# Subwoofer Cancellation: in cabin vs in trunk



## RocketBoots (Apr 16, 2011)

After doing some reading on subwoofer positions, wave reflections, cancellations, etc for a vehicle with a trunk, I realize first off that either sealing the trunk in an IB manner (to avoid cancellations/reflections alltogether) or corner loading the sub to minimize cancellations and move the sub as far towards the end of the car as possible, seem to be the best options for a trunk mounted sub. 

However, if the sub were to be placed inside the cabin, either in the front or rear passenger footwell, sidewall, whatever, would cancellations from reflections be eliminated (minimized), much like an IB setup? I would guess so, but wanted to check if I'm missing something... Also, the cone would be physically closer to the listener; what effect might that have?


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## SPAZ (Jan 7, 2009)

I'm no expert on this but what I can tell you is that when I placed my idq12 on the passenger floor I had more SPL and the bass seemed more "clean" as opposed to having it in the trunk. If I had more space I would make the sub on the passenger side a permanent fixture.


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## gijoe (Mar 25, 2008)

Subwoofer frequencies generally don't reflect. What you need to worry about is front-wave, back-wave cancellation, which is a completely different thing altogether. Many people mount subwoofers inside of the cabin without any issues. You won't have any issues as long as you don't mount it free-air (IB) inside of the cabin.


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## TOOSTUBBORN2FAIL (Jan 31, 2011)

It's entirely car dependent.

In my car, I lose spl with it under the glove box vs in the corner of the trunk. But, the under glove box sub doesn't excite as many resonant panels, and has far, far smoother response then at any position in the trunk.


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## RocketBoots (Apr 16, 2011)

TOOSTUBBORN2FAIL said:


> It's entirely car dependent.
> 
> In my car, I lose spl with it under the glove box vs in the corner of the trunk. But, the under glove box sub doesn't excite as many resonant panels, and has far, far smoother response then at any position in the trunk.


What was your car, if you don't mind me asking?


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## TOOSTUBBORN2FAIL (Jan 31, 2011)

2014 kia optima


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## RocketBoots (Apr 16, 2011)

TOOSTUBBORN2FAIL said:


> 2014 kia optima


Did you leave it up front? Sacrifice some SPL for SQ? 

I also realized why sometimes when I open my windows I would get a more boomy, louder bass response. No cancellation, and waves are summing to give peaky boost.


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## TOOSTUBBORN2FAIL (Jan 31, 2011)

Yep, it's my wife's car, and she already ok'd it, so it's going up front permanently. It's just not at all comparable in the trunk compared to up front in this car.


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## rpr13 (Jul 19, 2014)

Interesting thread, and unfortunately I will be of no help to anyone, but I have an interesting situation that's relevant to this question.

I have a JL StealthBox under the rear passenger seat in my Ram 1500. The whole system has been upgraded other than the HU and factory amp (BitOne DSP, Hertz Hi-Energy Speakers, Alpine PDX amps, full active install).

My bass is underwhelming, which is not surprising from a StealthBox, but here's the thing I can't figure out:

If I put the HU is "Surround" mode, the bass (and the whole system) really comes to life. I'm not talking the typical BS that most surround modes try to emulate, the SPL and SQ are much improved. My center channel isn't even connected.

I can't figure out exactly what the surround mode does, but with the bass being so much tighter and prominent, I feel like I must have an issue with my setup.

Alpine told me they typically only play with phase and crossover settings on their HU's that have surround modes. But I have triple checked phase and tried switching phase on the sub (and all channels for that matter) and I cannot reproduce the enhancements that the surround mode gives to my system. Again, I'm not talking some cheesy surround mode manipulation, I feel like I must have an issue that the surround mode is somehow reversing in my setup.

The BitOne has the factory settings de-EQ'd, so I'm thinking maybe the system was not de-EQ'd properly for some reason, or there is a cancellation that the surround mode is eliminating.

Any thoughts?


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## TheCountsLincolnator (Mar 14, 2015)

Its crazy to see how many factors there are to sound quality.


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## Elgrosso (Jun 15, 2013)

rpr13 said:


> Interesting thread, and unfortunately I will be of no help to anyone, but I have an interesting situation that's relevant to this question.
> 
> I have a JL StealthBox under the rear passenger seat in my Ram 1500. The whole system has been upgraded other than the HU and factory amp (BitOne DSP, Hertz Hi-Energy Speakers, Alpine PDX amps, full active install).
> 
> ...


Interesting yes, do you think it increases the midbass in the same time? Or change sub delay?


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## DynaudioNut (Jan 1, 2010)

I've had my sub firing through a ski shoot vs trunk mounted. Trunk mounted had more boom but the shi shoot definitely sounded better. Much more clarity and pop in the mid range. Crossed sub over @ 100


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## Jepalan (Jun 27, 2013)

RocketBoots said:


> I realize first off that either sealing the trunk in an IB manner (to avoid cancellations/reflections alltogether) or corner loading the sub to minimize cancellations and move the sub as far towards the end of the car as possible, seem to be the best options for a trunk mounted sub.
> 
> However, if the sub were to be placed inside the cabin, either in the front or rear passenger footwell, sidewall, whatever, would cancellations from reflections be eliminated (minimized), much like an IB setup? I would guess so, but wanted to check if I'm missing something... Also, the cone would be physically closer to the listener; what effect might that have?


There is no generalized answer to your questions. You can have excellent bass with a trunk mount box, a rear deck IB arrangement or a cabin mount box - it all depends on car, cabin gain, tuning and final position of the driver.

I found moving my 10" sealed box around in the cargo area of my CRV made a HUGE difference. in some cases, just sliding it 6" made a huge difference in bass at the driver's seat.

The car basically acts like a resonant chamber at bass freqs. The problem you are dealing with is standing waves. You may wind up with a null or peak at any given listening position depending on a number of factors. And you will not be able to EQ these out (for the most part).

IMO - The best thing to do is to try different positions in your car and see what sounds best


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