# BM mkIV comeback?



## Electrodynamic (Nov 27, 2007)

I've been weighing the options lately about coming back out with the BM mkIV. Let me be specific - *not* the mkV with the larger coil, single slug neo motor, custom tooled basket/carrier/surround/etc. What I *AM* talking about is an exact duplicate of the BM mkIV. The reason why I'm even entertaining the idea is again the new manufacturer I am working with. Same reason why I continued with the revised TM65. The new build house can provide very high quality turn-key products so I won't need to do very much testing of the products and most importantly I will not need to assemble anything here at my shop. 

I do not want to change anything about the mkIV so if this does happen it will be an exact duplicate. Literally everything will be an exact duplicate. And unless the new build house is way out in left field regarding my cost on the drivers the price of the mkIV will remain the same to you guys here on the forums of at/around $299 to $349. The latter prices are just an estimate - I have no idea what the new build house will charge yet so I'm just asking the question of continued production. If this happens I will send the new build house two BM mkIV's - one good driver and one driver that can be cut up and inspected so they can measure everything and duplicate the driver exactly.


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## jamesjones (Mar 8, 2007)

Dang it. I was thinking you were going to take back over the v because it seems Sundown put it on the back burner. I was hoping for a more "ballsy" xbl^2 sub.


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## thebookfreak58 (Jun 18, 2012)

Yes! I'd be in


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## frontman (May 1, 2013)

That would be awesome!


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## Woosey (Feb 2, 2011)

grabs popcorn....


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## Rob4607 (Apr 5, 2014)

Put me down for 3.


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## Kraken (Oct 2, 2015)

In line to buy 2 of these if it comes back.


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## WhiteL02 (Jul 25, 2014)

I would be interested in another. Really wish your V came out!


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## WhereAmEye? (Jun 17, 2013)

I'll admit I would love to put one or four in my closet for a rainy day..as long as the build house doesn't turn it to crap


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## kmbkk (Jun 11, 2011)

I'd be interested in 2 of them!


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## RRizz (Sep 4, 2012)

I would be in for 2 more, possibly 3.


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## SQLnovice (Jul 22, 2014)

I'll be interested in 2. As a side note. This will stop the price gouging.


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## Rob4607 (Apr 5, 2014)

Amen to that.....


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## Weigel21 (Sep 8, 2014)

I'd like to pick one up to give a go, though it seems many claim one just isn't "enough". Unfortunately, funds are a little tight right now (need to find/buy an engine to get a car back on the road) and I'm not sure when I'd have the spare cash to buy an MKIV and a set of the new TM65 mkII. Both are on my planned "buy list" though.


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## FordEscape (Nov 23, 2014)

I say 'go for it' .... as cool as many SI products are/were, IMHO the BM mkIV stands out as the one that in its absence has left a true void in the market.

Though perhaps the subject of much abuse/misuse by the 'uninformed/inattentive', for those with the installation constraints it is designed to accommodate, the wherewithal to use as intended, and the ear/tastes to appreciate truly stellar sub-bass, there is no substitute at any price.


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## Jscoyne2 (Oct 29, 2014)

Whats so special about the bm mkiv anyway?

Sent from my SGH-T999 using Tapatalk


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## seafish (Aug 1, 2012)

I think that it is a fine idea to restart produciton on these subs. That being said, I wonder if there could be some way to incorporate a protection device (thermal or current limiting??) without affecting SQ and that will protect the sub from those who simply pump too much power into it and then expect you to cover the "bad" sub even though it was caused by user error. 

Just an idea…not even sure it is a good one or even possible….please feel free to ignore it if it does not resonate with you.


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## Jscoyne2 (Oct 29, 2014)

seafish said:


> I think that it is a fine idea to restart produciton on these subs. That being said, I wonder if ther eis some way to incorporate a protection device without affecting SQ that may well protect the sub from those who simply pump too much power into it and then expect you to cover the "bad" sub even though it was caused by user error. Just an idea…not even sure it is a good one or even possible….please feel free to ignore it if it does not resonate with you.


Pretty sure thats not plausible otherwise every audio business would do it. Short of selling or supporting a specific amp. This amp at 500rms in this box. Box, source (music) , power, and sub all come into play when damaging a sub


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## seafish (Aug 1, 2012)

Jscoyne2 said:


> Pretty sure thats not plausible otherwise every audio business would do it. Short of selling or supporting a specific amp. This amp at 500rms in this box. Box, source (music) , power, and sub all come into play when damaging a sub


You may well be right, thugh Boston Acoustics used to install fuses right before the VC on some of their subs to rpevnt momentary overdriving from damaging the VC--

see the pic at post#9 here--

http://www.diymobileaudio.com/forum...7308-blowing-boston-sub-fuses-alpine-pdx.html

Sorry to Nick for the OT.


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## Jscoyne2 (Oct 29, 2014)

seafish said:


> You may well be right, thugh Boston Acoustics used to install fuses right before the VC on some of their subs to rpevnt momentary overdriving from damaging the VC--
> 
> see the pic at post#9 here--
> 
> ...


Ive heard the SI subs are very sensitive to over powering. I wonder if they used short blow or long blow fuses(probably not the proper term but i think you get what I mean). Long wouldnt blow from slight clipping or would blow from excessive clipping. That on top of fused at a particular amperage might work. 

Im honestly not knowledgeable enough to say enough on the subject but if it hasnt been done widespreadly in the market, im sure there's a reason.


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## nirschl (Apr 30, 2009)

I've got 2 of the original BM's. What's to gain from the upgrade to the IV? Are they direct drop-ins? 

The oringinals have been running in my van for about 4-5years now in a custom sealed enclosure. I've loved them from the get go. 

Cheers


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## Ted J (Aug 15, 2006)

Jscoyne2 said:


> Whats so special about the bm mkiv anyway?
> 
> Sent from my SGH-T999 using Tapatalk


Low distortion clean output with good displacement and shallow mounting depth and also does it all in a fairly small box for a 12. Nice sounding fun SQ sub.

If you search around you'll see a lot of reviews for it. Great shallow sub for SQ. If you like rocking loud SPL it's not the sub for you though for me as a SQ competitor it still cranked pretty good but I did have it up front by me when I used it and I like to rock out but not like really loud like a 'bass head' as some people call it.

For the people that wanted more output they just got 2 and sometimes 3 as you can see by some people in this thread in what they are wanting to order.


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## Ted J (Aug 15, 2006)

Jscoyne2 said:


> Ive heard the SI subs are very sensitive to over powering. I wonder if they used short blow or long blow fuses(probably not the proper term but i think you get what I mean). Long wouldnt blow from slight clipping or would blow from excessive clipping. That on top of fused at a particular amperage might work.
> 
> Im honestly not knowledgeable enough to say enough on the subject but if it hasnt been done widespreadly in the market, im sure there's a reason.


Don't know if I'd say sensitive to overpowering. They have there limits like any other speaker. It seems because of it having a clean output as it gets close to it's limit of what it can do people sometimes will over drive them and not know it. If I recall correctly the sub starts to make a clicking noise when it starts bottoming out the voice coil is the way to tell when it's being pushed to far physically. It just stays 'clean' sounding while it's moving a great amount so it's not as easy to tell when the limit is if that makes sense.

Could also be people using it in a bigger than the .5 cube box and the bigger you go with the box from there the power handling goes down. And there's also people that feed it a bunch of watts and if 450 watts is said to be it's RMS max intput you feed it more than that and issues may arise.

Not trying to start anything here, just sharing some info as to why it seems people talk about those issue. Now if you were within all the specs and still have issues that's where warranty comes into play and working it out with the place you bought it from. Now that's the part I can't comment on for I haven't had any warranty issues thankfully but that's a different subject and I don't know the rate of how many of warranty issues those subs had to know if it was an 'issue' or not though.


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## Ted J (Aug 15, 2006)

Electrodynamic said:


> I do not want to change anything about the mkIV so if this does happen it will be an exact duplicate. Literally everything will be an exact duplicate.


I voted yes make it again. It's a great combo of a sub and even though I own one I still sorta feel the void in the market that people are talking about so if there's still enough demand for you to make it and still make money yes go ahead and do it.


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## PorkCereal (Nov 24, 2009)

I love the two i have and really glad i jumped on the deal i got. They are thin 3.5 in, light <20lb, and power efficient good at 250-350w. Most other subs you can dump alot more than rms to get them to really wake up, but these you don't need to. It's a really good sound, something i didn't experience with my idq and my sundown sd3 as much as i liked those as well. 

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## Black Rain (Feb 27, 2011)

I heard this sub in different setups at the NCSQ Meet/GTG. This is a phenomenal sub and I would definite put 2 of them in my Sorento. This would work perfect with my Zapco Z1kd.

Nick, you definitely make some awesome product.


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## onebadmonte (Sep 4, 2008)

I vote no to keep resale value of the ones out there high.  Great subs.


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## RRizz (Sep 4, 2012)

seafish said:


> That being said, I wonder if there could be some way to incorporate a protection device ---------- user error.


Fixed your post, and answered your own question. Don't buy a 500 watt sub and feed it 1000 watts, or gobs of distortion.
If you picked up a fat chick in a bar, would you expect her to be skinny when you got her home????
The protection device IS the end users common sense, in my opinion.
By the way, I Love,Love,Love my MkIV.


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## Jscoyne2 (Oct 29, 2014)

So are these meant to be shallow mount subs with extreme sq?

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## RRizz (Sep 4, 2012)

Correct. And they do it quite well.


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## mailalan (Mar 28, 2015)

Yes yes yes! I have one brand new never hooked up MkIV and I've been looking all over for a second one that's never been hooked up. 

If you started making them again it would definitely fill a void in the market place. They are in high demand it seems.


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## adriancp (Feb 12, 2012)

Just a hypothetical question for Nick: Have you considered purchasing the rights to the MkV back from Jacob? This is not bashing him in any way at all, but this is not a priority market for his business when compared to his "spl clientele" and has put the MkV on the back burner. With your new access to a good build house would this allow you to produce the MkV profitably and bring the latest & greatest to market instead of reproducing the MkIV which might end up competing against the the Sundown MkV at some point?


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## schmiddr2 (Aug 10, 2009)

RRizz said:


> Don't buy a 500 watt sub and feed it 500 watts


Fixed.

For potential new owners: I powered mine with a JL 900/5, the sub died within a few hours. I would recommend to set the gains with a meter to 300W or so. If you model this sub with WinISD or whatever, do not even look at the xmax figure as a safe number, only use power to figure the output capability, and again don't stray much over 300W.


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## TOOSTUBBORN2FAIL (Jan 31, 2011)

schmiddr2 said:


> Fixed.
> 
> For potential new owners: I powered mine with a JL 900/5, the sub died within a few hours. I would recommend to set the gains with a meter to 300W or so. If you model this sub with WinISD or whatever, do not even look at the xmax figure as a safe number, only use power to figure the output capability, and again don't stray much over 300W.
> 
> ...


Agreed entirely. Winisd says it's safe to 450 watts, but from my personal real world usage I wouldn't use near that on it.


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## 2010hummerguy (Oct 7, 2009)

schmiddr2 said:


> Fixed.
> 
> For potential new owners: I powered mine with a JL 900/5, the sub died within a few hours. I would recommend to set the gains with a meter to 300W or so. If you model this sub with WinISD or whatever, do not even look at the xmax figure as a safe number, only use power to figure the output capability, and again don't stray much over 300W.
> 
> ...


I've had 500w on mine since it was released, zero issues. Was yours in a trunk?


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## danno14 (Sep 1, 2009)

schmiddr2 said:


> Fixed.
> 
> For potential new owners: I powered mine with a JL 900/5, the sub died within a few hours. I would recommend to set the gains with a meter to 300W or so. If you model this sub with WinISD or whatever, do not even look at the xmax figure as a safe number, only use power to figure the output capability, and again don't stray much over 300W.
> 
> ...


Let me know what you think it would be to 98391. Could be a good test enclosure. Thx


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## Alrojoca (Oct 5, 2012)

At 300W max power handling for both coils it's more like system for the wife or daughter. To be used with an entry level 5 channel amp and one sub, and where space needed, is a big factor. 

And if they will be over $300 each, it may not fly. $250 should keep it alive. Since Needing 2 or 3, or a 1 ohm stable amp to use based on the low output, although, if set properly a good option is use a good 4 ch amp with 2 subs, using the 4 channels at 150W per coil for the 2 subs. 

That may provide acceptable output for some SQL fans. Just an opinion and an extra option.


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## schmiddr2 (Aug 10, 2009)

Architect7 said:


> I've had 500w on mine since it was released, zero issues. Was yours in a trunk?


That's crazy. I don't understand the difference. But yes it was in the trunk. Previously had a GTO1214 and not one problem.


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## TOOSTUBBORN2FAIL (Jan 31, 2011)

The thing is, I do love the sub. But I would need several for myself, my wife is happy with one in the passenger footwell. But depending on the music, you could definitely kill it with less than 450 watts.


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## RRizz (Sep 4, 2012)

I'm running 500 on it as well. It's clean and strong. Best sub I've ever owned.


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## Electrodynamic (Nov 27, 2007)

schmiddr2 said:


> That's crazy. I don't understand the difference. But yes it was in the trunk. Previously had a GTO1214 and not one problem.


As with XBL^2 the drivers do not exhibit distortion levels like standard topology woofers. XBL^2 drivers sound extremely clean even when at the limit until WHACK it's too late. 450 watts is the maximum RMS wattage level. 250 watts RMS to 350 watts RMS is the safe spot for a BM mkIV. 

Out of all the BM mkIV's sold I think only one driver that came back actually had thermal coil damage. Most of the damages were due to over-excursion / too much power. 

I ran a ridiculous amount of power on my pair of BM mkIV but just because I had the power on tap did not mean that I HAD to use it all.


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## Jscoyne2 (Oct 29, 2014)

seafish said:


> I think that it is a fine idea to restart produciton on these subs. That being said, I wonder if there could be some way to incorporate a protection device (thermal or current limiting??) without affecting SQ and that will protect the sub from those who simply pump too much power into it and then expect you to cover the "bad" sub even though it was caused by user error.
> 
> Just an idea…not even sure it is a good one or even possible….please feel free to ignore it if it does not resonate with you.


https://xplicitaudio.com/shop/dioguardo-engineering-vci-1/

Voice coil temperature. Neato

Sent from my SGH-T999 using Tapatalk


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## Electrodynamic (Nov 27, 2007)

adriancp said:


> Just a hypothetical question for Nick: Have you considered purchasing the rights to the MkV back from Jacob? This is not bashing him in any way at all, but this is not a priority market for his business when compared to his "spl clientele" and has put the MkV on the back burner. With your new access to a good build house would this allow you to produce the MkV profitably and bring the latest & greatest to market instead of reproducing the MkIV which might end up competing against the the Sundown MkV at some point?


Technically I haven't sold anything to him yet. If I came out with the driver it would cost in excess of $500 each. Seeing how price sensitive the forums are (all forums) a $500+ price will not sell a shallow mount 12" woofer. Maybe a handfull per year but that doesn't put food on the table. No BM mkV from me.


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## adriancp (Feb 12, 2012)

Well that makes total sense. Was hoping with the new build house it would help you on the profit side & still reduce cost. Totally understand your stance on this. Thanks for the info


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## 2010hummerguy (Oct 7, 2009)

schmiddr2 said:


> That's crazy. I don't understand the difference. But yes it was in the trunk. Previously had a GTO1214 and not one problem.


I ask because the sub was probably making all sorts of bad mechanical sounds when it was pushed outside of safe operation but located in a trunk means you couldn't hear these indicators before it failed. Plus trunks attenuate output which tempts people to crank volume/gains beyond safe limits. I'm willing to bet you were sending it closer to your amp's peak power a lot, sending it outside of Xmech too much which fried it.



Alrojoca said:


> At 300W max power handling for both coils it's more like system for the wife or daughter. To be used with an entry level 5 channel amp and one sub, and where space needed, is a big factor.
> 
> And if they will be over $300 each, it may not fly. $250 should keep it alive. Since Needing 2 or 3, or a 1 ohm stable amp to use based on the low output, although, if set properly a good option is use a good 4 ch amp with 2 subs, using the 4 channels at 150W per coil for the 2 subs.
> 
> That may provide acceptable output for some SQL fans. Just an opinion and an extra option.


Of the 30+ people who have heard my truck system, not one person has complained about output. It's one reason why I haven't installed my 2nd brand new BM MKIV, no immediate need. You may want to listen to one before forming such an opinion.


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## schmiddr2 (Aug 10, 2009)

Architect7 said:


> I ask because the sub was probably making all sorts of bad mechanical sounds when it was pushed outside of safe operation but located in a trunk means you couldn't hear these indicators before it failed. Plus trunks attenuate output which tempts people to crank volume/gains beyond safe limits. I'm willing to bet you were sending it closer to your amp's peak power a lot, sending it outside of Xmech too much which fried it.


That may be, but I don't think so as I listened with the trunk opened when I installed it. I realize I put too much power to it (500w or whatever), but coming from a GTO1214 and 12w6 which can handle much more than their RMS figures, the SI just can't deal with the excess power and I didn't realize how true this was. I put 600w to the JBL, heard it bottom out and backed off the gain. Not saying the JBL is better, just saying it's nice not being so close to the ledge if you want to play loud music.


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## Alrojoca (Oct 5, 2012)

Architect7 said:


> Of the 30+ people who have heard my truck system, not one person has complained about output. It's one reason why I haven't installed my 2nd brand new BM MKIV, no immediate need. You may want to listen to one before forming such an opinion.


That's great, I have no doubts it's a good one, I heard one once, It was good, but maybe it needed more tuning or get a bit more loose, maybe it was too clean and too deep sounding for me, something im not used to, I don't listen to hip hop or rap. And among the shallow ones, I'm sure, it's on the top performers list, and a good choice where space is needed.

You know how it is, I read that some are not happy with 2 10"s or they need a 15" or an 18", still 2 $1000 12" subs is not enough with 1000W each when one has made many happy with just 800W.


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## hurrication (Dec 19, 2011)

Architect7 said:


> I ask because the sub was probably making all sorts of bad mechanical sounds when it was pushed outside of safe operation but located in a trunk means you couldn't hear these indicators before it failed. Plus trunks attenuate output which tempts people to crank volume/gains beyond safe limits. I'm willing to bet you were sending it closer to your amp's peak power a lot, sending it outside of Xmech too much which fried it.


I have schmiddr's blown bm and its cause of death was purely thermal. The coil was roasted and had started to unwind, but there was no damage to the former or the rest of the soft parts at all with no signs of bottoming.


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## schmiddr2 (Aug 10, 2009)

hurrication said:


> I have schmiddr's blown bm and its cause of death was purely thermal. The coil was roasted and had started to unwind, but there was no damage to the former or the rest of the soft parts at all with no signs of bottoming.


Thanks for confirming that for me. Hope you get some use out of it.


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## Electrodynamic (Nov 27, 2007)

adriancp said:


> Well that makes total sense. Was hoping with the new build house it would help you on the profit side & still reduce cost. Totally understand your stance on this. Thanks for the info


I wanted to produce the mkV but it was simply too expensive to build. Too expensive to build meant very expensive to purchase for DIY customers. Larger companies that have dealer networks can afford to sell more expensive shallow mount offerings and that's great for them but it simply will not sell well for direct sales DIY. But the new build house can build an exact duplicate of the BM mkIV and the build house can build it very well. Price should be the same. I might change the basket color to indicate the new drivers from the new build house.


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## adriancp (Feb 12, 2012)

Sounds good to me! The only thing that had me looking towards the MkV more was the greater output you said it should have. (For the inner bass head that comes out on occasion). But with what you are offering at this price level, how could one go wrong?


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## Guest (May 31, 2016)

Electrodynamic said:


> But the new build house can build an exact duplicate of the BM mkIV and the build house can build it very well. Price should be the same. I might change the basket color to indicate the new drivers from the new build house.


This would be fantastic... I'd be down for a pair...


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## mailalan (Mar 28, 2015)

So Nick have you definitely decided to start making the mkIV again?


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## fish (Jun 30, 2007)

I would consider using 2, 3, or 4 of these in my next car's install.


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## Electrodynamic (Nov 27, 2007)

Due to the results of the poll being heavily positive I'm going to send parts, a working driver, and all the technical drawings to my new build house and see what they report back with.


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## norurb (Jun 28, 2013)

Great news sir. I'm selling off all kinds of things to get 2 of those when they are ready. All SI system, all the time.


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## LaserSVT (Feb 1, 2009)

Just send me the damn MK Vs!


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## mailalan (Mar 28, 2015)

Electrodynamic said:


> Due to the results of the poll being heavily positive I'm going to send parts, a working driver, and all the technical drawings to my new build house and see what they report back with.


That is awesome news! Best news I've heard in a long time!


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## etroze (Dec 24, 2013)

Sweet can't wait, I really want a pair as near field subs for my HT system.


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## truckguy (Sep 2, 2013)

Is there a possibility of a MKIVv2 where you make a few changes but not a complete redesign like the MKV? I'd pay an extra hundred bucks for a slightly upgraded version. Like an Apollo upgraded another company offers. i know nothing about building speakers so it's probably not that easy and costs more than I would expect to offer some kind of "Apollo" version. I can dream though!


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## WhiteL02 (Jul 25, 2014)

truckguy said:


> Is there a possibility of a MKIVv2 where you make a few changes but not a complete redesign like the MKV? I'd pay an extra hundred bucks for a slightly upgraded version. Like an Apollo upgraded another company offers. i know nothing about building speakers so it's probably not that easy and costs more than I would expect to offer some kind of "Apollo" version. I can dream though!


Oh yeah!!!


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## Bruneti (Oct 31, 2006)

Anxiously awaiting the chance to buy another BM MKIV...


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## mailalan (Mar 28, 2015)

Me too!


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## Mattppi (Jun 21, 2011)

Im down for 2 of these as well.


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## dougc (Oct 24, 2009)

Let's do this Nick, I'm ready for 2


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## shillermanlite (May 18, 2014)

I'm not a regular here but I did have a BM MK 4 sub that was awesome. Unfortunately, it was stolen out of my truck and a used replacement is too expensive. I think a price point of $300 is the goal for sustainability. I would definitely pre-order 2.


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## aholland1198 (Oct 7, 2009)

Soooooo is this going to happen?


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## Weigel21 (Sep 8, 2014)

I'm probably alone on this, but hopefully not for a few months, cash is kinda tight, especially with the TM65 MKII on my "to get" list.


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## aholland1198 (Oct 7, 2009)

IMHO you are alone, but I'm sure it is going to take some time. Enough for you to collect funds I'm sure 


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## speakerman99 (Apr 18, 2016)

I could be talked into two of these. Any thoughts to when they would be available?


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## aholland1198 (Oct 7, 2009)

Nothing?


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## scotsman (Sep 8, 2015)

would definitely buy a couple!


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## Flyhogz (Nov 8, 2012)

Me as well. 


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## LaserSVT (Feb 1, 2009)

I need this to happen! I will make bad things happen if not. I have a kitten here and I aint afraid to pet it!


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## SQLnovice (Jul 22, 2014)

Maybe we can start an unofficial prebuy list to give Nick an idea of how many he can sell in the first run.


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## halloz (Aug 25, 2016)

haha this should be great


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## scotsman (Sep 8, 2015)

any update to this?


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## boardthis74 (Feb 8, 2010)

Yes please bring back the IV. Seems like every time I've been ready to pull the trigger on these they've been between models or in the case of V turning to Vapor. I'll definitely be down for 2


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## Golden Ear (Oct 14, 2012)

boardthis74 said:


> Yes please bring back the IV. Seems like every time I've been ready to pull the trigger on these they've been between models or in the case of V turning to Vapor. I'll definitely be down for 2




And used ones are selling for more than they sold for new!


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## Electrodynamic (Nov 27, 2007)

FYI: A b-stock unit along with other various parts were shipped to our current build house so they can take measurements of it and we can start getting the ball rolling for a re-vamped BM mkIV.


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## PorkCereal (Nov 24, 2009)

Good to hear, i've got 1 not in great health


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## mailalan (Mar 28, 2015)

This is great news!


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## Mattppi (Jun 21, 2011)

Very Exciting Times Indeed. ?


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## jbeck (Apr 8, 2014)

Just chiming in with some additional support - I'd take three, absolutely no question about it. 

Getting a truck soon and was JUST telling my fiancé yesterday how sad I am that these aren't in production anymore. Then I saw reference to this thread in a FS post for one BM MKiv.


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## freemars (Apr 22, 2015)

I missed the poll, but just to chime in positively, this sub is my #1 choice for my truck. I'd love to see them come back.


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## shillermanlite (May 18, 2014)

Any update on this? My BM mklV was stolen a year ago and I need a replacement. Nothing else sounds the same. 

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## seafish (Aug 1, 2012)

shillermanlite said:


> Any update on this? My BM mklV was stolen a year ago and I need a replacement. Nothing else sounds the same.
> 
> Sent from my Pixel using Tapatalk


There is a single one for sale right now in the classifieds.


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## shillermanlite (May 18, 2014)

seafish said:


> There is a single one for sale right now in the classifieds.


Thanks I sent him a pm. I still think an update on this project would be informative to the community. If this plan has been scrapped, I apologize. 

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## GEM592 (Jun 19, 2015)

Electrodynamic said:


> I've been weighing the options lately about coming back out with the BM mkIV. Let me be specific - *not* the mkV with the larger coil, single slug neo motor, custom tooled basket/carrier/surround/etc. What I *AM* talking about is an exact duplicate of the BM mkIV. The reason why I'm even entertaining the idea is again the new manufacturer I am working with. Same reason why I continued with the revised TM65. The new build house can provide very high quality turn-key products so I won't need to do very much testing of the products and most importantly I will not need to assemble anything here at my shop.
> 
> I do not want to change anything about the mkIV so if this does happen it will be an exact duplicate. Literally everything will be an exact duplicate. And unless the new build house is way out in left field regarding my cost on the drivers the price of the mkIV will remain the same to you guys here on the forums of at/around $299 to $349. The latter prices are just an estimate - I have no idea what the new build house will charge yet so I'm just asking the question of continued production. If this happens I will send the new build house two BM mkIV's - one good driver and one driver that can be cut up and inspected so they can measure everything and duplicate the driver exactly.


Okay ... sounds a little hyperbolic but I'm listening.


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## Electrodynamic (Nov 27, 2007)

GEM592 said:


> Okay ... sounds a little hyperbolic but I'm listening.


Hyperbolic? Why even reply to this thread then?


----------



## PorkCereal (Nov 24, 2009)

Electrodynamic said:


> Hyperbolic? Why even reply to this thread then?


Any updates while this thread has been revived?


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## SteveH! (Nov 7, 2005)

what's the latest update? i'm definitely interested in buying anoth pair from you if you bring them back!


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## PorkCereal (Nov 24, 2009)

He is still working with the build house. It's not dead, but not alive yet. Maybe something later this year.


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## Electrodynamic (Nov 27, 2007)

We are designing a new motor that will have the same physical OD as the mkIII and mkIV but will be a little shallower to allow a little more mechanical rearward (and total) stroke. I hated to see the previous pictures and total design of the mkV go away but the motor was simply WAY too expensive and the modular basket was not happening at all - both of the latter due to price and the overall $999+ cost of a driver like that.

If we use the same basket as the mkIII and mkIV, same neo radial motor, XBL^2, we can use a 3" coil instead and use the top section of the mkV so it will have the carbon fiber flat disk and the S surround. The driver will literally look like a 50/50 combo of the mkIV and the mkV. And it won't cost $900.


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## SHAGGS (Apr 24, 2011)

I'd say that's a pretty good compromise. Good to hear it's still moving forward.
Any change in power handling with the new coil?


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## Electrodynamic (Nov 27, 2007)

SHAGGS said:


> I'd say that's a pretty good compromise. Good to hear it's still moving forward.
> Any change in power handling with the new coil?


Not really. Thermally yes but the 2.5" coil from the previous version had no thermal issues. The issue is excursion limits in such a small box so bottoming out the driver becomes the primary issue. Power handling of the coil is no problem at all as this is not a 2,000 watt power soaking monster.


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## SteveH! (Nov 7, 2005)

sounds promising.looking forward to the future bm4 rmix, lol




Electrodynamic said:


> We are designing a new motor that will have the same physical OD as the mkIII and mkIV but will be a little shallower to allow a little more mechanical rearward (and total) stroke. I hated to see the previous pictures and total design of the mkV go away but the motor was simply WAY too expensive and the modular basket was not happening at all - both of the latter due to price and the overall $999+ cost of a driver like that.
> 
> If we use the same basket as the mkIII and mkIV, same neo radial motor, XBL^2, we can use a 3" coil instead and use the top section of the mkV so it will have the carbon fiber flat disk and the S surround. The driver will literally look like a 50/50 combo of the mkIV and the mkV. And it won't cost $900.


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## Electrodynamic (Nov 27, 2007)

Pictures of the 3" coil, 12 slug neo radial (previous version was a 10 slug), flat carbon fiber prototype:

Neo slugs loosely placed on the yoke (yes one moved prior to the picture being taken):









3" motor partially assembled with the shorting ring showing (top top plate not assembled yet):









Motor assembly and spider riser set in place:









Spider laid in place:









Flat carbon fiber diaphragm in place (please excuse the parts not being cleaned prior to the picture being taken):


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## gregerst22 (Dec 18, 2012)

^^ That looks encouraging!


----------



## Bruneti (Oct 31, 2006)

Good to see progress on this. Thanks for the updates and pics! 


Sent from my iPhone using Tapatalk


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## USS Enterprise (May 26, 2007)

Those pics are awesome!
Absolutely LOVE seeing build pics like this.

Thanks, Nick!


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## Boostedrex (Apr 4, 2007)

Electrodynamic said:


> I've been weighing the options lately about coming back out with the BM mkIV.


Stop BS'ing and take my money already Nick!!!!!!


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## Electrodynamic (Nov 27, 2007)

Finished assembly pictures and T/S parameters. Note this is a prototype. The finished version will look like the last picture with our "S" surround:





































T/S parameters:

Re: 4.0 Ohms
Fs: 20.6 Hz
Qes: 0.48
Qms: 5.01	
Qts: 0.43
Le: 4.5 mH
Sd: 551.55 cm^2
Vas: 93.4 L
BL: 17.27
Mms: 274 g
Sensitivity: 84.2 dB (1W/1M)
Power handling: 500 watts RMS
Xmax: 14 mm (one-way)
Xmech: 19 mm (one-way)

Recommended sealed enclosure volume: 0.50 ft^3 to 0.65 ft^3


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## PorkCereal (Nov 24, 2009)

Sexy, I'm assuming the 500w is max rms?


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## Electrodynamic (Nov 27, 2007)

PorkCereal said:


> Sexy, I'm assuming the 500w is max rms?


Yes sir. There is no need to chase the power handling race on a hi-fi driver like this. 500 watts RMS is more than enough power on a single shallow mount 12 inch driver.


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## speakerman99 (Apr 18, 2016)

Electrodynamic said:


> Finished assembly pictures and T/S parameters:
> 
> 
> 
> ...




Well just take my money again. Can you share expected price and availability yet? Or too soon?


Sent from my iPhone using Tapatalk


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## PorkCereal (Nov 24, 2009)

Oh i agree, just confirming its comparable to the previous version of a 2/300 nominal with a 500 max.


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## Electrodynamic (Nov 27, 2007)

PorkCereal said:


> Oh i agree, just confirming its comparable to the previous version of a 2/300 nominal with a 500 max.


I see. The previous 2.5" coil versions were rated at 450 watts RMS. This 3" coil version is rated for 500 watts RMS. Not a huge increase in rated power handling but the 3" coil will ensure more resistance to thermal failure [even though there are less than 5 mkIII or mkIV drivers that we are aware of with thermal damage out of thousands of our shallow mount BM series over the years].


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## gregerst22 (Dec 18, 2012)

I think I just found my next sub. Question is when can i get my hands on one...


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## seafish (Aug 1, 2012)

Dam, Nick, you're doing it again...incredibly sexy speaker with stats to die for!!!

Any ideas yet on preorder price and availability??


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## lv_v (Aug 24, 2005)

Ooooweeee that is one sexy woofer! ETA please!!


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## Electrodynamic (Nov 27, 2007)

I edited my last post but edits rarely get seen. Remember these are prototype pictures. Final production will have our "S" surround on it and will look like this from the front with the addition of a mounting gasket:


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## freemars (Apr 22, 2015)

This thing is a beauty. Can't wait for the release.


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## nineball76 (Mar 13, 2010)

Did I miss it? Mounting depth? Looks like a fun little sub. Might think about 3-4 in the Golf.


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## Black Rain (Feb 27, 2011)

Hey Nick, maybe I missed this, but this will be a DVC right?


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## nineball76 (Mar 13, 2010)

Black Rain said:


> Hey Nick, maybe I missed this, but this will be a DVC right?


There's 2 sets of terminals


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## onebadmonte (Sep 4, 2008)

Flat carbon fiber diaphragm, ooh la la.


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## Electrodynamic (Nov 27, 2007)

nineball76 said:


> Did I miss it? Mounting depth? Looks like a fun little sub. Might think about 3-4 in the Golf.


3.2" mounting depth. 



Black Rain said:


> Hey Nick, maybe I missed this, but this will be a DVC right?


DVC 2 Ohm


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## Electrodynamic (Nov 27, 2007)

Picture of the BM mkV during its power test session handling 480+ watts.


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## hdrugs (Sep 7, 2009)

in recommended enclosure may it touch linear limits off 300rms?


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## Electrodynamic (Nov 27, 2007)

hdrugs said:


> in recommended enclosure may it touch linear limits off 300rms?


The goal should not be to reach linear limits, but to stay under the linear limits of the driver. 300 watts is a perfect spot to be at in 0.65 ft^3.


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## dawaro (Jul 22, 2015)

Do you have an ETA of when they will be available?


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## Electrodynamic (Nov 27, 2007)

I managed to get the prototype BM mkV installed in a 0.5 ft^3 sealed box with zero acoustic treatment inside the box (no polyfill, acoustic foam, etc) and ran a sweep just a few moments ago. Very clean natural response, no EQ, from the crossover point on down to 10 Hz.


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## hdrugs (Sep 7, 2009)

Thats very nice i also notice the cone has abit more sd then the mkiv

Curious why neo radial over xbl^2


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## Dfunke (Apr 12, 2017)

I'm in for 2. Do you have an ETA?


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## Electrodynamic (Nov 27, 2007)

hdrugs said:


> Thats very nice i also notice the cone has abit more sd then the mkiv
> 
> Curious why neo radial over xbl^2


Neo radial is the type of magnet and the arrangement of the neo. The driver still utilizes XBL^2 topology.


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## Electrodynamic (Nov 27, 2007)

Dfunke said:


> I'm in for 2. Do you have an ETA?


Not yet but we will post more information shortly.


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## Firefighter9 (Sep 23, 2015)

Keeping an eye on this. Might be time to replace the SD3 soon!


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## hdrugs (Sep 7, 2009)

They look great more 

Decent xmax
Good sd
Good motor
Theoretically lower distortion then a xxls which a is what i run 
I might have to take a short holiday in the us if i want a pair


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## Boostedrex (Apr 4, 2007)

hdrugs said:


> They look great more
> 
> Decent xmax
> Good sd
> ...


Or have someone who has friends/family in Aus send you a pair...  If you wanted to take a holiday to California I could have a pair here waiting on you once they're available. Either way, just let me know.

Cheers,

Zach


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## hdrugs (Sep 7, 2009)

Sounds okay I had 2 pairs of the original tm65

Sold one, put one in my bros car 

They both very pleased


I do wonder down the track could there ever be the release of the initial mkv design


Even if its a small production run of 20 units or so

I mean there are people who were willing and did spend around the 1k mark for the illusion c12xl


The mkv original prototypes were both elegent and the performance could be presumed surperb

Just a thought might, could happen or may never happen


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## dowheelies (Jan 7, 2012)

Electrodynamic said:


> Not yet but we will post more information shortly.


Eagerly awaiting to hear. Just got a 2017 F350 and am on a hunt for 2. 

Last build in my 2011 F250 I went with the JL 13TW5, never was quit thrilled about the sub stage, but didn't have it in me to build a new box. Always wanted to try 1 or 2 of these instead. 

Eric


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## lostthumb (Dec 16, 2005)

dowheelies said:


> Eagerly awaiting to hear. Just got a 2017 F350 and am on a hunt for 2.
> 
> Last build in my 2011 F250 I went with the JL 13TW5, never was quit thrilled about the sub stage, but didn't have it in me to build a new box. Always wanted to try 1 or 2 of these instead.
> 
> Eric


I have one that I took out a few months ago that I replaced with another sub.
I might post in the classifieds soon.


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## rjorge (Feb 12, 2008)

I just installed 2 MKIV's, well worth all the trouble to make it fit! They keep on surprising me, specially how they can easily play transient bass. Very fast and accurate. Here is my build: https://www.tacomaworld.com/threads/limited-sound-quality-build.495094/

Thanks again Nick for the detailed dimensions.


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## Electrodynamic (Nov 27, 2007)

rjorge said:


> I just installed 2 MKIV's, well worth all the trouble to make it fit! They keep on surprising me, specially how they can easily play transient bass. Very fast and accurate. Here is my build: https://www.tacomaworld.com/threads/limited-sound-quality-build.495094/
> 
> Thanks again Nick for the detailed dimensions.


Thanks for the install pics and initial review...and also for the link to your thread over at Tacomaworld.  I'm glad you like the twin BM mkIV's - that's a pretty formidable subwoofer system with a pair of BM mkIV's!


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## WhereAmEye? (Jun 17, 2013)

rjorge said:


> I just installed 2 MKIV's, well worth all the trouble to make it fit! They keep on surprising me, specially how they can easily play transient bass. Very fast and accurate. Here is my build: https://www.tacomaworld.com/threads/limited-sound-quality-build.495094/
> 
> 
> 
> Thanks again Nick for the detailed dimensions.




Nice build!


Sent from my iPhone using Tapatalk


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## rjorge (Feb 12, 2008)

Thanks! Yes, 2 is PLENTY! It somehow still manages to disappear behind the seats somewhere... 

Any big differences between the MKIV and MKV? You're not going to make me want to swap them are you??


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## dowheelies (Jan 7, 2012)

rjorge said:


> I just installed 2 MKIV's, well worth all the trouble to make it fit! They keep on surprising me, specially how they can easily play transient bass. Very fast and accurate. Here is my build: https://www.tacomaworld.com/threads/limited-sound-quality-build.495094/
> 
> Thanks again Nick for the detailed dimensions.


Very nice install! Thanks for sharing.

Very similar speaker selection (actually the exact) than I'm leaning towards right now in my new set-up. 

Eric


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## ludachris939 (May 1, 2013)

I am interested in an mkiv if you have any available!  ive been looking for one for months.


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## Electrodynamic (Nov 27, 2007)

Our web page is going through some edits but here are a few images of what we have posted on our Facebook page. We are re-tooling a new surround which will have an incorporated gasket that meets flush with the edge of the basket. We also increased the OD of the cone to increase surface area because the S surround is so extremely capable. 

I have attached the images to this post instead of trying to link them.


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## Electrodynamic (Nov 27, 2007)

And images from the second prototype with an updated spider with the current surround tooling and CF diaphragm:


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## Electrodynamic (Nov 27, 2007)

Here is the rendering of the new surround with increased piston surface area that will fit flush with the edge of the basket. If you look at the drawing at the bottom of the image you'll see how the surround becomes the "thick" (6 mm) gasket at the basket flange to fit flush against the edge of the basket.


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## Driver of 102080 (Sep 19, 2016)

How high could this subwoofer be crossed over? I ask because my mids don't really play with authority until 80hz . 

Sent from my LGL52VL using Tapatalk


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## Electrodynamic (Nov 27, 2007)

Driver of 102080 said:


> How high could this subwoofer be crossed over? I ask because my mids don't really play with authority until 80hz .
> 
> Sent from my LGL52VL using Tapatalk


The BM mkV's upper frequency limit is going to be around 200 Hz.


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## Electrodynamic (Nov 27, 2007)

Second prototype has been completed with a revised spider. T/S's are as follows:

Re	4.0 ohms
Fs	25 Hz
Qes	0.50
Qms	6.01
Qts	0.46
Le	3.5* mH
Sd	530.9 cm^2
Vas	64.7 L
BL	17.6
Mms	250.4 g
Xmax (1-way)	14 mm
Xmech (1-way)	20 mm
RMS Power	500 watts

* Le spec will be measured when the prototype arrives at our facility. Above T/S parameters were measured using LMS software.


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## Weightless (May 5, 2005)

Just in case I missed it, is the basket the same? I was thinking about building a box using my spare Mk IV until the V is released. 

Will it be a direct drop in?

Sent from my SM-N920P using Tapatalk


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## Electrodynamic (Nov 27, 2007)

Weightless said:


> Just in case I missed it, is the basket the same? I was thinking about building a box using my spare Mk IV until the V is released.
> 
> Will it be a direct drop in?
> 
> Sent from my SM-N920P using Tapatalk


Yes the basket is the same so it will be a direct drop-in for the previous BM mkIII/IV models.


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## Electrodynamic (Nov 27, 2007)

When the new surround tooling is finished we will have a few more millimeters of clearance to work with so we are drawing up a revised motor to push Xmax into the 16-17 mm mark as we now have over 25 mm of Xmech to work with. The new motor drawing won't take us more than a day or two so we can get the third, and final, sample as performance-laden as possible.


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## Driver of 102080 (Sep 19, 2016)

Electrodynamic said:


> When the new surround tooling is finished we will have a few more millimeters of clearance to work with so we are drawing up a revised motor to push Xmax into the 16-17 mm mark as we now have over 25 mm of Xmech to work with. The new motor drawing won't take us more than a day or two so we can get the third, and final, sample as performance-laden as possible.


Your going end up building that $1000.00 subwoofer if you keep going Nick. Your remind me of myself when building a engine . I start with the intention of of a nice budget street then all of sudden I have race engine that wants 14 dollar a gallon race fuel.

Sent from my LGL52VL using Tapatalk


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## Electrodynamic (Nov 27, 2007)

Driver of 102080 said:


> Your going end up building that $1000.00 subwoofer if you keep going Nick. Your remind me of myself when building a engine . I start with the intention of of a nice budget street then all of sudden I have race engine that wants 14 dollar a gallon race fuel.
> 
> Sent from my LGL52VL using Tapatalk


Hahaha, very true. I've already done that with the two "unicorns" that are talked about on this forum (pictures attached). But the devolpment of the BM mkV has been a long road so far and now that we have the physical limitations ironed out and defined we see that we can add more "oomph" to the motor without sacrificing mounting depth. One more motor drawing package and a new coil spec sheet is all that's needed.


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## Driver of 102080 (Sep 19, 2016)

Electrodynamic said:


> Hahaha, very true. I've already done that with the two "unicorns" that are talked about on this forum (pictures attached). But the devolpment of the BM mkV has been a long road so far and now that we have the physical limitations ironed out and defined we see that we can add more "oomph" to the motor without sacrificing mounting depth. One more motor drawing package and a new coil spec sheet is all that's needed.


That basket looks to nice to hide in box. Production pieces will be cast? If not I am going to make my box from lexan.lol

Sent from my LGL52VL using Tapatalk


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## PorkCereal (Nov 24, 2009)

This guy, such a tease 

Sent from my SAMSUNG-SM-G935A using Tapatalk


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## Driver of 102080 (Sep 19, 2016)

PorkCereal said:


> This guy, such a tease
> 
> Sent from my SAMSUNG-SM-G935A using Tapatalk


I know right keeps all the goodies at his shop instead sharing. Lol

Sent from my LGL52VL using Tapatalk


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## Electrodynamic (Nov 27, 2007)

Driver of 102080 said:


> That basket looks to nice to hide in box. Production pieces will be cast? If not I am going to make my box from lexan.lol
> 
> Sent from my LGL52VL using Tapatalk


Stamped steel. The back of the drivers will look exactly like this minus the clear protective tape.


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## Electrodynamic (Nov 27, 2007)

PorkCereal said:


> This guy, such a tease
> 
> Sent from my SAMSUNG-SM-G935A using Tapatalk


One to Two months and pre-ordering will be open for the mkV's. Yes this project has drawn on far too long but I've got my boot staps on and are moving forward very fast. This driver will come to fruition in the next month or two.


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## Souldrop (Nov 2, 2014)

Looking forward to them!


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## Electrodynamic (Nov 27, 2007)

PorkCereal said:


> This guy, such a tease
> 
> Sent from my SAMSUNG-SM-G935A using Tapatalk


^ You need to update your signature now that you have the TM65 mkII's.


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## PorkCereal (Nov 24, 2009)

Electrodynamic said:


> ^ You need to update your signature now that you have the TM65 mkII's.


Ha, you're right

Sent from my SAMSUNG-SM-G935A using Tapatalk


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## pat_smith1969 (Feb 17, 2010)

I had a SI BMMkiV and ran it at 1200 watts RMS for years with no problems. Now I tend to under gain my amps and never listen to them at full output (in short I am careful with my equiptment)... I loved that sub. REAL excited for them to come back!!!


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## Weightless (May 5, 2005)

Hey Nick, I'm sure it's been asked before, but does the design of the MK IV scale up? Meaning, would it feasible to design a shallow mount, smallish box 15 based off a similar basket, cone, and soft parts?

I bet if you had a 3-4" deep, low inductance 15 that can be played in .75-.8 c.f., it would sell like hot cakes. 

Being able to fit 2 15's in your trunk without eating up space and without going IB would be nice...or having a single 15 in a 2016 Honda HR-V work vehicle would be stellar. 

Just curious...

Sent from my SM-N920P using Tapatalk


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## Electrodynamic (Nov 27, 2007)

Weightless said:


> Hey Nick, I'm sure it's been asked before, but does the design of the MK IV scale up? Meaning, would it feasible to design a shallow mount, smallish box 15 based off a similar basket, cone, and soft parts?
> 
> I bet if you had a 3-4" deep, low inductance 15 that can be played in .75-.8 c.f., it would sell like hot cakes.
> 
> ...


Sorry but there is no 15" basket that is similar. There is a 10" basket, but not a 15". And the BM mkV will be a 12" unit. No 15" plans at all.


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## Garcbomber (May 26, 2017)

In my opinion the contribution margin in modern 15"+ woofers would take too big of a hit, so profitable Audio manufacturers don't even produce larger than 12-13" drivers. The R&D engineers would have that answer.


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## Weightless (May 5, 2005)

The question was totally hypothetical, well for the most part anyway. It was more of a curiosity about the technology and design of the BM. 

Given the shallowness, magnet arrangement, soft part design, lfe and small box requirements, is the BM scalable? In either direction? 

You mention that there is also an available 10" basket. Is that only available in the two sizes because it doesn't scale well further or just because 10's and 12's sell the most?

Again, hypothetically, if one were to get a custom one-off 15" basket milled per spec of said design, could it be pulled off?

Also, if it could scale smaller, could a super shallow 6.5" be possible? Would the design limit the hfe? 

I know you have the TM65 available, which I have 4, but I really like the performance and aesthetic of the BM and was just curious how well it can scale.



Sent from my SM-N920P using Tapatalk


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## Electrodynamic (Nov 27, 2007)

Weightless said:


> The question was totally hypothetical, well for the most part anyway. It was more of a curiosity about the technology and design of the BM.
> 
> Given the shallowness, magnet arrangement, soft part design, lfe and small box requirements, is the BM scalable? In either direction?
> 
> ...


Yes, everything is scalable. A shallow 15" could be made. If somone is interested in funding the project shoot us an email and we can discuss it. 

A shallow 6.5? We already have the TM65 mkII if one chooses to use it in such a manner.  Sure we could make it a flat piston but when you reduce the size everything gets tight real quick.


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## truckguy (Sep 2, 2013)

Electrodynamic said:


> Yes, everything is scalable. A shallow 15" could be made. If somone is interested in funding the project shoot us an email and we can discuss it.


This might be dumb but have you ever thought about taking your company to a show like Shark Tank or some other way to get more funding to really unleash your creativity on speaker design? It would probably increase the cost to the end users like us with more overhead but you could be the next big speaker company. Seems like such a waste of your abilities to be scratching by when you could be doing so much more! It's a shame that funding is thing holding you back from making a 15, 8, 6x9, small midrange, and etc. that people would go crazy over. If I ever won the lottery I would fund a company like yours.


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## pwnt by pat (Mar 13, 2006)

Electrodynamic said:


> One to Two months and pre-ordering will be open for the mkV's. Yes this project has drawn on far too long but I've got my boot staps on and are moving forward very fast. This driver will come to fruition in the next month or two.



Nick, 

I don't know if you're keeping a tally sheet of customers or anything, but please let me know when the pre-order is ready. I'll be good for 5 or 6 units. And 2-3 sets of m25s.


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## Electrodynamic (Nov 27, 2007)

pwnt by pat said:


> Nick,
> 
> I don't know if you're keeping a tally sheet of customers or anything, but please let me know when the pre-order is ready. I'll be good for 5 or 6 units. And 2-3 sets of m25s.


Unfortunately it would be / is extremely difficult to send out PM's or emails, etc, about the BM mkV when it is finished so that's not an option. However, I will be keeping our Facebook page updated with all the latest news about the driver. Our web page will be edited also with pictures and information about pre-ordering, but FB is the quickest way to get info.


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## Electrodynamic (Nov 27, 2007)

Our new surround/gasket tooling finished up yesterday. I'm not sure what we have mentioned in this thread already but the surround and the gasket are the same piece - basically the thick outside gasket is seamless with the surround rolls. Obviously thickness varies massively between the two but they are out of our new custom one-piece mold. 

Here are pictures:



















Sorry for the gunk in the screw holes:


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## bertholomey (Dec 27, 2007)

Looks fantastic Nick!


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## Electrodynamic (Nov 27, 2007)

Final sample was built yesterday afternoon. We will be taking additional pictures and some videos next week.


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## norurb (Jun 28, 2013)

It's unlike anything else. It's a work of art.


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## Electrodynamic (Nov 27, 2007)

There's a lot of noise in the background but here is the first video taken of the BM mkV in action:


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## Golden Ear (Oct 14, 2012)

She's looking nice! Love the cf cone. Is she still going to need only .5 cubes? 


Sent from my iPhone using Tapatalk


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## dcfis (Sep 9, 2016)

Dont tell me thats a walkman


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## ryankenn (Mar 15, 2014)

dcfis said:


> Dont tell me thats a walkman


No I still have a Walkman, that is the far more modern Discman.

Its funny, for over a year and a half I've been working on my truck resto and ignored this site completely. I resigned myself to having a pair of Rockford shallow subs since the MKIV was it and the design was sold off. It was sad but it was what it was.

I had all my equipment except amp ready as the truck is going back together, and I thought I'd just look up SI's website. Clicked the link to the Facebook page and oh the joy! So happy to see this is back as a product and I'm finding out close to the end!

Subscribed again to get in on the pre-orders!


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## Electrodynamic (Nov 27, 2007)

Golden Ear said:


> She's looking nice! Love the cf cone. Is she still going to need only .5 cubes?
> 
> 
> Sent from my iPhone using Tapatalk


0.5 ft^3 is the smallest we are going to recommend but 0.65 ft^3 is more appropriate. We will know more once we get the prototype in our hands and test it thoroughly.


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## Electrodynamic (Nov 27, 2007)

ryankenn said:


> No I still have a Walkman, that is the far more modern Discman.
> 
> Its funny, for over a year and a half I've been working on my truck resto and ignored this site completely. I resigned myself to having a pair of Rockford shallow subs since the MKIV was it and the design was sold off. It was sad but it was what it was.
> 
> ...


Thanks for the kind words.  We are very happy to offer the improved BM mkV to the market and bring back the shallow BM series. 

Sorry for the fairly poor video with noise in the background but we were happy to see it in action for the first time so we posted the video quickly. We will take another video, or two, or three, etc, when the prototype gets in our hands in a few days.


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## jimmyjames16 (Dec 12, 2006)

can't wait..


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## Driver of 102080 (Sep 19, 2016)

Electrodynamic said:


> There's a lot of noise in the background but here is the first video taken of the BM mkV in action:


May I ask about the enclosure you have because my building skills are poor?

Sent from my SM-S320VL using Tapatalk


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## Electrodynamic (Nov 27, 2007)

The prototype arrived today.


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## Electrodynamic (Nov 27, 2007)

T/S Parameters:

We just measured the T/S parameters:

Re: 4.1 Ohms
Fs: 28.5 Hz
Qes: 0.55
Qms: 6.7
Qts: 0.51
Le: 3.4 mH
Sd: 557 cm^2
Vas: 33.3 L
BL: 23.4
Mms: 412.3 g
Cms: 75.2 uM/N
SPL: 86.0 dB (2.83V/1M)


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## mrichard89 (Sep 29, 2016)

Awesome. Can't wait to purchase mine


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## Electrodynamic (Nov 27, 2007)

Front:










Side:










Obviously this driver is the first built with the new toolings so on production they will look cleaner but we are still very happy with the outcome.


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## Weightless (May 5, 2005)

You know where that would look good?

Sent from my SM-N920P using Tapatalk


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## Electrodynamic (Nov 27, 2007)

Weightless said:


> You know where that would look good?


In your car?


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## Weightless (May 5, 2005)

Lol, am i that transparent? 

Looks good nick. Cant wait to hear it.

Sent from my SM-N920P using Tapatalk


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## Electrodynamic (Nov 27, 2007)

Haha. I'm going out in a few moments to take some RTA measurements of the driver in our Jetta. I have a feeling it will stay in the Jetta for a while after I'm finished with measurements.


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## Weigel21 (Sep 8, 2014)

So what's the chances just one would be enough for some folks? Last I was hearing, the BM MKIV lacked in output to where it wasn't worth using if a guy didn't use at least two.


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## Electrodynamic (Nov 27, 2007)

Weigel21 said:


> So what's the chances just one would be enough for some folks? Last I was hearing, the BM MKIV lacked in output to where it wasn't worth using if a guy didn't use at least two.


Out of the full production runs of mkIII's and mkIV's we never heard that they "weren't worth using" if someone did not run at least two of them. We managed to post a TermLab score in a 1990's Jeep of over 130 dB with a single BM mkIII so we suppose it's all about your frame of reference. If your frame of reference is 140 dB+ then yes you would need at least two of them.


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## Weigel21 (Sep 8, 2014)

Seemed that the word on here (DIYMA) was that if a guy was going to run the BM MKIV, they really needed to run multiple. Perhaps the "not worth useing if only running one", is putting words in other's mouths, but it's the way things seemed implied, that running just one tended to be underwhelming. 

Yeah, I don't need 130dB+, but I do like to feel the bass every now and then. Currently running a Polk MM1540 on JBL MS-A5001 and it seems to provide ample output for me most of the time. And we all know it's no SPL sub, not to mention JBL lied on it's specs. 

So, if one of these bad boys could compete with or put to shame my MM1540, then I'm on board. Just don't think I could swing for two any time soon, thus the reason for my asking.


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## seafish (Aug 1, 2012)

Weigel21 said:


> Seemed that the word on here (DIYMA) was that if a guy was going to run the BM MKIV, they really needed to run multiple. Perhaps the "not worth useing if only running one", is putting words in other's mouths, but it's the way things seemed implied, that running just one tended to be underwhelming.


I never got that impression even from the guys running THREE of them.

One was clean, two were better, and three were over the top!!!
Like Nick says, seems like ti is up to user preference.

All that being said, looks like the sensitivity is 3db higher on this new model!!!


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## Electrodynamic (Nov 27, 2007)

My apologies for the late response but I've been battling the 3sixty.3 for almost an hour trying to get it to save the correct settings in the correct slots. 

RTA of the car with the single BM mkV in 0.5 ft^3 crossed over at 60 Hz:










The enclosure is the smallest we recommend at 0.5 ft^3 but this will give you an idea of the LFE of the subwoofer system in the very small sealed box.


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## cjbrownco (Apr 30, 2014)

Do you have an estimated preorder date for these yet?


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## RRizz (Sep 4, 2012)

sub'd for the pre order


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## Weigel21 (Sep 8, 2014)

seafish said:


> I never got that impression even from the guys running THREE of them.
> 
> One was clean, two were better, and three were over the top!!!
> Like Nick says, seems like ti is up to user preference.
> ...


Alright, that's just the impression "I" got. Regardless, if one is capable up upwards 130dB, it should be plenty for myself. 

Guess many using the older models were more of bassheads, cause I remember there being talk about people blowing them by feeding them too much power in an attempt to get more output from them. Nick even said something about receiving requests for warranty work on them only to find they were given too much power. So yeah, to me, it seemed that many indicted running just one wasn't enough. 

Still, this version seems a little beefier in every way. I'll await preorder and see what my budget allows for come time.


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## -Kyle- (Feb 5, 2009)

Electrodynamic said:


> Out of the full production runs of mkIII's and mkIV's we never heard that they "weren't worth using" if someone did not run at least two of them. We managed to post a TermLab score in a 1990's Jeep of over 130 dB with a single BM mkIII so we suppose it's all about your frame of reference. If your frame of reference is 140 dB+ then yes you would need at least two of them.


What kind of box was that in Nick? That's impressive!


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## Garcbomber (May 26, 2017)

I didn't see excursion specs, I'm estimating ~10mm one way?


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## pwnt by pat (Mar 13, 2006)

How is that sub loaded in t the Jetta? Just a box in the trunk?


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## Electrodynamic (Nov 27, 2007)

-Kyle- said:


> What kind of box was that in Nick? That's impressive!


We actually did over a 140 but it was literally a huge 4'th order bandpass. But that was just for testing to see how loud we could get a single shallow BM regardless of enclosure size or type.


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## Electrodynamic (Nov 27, 2007)

Garcbomber said:


> I didn't see excursion specs, I'm estimating ~10mm one way?


14 mm one-way


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## Electrodynamic (Nov 27, 2007)

pwnt by pat said:


> How is that sub loaded in t the Jetta? Just a box in the trunk?


Yes sir. Just a box in the trunk.


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## pwnt by pat (Mar 13, 2006)

Very nice. I still need to get your info about this box I have. I just keep forgetting.


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## Weigel21 (Sep 8, 2014)

140dB from just one?! Don't need or want that, but good to know the potential is there, if someone really wanted such. I've been in a Jeep that was able to hit 143.xxdB and that **** hurt. Ability to hit Mid 120's is plenty loud for me. 

Bowing out of the thread for now and awaiting preorder.


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## Electrodynamic (Nov 27, 2007)

Weigel21 said:


> 140dB from just one?! Don't need or want that, but good to know the potential is there, if someone really wanted such. I've been in a Jeep that was able to hit 143.xxdB and that **** hurt. Ability to hit Mid 120's is plenty loud for me.
> 
> Bowing out of the thread for now and awaiting preorder.


Haha, keep in mind that was with a BM mkIII and we ruined the driver doing that number. Yes it was loud but it was one of those "if we mess it up, oh well" mentailties as we ignored the safety of the driver and pushed for the highest number we could get. And the enclosure was so big it wouldn't even fit in the trunk of a Jetta. ...but it was loud for one burp though.


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## dgage (Oct 1, 2013)

Electrodynamic said:


> Haha, keep in mind that was with a BM mkIII and we ruined the driver doing that number. Yes it was loud but it was one of those "if we mess it up, oh well" mentailties as we ignored the safety of the driver and pushed for the highest number we could get. And the enclosure was so big it wouldn't even fit in the trunk of a Jetta. ...but it was loud for one burp though.


Were you using the manufacturer recommended 500 watts? I know the owner and he won't support you if you use more than 500 watts.


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## Weigel21 (Sep 8, 2014)

Was it something like this?:laugh:


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## Electrodynamic (Nov 27, 2007)

dgage said:


> Were you using the manufacturer recommended 500 watts? I know the owner and he won't support you if you use more than 500 watts.





Weigel21 said:


> Was it something like this?:laugh:


^ Pretty much. We loaded it up, rolled the volume, and boom. Neat exercise though.


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## Electrodynamic (Nov 27, 2007)

Pre-ordering will open up this weekend for the BM mkV. I'll make a new thread so we can keep things separate.


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## cjbrownco (Apr 30, 2014)

For the mkv or the mkiv?


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## Electrodynamic (Nov 27, 2007)

Electrodynamic said:


> Pre-ordering will open up this weekend *for the BM mkV*. I'll make a new thread so we can keep things separate.





cjbrownco said:


> For the mkv or the mkiv?


The mkV.


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## mrichard89 (Sep 29, 2016)

Subscribed. Can't wait!


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## cjbrownco (Apr 30, 2014)

Please forgive my ignorance, but in my defense I am taking medication at the moment that really messes with my memory. I thought that within this thread you were getting close to opening up for preorders on the mkiv? Also, I thought Sundown bought the rights to the mkv and it was put on indifinate hold? I would love to order either one of them, just wanted to straighten this out in my mind.


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## mrichard89 (Sep 29, 2016)

cjbrownco said:


> Please forgive my ignorance, but in my defense I am taking medication at the moment that really messes with my memory. I thought that within this thread you were getting close to opening up for preorders on the mkiv? Also, I thought Sundown bought the rights to the mkv and it was put on indifinate hold? I would love to order either one of them, just wanted to straighten this out in my mind.


Might be a good idea to refrain from posting until the medications wear off!


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## dgage (Oct 1, 2013)

cjbrownco said:


> Please forgive my ignorance, but in my defense I am taking medication at the moment that really messes with my memory. I thought that within this thread you were getting close to opening up for preorders on the mkiv? Also, I thought Sundown bought the rights to the mkv and it was put on indifinate hold? I would love to order either one of them, just wanted to straighten this out in my mind.


Things change.  Sundown had other areas to focus so Nick decided to develop an improved mkIV that was more affordable as last year's "mkV" prototype was way too expensive. So the new model you're seeing is an improved mkIV that is using the BM mkV name. Either way, it is the same family but new and improved (it says so on the box ).


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## cjbrownco (Apr 30, 2014)

dgage said:


> Things change.  Sundown had other areas to focus so Nick decided to develop an improved mkIV that was more affordable as last year's "mkV" prototype was way too expensive. So the new model you're seeing is an improved mkIV that is using the BM mkV name. Either way, it is the same family but new and improved (it says so on the box ).


Thanks a bunch for clearing that up for me. I appreciate that


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## rob feature (Nov 15, 2015)

from the SI facebook page

_Pre-ordering will be open this weekend on our web page for our new BM mkV subwoofer at the pre-order price of $249 each shipped in the lower 48 continental United States. As soon as the drivers are finished being produced the price will go to the normal $299.
We expect to be shipping the BM mkV's to customers in December which makes November or late October the end of pre-order pricing._

Collect yer pennies kiddies. I don't really have a direct use for one, but might just order one anyway at two fiddy

And I assume he meant mkIV - not V. If it is the V, I'll probably need one of those too


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## ckm20 (Dec 6, 2014)

FYI Prices are $299 pre-order and $349.

Sent from my SM-N920V using Tapatalk


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## RRizz (Sep 4, 2012)

Just pre-ordered 2 of these beauties.... And its the MKV, by the way...


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## naiku (May 28, 2008)

Electrodynamic said:


> Pre-ordering will open up this weekend for the BM mkV. I'll make a new thread so we can keep things separate.


Awesome news, hope you sell a truck load of them!!


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## Electrodynamic (Nov 27, 2007)

ckm20 said:


> FYI Prices are $299 pre-order and $349.
> 
> Sent from my SM-N920V using Tapatalk


That is correct - the older prices for the previous version got published for a hot minute but the correct pricing is now listed.


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## abusiveDAD (Jan 7, 2009)

Following sir


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## schmiddr2 (Aug 10, 2009)

Will the MKV xmax be limited thermally or mechanically?


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## Electrodynamic (Nov 27, 2007)

schmiddr2 said:


> Will the MKV xmax be limited thermally or mechanically?


Thermally. We kept the same Xmax as the previous versions to allow the motor to keep the driver from bottoming out. Higher Xmax (taller coil and top plates) would have increased linear stroke but it would have also allowed the driver to hard bottom.


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## cjbrownco (Apr 30, 2014)

Got my two MKV's preordered, can't wait to get them,
except for that I will have to wait ? Like a kid waiting on Christmas to get here.


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## cjbrownco (Apr 30, 2014)

Wish I could have afforded 4. I would love to try to figure out a way for 2 under rear seat and 2 up front in custom molded fiberglass enclosures. That would be sweet.


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## rob feature (Nov 15, 2015)

Electrodynamic said:


> That is correct - the older prices for the previous version got published for a hot minute but the correct pricing is now listed.


d'oh


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## pwnt by pat (Mar 13, 2006)

Hey Nick.

I didn't want to post this in the actual pre-order thread and clutter it up. And this is not a criticism, just a question. I'm not a speaker manufacturer, so just curious.

The inductance on this driver seems fairly high for an sq sub. A lot of modern drivers have LE values below 1.5. The bm mk5 is 3.4. Is this a sacrifice in "musicality" for extra thermal capacity or is it a function of pulling t/s numbers with the coils wired in series?

Also, subquestion. If I order some tweeters and maybe mids with the bm order, will they ship at the same time or will the in stock drivers ship sooner?


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## madmaxz (Feb 11, 2009)

so wait is there going to be an mkv AND mkiv rerelease or is the mkv the updated mkiv?


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## pwnt by pat (Mar 13, 2006)

Just the 5


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## dgage (Oct 1, 2013)

pwnt by pat said:


> Hey Nick.
> 
> I didn't want to post this in the actual pre-order thread and clutter it up. And this is not a criticism, just a question. I'm not a speaker manufacturer, so just curious.
> 
> ...


I'm not a speaker designer either as I have Nick, who supplies my home theater subs. As I've told customers that start asking about the Q of an enclosure and similar minutiae, everything is a design decision. As I've stated to some of those customers, the drivers have slightly high inductance but I wouldn't want Nick to change that as we'd have to give up something else. And with a very minor DSP setting, the inductance hump completely disappears and is a non-issue. My guess is Nick has made a conscious decision to have slightly higher inductance but I'd gladly take that as his subs play deep and clean.

And then you have to ask, if Nick made the change which wouldn't all of a sudden make a perfect driver, it would just shift to something else being a potential issue as nothing is perfect. Would you or someone else then complain about or question why the driver was X? Not trying to be negative so please, don't get defensive, but you can easily see how something else could then be questioned as that is the nature of design decisions. As a business owner on the home theater side, I'm very happy with the design decisions and quality of the speakers and subs Nick designs so I'm definitely a fan, inductance hump and all. 

EDIT: Since you questioned musicality, I can tell you they are every bit as musical as any sub though I'm specifically speaking about the HST-18 and HS-24 based subs I sell. I've even played the 24 up to 120 Hz at THE Show Newport in LA a couple years ago just to show their capability. And I've sold subs to pipe organ, 2-channel, and of course home theater guys and the subs handle it all with ease. And I was able to DSP my subs to be flat (ground-plane in a field) within +- .75 dB from 14/17 up to 180 Hz with only 3 or 4 minor DSP changes. Incredibly capable and musical. Pretty easy when you have a 70 lb magnet-motor moving a 1.5 cone. When the motor tells the cone to move, it moves, and when it stops, it stops immediately. Simple physics.


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## Electrodynamic (Nov 27, 2007)

pwnt by pat said:


> Hey Nick.
> 
> I didn't want to post this in the actual pre-order thread and clutter it up. And this is not a criticism, just a question. I'm not a speaker manufacturer, so just curious.
> 
> ...


You need to look at both Re and Le (more importantly the ratio of Re:Le), not just Le by itself as Le changes with Re. But to provide more detail, what are the modern drivers with Le values below 1.5 mH that you're referencing?


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## pwnt by pat (Mar 13, 2006)

Like I said, I'm just trying to learn. Just curious. I'll still be putting in an order for several units, even for the utility of the design.

A couple woofers off the top of my head (maybe not the latest/greatest but still new enough to be relevant):

Npdang r12 re3.6 le 1.316
Dayton rs315 re3.1 le .96
Ae ib12au re2.7 le .16


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## pwnt by pat (Mar 13, 2006)

Oh no. I'm not asking Nick to change anything, or even justify any choices.
I understand compromises, especially for the footprint this sub fits in. I build turbo kits for modern cars and everything is a design compromise. I'm not doubting anything, just trying to learn something new.



dgage said:


> pwnt by pat said:
> 
> 
> > Hey Nick.
> ...


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## Electrodynamic (Nov 27, 2007)

pwnt by pat said:


> Like I said, I'm just trying to learn. Just curious. I'll still be putting in an order for several units, even for the utility of the design.
> 
> A couple woofers off the top of my head (maybe not the latest/greatest but still new enough to be relevant):
> 
> ...


Just a quick run-down of those drivers physical dimensions (mounting depth) and how they perform in their ideal enclosure volume to reach a 0.707 alignment and also their Qtc alignment in a 0.65 ft^3 enclosure along with the F3 of said 0.65 ft^3 enclosure:

DIYMA R12 D2
BL^2/Re = 134
Qtc of 0.707 = 0.52
Qtc in 0.65 ft^3 = 0.65
F3 in 0.65 ft^3 = 51 Hz
Xmax = 23 mm
Mounting depth = 6” 

Dayton RS 315 HF D2
BL^2/Re = 63
Qtc of 0.707 = 1.3 ft^3
Qtc in 0.65 ft^3 = 0.90
F3 in 0.65 ft^3 = 50 Hz
Xmax = 14 mm
Mounting depth = 5.7”

AE 12 AU
BL^2/Re = 28
Qtc of 0.707 = 6.8 ft^3
Qtc in 0.65 ft^3 = 1.44
F3 in 0.65 ft^3 = 54 Hz
Xmax = 18 mm
Mounting depth = 6”

BM mkV
BL^2/Re = 134
Qtc of 0.707 = 1.3 ft^3
Qtc in 0.65 ft^3 = 0.84
F3 in 0.65 ft^3 = 45 Hz
Xmax = 14 mm
Mounting depth = 3.4” 










Very low inductance is nice but not always THE target to shoot for depending on the application(s) of the subwoofer system design. Very low Le is often the result of a few things such as low number of coil layers (lowers BL and mass) or a pole sleeve (lowers BL) or both of the latter. We chose to still use an 8 layer copper coil even though the coil ID increased from a 2.5" coil to a 3" coil (technically 66.0 mm VC former ID on both the mkIII and mkIV and now a 75 mm VC former ID on the mkV). The extra coil mass helps with thermal power handling and also adds mass which helps with LFE as you need mass in a small sealed box to give you output down low. You can see by the above examples that the BM mkV plays lower than all of the other drivers in a small 0.65 ft^3 sealed box. The BM mkV also has the highest BL^2/Re (highest motor force factor) which helps with increased output at the higher levels. And keeping higher BL^2/Re aids in lowering the enclosure volume to achieve a 0.707 alignment and that was more important to us versus simply having lower inductance as the Le:Re ratio is below a 1:1 ratio even with the eight layer voice coil in the BM mkV. 

And most importantly none of the drivers compared above to the BM mkV will even physically fit the size enclosure that a BM mkV can fit. They are also heavier. The AE driver is a very nice unit with its specific applications and a lot of John's (AE) are designed to be mated to a tweeter, hence the importance of very low and linear inductance so mounting depth and/or other performance goals are not as important as is the ability to mate up to a tweeter or perform in a small sealed box (the AU series is an IB specific design).


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## RC_350 (Jul 18, 2017)

Will you be shipping to Australia


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## Electrodynamic (Nov 27, 2007)

RC_350 said:


> Will you be shipping to Australia


Yes we can ship to Australia.


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