Question about frequency response from different subs


New member
Username: Machman

Post Number: 7
Registered: Oct-04
I'm comparing the Infinity Kappa 12.1 and the Infinity Kappa Perfect 12 VQ and attempting to figure out which will produce stronger bass with my amp.

From the Infinity Website I find the following (using sealed 1 cu foot boxes):

Kappa 12.1: relatively flat frequency response (+/- 6 dB) of about 93 dB between 20 and 70 Hz. After that it drops off and is only at 70 dB when it hits 200 Hz.

Kappa Perfect 12 VQ: relatively flat frequency response of about 92 dB between 20 and 150 Hz where it rolls off slightly. At 200 Hz it's still at 88 dB.

My amp has a variable low pass filter of 50-200 Hz. Given that I like all types of music, wouldn't I be better off to go with the Kappa Perfect 12 VQs? My thinking is that they will give better response and higher output at higher frequencies with the same power input.

Having said that, it's going to cost me about $75 - $100 more for them and I'd like to know how audible the difference would be.


Silver Member
Username: Decde


Post Number: 178
Registered: Sep-04
There is some difference between the kappa and the kappa perfect. I'm not saying there is a HUGE difference, but you are better of with the perfects. I've heard bot of them, and i find the kappa is missing a bit of ''torque''... The perfects have amazing sq, and spl is pretty good also.

New member
Username: Machman

Post Number: 8
Registered: Oct-04
...I should have typed more carefully. They are both "Kappa Perfects", just that one is the 12.1 and the other is the 12 VQ.

The 12 VQ has the variable Q option which allows you to change motor force to reach ideal levels. The 12.1 doesn't.

Also, the listed frequency response are as follows:

12.1: 18-150 Hz +/- 3dB

12 VQ: 25-400 Hz +/- 3dB

...and don't forget my amp's low pass filter is variable between 50-200 Hz.

Is that significant? If so, in what ways. SQ? SPL? Overall listening experience for someone with a wide range in music?

Silver Member
Username: Insearchofbass

Post Number: 986
Registered: Jun-04
the question is easy from and spl standpoint because of the adjustable q id expect more in this area with them as far as an sq should be decent as well again this could be adjustable with the variable buy the 12vq

New member
Username: Machman

Post Number: 9
Registered: Oct-04
Is there a way to take advantage of the 12 SQ's frequency response from 200-400 Hz even though my amp's low pass only goes up to 200?

Silver Member
Username: Insearchofbass

Post Number: 988
Registered: Jun-04
you arent going to want to set your crossover higher than that anyway because vocals will come into play with your subwoofer most people set their crossover no higher than 80 hz

New member
Username: Machman

Post Number: 10
Registered: Oct-04
So if they both play at roughly the same levels up to say 100 Hz then the only benefit to the VQ is it's adjustable Q? Is that a significant advantage given that it'll cost about $60 more?

Gold Member
Username: Glasswolf

NorthWest, Michigan USA

Post Number: 5204
Registered: Dec-03
these are SUBS yyou're talking about here.
The amp's LPF will be set somewhere between 50-80Hz.
Probably closer to 50Hz, especially for a sealed box.
A sealed box in a car, will play flat to about 9Hz in actuality since cabin gain will compensate for the natural rolloff of the speaker, and no infrasonic filter is required.

Now, above the LPF's cutoff, the sub should roll off to your midbass or midrange drivers, which will have a HPF set to around 100Hz with a Q of 12dB.
That in short means the mids will roll down to where the subs roll off and everything will blend smoothly.

If you cross over the subs anywhere above 80Hz, they're going to sound like absolute crap.

home theater subs are set at 120Hz. car audio sybs are set much lower.
totally different systems here.

Gold Member
Username: Jonathan_f


Post Number: 2502
Registered: May-04
The variable Q is made so that you can use the subwoofer in different box types, such as have a sealed box for daily piddling around, and an SPL box laying around for SPL. IMO, the Perfect really isn't well suited for SPL (not very serious SPL, anyway). The Q is made to optimize the sub to the box you intend to use, and if you change the Q in the wrong box for it, response will not be optimal (too boomy or too tight, depending on which box you're using and the Q). You're cheaper off to get the 12.1, performance is about the same minus the variable Q, and most people don't have a lot of boxes lying around nor do they intend to. It's more optimal to have a sub that rolls off above 100hz anyway. For example, Dynaudio's drivers are designed with their intended frequency response in mind, and above and below their required range, they roll off, thus simplifying crossover design and improving sound quality of the drivers without having to use as complicated of a crossover as a crutch.
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