# Experiment with mid/midbass in kickpanel enclosures



## jsun_g (Jun 12, 2008)

Out of curiousity, I made a kickpod out of fiberglass (probably 3 layers of FG, a little bondo on top for smoothing out while sanding) and also an enclosure out of 3/4" MDF which could be placed into the passenger kickpanel area of my car (2004 Acura TSX).
The kickpod's internal volume is approx 0.1 cubic feet, and it is sealed except for an approx. 2" diameter opening in the back where it vents into the carpet. The MDF enclosure is sealed and is about 0.3 cubic feet internal volume. Both enclosures were stuffed with polyester fiberfill.

Ran a sine sweep and took measurements with a Radio Shack meter on C weighting (I know, not the best measurement device, but this is a comparison test). The amp was an old Coustic at 65 WPC, one channel being driven. No EQ or xover was used.

I used 2 drivers, a CDT Classic 6.5" mid and a Vifa MG18SK09-04 mid, both rated at 4 ohms. As you can see, the big difference in response is not between the drivers, but in the enclosure setup itself. I can't begin to describe the coloration of the midbass in the kickpod setup.


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## mda185 (Dec 14, 2006)

Great post. The bass response seems to extend an octave lower in the enclosure which is to be expected. I have always thought that putting an enclosure behind a midbass was a better way to go if the installation permits it. I wonder what caused that huge peak around what looks like 150 Hz in the kick pod vs. the enclosure. That frequency range usually corresponds to a standing wave (resonance) in the car's interior and you should have seen it for both measurements. 

If you have any pics of the enclosure and how you mounted it, I am very interested.


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## jsun_g (Jun 12, 2008)

I am guessing the peak in the kickpod was caused by a combination of the enclosure being too small and also not dead enough (resonance). It was most pronounced in the 120-150Hz range. I have since thrown the kickpods away but let me see if I can dig up some pictures of the kickpods and the test box (the box was not thrown away  )

Moral of the story, don't put a driver that is handling midbass in tiny/flimsy enclosures 




mda185 said:


> Great post. The bass response seems to extend an octave lower in the enclosure which is to be expected. I have always thought that putting an enclosure behind a midbass was a better way to go if the installation permits it. I wonder what caused that huge peak around what looks like 150 Hz in the kick pod vs. the enclosure. That frequency range usually corresponds to a standing wave (resonance) in the car's interior and you should have seen it for both measurements.
> 
> If you have any pics of the enclosure and how you mounted it, I am very interested.


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## jsun_g (Jun 12, 2008)

Couple pics of one of the kickpods. The test was performed using the passenger's side kickpod but this one is very similar:



















I have to take a pic of the MDF enclosure and post it. It's just a rectangular box made of 3/4" MDF just small enough to fit on the floor, under the glove box. I tilted it upward slightly, similar to the upward angle of the kickpanel, but the enclosure-mounted mid was not on-axis from the perspective of the microphone at the driver's head. The speaker was mounted on the far right of the rectangular face panel (i.e. close to the far right of the car).


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## Mless5 (Aug 21, 2006)

mda185 said:


> That frequency range usually corresponds to a standing wave (resonance) in the car's interior and you should have seen it for both measurements.


That would explain my huge peak at 200hz, eh?


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## mda185 (Dec 14, 2006)

Mless5, 

Yes, 200 Hz would be a typical cabin resonance. The frequency it happens at depends on dimensions of your cabin. I guess with jsun_g, the resonance was the kick pod itself. 

I am in process of testing a bunch of 6.5" midbass drivers in a 2001 Pathfinder door. I will be on the lookout for resonances of both kinds. I will post results including SPL measurements when available. Right now, the weather is killing me. Either too hot or raining too hard. I need to clean out my garage and stop working on the driveway.


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