# Underseat sub placement



## bilboaudio (Jan 7, 2020)

I have a medium size hatchback, with an 8 inch powered sub under my seat. I have been contemplating moving it to the boot/trunk on the back of the rear passenger seats facing the tailgate or maybe mounting it under the dashboard on the passenger side pointing into the passenger footwell.

I know its unique to cabin but does anyone have any experience what effect this might have on the perception of the subs bass output if any based on past experience of doing similar?


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## Salle2061 (Jan 12, 2020)

in my opinion, under-the-seat sub placement is more about the vibrations it produces than the sound it makes. Passenger footwell facing down may be even worse as the sound would largely be absorbed by the carpet. 

Your first option is likely the best but put it in the trunk and face it towards the back of the car. The reason you see subs oriented in this way, with most builds, is because of the characteristic of low frequency sounds. The lower the frequency the longer it takes it to form the full sound wave, so facing it backwards will reflect the sound of the back of the car, usually not padded or mostly glass in your case, and than get it to your ear. Hatchbacks are actually the best for these kinds setups as they have a lot of open air between the trunk and driver. (well maybe better are minivans but there is a alot of other negatives there 

I'm sure you heard people drive by while listening to bass track pounding in their car. Than you think, if I can hear it this loud out side imagine how loud it is in the car? Well it is not, for the reason i stated above. They just FEEL more bass not necessarily hear more.

You may be fully aware of this, I was just trying to explain the reason for my recommendation on positioning. This is all in theory and end result will vary based on the components used, off course.

If you get a tactile transducer and install it under your seat you will likely feel the same bass in a much smaller package. Now that I think of it, not sure why I haven't done this already. I installed it on my computer chair and it is great. Humans receive low sound frequencies by sound and by vibrations so when we feel the bass we also, in our heads, hear the bass. A little of topic  Good Luck


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## syc0path (Jan 23, 2013)

With the sub under the front seat, some of the bass goes toward the front of the car and some goes to the back. These waves then reflect and come back towards each other. Whether they are in phase or not depends on freq, size of the vehicle, shape of the reflection surface, etc. Often they will not be in phase and your bass will not be as loud or tight as it should be. 

Putting the sub against the rear seat facing toward the back of the car means that most of the bass reflects off the hatch and goes forward. This minimizes phase issues and should improve bass response.


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## dgage (Oct 1, 2013)

Salle2061 - I liked everything about your post except the carpet absorbing bass waves. The bass waves will go through carpet like it isn’t there so I don’t expect any attenuation. I’m attaching a list of frequency absorption based on insulation material and thickness. Realize you have to get pretty thick before you get much absorption below 500Hz, which means there isn’t much you can do in a car for audio waves below 2,000hz.



https://www.bobgolds.com/AbsorptionCoefficients.htm


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## Salle2061 (Jan 12, 2020)

dgage said:


> The bass waves will go through carpet like it isn’t there so I don’t expect any attenuation.
> 
> 
> https://www.bobgolds.com/AbsorptionCoefficients.htm


An interesting read, thx. 

To correct myself, carpet will not “reflect” a lot of sound 

OP, syc0paths point is also very valid and is probably the number one reason not to put the sub under the seat.


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## diy.phil (May 23, 2011)

Normal answer is... the closer a speaker is to us, the louder it will sound (physics) or feel with the same wattage. May be less noticeable for bass but maybe just try it with a dB meter/equipment (or phone app). With the subs under the seats, put the dB equipment/phone in the trunk area and test/read it there. That'll be about the same distance as putting the sub in the trunk and listening from the front. If there's nothing wrong under the seats... I would really keep it there.


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## bilboaudio (Jan 7, 2020)

Thanks for all the insights!

One thing I have noticed is that when I have passengers in the rear of the car, this seems to make it more bassy, this is one of the reasons I had been thinking about moving it as well as the rear foot space.

The nice thing about it under my seat is that I do feel it vibrating my seat as it is jammed in between it and the floor, but I had also been wondering if my seat might be blocking some of the sound.


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## imickey503 (Dec 16, 2015)

All this crap about you can't hear the bass and where it is coming from? Yea.. Maybe in a home.. Not so in a car. DSP, Phase it all you want. I can TELL its back there due to Vibration of the cabin. 

The Car Audio *** magazine that IMO knew DICK about Car audio, were always saying MOVE the SUBWOOFER FORWARD.. Well. They were only HALF RIGHT. Hence why those sound exciters make so much MORE of a DIfference then subs being mounted in the front. 

As a cheap experiment, get ANY crappy 6x9 speaker with a LARGE magnet. Just mount it under the rear seat frame rails firing into you ass. Put the other one out of phase on your back. Cross it over at 50hz at a strong 24Db or higher octave and muffle the the back of it with towels, water you got. Try it out. Everyone has a pair of Crap 6x9s just laying around. It will feel like the subwoofer is up in front in the dash. 

Madisound has some Aura Bass shakers for sale for $25 bucks right now they used in a demo on their site in the deals section. 

If you can swing it? Mount it on under the seat back inside the frame rails of the seat on most OEM seats. Get some **** cheap amp. that does 50 clean watts and has a bass knob. Use them in stereo on the other seat if possible. It will "Sound"...--Like the bass is in front. Placement is critical. You don't want it to Vibrate anything so you can "HEAR IT". But just so that you can feel the vibration. Anything audible to the Ear is going to ruin the effect. 

I crossed mine Higher when I had it in my Volvo a while back. I also made some Makeshift one to test on a home theater setup a while back. If you can give it some delay from the main speakers, that is the best way to do it with a DSP. You want it almost so that it Makes the initial first part of the sine wave, and then it dies off. Basically. 
The nest way to describe this is a Super Damped woofer High Q woofer. The Ringing kills the effect. If you time it so that by the time the sound reaches your ears, the Tactile Transducer dies off leaving only the audible portion of the wave to do the work, it will sound like magic. 

Also, if you KNOW how to do it on High frequencies up to about 500 Hz, you can do the back part of the sound wave? Its hard to explain, but if you time it right, it sounds like the Old Q sound stuff where it can sound like the Action is happening around you. More so then just speakers alone. 


That's why its so satisfying to hear live music done in front of you. 

The effect is like a warm Masonry Fireplace and HVAC. They on paper make heat. One is just more enjoyable. 

Only thing to note is? If you are going to use an amp with these Bass shakers? The DRYER NASTY the Audible sound is. I mean has a VERY high Slew rate I think they call it works best. So those Digital sound chips amps just work a treat. Are cheap and you can fit them anywhere. 

Keep the Sub under the seat if you ask me. Put one under HER seat as well. GREAT FOR DATES MAN. Making out in your car gets you a line.


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