Click here to learn about the new Mag

[Electrodynamic]

I posted this over on SSA, but I don't want this thread to be lost if we can't get the posts transferred over to this forum.

Some of you have seen pics or drawing of the new Mag's basket and read about its shallow 5.5" of mounting depth. You might have also heard about the super-small enclosure requirements.

As much as I love my current Mag 12's, and love beating the absolute piss out of them, I have also given a lot of though as to the design in general. The current Mag (the one's we are sold out of) are a decently efficient, are extremely versitile, and have the ability to soak up a LOT of power. That last sentence has a key word in it - soak. I can count on one hand how many times I have bottomed out my pair of Mag's with a 3200 watt amplifier, two big batteries, and an HO alt. And even then, I did it on purpose.

Now, I want everyone that has downloaded a copy of WinISD (can be downloaded for free at www.linearteam.org) to do the following: Load any 12" subwoofer and put it in 1 cubic foot sealed. Put the input signal at 1000 watts. Pull down the toolbar and take a look at excursion. You won't see the excursion plot go over 38/40mm of total travel. ...yes I used WinISD, but I used it because it is free and it works very well to show cone excursion per given application.

What people are failing to realize with most super-subs is that they are paying for something that will never use. Sure you might have 27-30mm of one-way travel, but how much of you are actually using that travel? Also, how much power does it take to get to 54-60mm of total travel in 1 cubic foot sealed? Do the homework in WinISD and you'll be very surprised.

That is why the new Mag's and BM's have been totally re-designed. In practical applications, you aren't getting your 12" subwoofer to move over 20mm one-way with 1000 watts in 1 cubic foot. So why pay for all that extra weight and inefficiency if you don't have to? Not to mention the fact that a "super-sub" is almost always 6.75" or more deep.

I have attached a screen shot of the excursion plots for the JL 12W7 and the current SI Mag 12 (the one's we are sold out of) in 1 ft^3 sealed with 1000 watts of input. The JL is the yellow plot, the Mag is the orange plot. Notice how much cone excursion is going on above 20 Hz.



The verticle plane is total excursion in milimeters and the horizontal plane is frequency.

Here are the graphs of ported cone excursion for the 12W7 in its recommended 1.75 ft^3 enclosure with 1000 watts and the new Mag in 1.5 ft^3 with 1000 watts.



Cone excursion goes over 40mm total when you get about 10 Hz below tuning (you should have a subsonic filter on your system with a ported enclosure to avoid sending your system something that low anyway).

Here is the graph of the same thing but with 800 watts:



Notice the similarities and differences? Note that excursion only becomes an issue below tuning. At/above tuning, both drivers are moving less than 32mm total with 1000 watts.

Now why spend all the extra money and have all that extra weight for something that you're never going to use (ie. 30+mm of one way excursion)? Not to mention that the Mag is still going to hold its T/S's more constant and have less distortion and lower inductance than a driver that can do 25+mm one-way anyway.

[Kickerlivinloud]

Very interesting information. Hopefully people will read and understand this and see why you don't need huge subs and huge price tags to get good performance!!

Good thread!!!!!!!!

[hobie1dog]

Originally Posted by Kickerlivinloud

Very interesting information. Hopefully people will read and understand this and see why you don't need huge subs and huge price tags to get good performance!!

Good thread!!!!!!!!

That's why he's "
The Man

[reson8]

Wow, that was a nice read, and taught me some things I did not know!

[sprtwin1]

I just read this and wow...these are things most people would never think about. Thanks for the information Nick.

[Electrodynamic]

Originally Posted by sprtwin1

I just read this and wow...these are things most people would never think about. Thanks for the information Nick.

No problem. I figured I'd address the things that most people are afraid to talk about. Excursion and Xmax are two of the taboo things on forums you just don't talk about because you'll get flamed. Well, there's proof (albeit in WinISD form but I can show you graphs from other software that shows the exact same thing) that you don't need 30mm of one-way linear travel. You simply won't use it. Not to mention if we're talking about 25mm of a regular topology compared to 20mm of XBL^2, the XBL^2 sub will still maintain its parameters longer over stroke and be more distortion-free up until the 70% BL drop off. Eh...I could go on and on about this stuff.

[sundownz]

Indeed - very rare to use over 20mm of throw for anything resembling SQ.

[pKelly]

Originally Posted by Electrodynamic

No problem. I figured I'd address the things that most people are afraid to talk about. Excursion and Xmax are two of the taboo things on forums you just don't talk about because you'll get flamed. Well, there's proof (albeit in WinISD form but I can show you graphs from other software that shows the exact same thing) that you don't need 30mm of one-way linear travel. You simply won't use it. Not to mention if we're talking about 25mm of a regular topology compared to 20mm of XBL^2, the XBL^2 sub will still maintain its parameters longer over stroke and be more distortion-free up until the 70% BL drop off. Eh...I could go on and on about this stuff.

Then do it

[BEAVER]

I have a dumb question about the new Mag...

I know it's going to be 5.5" deep, but what is the shallowest enclosure I can put it in? (min. recommended space for pole vent)

[Electrodynamic]

0.5" behind the pole vent is adequate, so an enclosure that is 5.5" deep internally will be fine if you're using material equal to or thicker than 0.5" (most of you will probably use 0.75" thick MDF) and you surface mount the Mag.