Designing a box for the Infinity Perfect 12.1

I took a look at Mark's work with it and realized the box specified was actually smaller than the Kappa. This works to my advantage as I hope to make this sub a bit more aesthetic. I plan to work out the math and do some more research, but I figure I would give people the chance to review my design and offer any pointer / advice.

Box Properties
--Description--
Name:
Type: Vented Box
Shape: Prism, square (optimum)
--Box Parameters--
Vb = 3.218 cu.ft
V(total) = 3.566 cu.ft
Fb = 20.18 Hz
QL = 6.52
F3 = 22.59 Hz
Fill = minimal
--Vents--
No. of Vents = 1
Vent shape = round
Vent ends = two flared
Dv = 4 in
Lv = 23.86 in

Courtesy of Dr. Mark

I will be building 2 of these, but the power requirements won't be super high for my immediate application since I am an apartment dweller atm. I figured one ep2500 would have plenty of room for these subs. obviously I still need to work out a low pass filter. Eventually adding a nice eq is also in the plans. But baby steps.

Thanks in advance. This will be so much fun.

lsiberian said:

I took a look at Mark's work with it and realized the box specified was actually smaller than the Kappa. This works to my advantage as I hope to make this sub a bit more aesthetic. I plan to work out the math and do some more research, but I figure I would give people the chance to review my design and offer any pointer / advice.

Box Properties
--Description--
Name:
Type: Vented Box
Shape: Prism, square (optimum)
--Box Parameters--
Vb = 3.218 cu.ft
V(total) = 3.566 cu.ft
Fb = 20.18 Hz
QL = 6.52
F3 = 22.59 Hz
Fill = minimal
--Vents--
No. of Vents = 1
Vent shape = round
Vent ends = two flared
Dv = 4 in
Lv = 23.86 in

Courtesy of Dr. Mark

I will be building 2 of these, but the power requirements won't be super high for my immediate application since I am an apartment dweller atm. I figured one ep2500 would have plenty of room for these subs. obviously I still need to work out a low pass filter. Eventually adding a nice eq is also in the plans. But baby steps.

Thanks in advance. This will be so much fun.

Click to expand...

Changed my mind lol. I will just build the MidVQ box. If i'm dissapointed with the response of these I can always sell em and setup up.

Are you still doing this project? I just found some used 12.1's for a pretty decent price, and was wondering how much of a performance trade off there was, and let you be the Guinea pig

lsiberian said:

I took a look at Mark's work with it and realized the box specified was actually smaller than the Kappa. This works to my advantage as I hope to make this sub a bit more aesthetic. I plan to work out the math and do some more research, but I figure I would give people the chance to review my design and offer any pointer / advice.

Box Properties
--Description--
Name:
Type: Vented Box
Shape: Prism, square (optimum)
--Box Parameters--
Vb = 3.218 cu.ft
V(total) = 3.566 cu.ft
Fb = 20.18 Hz
QL = 6.52
F3 = 22.59 Hz
Fill = minimal
--Vents--
No. of Vents = 1
Vent shape = round
Vent ends = two flared
Dv = 4 in
Lv = 23.86 in

Courtesy of Dr. Mark

I will be building 2 of these, but the power requirements won't be super high for my immediate application since I am an apartment dweller atm. I figured one ep2500 would have plenty of room for these subs. obviously I still need to work out a low pass filter. Eventually adding a nice eq is also in the plans. But baby steps.

Thanks in advance. This will be so much fun.

Click to expand...

The vent design is totally unacceptable. It will cause substantial port compression at and around tuning frequency with moderate to high power.

I recommend conforming to the avaserfi specified design that I originally outlined if you want to get the potential performance this driver is capable of producing.

-Chris

WmAx said:

The vent design is totally unacceptable. It will cause substantial port compression at and around tuning frequency with moderate to high power.

I recommend conforming to the avaserfi specified design that I originally outlined if you want to get the potential performance this driver is capable of producing.

-Chris

Click to expand...

That alignment was done for an apartment dweller who wanted a smaller enclosure and was not going to play it loud. At full power vent velocity would be 27 m/sec, which is not way out of bounds.

The low q insert enclosure can be built with this slot vent, that reduces vent velocity to 12 m/sec.

Name: Kappa Perfect 12 VQ low inst
Type: Standard one-way driver
Company: Infinity Systems Inc.
No. of Drivers = 1
Fs = 22.9 Hz
Qms = 10.29
Vas = 96.43 liters
Cms = 0.323 mm/N
Mms = 176.4 g
Rms = 2.398 kg/s
Xmax = 16.75 mm
Xmech = 25.13 mm
P-Dia = 250 mm
Sd = 491 sq.cm
P-Vd = 0.822 liters
Qes = 0.36
Re = 4.42 ohms
Le = 1.14 mH
Z = 4 ohms
BL = 11.92 Tm
Pe = 400 watts
Qts = 0.34
no = 0.141 %
1-W SPL = 83.65 dB
2.83-V SPL = 89 dB
-----------------------------------------
Box Properties
Name:
Type: Vented Box
Shape: Prism, square (optimum)
Vb = 3.024 cu.ft
Fb = 21.38 Hz
QL = 6.563
F3 = 21.58 Hz
Fill = minimal
No. of Vents = 1
Vent shape = rectangle
Vent ends = two flush
Hv = 3 in
Wv = 8.75 in
Lv = 48.1 in

WmAx said:

The vent design is totally unacceptable. It will cause substantial port compression at and around tuning frequency with moderate to high power.

I recommend conforming to the avaserfi specified design that I originally outlined if you want to get the potential performance this driver is capable of producing.

-Chris

Click to expand...

I've already decided this

I would rather have an enclosure that could take the midvq if the 12.1 doesn't fulfill expectations than have a worthless enclosure.

jwenthold99 said:

Are you still doing this project? I just found some used 12.1's for a pretty decent price, and was wondering how much of a performance trade off there was, and let you be the Guinea pig

Click to expand...

Right now I'm building my front sound stage. But i will be starting this project soon. The greatest issue for me is the cost of the DCX and EP2500 atm. I may have to find something cheap to hold me over. I've considered just grabbing a reckhorn for one of the subs and then when I get the funds setting them both up a with an ep2500 DCX combo

lsiberian said:

Right now I'm building my front sound stage. But i will be starting this project soon. The greatest issue for me is the cost of the DCX and EP2500 atm. I may have to find something cheap to hold me over. I've considered just grabbing a reckhorn for one of the subs and then when I get the funds setting them both up a with an ep2500 DCX combo

Click to expand...

I agree, the mid Q is he best ported alignment. If you have the space, that is the one to go for.

TLS Guy said:

I agree, the mid Q is he best ported alignment. If you have the space, that is the one to go for.

Click to expand...

Well I think I will end up building some matching shelves for the front one and placing one at the bottom of my rack in the rear. It's a very open so boundary effects aren't a huge concern.

Besides it's only 2X 2 X2 Not that large for a sub IMO

Modeled in the MidVQ box with no changes to the design and no high pass filter

at 300whighest safe wattage)


Very flat and nice extension to 20hz



Flat from 20 to 150hz. 110 to 111 db range. Very impressive. I will probably never have it that loud, but more than sufficient for many small to medium size rooms.



will need to be high passed at 20hz if you plan to push this driver. High passing should be paired with an EQ for best response, but in budget build the roll off is still good enough.



this is high passed at 20hz

still very flat IMO. This driver is a suitable and often cheaper alternative to the Infinity Kappa 12.1 midVQ in Andrew's build.

ok, i'm not understanding. at first its not good. now it is good ? what am i missing ?

just-some-guy said:

ok, i'm not understanding. at first its not good. now it is good ? what am i missing ?

Click to expand...

The modeling is in the MidVQ box.

That box is an amazing design and a good starter for a vented sub.

The first modeling was in a different type of box.

I posted the link for folks looking for a budget option to the midVQ

Your box was modeled in WinISD using this driver on the other thread. I'm sure a 12.1 midVQ would have similar response.

I just want to re-iterate to readers that modelling is theoretical. Usually, a driver will almost never perform like it models at moderate high to high power and at high excursion levels. This is because most drivers have motors and/or suspensions that are highly non-linear as the exceed just 1/3 the specified x-max. This causes loss of motor power/linearity (increase in distortion radically and failure to perform in the cabinet design accurately) and in addition, power compression usually is a factor (where the voice coil heats up, increasing DC resistance, resulting in loss of SPL and further change of expected response). The cabinet is also very important to consider. If the port has an even moderate air velocity, then the port will start limiting SPL at and around the port tuning frequency (this is not reflected in the modeled response curve output; but can be predicted by viewing the modeled air velocity of the port).

That being said, the Kappa Perfect 12.1 and 12VQ drivers are NOT by any means typical. They have a very linear response even at high power and high excursion(relatively speaking). This means that they can actually perform rather close to the modeled response.

If the design is to be used for home theater(movies), then the subsonic filter IS NOT optional. It MUST be used to protect the driver. A high amplitude signal at say 14 Hz could mean terminal damage to the driver in this cabinet that is tuned for around 20Hz. Under the tuning frequency, the driver rapidly unloads, as the port is no longer dampening the cone movement and the port (hole) begins to act like a simple air leak, thus no back air compression is present under tuning to limit driver movement as it would in a sealed cabinet. This issue of a subsonic filter is true with ANY high powered ported design with a port tuning above the lowest frequency found in sound F/X.

-Chris