertholomey said:


> I'm using a Mosconi AS200.4 - one side of the amp bridged - the sub wired so the amp sees a 2 ohm load and the amp is rated at 950 watts at 2ohm.


Wow!!! That is quite the headroom 

For those interested, these perform very well with lower power, I have 500 watts on the MKIII in my wife's Jeep and it is extremely well matched.


----------



## bertholomey

Architect7 said:


> Wow!!! That is quite the headroom
> 
> For those interested, these perform very well with lower power, I have 500 watts on the MKIII in my wife's Jeep and it is extremely well matched.


That is exactly right - I have played the mkIII with under 500 watts, and it played very well - with plenty of output. This just so happened to be the amp I had available.


----------



## dgage

bertholomey said:


> That is exactly right - I have played the mkIII with under 500 watts, and it played very well - with plenty of output. This just so happened to be the amp I had available.


Where's the gain set on the bridged channels?


----------



## bertholomey

dgage said:


> Where's the gain set on the bridged channels?


1 out of 5 on the dial.


----------



## dgage

Thanks so you're definitely not over powering them.

Guess where I'm going to try my BM MK IV first when I get them? Under the seat of my couch in the living room/home theater. Someone jokingly suggested on AVSForum but I think it's a great idea as a test. A speaker is after all a transducer, just not what they normally refer to when they say putting a transducer on the couch. So I'll get to see if it adds any tactile feel...over what my 3 LMS 5400 18" subwoofers already give to the room.


----------



## 2010hummerguy

Just be careful, the SI subs are so low distortion that you will not hear them stress before bottoming out. Which is definitely a risk in a home environment where you don't have as much cabin gain as a car.


----------



## dgage

Good point and thanks for the heads up. I also probably won't hear them over the 3 LMS 5400s driven by 2000 watts each. I'll only be putting 190 on each voice coil so at least I won't be pushing too much power and I'll also enable a subsonic filter. I'm just trying to see if I get a little more tactile feel in the 30-60 Hz range due to them being in such close proximity.


----------



## Electrodynamic

dgage said:


> Good point and thanks for the heads up. I also probably won't hear them over the 3 LMS 5400s driven by 2000 watts each. I'll only be putting 190 on each voice coil so at least I won't be pushing too much power and I'll also enable a subsonic filter. I'm just trying to see if I get a little more tactile feel in the 30-60 Hz range due to them being in such close proximity.


Wow, I think that treating a BM mkIV like a bass shaker might not be the right application...especially against three 60+lb 18" subwoofers being fed by 6,000 watts combined.


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## dgage

Electrodynamic said:


> Wow, I think that treating a BM mkIV like a bass shaker might not be the right application...especially against three 60+lb 18" subwoofers being fed by 6,000 watts combined.


I'm not going to abuse it, that's for sure. I'll just see what it does. If nothing in that setup then I'll have the box done to do testing in the car when it warms up.


----------



## ktmkev_74

I have a full size GMC crew cab with the Bose system. Looking for a little more hit down low. However, I don't want to take too much space. Would this sub have a significant upgrade to my system?


----------



## captainobvious

Electrodynamic said:


> Wow, I think that treating a BM mkIV like a bass shaker might not be the right application...especially against three 60+lb 18" subwoofers being fed by 6,000 watts combined.


Indeed. Impact in that passband with the ability to keep up with the subs is the correct job for a quality proaudio driver.


I love what you've done with the new BM mkIV. Really terrific sounding driver. If I didn't have a 13TW5 already, I'd love to run a pair of these in my Mazda.


----------



## rton20s

ktmkev_74 said:


> I have a full size GMC crew cab with the Bose system. Looking for a little more hit down low. However, I don't want to take too much space. Would this sub have a significant upgrade to my system?



In a word, yes. You will need proper amplification and enclosure for the subwoofer. I have a feeling though, that once you upgrade the subwoofer you'll start noticing how "lacking" the rest of the system is.


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## ktmkev_74

Thanks for the quick response rton20s. That's what I figured about the rest on the system. O well...I'll start with the sub and go from there.


----------



## rton20s

ktmkev_74 said:


> Thanks for the quick response rton20s. That's what I figured about the rest on the system. O well...I'll start with the sub and go from there.


Just a quick tip... When you are planning your equipment layout and amp for the subwoofer, keep in mind a matching 4 channel amp and where it might fit as well. Always better to plan ahead and be prepared for future upgrades than to have to redo a bunch of work and/or swap out equipment.


----------



## ktmkev_74

rton20s said:


> Just a quick tip... When you are planning your equipment layout and amp for the subwoofer, keep in mind a matching 4 channel amp and where it might fit as well. Always better to plan ahead and be prepared for future upgrades than to have to redo a bunch of work and/or swap out equipment.


Will do. Thanks

Are you in SoCal?


----------



## bertholomey

ktmkev_74 said:


> I have a full size GMC crew cab with the Bose system. Looking for a little more hit down low. However, I don't want to take too much space. Would this sub have a significant upgrade to my system?





captainobvious said:


> Indeed. Impact in that passband with the ability to keep up with the subs is the correct job for a quality proaudio driver.
> 
> 
> I love what you've done with the new BM mkIV. Really terrific sounding driver. If I didn't have a 13TW5 already, I'd love to run a pair of these in my Mazda.





rton20s said:


> In a word, yes. You will need proper amplification and enclosure for the subwoofer. I have a feeling though, that once you upgrade the subwoofer you'll start noticing how "lacking" the rest of the system is.


I completely agree with rton20s.......this would be a significant upgrade.....to most systems, but especially a stock Bose system. Captainobvious has heard this sub in my car (before I got it in the correct enclosure), and he has heard and felt the impact. If you get this installed in a 0.5 cu ft enclosure with a decent little amp, as rton stated.......you will certainly be bit by the bug


----------



## ktmkev_74

bertholomey said:


> I completely agree with rton20s.......this would be a significant upgrade.....to most systems, but especially a stock Bose system. Captainobvious has heard this sub in my car (before I got it in the correct enclosure), and he has heard and felt the impact. If you get this installed in a 0.5 cu ft enclosure with a decent little amp, as rton stated.......you will certainly be bit by the bug


Sub has been ordered!! Prob not the place to ask but and suggestions on the rest of the system (amp/speaker)?

Thanks


----------



## rton20s

ktmkev_74 said:


> Will do. Thanks
> 
> Are you in SoCal?


I'm in central California (Visalia). If you are in SoCal, I would highly recommend checking out the get together we are having on March 8th. There should be some truly world class vehicles there. 

http://www.diymobileaudio.com/forum/12-volt-events-team-diyma/157887-so-california-march-8-2014-meet.html



ktmkev_74 said:


> Sub has been ordered!! Prob not the place to ask but and suggestions on the rest of the system (amp/speaker)?
> 
> Thanks


I would post your questions in the "System Design" forum. Make sure you list your budget and space requirements. You'll likely see much more response there.

http://www.diymobileaudio.com/forum/system-design-help-me-choose-equipment-my-car/


----------



## 2010hummerguy

Per the Facebook update, the subs have arrived and are now being tested before preorders will ship. IT'S LIKE CHRISTMAS!!!!


----------



## bertholomey

Guys.......you are going to love this sub. I have heard bass like never before.....just been too darn busy to finish this review........I'm going to get snowed in this week, so I'm going to try my best to get it done!


----------



## Electrodynamic

Yes the subs are here. A couple handfulls of pre-orders got shipped out today. Too bad the woofers showed up late or I could have had more of them shipped.  However, it looks like we here in NC are about to get hit with a bunch of snow tomorrow. If that is the case I won't be able to make the hour long drive into work (where my shop is located is going to worse weather than where I live) to test more woofers so it may be Thursday before I'm able to ship more pre-orders out. 

This is the first time in my life that production units have been better than prototypes. Usually the prototype crew of any assembly/build house can do much better work than their production lines can. The latter is NOT the case with the BM mkIV's. The production units are testing *better* than the prototypes. :beerchug: 
I am _extremely pleased_ with the finish on these production units. The flat-black paint on the diaphragms, the gloss black paint on the basket, the chrome finish on the motor and mesh inserts, the total overall look of the woofers, everything is actually above what I was expecting. I am very, very, happy. epper:

Here is a video I took today of the first production woofer being tested:


----------



## 2010hummerguy

Oh wow, now I am REALLY excited! No hurry with my pair, I still need to finish my enclosure


----------



## 1fishman

Im looking forward to getting one installed and hearing for myself. 

No hurry though, i'm pretty sure Atlanta will be closed till next week.


----------



## quality_sound

I knew I should have gotten in on the presale.


----------



## bose301s

quality_sound said:


> I knew I should have gotten in on the presale.


Same, I waited too long and now it's out of my price range


----------



## quality_sound

I can still afford it. Just kicking my own ass for not pulling the trigger.


----------



## cajunner

I've never heard the SI shallow design, but this looks great!

I assume there was an incremental increase in a positive direction from the last series?


----------



## quality_sound

More excursion, further optimization for use in .5cf, and IIRC, more power handling.


----------



## bertholomey

I'm have been doing a lot of thinking about this review, but I haven't been able to do a lot of listening. I've been doing more traveling, and I didn't have the car for awhile when I was getting it fixed after hitting the coyote. I'm also going through a complete re-tune. So, I'm going to go ahead and post what I have now, and I may add to it later. 

The pre-sale units are being shipped out according to the posts here and the Facebook posts. Also, I'm going to Freezefest this weekend, and I'll get some additional ears in the car to hear the sub. 

I have already posted some impressions, pics of my install (and some comments concerning enclosure recommendations), and some impressions of others who have heard the sub in my car. In this 'Review', I'm going to post a few FR graphs with my tune, in my car. I'm going to post a small amount of information about XBL technology, and then a summary of what I like about this sub system. 

I did a search for information about XBL technology - I really wanted to know more about what makes up a speaker system, and what makes this technology different than other types. What I really wanted to know.......what is it about the physical aspects of this driver that translates into a sound that I prefer. 

From Adire:

Adire Audio - XBL Technology explained

This is from a discussion I saw on one of the sites - not sure where now, unfortunately. I haven't run this by Nick, so he may need to correct anything that doesn't quite jive. 



> As far as the technical aspect, it breaks the magnetic gap into more than one region, meaning instead of a typical motor that has a single high flux gap in the center, there are two or more gaps in the motor that have narrower high flux regions. Then, the coil is sized to optimize BL over the curve, mainly so that the coil will extend from the center of the top gap to the center of the bottom gap, that way when it leaves one high flux region, it enters the other. Most subwoofers use the voice coil to achieve a higher excursion, the downside of that is that the higher the excursion, the less coil is in the gap, so you lose motor strength and control, so distortion is increased and overall BL is decreased. Adire's method uses the gap more effectively and distributes it over a shorter coil, while decreasing required top plate length, thus the production cost. Coil length is decreased compared to designs like overhung and evenhung, so inductance is less and transient performance and efficiency is better. It's one of the best, if not the best motor design out there.
> 
> BTW, the main benefit of this topology isn't fully realized with subwoofers. This actually sees more benefit with midbasses, midranges, tweeters, and full range drivers. Typically, and XBL^2 driver will still only have 30% of the distortion other designs have at 70% of maximum linear excursion (x-max). In many cases, this translates to around a 1% distortion rating at 70% excursion, while others are between 3 and 5%. This allows a design that yields very clean sound at higher volumes and can fully realize the potential of enclosures such as sealed and infinite baffle, where excursion is naturally higher and SQ tends to suffer at high volumes due to that.
> 
> The biggest benefit of XBL^2 is that it allows a smaller driver to have higher output levels and a wider bandwidth, meaning a 6" midbass driver could potentially have the depth of a typical 8" driver and rival some 10" drivers for depth, and be very linear and accurate doing it. Their Extremis midbass driver is a good example of this, it is a 6.8" driver having a 13mm one way X-max, only a .13mH inductance, and is ideal for ported boxes tuned in the 30s, offering in-room extension down to the 20s. Inductive rolloff occurs around 8khz and there are no nasty breakup modes from the cone, crossover will typically be 2-3khz. To give you an idea, the Scan-Speak Revelator and SEAS Excel drivers, which are renowned high end home audio drivers, have a good bit more inductance, right at half or less than half the excursion level, less motor strength, and less bandwidth. As their designs progress even further, Adire is going to be a very difficult manufacturer to beat, or even level with for that matter.
> 
> *Personally, I really liked this explanation of how the voice coil works. *
> 
> Apocalypse, think about a magnet reacting to another magnet. The most strength will naturally occur when the magnets are closest together, and become weaker as they move further away. Similarly, in the case of a speaker, you have a fixed magnet and the voice coil, in which the coil is an electromagnet. They will either repel or attract each other with current applied. With a typical speaker, the center point of the motor (permanent magnet) is where the strength is focused, and at rest, the voice coil is centered in that. As current is applied, forces either repel or attract this, moving the coil up or down. As you can imagine, as it moves, less and less of the voice coil is retained within the gap, so magnetic control over the entire voice coil is reduced. The idea with these motor designs is that the longer the coil, the more there is to apply strength to, so you'll get more excursion with a longer coil. XBL^2, from a functional standpoint, has two or more points that focus strength over a narrower gap, just think of it as two magnets, and as the coil leaves one gap, it will enter another, which allows a higher level of control and motor strength than if it were one. As the coil moves further from one gap, it moves closer to the other, so you will have more control over the coil since you are always within a strong point of flux, and you will get more motor strength over the excursion limitations.
> 
> About efficiency, XBL^2 is actually more efficient than most motor designs out there overall, it is the soft parts that tend to bring down the efficiency of the subs they are used in. Adire uses epoxy treated paper cones in their subs, which are heavier than many other materials, but chosen for their damping ability, they also use a wider profile surround as opposed to a taller one, which controls the subwoofer very well, but cuts down surface area, and tighter suspension designs than many. XBL^2 isn't really the reason a Brahma isn't as efficient than other subs, but rather the reason it isn't less efficient than it already is. Adire is also more true with their sensitivity specs than many other manufacturers. Remember as well, that sensitivity specs are very misleading and give no clue to how loud a subwoofer will be at higher volumes. Excursion is low at 1 watt , a subwoofer with a parabolic BL curve will do well at 1 watt, but lose motor strength (thus efficiency) at higher volumes. XBL^2, on the other hand, offers flat BL and will give more BL at higher volumes than many other motor designs, making it more efficient with the power.


Now - the review.......

0.5 cu ft sealed enclosure mounted in the front floorboard of my Subaru BRZ. I have roughly 950 watts wired at 2 ohm on a Mosconi 200.4.

To get the few measurements I'm posting here using REW: Volume on Head Unit = 30 / 62; 13.3v - on my power supply; and the sub is set at 0db on the HU. Note: these graphs are with my tune, in my car. I have a dip at 30hz that is vehicle / tune specific - I choose not to pull down 40-80hz to flatten it out. Now - don't beat up on me with these graphs.....I know they are fairly meaningless because it is my tune and my car, but some have asked for graphs in the past. They just show how the response changes based on the various crossover point. 

Showing the voltage readout:









Showing the power supply:









Most of my listening is at 63hz @ 6db - just what I prefer. Here are some graphs at various crossover points / slopes:







































I really feel this subwoofer works very well (especially in the front of the car) with a steep slope and with a shallow slope. 

I was also going to post about a hundred tracks with notes about each one, but I have decided to give a summary and paste in here my impressions of a handful of tracks I listened to on Sunday evening. 


I'll post these few tracks that I listened to on Sunday. 



I may know the word - natalie merchant - kick drum - 3 strikes - perfect tonality for tight kick drum - very tight - great impact. bass guitar comes in, picked up by the sub - great sustained tones

Great & Mighty - Cru - live - kick strike, then 2 toms - solid kick hit - big live sound - impact felt throughout the car at 40/62 - low extension on bass guitar.

Is this what you wanted - jill phillips - kick drum + bass guitar - bass guitar detailed moving part - excellent definition; Buried Alive - same thing - extremely solid kick drum with a very present moving bass guitar. 

Is it alright - Maya Isacowitz - kick drum strikes, solid then - fantastic bass guitar - very full, thick - great extension; Roses - solid kick to start track, solid bass guitar - full notes, deep extension.

Arms of a woman - Amos Lee - stand up bass - lowest note, absolutely no problem at all - very solid, great tone - 

In the air tonight - Naturally 7 - 40hz strobes according to the RTA - then percussion comes in - 40-90hz extremely strong - solid!

Warrior Sound - Rockamovya - flowing low bass guitar - completely solid - all in front of me - deep!!!

streetlight in the egg - kaki king - foot tap on wooden platform - picked up perfectly with the sub to compliment the mid bass - very fast paced.

slippery people - talking heads - tight! deep, fast - impact!!!

Ghosts that we knew - Mumford and Sons - stand up bass - perfect pitch, finesse! gets all the deepest notes - full, rich sound - anchored in the stage; After the storm - kick drum that comes in - perfect tonality of a simple kick drum on the stage that he hits. 

Always something better - trentemoller - unbelievable, low articulate bass - full and deep - exactly what I want out of a sub when playing electronic music- Amazing!

Elves vs Mecha - Lowest notes played with absolute authority - big!!! car shaking - great tone - sweeps - lowest notes did not get quieter at all - stayed the same level. 85db 40hz hits with the HU vol at 30/62 - 

July - lee ritenour - extremely low, full bass parts - no drop off on output at the lowest notes

sail - awolnation - fantastic kick drum impact - big!

Orion - Metallica - Live - perfect representation of the kick drum from Lars - impact, tone, live sound, fast

Avenged Sevenfold - same - big kick drum - very much like a live concert - perfect pitch - impact 



*Summary:*

With this fantastic enclosure that Mark built, with a terrific amplifier pushing the sub, and with my tune...........

I feel that this is my favorite subwoofer system that I have ever had. This driver excels at the following 

1) Acoustic Bass - especially at the finesse game - stand up bass, acoustic bass guitar, and cello

2) Acoustic Kick Drum - might sound like a weird description, but what I mean is a very naturally mic'd kick drum - like it is in the room with you 

3) Electric Bass guitar - either very tight, slap bass or full, fat low electric bass

4) Electronic Bass - techno - like Trentemoller and Cirez D; and dub step - like Winside and Logic Bomb - car shaking output - sounds a lot more than a shallow mount 12" in a small enclosure. 



Very low bass - Extremely clean sound - fast pace - incredible impact - amazing finesse (think Nickel Creek and Mumford and Sons). I'm extremely pleased and satisfied with this subwoofer. After a few initial listens to this sub in a sub-standard box - I was smitten - enough to displace the excellent JL TW3 sub.

I'm hoping that some of the folks that will listen to the sub system this weekend might provide some feedback as well. Thanks for reading.


----------



## TOOSTUBBORN2FAIL

Really interested in this now that I'll be putting my wife's sub up front in the passenger foot well. Not sure it will fit yet, but like the review.


----------



## evangojason

I pre-ordered two of them and will be installing them in the false floor of my Scion xB as soon as they show up. The enclosure is already made (.5cuft per driver) and they will be powered by a pair of JL HD750/1's. Thanks for the review.


----------



## bertholomey

TOOSTUBBORN2FAIL said:


> Really interested in this now that I'll be putting my wife's sub up front in the passenger foot well. Not sure it will fit yet, but like the review.





evangojason said:


> I pre-ordered two of them and will be installing them in the false floor of my Scion xB as soon as they show up. The enclosure is already made (.5cuft per driver) and they will be powered by a pair of JL HD750/1's. Thanks for the review.


Thanks guys for the feedback. Feel free to post up your impressions when you get those installed in the xB - that sounds like it will be an amazing set up.


----------



## casey

thanks for the thorough review Jason. I havent heard yours yet but havent heard any negative comments from people that have.


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## captainobvious

Jay, nice write up and review- thanks for taking the time to share it. These are really excellent subwoofers.


----------



## BEAVER

When will all of the pre-orders be filled and stock replenished? I guess what I'm asking is when would I be able to buy one of these?


Sent from my iPhone using Tapatalk


----------



## casey

any update on when i can pick my 2 up from you? have emailed and asked on fb. thanks


----------



## bertholomey

BEAVER said:


> When will all of the pre-orders be filled and stock replenished? I guess what I'm asking is when would I be able to buy one of these?
> 
> 
> Sent from my iPhone using Tapatalk





casey said:


> any update on when i can pick my 2 up from you? have emailed and asked on fb. thanks


Thanks for posting, but I would rather see these kinds of posts on the following thread and not on my review thread. 

Pre-Order Thread



Thanks


----------



## nineball76

Are these only for sealed? How would they perform in a Tline?

sent from Tapatalk, via Sony Z1 badassness!


----------



## Electrodynamic

BEAVER said:


> When will all of the pre-orders be filled and stock replenished? I guess what I'm asking is when would I be able to buy one of these?
> 
> 
> Sent from my iPhone using Tapatalk


Hopefully all the pre-orders will be handled by the end of this coming week.


----------



## BEAVER

Electrodynamic said:


> Hopefully all the pre-orders will be handled by the end of this coming week.



Will there be any stock remaining to fill new orders? If not, any idea how long of a wait we're looking at on new orders?


Sent from my iPhone using Tapatalk


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## Electrodynamic

Yes there will be drivers left over from the pre-orders.


----------



## 1fishman

@ Nick
Does *all* the FAQ on the SI web site for the BM MKIII apply to the new MKIV?
I assume the 0.05cu ft, of the speaker displacement the same? 
("The BM mkIII 12” subwoofer displaces 0.05 ft^3.")


----------



## Electrodynamic

1fishman said:


> @ Nick
> Does *all* the FAQ on the SI web site for the BM MKIII apply to the new MKIV?
> I assume the 0.05cu ft, of the speaker displacement the same?
> ("The BM mkIII 12” subwoofer displaces 0.05 ft^3.")


Yes all of the FAQ remains the same for both the mkIII and the mkIV.


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## nineball76

No tline info? 

sent from Tapatalk, via Sony Z1 badassness!


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## Electrodynamic

nineball76 said:


> No tline info?
> 
> sent from Tapatalk, via Sony Z1 badassness!


That is correct.


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## Electrodynamic

BEAVER said:


> Will there be any stock remaining to fill new orders? If not, any idea how long of a wait we're looking at on new orders?
> 
> 
> Sent from my iPhone using Tapatalk


We will have all of the pre-orders buttoned up by the middle of this coming week. At that time I will take down the note about the 1 to 1.5 week long wait time on the Order page.


----------



## 2010hummerguy

Wife just texted me that my pair of MKIV's arrived today, can't wait to throw one in a box for testing over the weekend!!!


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## bertholomey

Awesome! I gave a fellow forum member a demo today - I think he came away pretty impressed with my one mkIV in a small sealed enclosure. 

Let us know what you think after the weekend.


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## Electrodynamic

Architect7 said:


> Wife just texted me that my pair of MKIV's arrived today, *can't wait to throw one in a box for testing over the weekend!!!*


Good to hear they arrived at your house. Let us know what you think once you put in some solid listening time.


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## 2010hummerguy

Will do, driving around 500 miles this weekend so I will have plenty of time to spend listening.


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## 2167

Thanks mr. nick mine just showed up on my porch...now for an attempt in the passenger foot well


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## jdc753

Got mine last week while on vacation, looks awesome, but I need to rip out my console and padd down the box so I can swap the Mag V4 out for some testing with the mkIV. Can't wait to hear this sub, just wish it was warmer than 20° out.


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## 2010hummerguy

Just spent about 15 minutes listening to this sub in a .5 cu. ft. box with 500 watts and holy wow it is incredible. Definitely has more output than the MKIII but same phenomenal sound quality. Installing two of these under my back seat is going to be ridiculous...ridiculously awesome


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## 2010hummerguy

Okay I spent about 4 hours on the road today listening to a wide range of music including David Guetta, Pharrell, the new Skrillex, Lorde, Alterbridge and NIN. I am positive that this sub plays even "fuller" than the MKIII. Even at low volumes it fills the cabin with deep, intoxicating bass that is clean as can be. I even had to turn my amp gain down to MINIMUM and also turn down the deck gain 3db for the sub channels because it is so much more efficient than the Alpine SWR-T10 I was using. Though the comparison between a 10" and a 12" is unfair, the output difference is far greater than the difference in cone area. On complex high output tracks on the new Skrillex album this sub just goes and goes. It helps that my cabin is small, being a mid-size quad cab but the MKIII would never play this loud. I was playing the sub at ~70% and I hope to take it to the limit tomorrow when my wife isn't around (she loves good bass but not as loud as I prefer ).

Just like the MKIII, this one digs deep, playing lower than most single 12's I have heard and even many larger subs. It reminds me more of the bass created by the Rythmik FV15HP in my living room. Tight, servo-like but output for days like a conventional sub, nothing like its distant shallow cousins. Once again, SI is in a league of their own


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## The Dude

Great review, thanks.


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## bertholomey

Absolutely agree - great feedback! I also completely agree with your assessment - this is exactly the experience I have had with this remarkable sub.


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## captainobvious

Great review. I couldn't agree more. This does NOT sound like a "shallow sub". Surprisingly deep extension and excellent, clean output.


----------



## cajunner

getting wood, looking hard...


----------



## 2010hummerguy

I forgot to add how beautiful these are in person. The black basket with chrome motor vent grills is truly eye catching. The first night these arrived I flipped one upside down and stared at it during commercial breaks while watching TV. Mesmerizing! Too bad you have to hide that pretty basket when they are installed. The new gasket with holes for screws is a welcome change over the MKIII's hidden screw gasket. No chance of slipping a screw driver with these.


----------



## Electrodynamic

Architect7 said:


> Okay I spent about 4 hours on the road today listening to a wide range of music including David Guetta, Pharrell, the new Skrillex, Lorde, Alterbridge and NIN. I am positive that this sub plays even "fuller" than the MKIII. Even at low volumes it fills the cabin with deep, intoxicating bass that is clean as can be. I even had to turn my amp gain down to MINIMUM and also turn down the deck gain 3db for the sub channels because it is so much more efficient than the Alpine SWR-T10 I was using. Though the comparison between a 10" and a 12" is unfair, the output difference is far greater than the difference in cone area. On complex high output tracks on the new Skrillex album this sub just goes and goes. It helps that my cabin is small, being a mid-size quad cab but the MKIII would never play this loud. I was playing the sub at ~70% and I hope to take it to the limit tomorrow when my wife isn't around (she loves good bass but not as loud as I prefer ).
> 
> Just like the MKIII, this one digs deep, playing lower than most single 12's I have heard and even many larger subs. It reminds me more of the bass created by the Rythmik FV15HP in my living room. Tight, servo-like but output for days like a conventional sub, nothing like its distant shallow cousins. Once again, SI is in a league of their own


Thanks for posting your initial thoughts. I couldn't agree more.  I'm glad you like the woofer.


----------



## 2010hummerguy

I had to move the sub for our drive home because we had so much stuff in the back seat (baby shower gifts!). I moved the MKIV to the floor directly behind my seat facing forward. It still sounded great! This sub literally sounds good everywhere (the MKIII seemed pickier about placement). This is probably due to increased output. Can't wait to have two of these installed though to be honest I would be perfectly happy with just the one.


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## ktmkev_74

I am am upgrading then Bose system in my Sierra Crew cab. Want to go with a SQ system. Considering HAT Clarus 6.5 up front and BM mkIV for the sub. Would 1 mkIV be enough or do I need 2?


----------



## bertholomey

Well - it depends on your definition of 'enough'. My one MKIV is more than enough for me with many genres of music. I guess if you gave more description of your goals concerning the sub system, we could offer additional opinions. Easy answer is, buy one and install it, if you want more, but another one......or, go ahead and buy 2, you can always turn it down to blend.


----------



## ktmkev_74

My goal is to have a nice quality sound. Not trying to blow anyone's doors off. I listen to mostly to r&b,top 40, jazz and some hip/hop(not much).


----------



## bertholomey

One in a good 0.5 cu ft box with about 300 watts would probably satisfy your needs perfectly. Two with more power in a good enclosure would be very impressive, but it depends on your resources.....cost of another sub, larger enclosure, more wattage - all of that is completely doable.......


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## captainobvious

Completely agree with Jay. You can get to spirited levels with just one, no problem. If you're a closet basshead, you might want 2 of them, but I'd be more than happy with one. One will get you to SQ reference levels with ease.


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## quality_sound

I'm gonna see if I can get 4 in my STI. ;-)

Sent from my Moto X using Tapatalk


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## ktmkev_74

Thank you all for the advice. Gonna have to sleep on it and figure out what I want to do. Right now, I leaning towards 1.


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## quality_sound

If you even have to think about it, you need two. Better to have too much and be able to turn it down than to not have enough and be screwed. 

Sent from my Moto X using Tapatalk


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## bertholomey

This goes along with the enclosure as well. If you can easily fab up a temp .5 cu ft box that is well constructed to see if one works, then fine. If you will pay someone else to build the box, Paul's point is right on. Hate to spend the $ on one, not be totally satisfied and wish you had 2, or pay to have another built. That was my comment about resources.....choice to order one, fab a temp box = thrilled, or want more.....order 2nd one - bud permanent 2 driver enclosure. 

Soon I'll be hearing Casey's car with 2 of these installed - I'm looking forward to it!


----------



## eddieg

Jason, 

Been a while but you got me influenced and as well started - The SI BM currently is not my decision as I am not sure at all if I want to go back to 12" diameter and stay at the 8inch ralms but go to a higher wattage sub. 

Never mind that - what you got me started with is - 

I've recently upgraded my wife's car and we decided that we would not require an amplified audio system in it - so what ever was there such as MDSP (mini DSP 2x4 processor) HAT L3SE's, HAT C5, DLS RA20 and JBL CS300.1 and last but not least which is the point for my message: 

A MicroSub by JL Audio in a half lunar enclosure that what do you know... fits right and tight into my Avensis 2006 front passenger foot well 


It is just a 150Watt 8W1 JL sub - but it actually is very tonal and good sounding! 

Since I moved recently from a 3way active setup to a 2way active setup (ES-02 by CDT with HAT L6 for which I attend to write a member review in the upcomming week or two) - I've got two channels freed up on my ZED audio Leviathan (bridged would output over 400watts at 4 ohm - more than plenty to a microsub like that) 

So I am about to run it in conjunction with my DD 8 inch sub but the JL would be up front - gotta try it for my self - you got me curious! 


Just need to find a time to facricate a good grill, an original kick panel as the built ones are too intrusive to fit it right in and a piece of black fleece to hide it from the eye (it is gray fleece covered) and then I'll give it a go.


I've been reading your review and it sounds like a fantastic sub - a 0.5cf enclusoure is really making me scratch my teeth together trying to...

must... resist... wife will... kill me!!! 

Stay safe! keep in touch


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## bertholomey

Wow! that sounds like great stuff there......please keep me informed of your progress!


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## captainobvious

quality_sound said:


> I'm gonna see if I can get 4 in my STI. ;-)
> 
> Sent from my Moto X using Tapatalk


:laugh:

Nuts


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## jdc753

quality_sound said:


> I'm gonna see if I can get 4 in my STI. ;-)
> 
> Sent from my Moto X using Tapatalk





quality_sound said:


> If you even have to think about it, you need two. Better to have too much and be able to turn it down than to not have enough and be screwed.
> 
> Sent from my Moto X using Tapatalk


This is where I'm at. 

I've wanted to put 4 behind the seat in my truck since the BM mkIII's came out.


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## sundownz

captainobvious said:


> Great review. I couldn't agree more. This does NOT sound like a "shallow sub". Surprisingly deep extension and excellent, clean output.


Indeed -- they will surprise you for sure


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## ktmkev_74

bertholomey said:


> One in a good 0.5 cu ft box with about 300 watts would probably satisfy your needs perfectly. Two with more power in a good enclosure would be very impressive, but it depends on your resources.....cost of another sub, larger enclosure, more wattage - all of that is completely doable.......


Cost is not an issue. For the enclosure of 2 mkIV's, would it basically be 2 separate 0.5 cu ft chambers(1 for each sub)? Also, what kind of wattage would you put to them?


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## bertholomey

ktmkev_74 said:


> Cost is not an issue. For the enclosure of 2 mkIV's, would it basically be 2 separate 0.5 cu ft chambers(1 for each sub)? Also, what kind of wattage would you put to them?


Good question - I'm sure I'll be corrected, but I believe I have seen guys say that it doesn't really matter to the sub - whether it is in 2 separate .5 cu ft enclosures or sharing 1 cu ft common space. As long as the bracing is good, I don't think it matters. 

The wattage question......you will get a lot of different answers on that - there have been some discussions about that on this thread. If you have 700 watts as a final load on the 2 subs.....that should be more than plenty.


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## ktmkev_74

bertholomey said:


> Good question - I'm sure I'll be corrected, but I believe I have seen guys say that it doesn't really matter to the sub - whether it is in 2 separate .5 cu ft enclosures or sharing 1 cu ft common space. As long as the bracing is good, I don't think it matters. QUOTE]
> 
> Really?!? I would have never guessed that. Glad I asked.
> 
> Is 600 watts OK?


----------



## Electrodynamic

bertholomey said:


> Good question - I'm sure I'll be corrected, but I believe I have seen guys say that it doesn't really matter to the sub - whether it is in 2 separate .5 cu ft enclosures or sharing 1 cu ft common space. As long as the bracing is good, I don't think it matters.
> 
> The wattage question......you will get a lot of different answers on that - there have been some discussions about that on this thread. If you have 700 watts as a final load on the 2 subs.....that should be more than plenty.


No need to correct anything.  The separate chamber discussion could go on for many pages. However, my input on the question of "should I use a common or separate chamber enclosure" is the following:

Common chamber - easier to build and technically there is more overall volume for the multiple subwoofers (thickness and size of the material being used takes up a tiny bit of volume). 
Separate chamber - harder to build by adding the divider. The divider also acts as a brace to the enclosure. The divider takes up a tiny bit of volume. 

If you want to use two woofers and are stretching as FAR as you can go to allow even 0.5 ft^3 per driver [1.0 ft^3 total] go with a common chamber. If you have the space to allow for 0.6 ft^3 per driver without any issues and you don't mind making the chambers separate go ahead and make them separate chambers. 

The enclosures for these woofers are very very small and are inherently pretty strong as most of the panels are not very big nor are any of the panels very far apart so a brace is not needed in most applications. Keep in mind that the BM mkIV's are also not intended to be an SPL generating monster capable of 140+ dB from a single woofer so they will not be putting a huge strain on the enclosure. However, on a very wide, flat, box a brace in the middle can help if you have the tools and room/volume to do so.

Lastly, I do NOT recommend sending a BM mkIV more than rated power. Power ratings are not power requirements.


----------



## quality_sound

There are two other considerations.
1) Panel flex in the common chamber enclosure
2) IF you blow one sub, you'll like lose the other since now you have one functional sub in an enclosure that's twice the size it should be. 

The space the divider takes up is irrelevant because you would just add it's thickness to the overall width and you're good to go. 

Sent from my Moto X using Tapatalk


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## eighty5iv

Here is my enclosure for the MKIV. its a two chamber box. each chamber is right at .5cuft and using 3/4in birch material.


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## bertholomey

Very nice - what vehicle will it be going into? (On Tapatalk)


----------



## moparman79

If doing more then one sub each gets its own chamber.


----------



## eighty5iv

bertholomey said:


> Very nice - what vehicle will it be going into? (On Tapatalk)


my grocery getter, an 07 camry.


----------



## bertholomey

I recently made a change to the tune concerning this sub system, and I wanted to provide my feedback. 

I went to Freezefest recently with a setting of 80hz @ 12db, and the sub sounded really good to me. Well, I had points taken off due to a sound that was described by one judge as 'straining, over-processed, boomy bottom end' and by another judge as 'seems a bit unclear, a little distorted'.

The reason I provide that feedback (very disappointing at the time) is to show how much the tune has to do with the ability of the sub system (and the other parts of the system) to sound 'right'. One could have the best equipment and an awesome install......but if the tune is jacked up.......it won't score well, and more importantly, it won't sound 'right / natural'. 

That is what is so challenging when you read on the inter webs something like....."I heard the (insert speaker name here) in a car once, and it sounded terrible". _Well....how was it installed, and how was it tuned? _ "I have no idea, I just know it was awful". Hard to trust that feedback. 

The tune that I had at FF sounded 'decent' to me, but it wasn't until after it was 'fixed' did I realize how bad it was - the judges feedback was dead on. This sub does play well crossed high, but I had some Frequency Response issues that seriously needed to be dealt with. 

My friend Matt tamed those by ear in about 2 minutes, and the sub system sounds incredible now. I realized that I had too much output at a few frequencies that was causing a boomy, unclear sound.......as evidenced by my constant raising / lowering the sub volume level from track to track. 

Now that the crossover is set where it is, and the FR issues were addressed, I never have to adjust the sub volume - it reproduces what is in the source music - at the appropriate levels. What I am hearing now is exactly what Nick responded in another thread to someone who was asking about the sound signature of the sub......I just had to copy it hear as well 




Electrodynamic said:


> The thing to keep in mind is that it's not that the BM mkIII or mkIV doesn't have any midbass, low end, play loud, etc, it's that the BM mkIII/mkIV woofers do not distort like most woofers do and therefore it does not sound like most woofers do. The main thing the BM mkIV does can be summed up with this - The BM mkIV plays so smoothly that it makes your front stage sound huge. You will not be able to pin-point where the woofer is lcoated (a very good thing in audio) and it blends effortlessly with your main speakers. If possible put an on/off switch on the remote wire to your subwoofer amplifier so you can turn it off and listen to how your system sounds _without_ the BM mkIV and then turn the amplifier back on and see how your system sounds _with_ the BM mkIV. If you are able to do the latter either in a vehicle or in a room you will be able to fully take in everything the BM mkIV offers.


----------



## casey

good to hear Jason, glad youre still enjoying it and getting it dialed in


----------



## 2010hummerguy

bertholomey said:


> I recently made a change to the tune concerning this sub system, and I wanted to provide my feedback.
> 
> I went to Freezefest recently with a setting of 80hz @ 12db, and the sub sounded really good to me. Well, I had points taken off due to a sound that was described by one judge as 'straining, over-processed, boomy bottom end' and by another judge as 'seems a bit unclear, a little distorted'.
> 
> The reason I provide that feedback (very disappointing at the time) is to show how much the tune has to do with the ability of the sub system (and the other parts of the system) to sound 'right'. One could have the best equipment and an awesome install......but if the tune is jacked up.......it won't score well, and more importantly, it won't sound 'right / natural'.
> 
> That is what is so challenging when you read on the inter webs something like....."I heard the (insert speaker name here) in a car once, and it sounded terrible". _Well....how was it installed, and how was it tuned? _ "I have no idea, I just know it was awful". Hard to trust that feedback.
> 
> The tune that I had at FF sounded 'decent' to me, but it wasn't until after it was 'fixed' did I realize how bad it was - the judges feedback was dead on. This sub does play well crossed high, but I had some Frequency Response issues that seriously needed to be dealt with.
> 
> My friend Matt tamed those by ear in about 2 minutes, and the sub system sounds incredible now. I realized that I had too much output at a few frequencies that was causing a boomy, unclear sound.......as evidenced by my constant raising / lowering the sub volume level from track to track.
> 
> Now that the crossover is set where it is, and the FR issues were addressed, I never have to adjust the sub volume - it reproduces what is in the source music - at the appropriate levels. What I am hearing now is exactly what Nick responded in another thread to someone who was asking about the sound signature of the sub......I just had to copy it hear as well


What frequencies needed attenuation? All cabin gain?


----------



## bertholomey

Architect7 said:


> What frequencies needed attenuation? All cabin gain?


Good question. For some reason I had +2.0 @ 31.5hz - so that needed to come down, and then he brought down 40hz and 50hz - attributable to cabin gain. Smoothed out the response tremendously.


----------



## dgage

By the way, I met Nick (Electrodynamic) of Stereo Integrity at an AVSForum home theater Get ToGether and he is a great guy. His SI HS24 24" subwoofer is an absolute beast and we tried to destroy it with 8,000 watts but two amps couldn't bring it to its knees. For any sub, it sounded clean and tight but for a 24" sub, it was truly impressive, even more so when I realized the crossover point was 100 Hz. As great as it sounded, it was strong down to single digits. By the way, I brought my 2 LMS 5400 (Ultras) and the HS24 dismissed the uber subs without much effort, especially below 15 Hz. Truly impressive. 

After that meet, it made me that much more excited to build a box and install my BM MKIV but I'm trying to finish up the theater first. Soon, though.


----------



## low4ever

So will these sound good in a car trunk with all the insulation or metal in between, or is this for inside the cabin style setups?


----------



## bertholomey

Most people will likely be installing these in a trunk set up. Their size makes them versatile enough to mount in the floorboard, behind the seat in a pick up, under the seats in a Scion xB, side walls of SUVs, etc., but most guys will likely have these in the trunk. Here is an install that is still in process, and I'm going to help with the tune - should be fantastic!











http://www.diymobileaudio.com/forum...nc-meet-26-april-2014-near-greensboro-nc.html


BTW - where are you in NC? We are having a big meet tomorrow near Greensboro. Nick of SI will be there with some drivers.


----------



## mSaLL150

bertholomey said:


> We are having a big meet tomorrow near Greensboro. Nick of SI will be there with some drivers.


Hey Jason, tell Nick I have monies waiting for him!  He has my mkIII, I'm dying for the mkIV. Starting my new install this weekend.


----------



## low4ever

bertholomey said:


> Most people will likely be installing these in a trunk set up. Their size makes them versatile enough to mount in the floorboard, behind the seat in a pick up, under the seats in a Scion xB, side walls of SUVs, etc., but most guys will likely have these in the trunk. Here is an install that is still in process, and I'm going to help with the tune - should be fantastic!
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> http://www.diymobileaudio.com/forum...nc-meet-26-april-2014-near-greensboro-nc.html
> 
> 
> BTW - where are you in NC? We are having a big meet tomorrow near Greensboro. Nick of SI will be there with some drivers.


I'm in fayetteville. I have a 83 Fleetwood Brougham Coupe with very low miles and wanted to put a simple sq setup in it. I wanted to go with the IDMax but with that small size i'm really interested in these now. If it hits the lower frequencies pretty good this might do what i need and take up a lot less space.


----------



## Electrodynamic

low4ever said:


> I'm in fayetteville. I have a 83 Fleetwood Brougham Coupe with very low miles and wanted to put a simple sq setup in it. I wanted to go with the IDMax but with that small size i'm really interested in these now. *If it hits the lower frequencies pretty good *this might do what i need and take up a lot less space.


You mean *when it hits* the lower frequencies. Don't let the mounting depth fool you. They have big-boy sound.


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## low4ever

@electrodynamic Thanks bro, that is just what i wanted to hear. I'm gonna order one soon…I hope.


----------



## captainobvious

low4ever said:


> @electrodynamic Thanks bro, that is just what i wanted to hear. I'm gonna order one soon…I hope.



You mean I WILL. 

The BM mkIV is not a typical "shallow sub" by any other description than mounting depth. It does things most full size 12" drivers can't. As I said in another thread, this sub plays extremely low and does it very cleanly. The fact that it can do so with a tiny box and small mounting depth is a _huge _bonus.


----------



## crea_78

Can't wait to hear the 2 I purchased at the NC meet.

Sent from my Nexus 5 using Tapatalk


----------



## bertholomey

I can't wait either - with them installed well with a good tune - they will be extremely impressive! I'm looking forward to hearing Casey's double BMs soon!


----------



## jsnstanley

Curious, What does the initials BM stand for? Great promo going on right now btw!


----------



## sirbOOm

Okay, I'm going to need two of these for my Silverado Doublecab. Underseat has very little room. Question: are these robust enough to downfire?


----------



## 2010hummerguy

jsnstanley said:


> Curious, What does the initials BM stand for? Great promo going on right now btw!


Baby Mag


----------



## Electrodynamic

sirbOOm said:


> Okay, I'm going to need two of these for my Silverado Doublecab. Underseat has very little room. Question: are these robust enough to downfire?


Yes.


----------



## Electrodynamic

Architect7 said:


> Baby Mag


Ssssshhhhh.....


----------



## 2010hummerguy

Electrodynamic said:


> Ssssshhhhh.....


I'm just the messenger, I have no idea what it means lol


----------



## naresh

Wow I I'm adding this to my list of sub for my 2011 scion xb to fit under the passenger seat.


----------



## wrcrs24

So just here reinforcing what's already been said here by so many others here. This sub AMAZING!


----------



## horse

I had wanted this sub but being down under it made things a bit more costly. But Nick's timing to have the special pricing made it much more worthwhile, and it cost the same to get two so why not 

I'll be putting one into each of my cars, different setups in both.

First car is a supra jza80. Hertz HDP5, Focal Polyglass coaxials rear fill and front stage is a bit of a mash of parts. Dynaudio MW160, Alpine/Scanspeak 2904 tweeter and Alpine SPX-F13M crossover in biamp mode. Anyway on the SI. 

Installation will be in a fibreglass enclosure so that it sits below the boot floor. Supra's don't have much space to begin with but the SI BM MKIV requiring only .6ft^3 made thins much easier. I've gotten to the point of laying down 3 layers of glass but then fell sick and now it's the middle of winter and it's pointless doing any further glass work now. So I've knocked up a temporary MDF box which does the job fine.

Firstly an embarassing stuff up on my part was that in my haste to wire it up at 2am I actually stuffed up the DVC coils and it ended up with me only powering up one coil. BUT it still sounded good. It all hit me the next day and once I had wired it up properly things were really moving. 

The sub presents very well, like others have said there it's highly transparent and can easily handle lows. Initially I was a bit hesitant with whether I'd enjoy it or if I'd perfer another sub with more distortion. Once I had the MKIV running it was pretty clear that I'd made the right decision.

I've tried a number of tracks such as Temper Trap Conditions album, silverchair Frogstomp, Warren G - Return of the Regulator, some house mixes and some other bass test tracks from the local car audio group. One of them is Headphone Activist - North End Night Life  which just wakes things up so well. In testing the system I would turn the sub on and off via the headunit at various points and you really notice that the it provides so much more depth and warmth. 

What the BM MKIV does so well is handle the various styles of music effortlessly. To date i've only played the sub for around 3 hours max as the car is rarely driven, and because one of the tweeters I bought was DOA and I've been waiting for some scanspeak 3004's to arrive as their replacement.

I'll get some pics of the setup later once I get pics off my phone.

The other sub will go into my other car a Caldina ST246W. It too will be glassed into the side cubby and run off a JL XD600/1. The rest of the factory sound sytem wil be left as is for now. But I may need to wait for things to get warmer first before I can glass things in and will probably make another mdf box for the interim. the car comes with an underseat sub so the BM MKIV will act as it's replacement, albeit with more oomph.


----------



## 2010hummerguy

Great review and glad to hear another person has converted. And I love Temper Trap, some amazing bass lines on their songs. My friend is married to one of the members too!

A few weekends ago I listened to my MKIV for roughly 9 hours straight at 70-80% during a road trip. It didn't break a sweat


----------



## bertholomey

Thanks for the review Horse! I would be interested to hear an update once you get that glassed in the permanent box. It is cool to read that your impressions of the sub's sound and performance matched mine. 

I have been without mid bass drivers for a couple weeks, and I moved the crossover point up on the BM to 63hz @ 6db, and I am not very surprised that the BM sounds amazing covering that range. Solid kick drum and bass guitar / stand up bass on top of the dash. If I had 5 1/4s in the pillars, I don't think I would need mid bass drivers at all, because the only thing I'm missing is lower range vocals ?


----------



## horse

@bertholomey I need to finish my doors off as they're the one thing letting my front stage down. needs to be sound deadened and sealed up. regarding sound impressions I was skeptical on your review but it was good to know that it delivered accordingly. There are time's I'd like massive hits but that's only after getting out of SPL cars  SQ always wins for me

@Architect7 I'm hanging out for a road trip!

here are some pics

Packaged extremely well









Overall box is quite small. I should have made it shallower so it would sit under the rear hatch cover better. But that thought never occurred to me until after


















And where it sits at the moment in the car, mainly for testing purposes.









Here's the fibreglass enclosure from the side









And from above if you stood behind the car on the left hand side. I initially based the design off 0.6 cu ft of bean bag fill in a huge garbage bag then glassed away. After removing it and double checking with water it was spot on 0.6 cuft. Add a few more layers and the top and I'll still be in range. 









now to just wait for warmer days. I have found person selling another box made for supra, but was for a 13.5" JL driver. for $50 it's worth getting and just getting another front panel cut to 12"  I'll post this up once it arrives.


----------



## CBS13WRX

I have just stumbled across this thread googling for a sub for my new truck, Silverado regular cab. I am not looking to bust the seal out of my windshield or to provide back massages for my passengers but some good bass in my commute. I am also not as intelligent on sound quality as many of the the users on here. So would one be quite efficient in a regular cab truck, where would be a good place to have the enclosure, behind the passenger or driver seat, or perhaps under one of those locations? My last car was a WRX hatch and I installed Raamat, ensolite, and a MLV on the floor in the set up. My system I used OEM head unit and the following Alpine PXE-H660 sound processor, 2 Rockford Fosgate PBR300X2 amps, 1 Kenwood KAC-6104D amp, a pair of Polk DB6501 speakers, a pair of Polk DB651S speakers, one Rockford Fosgate 10" P3 sub-woofer. With this system I may try to keep my OEM head unit once again because I prefer to surprise people with my factory radio. Although, my intention with my trick is to completely astonish with them on how great it sounds. Sorry for such a long post, any and all help is greatly appreciated.


----------



## bertholomey

CBS13WRX said:


> I have just stumbled across this thread googling for a sub for my new truck, Silverado regular cab. I am not looking to bust the seal out of my windshield or to provide back massages for my passengers but some good bass in my commute. I am also not as intelligent on sound quality as many of the the users on here. So would one be quite efficient in a regular cab truck, where would be a good place to have the enclosure, behind the passenger or driver seat, or perhaps under one of those locations? My last car was a WRX hatch and I installed Raamat, ensolite, and a MLV on the floor in the set up. My system I used OEM head unit and the following Alpine PXE-H660 sound processor, 2 Rockford Fosgate PBR300X2 amps, 1 Kenwood KAC-6104D amp, a pair of Polk DB6501 speakers, a pair of Polk DB651S speakers, one Rockford Fosgate 10" P3 sub-woofer. With this system I may try to keep my OEM head unit once again because I prefer to surprise people with my factory radio. Although, my intention with my trick is to completely astonish with them on how great it sounds. Sorry for such a long post, any and all help is greatly appreciated.


Welcome to the thread! The goals you stated above would appear to fit perfectly with one SI BM mkIV in a well built .5 cu ft enclosure. 

Depending on the size restrictions of the locations you have mentioned, either should work from a sound perspective - would come down to how much space you are working with and the shape of the box you want to build. 

If you installed in a good box with an amplifier that provided about 300 clean watts with a decent tune, you should be extremely happy with the detailed, deep, clean bass the BM produces.


----------



## deltasaurus

I am very curious and figured that I was ask for a general consensus as to how the BM MkIV would compare to the JL 13TW5. I have never heard any of the SI speakers and cannot seem to find anyone within a couple of hours from me that has any installed, so am afraid that I may not get the chance to hear them. I am currently putting together a 2009 Dodge Ram and more than likely am going to have to go the shallow sub route. Id anyone could comment on the 13TW5, Illusion C12, and the MkIV I would greatly appreciate it. In each case they would be as close to the manufacturers recommended box size with any amount of power needed. From 500 to 1500 watts each. I know listening and preferences are subjective, but just looking for a general idea. Not looking to rattle dishes out of the cabinets or SPL over about 135, would do 18's in a blow through if that were the case. Thank you for any input and I appologize if this is hijacking the OP.


----------



## subwoofery

deltasaurus said:


> I am very curious and figured that I was ask for a general consensus as to how the BM MkIV would compare to the JL 13TW5. I have never heard any of the SI speakers and cannot seem to find anyone within a couple of hours from me that has any installed, so am afraid that I may not get the chance to hear them. I am currently putting together a 2009 Dodge Ram and more than likely am going to have to go the shallow sub route. Id anyone could comment on the 13TW5, Illusion C12, and the MkIV I would greatly appreciate it. In each case they would be as close to the manufacturers recommended box size with any amount of power needed. From 500 to 1500 watts each. I know listening and preferences are subjective, but just looking for a general idea. Not looking to rattle dishes out of the cabinets or SPL over about 135, would do 18's in a blow through if that were the case. Thank you for any input and I appologize if this is hijacking the OP.


If you plan to use more than 500 watts per driver, you can take the MkIV off that list. They won't like it if you fit them in their recommended enclosure: 0.5cuft 
Other than that, can't help you much - have 2 MkIII and love them. 

Kelvin


----------



## 2010hummerguy

deltasaurus said:


> I am very curious and figured that I was ask for a general consensus as to how the BM MkIV would compare to the JL 13TW5. I have never heard any of the SI speakers and cannot seem to find anyone within a couple of hours from me that has any installed, so am afraid that I may not get the chance to hear them. I am currently putting together a 2009 Dodge Ram and more than likely am going to have to go the shallow sub route. Id anyone could comment on the 13TW5, Illusion C12, and the MkIV I would greatly appreciate it. In each case they would be as close to the manufacturers recommended box size with any amount of power needed. From 500 to 1500 watts each. I know listening and preferences are subjective, but just looking for a general idea. Not looking to rattle dishes out of the cabinets or SPL over about 135, would do 18's in a blow through if that were the case. Thank you for any input and I appologize if this is hijacking the OP.


Two MKIV's in .5 cu. ft. each will only need 500w each and you'll probably reach well over 130db on the dash depending on how they are aimed and the vehicle/location. I haven't heard the C12 yet but you'll like the MKIV better than the 13TW5. I believe the TW5 has similar power constraints as well but does not play low as well and overall just doesn't create the "full" bass sound that the MKIV is famous for.


----------



## low4ever

Can you mount these inverted?


----------



## edzyy

nvmm


----------



## subwoofery

low4ever said:


> Can you mount these inverted?


You can but why do that? 

Kelvin


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## low4ever

i like the way it looks.


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## deltasaurus

Thank you for the thoughts on the sub choice and a heads up on the power requirements. I think that I am going to have to get one or maybe 2 of the woofers and give them a try. Won't be the first time, and probably not the last time, that I buy a speaker without hearing them.


----------



## captainobvious

deltasaurus said:


> I am very curious and figured that I was ask for a general consensus as to how the BM MkIV would compare to the JL 13TW5. I have never heard any of the SI speakers and cannot seem to find anyone within a couple of hours from me that has any installed, so am afraid that I may not get the chance to hear them. I am currently putting together a 2009 Dodge Ram and more than likely am going to have to go the shallow sub route. Id anyone could comment on the 13TW5, Illusion C12, and the MkIV I would greatly appreciate it. In each case they would be as close to the manufacturers recommended box size with any amount of power needed. From 500 to 1500 watts each. I know listening and preferences are subjective, but just looking for a general idea. Not looking to rattle dishes out of the cabinets or SPL over about 135, would do 18's in a blow through if that were the case. Thank you for any input and I appologize if this is hijacking the OP.


I own the 13TW5 and run it currently in my system. I've also heard Bertholomey's BM mkIV extensively and will say this with experience with both- The BM mkIV plays deeper and does so in a smaller enlcosure size. It is an exceptionally musical sub and perfect for SQ applications. Nick really hit a home run with this driver. The JL has a bit more output, but in extension and clean, low distortion sound, it has a clear advantage to my ears. Both are excellent, but If you're in the market, I'd steer you to the Si BM mkIV. It's a truly excellent subwoofer.
Both JL and Nick of SI provide great customer service so no worries either way. I'd say pull the trigger and go for it. You won't be disappointed.


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## CBS13WRX

I wish Nick or JL would contact me.


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## 2010hummerguy

CBS13WRX said:


> I wish Nick or JL would contact me.


For Nick at SI try htsales at stereointegrity dot com


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## CBS13WRX

I am trying to get this sub from FedEx delivered and I am my wits end. I can not be home when they deliver and Nick requires a signature. They are attempting one more time tomorrow then it gets shipped back to the shipper.


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## Weightless

I just went through the same thing with my mkiv. Did they leave a doortag? If so, there is a new tracking number on it. Go online and track it. It should give you the option to have it delivered to a local fedex office. Then you can pick it up whenever. I am fortunate that my local fedex/kinko's is 24/7.


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## CBS13WRX

I can do that but I live in the sticks. I already paid over 22 dollars for shipping and driving over 20 miles to pick up a delivery that is suppose to be to my door is not acceptable.


----------



## mires

Weightless said:


> I just went through the same thing with my mkiv. Did they leave a doortag? If so, there is a new tracking number on it. Go online and track it. It should give you the option to have it delivered to a local fedex office. Then you can pick it up whenever. I am fortunate that my local fedex/kinko's is 24/7.


What I was going to suggest.


----------



## sirbOOm

I agree that signatures are annoying but, I'm sorry, you're allowing a petty issue to degrade what will otherwise be an excellent experience. For what I paid for shipping, mine arrived entombed in layers of boxes protected by foam - all of that packaging, if I went to go buy it, would cost me more than $22 not counting the shipping! The final most box looked like it had just been manufactured. The subwoofer itself is beautiful and was individually tested by a human being and, when I finally get it installed, I expect it to sound amazing. 

When you do, you're going to have this ridiculous memory clouding the experience that Nick and Stereo Integrity are terrible because they shipped the package containing, in effect, a rare and expensive piece of equipment to a destination in an unknown (to them) area with a signature requirement protecting them and you from the threat of theft. Over a 20-min. drive? Bro it takes me 20-min. just to get to the highway toward downtown where I then spend another 20-40 min. driving every single morning and evening to/from work! The hell is this whining? Drive the g'dam 20 miles to the FedEx shop and pick it up. Get your sub, install it, review it, and love it.

Sorry... but stop. I've been pissed by unnecessary, IMO, signature requirements but my opinion doesn't matter - it's Nick's subwoofer until you accept delivery and he wanted to make sure YOU got it. Don't damn him or his company for that.


----------



## subwoofery

Agreed with the ^ above ^ on all counts 

Kelvin


----------



## 1fishman

Not positive but doesn't the "missed delivery notice" have the option to sign it on the back and leave it on your door? Mine did.

The nature of selling and buying nowadays requires all safety step possible IMO.


----------



## 2010hummerguy

$22 shipping is cheap, I just paid $35 to ship a pair of HAT Unities via cheapest USPS option. Times have changed 

Agreed with the door tag. And unfortunately people blame the shipper when stuff is stolen off their front door because they live in a sketchy neighborhood. When I worked at Xbox corporate we saw that issue a lot.


----------



## CBS13WRX

At no point have I blamed or damned Nick or Stereo Integrity, all of my issues are with FedEx and their total lack of communication and customer service.


----------



## Weightless

I do agree with your frustration with FedEx. Right after Nick shipped my sub I called fedex to have them reroute the package to my local fedex office because I knew that I wouldnt be available to sign for it ( I live and work in different states). They told me that I could not choose that option with this specific package and couldn't/wouldn't tell me why. In the end, I missed the delivery and tracked the new tracking number from the door tag to try get them to reroute it to the local office and this time they were able to.

Next time I order anything online that will expect a signature, I am going to let the shipper know to send it to my local fedex office instead.


----------



## CBS13WRX

Any suggestions for a 5-channel amp that will produce the power needed for my 1 BM mkIV?


----------



## subwoofery

Audison has 1, same for Phoenix Gold, JL Audio, Alpine. @ 2 ohm

Possibly more but that's all I can think of right now. 

Kelvin


----------



## bobc04

i got a tru 6 channel. and you could bridge the sub stage part


----------



## jsnstanley

Arc Audio has some exceptional 5 & 6 ch. amps with nice reviews.


----------



## Derepente

horse said:


> @bertholomey I need to finish my doors off as they're the one thing letting my front stage down. needs to be sound deadened and sealed up. regarding sound impressions I was skeptical on your review but it was good to know that it delivered accordingly. There are time's I'd like massive hits but that's only after getting out of SPL cars  SQ always wins for me
> 
> @Architect7 I'm hanging out for a road trip!
> 
> Overall box is quite small. I should have made it shallower so it would sit under the rear hatch cover better.
> 
> 
> Question for you: Did you use wood screws for the BM MKIV as well? Any advantage to using washers so that the screws set above the gasket? Seems like yours, not visible, are inside the gasket. Thanks in advance.


----------



## legend94

CBS13WRX said:


> I can do that but I live in the sticks. I already paid over 22 dollars for shipping and driving over 20 miles to pick up a delivery that is suppose to be to my door is not acceptable.


I live near that Fedex


----------



## horse

Derepente said:


> Question for you: Did you use wood screws for the BM MKIV as well? Any advantage to using washers so that the screws set above the gasket? Seems like yours, not visible, are inside the gasket. Thanks in advance.


I used pan head screws and it sits on top of the gasket. The gasket is shaped like a C so the top part is just a cover. The previous design didn't have those holes so it was harder to screw the sub in as you'd need to pull the gasket top back to get to the holes.


----------



## Electrodynamic

horse said:


> I used pan head screws and it sits on top of the gasket. The gasket is shaped like a C so the top part is just a cover. The previous design didn't have those holes so it was harder to screw the sub in as you'd need to pull the gasket top back to get to the holes.


The gasket holes are C shaped but even then I *always* advise using washers between the screw head and the gasket. The last thing you want to do is twist the foam or rubber surround on the speaker when you are mounting it. In the case of the BM mkIII and mkIV the surround is rubber but you want to make sure to not damage the surround during installation. Washers are inexpensive and available in a plethora of different sizes which makes using them a no-brainer.


----------



## GV713

Ive read all the contributions by members up to this point. This is really my first step into car audio and I'm trying to do it properly. I've been collecting components for about 2 years now (school) and just about ready. The subwoofer purchase is going to be the last component I need in order to commence the install.

I own a Honda S2000 and theres not much space in the trunk or anywhere else for that matter. Fortunately there is an area where I can fit a .5^ft3 box (or larger) so this sub is right up my alley plus the company owner being active here is a significant plus !! Unfortunately I've already purchased the amplifiers (JL HD 750/1 and 600/4) as I decided that I would be using the Alpine SWR-T12, Hertz ML 1600 and ML280. Now that I've read all of the positive reviews and other posts on the forum. I decided to give the BM mk IV a try, but does it mean that I would not be able to use my JL HD 750/1 ?

I'm asking because both subs are around the same price and I dont want to fry a brand new subwoofer, Also the thought of having to get a less powerful amplifier already hurts. I did read from a post in this thread that the MK IV does not like anything above 500w in a.5^ft3 enclosure  , so what are my options? Would I be ok with a larger enclosure ? if so what size. Any input will be greatly appreciated.


----------



## casey

youll be fine to use the 750/1. You can adjust gains to match the power the sub needs. a larger enclosure will allow less power handling, stick with the .5cu ft recommendation and set your gains accordingly and you will be fine


----------



## sirbOOm

Keep the gain down and run it at 8-ohms. The amp I intend to use mine with is capable of 1300 watts at 2 ohm, 700 at 4-ohm. I'm not worried about it. I'll be running mine at 8-ohm.


----------



## GV713

Thanks guys, I got an SMD DD1 and CC1 as gifts last christmas but it seems that I won't be able to set the gains at the recommended wattage using the DD1 because it doesnt have a display so I'd have no idea what the output wattage of the amp is at any point in time. So im guessing I'll have to read up on using a DMM to set gains. Edzy and others here have contributed a great deal on the topic in other threads so im going to have to look into it.


----------



## captainobvious

GV713 said:


> Ive read all the contributions by members up to this point. This is really my first step into car audio and I'm trying to do it properly. I've been collecting components for about 2 years now (school) and just about ready. The subwoofer purchase is going to be the last component I need in order to commence the install.
> 
> I own a Honda S2000 and theres not much space in the trunk or anywhere else for that matter. Fortunately there is an area where I can fit a .5^ft3 box (or larger) so this sub is right up my alley plus the company owner being active here is a significant plus !! Unfortunately I've already purchased the amplifiers (JL HD 750/1 and 600/4) as I decided that I would be using the Alpine SWR-T12, Hertz ML 1600 and ML280. Now that I've read all of the positive reviews and other posts on the forum. I decided to give the BM mk IV a try, but does it mean that I would not be able to use my JL HD 750/1 ?
> 
> I'm asking because both subs are around the same price and I dont want to fry a brand new subwoofer, Also the thought of having to get a less powerful amplifier already hurts. I did read from a post in this thread that the MK IV does not like anything above 500w in a.5^ft3 enclosure  , so what are my options? Would I be ok with a larger enclosure ? if so what size. Any input will be greatly appreciated.


Since you're an S2K guy, please check out the build here that I did for my dad: http://www.diymobileaudio.com/forum...-gallery/162109-honda-s2000-sq-build-s2k.html

I put a full size 10" subwoofer in the storage bin in the basin on the trunk. You could very easily fit the SI BM mkIV in there and a 0.5" enclosure is all you need. In fact, you could take a similar approach to what I did and very likely fit that sub and both HD amps in there, all hidden. 
For the spare tire tools, you can buy some craft foam and press the tools into it, trim it to a small size and put it up inside of the spare tire in the trunk so they don't rattle around and they are right where you need them.

Good luck !


-Steve


----------



## captainobvious

GV713 said:


> Thanks guys, I got an SMD DD1 and CC1 as gifts last christmas but it seems that I won't be able to set the gains at the recommended wattage using the DD1 because it doesnt have a display so I'd have no idea what the output wattage of the amp is at any point in time. So im guessing I'll have to read up on using a DMM to set gains. Edzy and others here have contributed a great deal on the topic in other threads so im going to have to look into it.


Don't worry about the output wattage of the amp. If you wire the sub for an 8ohm load instead of 2, you'll draw less power and the amp will run cooler which will extend its life.

You won't be overpowering the sub with the 750/1 at 8ohms. Just use some test tones through your HU, find the clipping point with the DD1, then keep the HU one volume click below that point. Then, play test tones through the HU and into the amp and adjust the gain until just before the DD1 shows distortion and you're all set.


----------



## GV713

Thanks for all the help guys. CaptainObvious I'm using an amp rack built by a member of the s2ki forum, his name is PAS2K. The amp rack fits in the spare tire area and I will be placing my sub in the tool well, same as you.

I'm really excited to get this sub from Stereo Integrity. Has anyone compared it to the Alpine SWR-T12 ? From my reading the posts in this thread so far it seems that it is superior to the JL TW model but the Alpine SWR-T12 seems to have the JL beat also. Any views on this ? I'm eager to learn.


----------



## captainobvious

GV713 said:


> Thanks for all the help guys. CaptainObvious I'm using an amp rack built by a member of the s2ki forum, his name is PAS2K. The amp rack fits in the spare tire area and I will be placing my sub in the tool well, same as you.
> 
> I'm really excited to get this sub from Stereo Integrity. Has anyone compared it to the Alpine SWR-T12 ? From my reading the posts in this thread so far it seems that it is superior to the JL TW model but the Alpine SWR-T12 seems to have the JL beat also. Any views on this ? I'm eager to learn.


I don't think you'll do better in that space and size than the BM mkIV can do. 

I mentioned the tool well build as I fiberglassed an enclosure there and _*still *_had room to mount the amp on top and *still *keep it below floor level so it can be covered and hidden, *and *retain the spare tire in it's location 
If you're not worried about that stuff though, then no problem 













There are threaded inserts installed in the box face, then steel standoffs to raise the amplifier above the subwoofer surround, then the amp is mounted with stainless allen bolts. There is about an inch of extra space between the top of the amp and the trunk floor so I just have to cut out a cover piece to put over top and then you can throw anything back there without worries 
The BM mkIV is quite a bit more shallow and will yield even more space. Plus the JL amps arent nearly as tall as that Massive NX amp.


----------



## viper073

Hello everyone,
I’d like to share my review of the SI BM mark IV
I own a Toyota 86 and wanted to upgrade my speakers. I bought some dynaudio component speakers for the front, and an Alpine PDX-V9 amplifier. And then it was time to get some bass.
After reading the reviews of this sub, I knew it was the one for me. Not only was it perfect for the confined space in my boot, but the specs on this baby sounded awesome.
After a few emails back and forth with Nick (who was extremely helpful) I pulled the trigger and placed the order.
As a side note, I live in Australia and I found it cheaper to use a freight forwarder (I used shipito) to get it delivered. Again, Nick was very helpful and cooperative with this process.
After it arrived I started making my box.
I've attached some pics below.
It fit perfectly inside my boot with no space sacrificed (my car came with no spare tyre)
The amplifier sits just behind the sub too.

Then it came time to turn this baby on. Well, I’m not really saying anything new here to everybody else.
Really impressive bass. Clean. Deep. Punchy. Everything you want.
I also experienced what everyone refers to as front stage. In the beginning I thought I wired my speakers wrong, because I thought the bass was coming from my tweeters!! The low distortion means the bass sounds like it is in front of you. Again, exactly what you want.
With that being said, I think there is room for improvement in my system. When I was wiring it all up, I was disappointed to find out there was no RCA out from my stock head unit. So I had to use a high/low level converter and tap into the speaker output.
I know this is not good so I’m hunting for a good replacement unit. Thinking of the kenwood DDX635WBT. Anyway when I get this up and running I’m sure I’ll be even more impressed.
So I’d like to thank Nick for this excellent product and equally impressive customer service. I'm sad to hear he is not selling as many as he wanted.
I’m planning to do a write up of my speaker upgrade on the toyota86 Australian forum, and I will definitely be recommending this sub.
I will check back in and paste the link once it is done for those who are interested. I made some pretty cool 3D printed brackets!
Cheers.


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## rton20s

Looks very nice viper. Are those 3d printed tweeter and mid mounts?


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## LaserSVT

Nice work Viper.

The SI BM MKIV subs are so sweet sounding. Wait till it breaks in all the way. That's when you really see how low these can get.


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## Electrodynamic

Nice enclosure and nice writeup.  I'm glad you like the woofer. And yes, low distortion is something you have to get used to but once you get used to it it's hard to go back.


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## sirbOOm

I just tried two of these in my truck... blew a load all over myself. Thank goodness I have leather...


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## REGULARCAB

sirbOOm said:


> I just tried two of these in my truck... blew a load all over myself. Thank goodness I have leather...


Now that is a glowing review :laugh:


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## viper073

rton20s said:


> Looks very nice viper. Are those 3d printed tweeter and mid mounts?


Yes thats right. I used the opportunity to angle the tweeter mounts away from the windscreen. Worked a treat!


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## deltasaurus

SirBoom so you have the time somewhere in the near future to demo the BM MkIV's? We are pretty close within a 40 minute diatance, and I will go wherever I need to. You are the only one I know of in GA with any hooked up. I am leaning heavily toward getting at least one pair but really want to listen before buying. If not, I may just have to make an orser anyway.


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## bertholomey

viper073 said:


> Hello everyone,
> I’d like to share my review of the SI BM mark IV
> I own a Toyota 86 and wanted to upgrade my speakers. I bought some dynaudio component speakers for the front, and an Alpine PDX-V9 amplifier. And then it was time to get some bass.
> After reading the reviews of this sub, I knew it was the one for me. Not only was it perfect for the confined space in my boot, but the specs on this baby sounded awesome.
> After a few emails back and forth with Nick (who was extremely helpful) I pulled the trigger and placed the order.
> As a side note, I live in Australia and I found it cheaper to use a freight forwarder (I used shipito) to get it delivered. Again, Nick was very helpful and cooperative with this process.
> After it arrived I started making my box.
> I've attached some pics below.
> It fit perfectly inside my boot with no space sacrificed (my car came with no spare tyre)
> The amplifier sits just behind the sub too.
> 
> Then it came time to turn this baby on. Well, I’m not really saying anything new here to everybody else.
> Really impressive bass. Clean. Deep. Punchy. Everything you want.
> I also experienced what everyone refers to as front stage. In the beginning I thought I wired my speakers wrong, because I thought the bass was coming from my tweeters!! The low distortion means the bass sounds like it is in front of you. Again, exactly what you want.
> With that being said, I think there is room for improvement in my system. When I was wiring it all up, I was disappointed to find out there was no RCA out from my stock head unit. So I had to use a high/low level converter and tap into the speaker output.
> I know this is not good so I’m hunting for a good replacement unit. Thinking of the kenwood DDX635WBT. Anyway when I get this up and running I’m sure I’ll be even more impressed.
> So I’d like to thank Nick for this excellent product and equally impressive customer service. I'm sad to hear he is not selling as many as he wanted.
> I’m planning to do a write up of my speaker upgrade on the toyota86 Australian forum, and I will definitely be recommending this sub.
> I will check back in and paste the link once it is done for those who are interested. I made some pretty cool 3D printed brackets!
> Cheers.


Thanks for your impressions, and fantastic job on installing what should be a fantastic sounding system in your 86! I love that sub box / amp rack, and I like what you did with the tweeters - excellent!



sirbOOm said:


> I just tried two of these in my truck... blew a load all over myself. Thank goodness I have leather...


That is so Nick!



deltasaurus said:


> SirBoom so you have the time somewhere in the near future to demo the BM MkIV's? We are pretty close within a 40 minute distance, and I will go wherever I need to. You are the only one I know of in GA with any hooked up. I am leaning heavily toward getting at least one pair but really want to listen before buying. If not, I may just have to make an order anyway.


Well, hopefully you two will hook up or hopefully you could make it to the NC meet and hear one in my car, maybe one in Steve's car (if he can make it), or two in SB Nick's truck, or more than one in SI Nick's car.


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## sirbOOm

We can meet up, sure. I will be at the NC meet, if you're going. Unfortunately I don't have my ZED amplifier or the JBL mono on them so they're not as delightful as they were with half the power from a cheap 5-channel but... again... happy to demo. I can bring a single Morel Ultimo 12" for comparison if you want to be crafty. If you're not going to the meet, I can probably meet in Midtown somewhere near the Fox after work (after 5PM, except Wednesday).


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## deltasaurus

I am just waiting on approval from the wife to make the trip to the NC gtg. I am pretty sure that I will get the go ahead so I can get to hear some of the beautiful cars in that area. That way I can hear multiple BM MkIV installs, goody goody. Thank you for the invitation and definitely looking forward to it, much more so that I had to miss Finals.


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## newkoi

I am new and this is my first post here. Hello everybody!

Just wondering if you guys could advise me the best matching amp for a BM mk IV 12" subwoofer. I am currently thinking of: 

(1) Alpine MRV - 500, which I found lots of good reviews but wonder if it could have enough power to the sub (300W - 4Ohm).

(2) JL Audio Slash 600/1v3, which I found few reviews and much expensive 

(3) Rockford Fosgate R500X1D

Thanks for the help!


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## Coppertone

Hello to you and welcome to the forum. As far as power, you can run this with 300 watts and it will be just fine. Some guys have double that on it albeit dialed back and still it's good. As far as your choice of amp, you can run the Alpine and do just fine.


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## newkoi

Thank you, Coppertone. 

Apart from the power issue, is there any amp brandname that could go very well with SI sub? 



Coppertone said:


> Hello to you and welcome to the forum. As far as power, you can run this with 300 watts and it will be just fine. Some guys have double that on it albeit dialed back and still it's good. As far as your choice of amp, you can run the Alpine and do just fine.


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## saridi

nice subwoofer,nice review, very helpfull.


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## captainobvious

newkoi said:


> Thank you, Coppertone.
> 
> Apart from the power issue, is there any amp brandname that could go very well with SI sub?


As long as it is good, clean power you're fine


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## 2010hummerguy

I am about to test mine with 360wrms from a Hypex UcD180HG...the size of a credit card but flat to 12hz . There is virtually zero spare room in my truck cab so tiny amps are a must.


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## CDT FAN

I am installing my system and I am planning on mounting one of the SI BM mkIV's under the front passenger seat. I have HAT L4's and a set of tweeters mounted in the kick panels and HAT L8's in the doors. Since the sub will be mounted close to the front of the cabin, I am wondering if I even need the L8's now. Would it sound right to let the sub cover the midbass and then cross over to the L4's at around 300 Hz. What do you guys think?


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## sirbOOm

Use it for a sub only.


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## CDT FAN

Thanks. It was a thought.  Right now, I am playing the L8's with no high pass filter. I'm not using an amp on them. Just the Pioneer PRS80 driving them. I am surprised at how low they hit by themselves.


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## bertholomey

CDT FAN said:


> I am installing my system and I am planning on mounting one of the SI BM mkIV's under the front passenger seat. I have HAT L4's and a set of tweeters mounted in the kick panels and HAT L8's in the doors. Since the sub will be mounted close to the front of the cabin, I am wondering if I even need the L8's now. Would it sound right to let the sub cover the midbass and then cross over to the L4's at around 300 Hz. What do you guys think?



If you have the channels of processing and amplification, then probably best off to add the sub to the L8's. Steve's car is set up this way - L8's in kicks and BM in the dash - sounds phenomenal. 

But, if you are going to continue with the PRS and only have processing for Tweet, L4, and one more - try the BM (running off of an amp of course ?) without the L8's playing and see what you think. One of the best cars I've ever heard is running Tweets, 5.25 Mid Range, and a 12" sub in the floorboard. So it is worth trying in my opinion.


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## captainobvious

It might be a stretch to do for a few reasons, but one in particular- Your staging/imaging will be a wreck because you'll have one driver under the right seat pulling frequencies to its location. Of course, that's not all that important if you're simply after a loud, clean sounding vehicle and don't really worry about staging/imaging, etc. But if that is a concern, you WILL have issues with lower midrange/upper midbass frequencies being pulled to that side. If you were talking about stereo BM's one under each seat, then I'd say you have a much greater chance of getting away with it. But you'll be summing L and R to the single sub under that seat playing into a range where it's localizable.

Like Jason said, if you have the processing for it, keep the L8's and _*add *_the BM to the mix.


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## papasin

If I could give another perspective Steve, I think it could be done without the L8s, but it would require "pushing" the L4s lower into the pass band. There were a couple setups at CA state finals that did quite well, one of which included a truck that had an SI BMMK4 with 5s on the dash and tweets. He intended to run the 8s he had in the doors, but had technical issues with one of the 8s and ended up having someone help him retune the truck to forego the midbass drivers. The result I think surprised himself as he ended up doing very well and one of the top 3 vehicles out of over 25 at state finals...so can be done, just requires a little different tuning.


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## captainobvious

papasin said:


> If I could give another perspective Steve, I think it could be done without the L8s, but it would require "pushing" the L4s lower into the pass band. There were a couple setups at CA state finals that did quite well, one of which included a truck that had an SI BMMK4 with 5s on the dash and tweets. He intended to run the 8s he had in the doors, but had technical issues with one of the 8s and ended up having someone help him retune the truck to forego the midbass drivers. The result I think surprised himself as he ended up doing very well and one of the top 3 vehicles out of over 25 at state finals...so can be done, just requires a little different tuning.


I could see it in an emergency, competition setting with a 5.25" But when I think about a 4" (and I love that L4 midrange driver) having to play that low, at higher output and on a daily basis... I don't know, just doesn't sound like a good idea. Combine that with the fact that they are in the kicks and you're likely going to need to drive them even harder for the desired output.
Plus, I still think that you're going to have localization in the midbass to that side. Again, not a big concern though if it's not a competition vehicle or the owner isn't concerned with some staging/imaging issues.

If the L8's were going to be dropped, I'd really recommend dropping the L4's and getting a little larger midrange in there so it's not stressing on the lower end.


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## lkptpete

Just powered up my recently purchased BM MkIV. I built a simple little sealed box sized per recommendations from Stereo Integrity. I decided to try it out head to head with the Polk Audio MM1240DVC that I have in my Nissan Cube. This is not the car it will eventually live in. Going into my BMW M3 (just starting audio system for the car) ANYWAY... Subjective comparison BM MkIV in .5 cubic foot sealed box vs Polk MM1240DVC in .9 cubic foot sealed box. Powered by mono sub channel of a 5-channel Polk PA-D5000.5 amp. BM seems to have a teeny tiny bit less output (I set up an A/B speaker switch to quickly switch back and forth to compare sound while sitting in car) but... It sounded crisper. It kinda made the polk in the sealed box sound a little bit boomy (like it was in a ported box almost). Very happy with the sound quality. I will probably feed it with a 5-channel with a bit stronger sub channel. Maybe an Alpine PDX-V9 or a JL XD1000/5v2. Open to other suggestions for an amp...


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## 2010hummerguy

So I went crazy and bought a pair of Dynaudio Esotar 1200 subs today which I plan to install IB in an upcoming build. But first I want to see how they compare to the BM MKIV in my truck...stay tuned  $299 SI vs. $1.5k uber sub, though I am willing to bet the SI will put up a good fight.


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## quality_sound

Architect7 said:


> So I went crazy and bought a pair of Dynaudio Esotar 1200 subs today which I plan to install IB in an upcoming build. But first I want to see how they compare to the BM MKIV in my truck...stay tuned  $299 SI vs. $1.5k uber sub, though I am willing to bet the SI will put up a good fight.


How'd the comparison go?


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## 2010hummerguy

I haven't tried the Esotar yet...part of me doesn't want to in case I like it LOL.

I ended up getting a pair of AE IB12AU subs for my other build...$2k in subs in my trunk is kind of crazy and I need $$$ for xmas shopping. But I'll probably try an Esotar sub in my truck tomorrow


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## quality_sound

Sweeeeet


Sent from my iPhone using Tapatalk


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## Gomer Pilot

Got everything finally put in yesterday. Running two MKIV off of an Alpine PDX-V9. Only getting around 250 watts a piece (555 on the birth sheet), but wow, these things are ridiculous. Still have some tuning to do, but for a shallow sub they are so clean and plenty loud. Running them in a box under the seat of the F-150 in 0.6 each with a small amount of poly as recommended by multiple people.

Listened to Fall Out Boy - Centuries today and I never even knew that low bassline was there. The MKIVs just growl when those notes hit, it's beautiful. Miss so much with factory garbage and it's been too long since I've had a nice system running.

Thanks so much to Nick (Electrodynamic) and LaserSVT for all of the help and advice and especially to Rick Paul (speakerpimp) for the install work. 

Now that the addiction is fully back in effect, might have to look for an amp that would allow me to give these things a little more power, but for now they're doing great. Going to work with Rick again Tuesday morning to finish up the tuning, but loving everything so far.


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## captainobvious

Good stuff Gomer 

I'm loving mine too.


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## DavidRam

+1 on loving the BMs!


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## specc00

After reading all the good reviews I am leaning away from jl tw3 and towards the bmiv more and more. Just debating if I should get it new from si or just wait for someone to get rid of theirs.


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## Gomer Pilot

Get it new now with the closeout sale.


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## Coppertone

Buy now, and be happy.


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## legend94

specc00 said:


> After reading all the good reviews I am leaning away from jl tw3 and towards the bmiv more and more. Just debating if I should get it new from si or just wait for someone to get rid of theirs.


Not much difference as they hold value like a Honda or Toyota.


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## 2010hummerguy

specc00 said:


> After reading all the good reviews I am leaning away from jl tw3 and towards the bmiv more and more. Just debating if I should get it new from si or just wait for someone to get rid of theirs.


Go SI, you won't be disappointed


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## captainobvious

specc00 said:


> After reading all the good reviews I am leaning away from jl tw3 and towards the bmiv more and more. Just debating if I should get it new from si or just wait for someone to get rid of theirs.



Agreed. The discount pricing is excellent. You can get 2 SI BM mkIV's for the price of one 13TW5v2.


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## RocketBoots

Recently bought this sub based on the excellent reviews, and the fact that it just seems like an awesome product, and am trying to figure out where to put it. The diminutive depth and box requirement allow so much flexibility. It's going in a coupe, and I initially thought I would put it in the cabin, up front in the passenger footwell or flat on the floor of the rear passenger footwell. But now I'm considering putting it in the trunk.

Any input on the pro's and con's of either?

Will I feel the speed, accuracy, impact, etc of the sub if it's in the trunk?? (the trunk is pretty well sealed)

Thanks!


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## bertholomey

I kind of like mine in the front footwell - just my experience - it has worked out rather well in my opinion. I can't really tell you much about one mounted in a sealed trunk.


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## TOOSTUBBORN2FAIL

Mines going up front as well, response is just better in my car up front. All cars are difference, but I've never been disappointed with a front sub car.


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## RocketBoots

TOOSTUBBORN2FAIL said:


> Mines going up front as well, response is just better in my car up front. All cars are difference, but I've never been disappointed with a front sub car.


Your car or wife's?


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## CBS13WRX

I am bringing this back to the top for any suggestions for someone that can build me a box in the Asheville, NC or Johnson City, TN area for a single 12" BM mkIV for my regular cab 2014 Chevy Silverado.


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## RicMoon

So glad that I found this thread. I have 2 Hertz HX300's that were in the trunk of my old car, but they won't fit in my truck and this seems like the best solution. Thanks you to everyone for this, it really helped!


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## Coppertone

^^^. I have to say, good luck trying to find any. Plus the ones that are for sale are going for at least more then they cost originally.


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## RicMoon

Coppertone said:


> ^^^. I have to say, good luck trying to find any. Plus the ones that are for sale are going for at least more then they cost originally.


Thanks, I'm searching every place I can think of trying to find a decent deal on 1 of these. It's a shame my current subs won't fit, hopefully these will be comparable.


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## Coppertone

Well hopefully this will help somewhat.

http://www.diymobileaudio.com/forum/4035193-post1.html


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## Guest

Coppertone said:


> Well hopefully this will help somewhat.
> 
> http://www.diymobileaudio.com/forum/4035193-post1.html




Thanks for the link....


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## Coppertone

Thumbs up and I hope that it works out for the both of you.


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## RicMoon

Coppertone said:


> Well hopefully this will help somewhat.


Thanks again. I see you have a Ram 1500 with a JL TW3. I'm looking for something like this for my Ram as well. If I can't get the MK IV I'll probably end up with the JL too.


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## Coppertone

Oh no lol I have a Legacy with that sub in it. I also have my Ram which only has a Pioneer 4100NEX plus a Helix dsp. There isn't any sub/s in the Ram.


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## LaserSVT

I cant keep up with the damn Subarus changes. lol Does it still have Sinfoni components?

I need a spare set of SI subs. I am always scared I will hurt mine and then have no clue what I would replace them with.


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## Coppertone

Lol the only thing being added to the Subaru will be the X3. I'm still running the Sinfoni and well as everything else in my signature. If and its a BIG if I were to change anything, it would be swapping those tweeters from under their oem housing to an A pillar build.


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## LaserSVT

Nioce. How do you like the JL compared to the SI? I was thinking of trying them out myself.


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## Flyhogz

Don't go with a single BM MK IV in the trunk or you'll be disappointed. Great SQ but the output will be disappointing. I ended up going back to my JL 13TW5. This is in no way bashing the SIs, I'm just waiting for the re-rerelease so I can push two. 


Sent from my iPad using Tapatalk


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## BMWTUBED

Can anyone "in the know" tell me the small diameter of the woofer basket? I see that the cut out diameter is 11.10" but the diameter steps down from there. I'm trying to do a test fit, but can not find this info anywhere. Thanks in advance for any help.


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## PorkCereal

Pm me your email, ill send ya the spec sheet

Sent from my SAMSUNG-SM-G935A using Tapatalk


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## Electrodynamic

BMWTUBED said:


> Can anyone "in the know" tell me the small diameter of the woofer basket? I see that the cut out diameter is 11.10" but the diameter steps down from there. I'm trying to do a test fit, but can not find this info anywhere. Thanks in advance for any help.


If you are making clearance for the OD of the basket make the OD cutout 318 mm.


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## FordEscape

BMWTUBED said:


> Can anyone "in the know" tell me the small diameter of the woofer basket? I see that the cut out diameter is 11.10" but the diameter steps down from there. I'm trying to do a test fit, but can not find this info anywhere. Thanks in advance for any help.


This any help?

http://stereointegrity.com/wp-content/uploads/BMmkIV_spec_drawing.pdf


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## BMWTUBED

Thank you! It's the 246mm diameter that I was unsure of. I am mocking up the size to make sure it will fit in my foot well. Looks like I should be good. 
Thanks again.


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## CBS13WRX

I have one NIB 12" BM mkVI what amplifier would you all recommend? I had purchased this for a Silverado which I never got around to doing so now I am contemplating on using it for a Jetta. Will this be sufficient or should I possibly switch out for a more traditional sub? Since my space requirements have changed.


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## Electrodynamic

CBS13WRX said:


> I have one NIB 12" BM mkVI what amplifier would you all recommend? I had purchased this for a Silverado which I never got around to doing so now I am contemplating on using it for a Jetta. Will this be sufficient or should I possibly switch out for a more traditional sub? Since my space requirements have changed.


Unless your listening preferences have changed (unless you're after full-tilt SPL now) I would keep the BM mkIV. Or unless you feel like you must build a 3 ft^3 box. 

Anything under 400 watts RMS will be more than sufficient to power a single BM mkIV. Stay away from the Audiopipe and PPI mini amplifiers and you will be good.


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## CBS13WRX

Electrodynamic said:


> Unless your listening preferences have changed (unless you're after full-tilt SPL now) I would keep the BM mkIV. Or unless you feel like you must build a 3 ft^3 box.
> 
> Anything under 400 watts RMS will be more than sufficient to power a single BM mkIV. Stay away from the Audiopipe and PPI mini amplifiers and you will be good.


So your 11" woofer inside a box would take up a lot of space in the trunk of a Jetta?


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## Electrodynamic

CBS13WRX said:


> So your 11" woofer inside a box would take up a lot of space in the trunk of a Jetta?


It would take up twice the room of a single BM mkIV and weigh 6x more but this is a review thread of the BM mkIV, not a thread about the HST-11 and the physical footprint of each enclosure.


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