# SI BM mkIII T/S's



## Electrodynamic

I know this is weird, but our server is down right now. However, when it comes back up we will have posted the T/S's on the new BM mkIII subwoofers on our forum. As soon as we post them on our forum I will post them here in this thread. 

You know what, screw it. Here you go:

The below parameters are with the dual 4 Ohm voice coils wired in series for an 8 Ohm load:

Fs: 15.8 Hz
Qms: 5.22
Qes: 0.421
Qts: 0.386
Vas: 130 liters
Re: 6.1 Ohms
Le: 2.4 mH 
Sd: 490 cm²
Xmax: 14mm one way linear
SPL: 83 dB @ 1W, 1m
BL: 19.6 N/A
Mms: 263 grams

The above parameters are final production specifications of a broken-in driver.


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## [email protected]

So has production started?


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## Electrodynamic

Not yet, it will soon though. We're going over final cosmetics now. We will let our forum and newsletter know as soon as possible. However, the above _*will be*_ the final T/S's on the production drivers.


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## TREETOP

Electrodynamic said:


> Fs: 15.8 Hz
> ...


  Hubba hubba!


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## invinsible

Good Specs Indeed. 
What would be the Fs in runned in parallel at 2 ohms or 1 ohm load incase with 2 of them?


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## Electrodynamic

invinsible said:


> Good Specs Indeed.
> What would be the Fs in runned in parallel at 2 ohms or 1 ohm load incase with 2 of them?


Fs doesn't change at all, as Fs is a factor of Cms and Mms and both of those are constant whether you wire the driver up in series or parallel.


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## Boostedrex

Thanks for posting the T/S specs Nick. I'll be looking forward to getting a MKIII to play with. Nice light neo motor FTW!!


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## 1sashenka

Great!!! It would be good to know the weight.


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## bsvrs

It weighs under 12 lbs according to Nick's email earlier today.


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## bsvrs

And also, 15 hz? Joyzus, this thing must play LOW.


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## mSaLL150

And thats in .5 cu ft!!


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## azngotskills

mSaLL150 said:


> And thats in .5 cu ft!!


if those are accurate t/s parameters then it shouldnt have been in an enclosure for testing


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## JayBee

These are at the top of my short list for subs for a false floor in the jeep.


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## Electrodynamic

azngotskills said:


> if those are accurate t/s parameters then it shouldnt have been in an enclosure for testing


He was referring to the enclosure spec, not the enclosure the driver was in for testing because it wasn't in an enclosure.


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## azngotskills

Electrodynamic said:


> He was referring to the enclosure spec, not the enclosure the driver was in for testing because it wasn't in an enclosure.


I know specs were obtained correctly, i assumed that he didn't understand that the t/s parameters are independent of enclosures since that was how i understood his comment

BTW Looking forward to the production and release of this driver


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## el_chupo_

Is it just me, or does this model to a 2cube box?

Looks excellent in 2, not so hot at .5


Matt


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## Electrodynamic

If your listening room is an anechoic chamber or a huge room in a house, then the small enclosure wouldn't be the best. However, in a car environment everything changes. Even in the suggested alignment the F3 is still in the mid/high 30's outside of a vehicle, which is plenty to reach down to and/or below 20 Hz in a vehicle because of cabin gain. And there's also less than a 1.5 dB rise in the response due to the enclosure alignment we recommend. Wait until the reviews start being posted on the mkII version.  I'll let you know the alignment the mkII is in after the reviews are posted.


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## el_chupo_

Nick, I question you simply based on a WINISD model

It shows, for me, a ~2.5-3db bump at 60hz.

While the F3 looks to be about 36, which looks fine, I am simply concerned that a 3db hump at 60hz, coupled with cabin gain, will not be as ideal as other options.

Again, looks sick at 2 cubes, almost looks like an IB alignment at 2 cubes...

Thanks for entertaining the conversation.


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## mSaLL150

azngotskills said:


> if those are accurate t/s parameters then it shouldnt have been in an enclosure for testing


I know that. I was refering to the comment "these must play low" and I was basically saying "yeah in a .5 cu ft recommended box, pretty neat."


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## azngotskills

my bad, misunderstanding :blush

BUMP for a highly anticipated driver!


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## Electrodynamic

el_chupo_ said:


> Nick, I question you simply based on a WINISD model
> 
> It shows, for me, a ~2.5-3db bump at 60hz.
> 
> While the F3 looks to be about 36, which looks fine, I am simply concerned that a 3db hump at 60hz, coupled with cabin gain, will not be as ideal as other options.
> 
> Again, looks sick at 2 cubes, almost looks like an IB alignment at 2 cubes...
> 
> Thanks for entertaining the conversation.


In our modeler it is less than 1.5 dB, which is pretty darned good for a shoe-box sized enclosure while still having such a low F3. The mkII that Jason has is in an alignment that is worse than the mkIII but you can't tell when it's in a vehicle. I think bertholomy (Jason) has posted up initial listening impressionss in another thread somewhere.

The BM mkIII is not designed to have a .707 in 0.5 ft^3, just like the Mag v4 was not designed to have a .707 in 1 ft^3. In a car, the response changes drastically and the goal is to have a large bandwidth with negligible / undetectable rise in the target bandwidth while still maintaining extension down to / below 20 Hz. 

The BM mkIII is in the same ballpark Qtc-wise as the rest of the competition in the same sized sealed enclosures. I'm not sure why WinISD shows it that way, as we stopped using that program a long time ago. WinISD is a great program for figuring port lengths though.


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## jdc753

Looking forward to the final product Nick. Will be nice to see an intermediate step in the shallow sub game and something to beat up on the JL TW if all works out good, and for much cheaper too. 

0.5ft^3 and only 3.5" deep will sure make mounting much easier and installs more creative


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## [email protected]

I think I am in for a pair of these when they are ready, maybe 3


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## bertholomey

I'm working on getting my little review typed up for the MKII prototype - I apologize for the delay - work / travel has been killing me lately. Slade1274 will get it tomorrow!


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## bose301s

I want to get the MKII to try Nick


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## DAT

We are ready for some reviews, hoping this is tons better if not equal to a JL TW. FTW in $$ in the pocket.


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## Electrodynamic

We should be starting production either late this week or early next week. 

Steven has the mkII version of this sub, and I believe Mir got to listen to it also.


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## subwoofery

So all the modifications are done now? When can we expect shipping (excluding the custom problems you had )


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## Megalomaniac




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## Electrodynamic

Hey, I know that HU!!  

BTW: That box has a big air leak right where the wires enter the enclosure. Hopefully Steven sealed it up. And the cutout is a bit large. I read where Steven liked the Variovent in the 0.3 ft^3 enclosure that he built for the IS's.


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## Electrodynamic

Yes, production is starting this week (hopefully). I'm putting a serious discount on this initial production run because the top diaphragm won't be completely finished from a cosmetic standpoint, but the drivers will operate perfectly.


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## Megalomaniac

Electrodynamic said:


> Hey, I know that HU!!
> 
> BTW: That box has a big air leak right where the wires enter the enclosure. Hopefully Steven sealed it up. And the cutout is a bit large. I read where Steven liked the Variovent in the 0.3 ft^3 enclosure that he built for the IS's.



Yea I got to hear that too. It performed quite well. from .3 without the aperiodic vent compared to the .3 with the vent it sounded like the sub was in .5 that we got to test it in too.. Although I noticed the box you sent was stuffed pretty liberally .


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## bsvrs

That video is going to make me spend some money..


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## Megalomaniac

IMHO, it does sound better than the Mag, doesnt extend as low(says a lot) but for the size its going to be tough to beat in the shallow market. I would definitely use this sub if I was really caught up in saving space and weight.


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## DAT

Megalomaniac said:


> IMHO, *it does sound better than the Mag*, doesnt extend as low(says a lot) but for the size its going to be tough to beat in the shallow market. I would definitely use this sub if I was really caught up in saving space and weight.


So are you saying it sounds better than the Mag v4? Have you compare this to the JL 13TW5 ?


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## Megalomaniac

DAT said:


> So are you saying it sounds better than the Mag v4? Have you compare this to the JL 13TW5 ?


Yes. No. Comparing to an shallow RF and a eD SQ10. 2 different sizes i know.


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