HELP - Efficient Enclosure for Mutant MT1207 12" Subwoofer

[GoldenWhale]

Hey all, I have a Mutant MT1207 800w 12" car subwoofer which is in very good condition but lacking an enclosure. I've looked around quite a bit and haven't managed to dig up any of the T/S parameters, just a few conflicting spec sheets regarding the MT1210, which seems to be my subwoofer's big brother.

What I need in my enclosure is efficient bass. From the research I've done, it seems like either a tapped horn or possibly a HOG scoop would be what I'm after, but all the plans I've found are for larger Sd drivers. A 6th or even 8th order bandpass could also be an option, but from what I've read these seem to rely more critically on the correct T/S specs. (maybe that's a false assumption?)

Space is not really a huge constraint, I have about a 1m x 1m x 600mm area, which happens to be in the corner of a small-ish room.

Any and all help would be really appreciated! Thanks!

 

[planet10]

You need the T/S.

Often car woofers have higisg Q which makes them somewhat difficult to put in a box.

dave

 

[GM]

DIY sub for a newbie | AVForums

I've found the thiele small details for the mutant 1207..........

PARAMETERS THIELE SYMBOL MUTANT
MT 1007 MT1207
Max Power (Watts) 400
RMS Power (Watts) 200
Impedance (Ohms) 4
Frequency Response (Hz) 32-2000
Magnet Size (oz) 50
Voice coil diameter (inches) 2
Sensitivity (dB) dB (1W/1M) 87.6
Resonant Frequency (Hz) fs 30.265
Mechanical Q Factor Qms 3.147
Electrical Q Factor Qes 1.041
Total Q Factor Qts 0.682
Equivalent Volume (Ltr) Vas 48.859
DC Resistance (ohms) Re 3.6
Linear Excursion (mm) X-Max 9
Effective Piston Area (mm2) Sd 51.071
Mechanical Mass (g) Mms 163.542
Mechanical Compliance (mm) Cms 131.92
Force Factor ™ Bl 11.037
Reference Efficiency (%) No 0.183
Diaphragm Mass (g) Mmd 150.27

GM

 

[chris661]

That's a pretty high Qts, which usually demands a big box. However, with 600L to play with, I'm sure something can be done.

What LF cutoff are you looking for?

Chris

 

[GM]

I've looked around quite a bit and haven't managed to dig up any of the T/S parameters, just a few conflicting spec sheets regarding the MT1210, which seems to be my subwoofer's big brother.

Greets!

These specs don't need two sheets since the T/S Vs raw/calculated measurements conflict plenty as is plus the published Qts is off from 0.682 to 0.782.

Comparing between the two sets of specs, 'raw' shifts Fs up to 34.97 Hz, lowers Qts = 0.742.

Averaging these out:

Fs = 32.53 Hz
Qts = 0.761
Vas = 48.97 L

Anyway, this is too weak a motor to efficiently drive BP4, etc., except over a very narrow BW, i.e. only has an upper mass corner [Fhm] = 2*Fs/Qts = ~85.6 Hz, which will go lower once wiring, Vc heating losses further weaken it due to raising Qts, rolling off what bass it has.

In short, combined with a [sure to be] stiff suspension [low Vas], best suited for small sealed mobile audio sub, EQ'd to suit.

Without measured specs, you can try the averaged specs to sim with, but you'll find that it doesn't take much error to ruin a BP alignment, whereas you can get a bit more output over a wider BW [more tolerant] with a 2x Vas tuned to Fs [or lower] vented alignment EQ'd to suit.

GM

 

[papasteack]

So, if we want to sim something, we need :

Driver : Mutant MT1207 800w 12"
Volume : 1m x 1m x 600mm
Efficiency : efficient bass
Target bandwith and filtering capabilities : ? / ?
Amp power available : ?

 

[GoldenWhale]

DIY sub for a newbie | AVForums

I've found the thiele small details for the mutant 1207..........

PARAMETERS THIELE SYMBOL MUTANT
MT 1007 MT1207
Max Power (Watts) 400
RMS Power (Watts) 200
Impedance (Ohms) 4
Frequency Response (Hz) 32-2000
Magnet Size (oz) 50
Voice coil diameter (inches) 2
Sensitivity (dB) dB (1W/1M) 87.6
Resonant Frequency (Hz) fs 30.265
Mechanical Q Factor Qms 3.147
Electrical Q Factor Qes 1.041
Total Q Factor Qts 0.682
Equivalent Volume (Ltr) Vas 48.859
DC Resistance (ohms) Re 3.6
Linear Excursion (mm) X-Max 9
Effective Piston Area (mm2) Sd 51.071
Mechanical Mass (g) Mms 163.542
Mechanical Compliance (mm) Cms 131.92
Force Factor ™ Bl 11.037
Reference Efficiency (%) No 0.183
Diaphragm Mass (g) Mmd 150.27



GM

Thank you very much! Yes, what people are saying about the Q factor is definitely correct, it's a very stiff feeling driver even for a car sub. Worth mentioning, however, that the driver has "800W" printed right in the center. So maybe the 400w max rating is Program? Not much difference for my rig anyway

I would say I'm aiming to hit down to around 35 Hz. Hoping I don't need to use all 600L of available space, but if that is what it'll take then so be it. Does that sound achievable to you all? Also, would the quoted frequency response of 32-2000 be f3 or f10?

To answer the amp question, I'm currently getting about 150w RMS by bridging a very old Bogen PA amp. On the lookout for something better...

So from what you're saying I feel like I should probably not try for a BP. Any advice on a tapped horn or scoop? Are these possibilities? Or would a simple vented box be the best option?

Either way thank you all very much for your help so far!!!

 

[GoldenWhale]

As an update:

Yesterday I built a 2x Vas (98L) ported enclosure (designed on SubBox Pro) which is tuned to about 32 Hz. Response seems pretty clean, hits down to around 35 without sweating, definitely not much below that though.

Subwoofer Box for Sundown Audio 12 inch subwoofer | Ported Box | Slot

This is certainly an improvement from my sealed box, a much deeper sound. Only wish it were slightly more sensitive. Does anyone have any thoughts on how a large waveguide would affect the sound? I still have about 400L of air space to play with, could easily turn this into a 5th order enclosure. Bear in mind that the cabinet is placed in the corner of the room.

I could also restart from scratch if people have better ideas. I've got access to a wood shop and a basically limitless supply of MDF, so it's just a matter of time.

Cheers!

 

[GM]

Hmm, been doing this stuff off n' on for many decades and never been exposed to a 5th order alignment.

Anyway, based on folded up in a corner to minimize size, HR predicts a ~1474 L, 28 Hz hyperbolic flare horn, 35 Hz = ~755 L, both with a ~108 dB/m avg. eff., though due to dubious driver specs, room construction variances, HR's limitations, guessing more like 98-101 dB/m with the driver's ~ 84.3 dB/m base eff. [averaged specs].

A true WG would be ~ 8x larger IIRC.

These are net of course, so construction will make them somewhat larger.

As you can see, it takes a huge horn to go low at high efficiency, especially with such a weak motor.

GM

 

[waxx]

i did a quick sim in winisd with the given specs (wich are incosistent) and a 100L sealed should give you a 35hz on 102dB with this driver (mono box). That is very loud in a small space like you discribe and will be louder than you probally ever use. Set a pair there and you got 3dB extra. As for a sealed exact specs are not that critical, this could be a safe guess. But don't expect hi end hifi sound with this, this driver is not for that. But it will be very loud and low.

 

[GoldenWhale]

Are you sure you entered it right? I have a 98L vented enclosure, so to test I stuffed a hoodie into the port and lost much of my low bass. It's definitely not 102 dB...

You're right though, it's a pretty muddy-sounding sub. Transients are, as predicted, horrendous ;-;

 

[chris661]

Might be time for a better driver..?

Chris

 

[waxx]

Are you sure you entered it right? I have a 98L vented enclosure, so to test I stuffed a hoodie into the port and lost much of my low bass. It's definitely not 102 dB...

You're right though, it's a pretty muddy-sounding sub. Transients are, as predicted, horrendous ;-;

I used the specs published here. But i can see that they are not consistent, and so probally not exact or right... ifyou want to be sure, you need to measure the driver.

 

[GoldenWhale]

As it stands, I'm pretty happy with what I've got. I don't have measuring equipment or really any budget to speak of, but the 2x Vas bass reflex is working all right. I appreciate the advice from everyone! Let you know when I start my next project!