Adding a subwoofer, in a very different way - Page 2 - Kia Niro Forum
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post #11 of 63 (permalink) Old 01-29-2019, 05:58 PM Thread Starter
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Originally Posted by cockedandglocked View Post
I'm also glad that people have started to realize that ported boxes are awful.

When I was in high school, they were all the rage, because they made your bass go boom. The only problem is the bass only went boom in a very narrow bandwidth (say 70-80hz), but at other frequencies the bass was almost non-existant because of 1) a complete lack of air suspension and 2) the bass coming out the port was invariably out-of-phase with (and thus cancelling out) the bass coming from the cone. The result was bass that was only audible in one or two very specific and very small low-frequency bandwidths, so it only sounded good when playing a song that had a bass track that happened to coincide with that bandwidth. In other words, they sounded really impressive as long as you only ever played one specific track on one specific cd [IMG class=inlineimg]/forum/images/KiaNiroForum/smilies/tango_face_grin.png[/IMG]

That also describes bandpass enclosures when people first started building them. One note wonders if you will. Both ported and bandpass enclosures have gotten a lot better, but for their small size and smooth roll off you just can’t beat a sealed box. I prefer a sealed box.
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post #12 of 63 (permalink) Old 01-31-2019, 09:08 PM
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Great thread! Good luck with your build, really looking forward to your report of how it all turns out. Having better bass is the one thing I wish the non-premium sound system I have in my Niro featured. Unfortunately I do have the power seats so I couldn't go this route... and like the OP, am absolutely unwilling to sacrifice storage space, which is already pretty small.

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post #13 of 63 (permalink) Old 02-01-2019, 09:09 AM
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I have simply concluded that no matter what you do, a car will never sound at all good, so why bother. If I wanted to listen to music then I would just go to my dedicated media room in the basement where I've got propper designed accoustics. I do play music in the car sometimes while driving but it's just for passing distraction. no where near the same level.

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post #14 of 63 (permalink) Old 02-01-2019, 12:31 PM
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And no sound system will ever be as good as live music, so why bother? Kidding of course, but I suspect a drive in a well equipped car would change anyone's mind. I'm pretty much in the do not bother camp in a car too, and in the home now too.

More news on the lo-fi front, I picked up a new iPhone model to try yesterday (as a trial) and so far the most compelling feature is the audio speakers. Loud enough, and really nice sound.

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post #15 of 63 (permalink) Old 02-01-2019, 02:55 PM Thread Starter
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In my younger days, I helped out a friend of mine who competed professionally in sound quality competitions. This was 20 years ago when my hearing was much better. The competition car was a Honda Civic sedan that, due to the massive stereo system and sound deadening, weighed a whopping 5,000 pounds!

That car had perfect imaging thanks to custom mounted speakers in the foot well/fire wall area that faced directly to the occupants. The front seats were also relocated 6” back to diminish the length differences between the left and right speakers to the occupants.

From 20hz to 20k hz there was only about 3db difference which is about as good as can be done. It had a pair of 1/3 octave mono equalizers to fine tune it all. The factory trunk was also 100% useable as the subwoofer enclosure was below the trunk floor where three 12” subs were mounted. 5 1/2” midbass drivers were installed in custom enclosures into the bottom seat cushion of the front 2 seats! The car was over the top and, at that time, cost $50k to complete.

Rarely have I heard home audio systems that rivaled this car. Play well recorded classical music, close your eyes, and you could point out exactly where each instrument was located on the stage when the piece was recorded.

I said all of that to say this. Anything is possible with enough money. With my diminished hearing and with the increase in quality of factory car audio systems, about all that is lacking to me in the base stereo are the subwoofer frequencies of around 60 hz on down. With my musical taste, there is a lot missed in the factory stereo. Hence this build.

My apologies on the long winded posts.
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post #16 of 63 (permalink) Old 02-01-2019, 03:59 PM
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Classical or other music with a high dynamic range is quite the test of a car audio system with a typical noise floor of 70 dB at highway speeds. When I was very young, I flirted a bit with figuring out ways to compress the dynamic range (dbx had one system - analog back then) so you could hear the quiet bits without getting blasted in the loud bits. Same thing radio stations do (or did) for their largely car driving audience. Commercials also compressed audio even more so it would sound louder and pop better than the radio station content. Vinyl records and audio tapes do the same thing, for practical physics reasons and noise reduction, with the playback device decompressing the audio into something similar to what the recording engineer intended.

From what I read, noise reduction in cars is one of the better ways to get better sound. Of course, it is not easy or cheap and requires a lot of trial and error. Best is to do that during car manufacture, and so luxury cars automatically will have better sounding audio. High end audio brands also do better with new cars as they can more efficiently map the car's response curves for a production run rather than one car at a time. Still expensive, and they don't always get it right. Lots of choices for speaker placement and equalization curves in a very complex environment, several magnitudes more complex than home environments.

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post #17 of 63 (permalink) Old 02-04-2019, 12:14 PM Thread Starter
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Got some progress, but not much.

Total times the front seat has been unbolted to date; 2

So after some rough measurements, it appeared as though the bottom of the box had a 10” X 20” measurement. So I cut this out and did a test fit. It was not quit a perfect fit and there was extra room that could be utilized if I were to step up 3/4” from the base. So that is exactly what I did.

I also saw that the cut out in the carpet for the air bag wires on the seat looked nasty, and was getting in the way. So a simple cut on the carpet now allows the carpet to sit where it should be.

My next step is to find my pneumatic brad nailer, measure and cut out all of the sides, and then start the slow process of assembly. I’m also concerned about clearance issues with the air bag connectors under the seat. They hang down quit a bit. If I can rotate and resecure them, I might be able to gain another 1” of depth for the box, or an extra inch in clearance for the subwoofer.

In the meantime, here are some pictures from today’s activities;
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post #18 of 63 (permalink) Old 02-11-2019, 10:11 PM Thread Starter
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The weather has not been cooperative the last several days so no progress has been made. I did decide on what amplifier will be used and when I’ve got more time I’ll elaborate more about it. What I will say is it is Korean made, puts out a true 650 watts at 2 ohms, and can be had brand new for less than $100.
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post #19 of 63 (permalink) Old 02-14-2019, 12:12 PM Thread Starter
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More progress

Total number the seat has been removed since the beginning of this project;


The 2 pieces that make up the bottom of the box were glued and screwed together a couple of days ago. The weather and my allergies have not allowed much work at all over the last week till today.

So with the bottom of the box complete, now I can measure and start working on building the box up. Got the measurement on one side of the box, so I just made 2 of these cuts without thinking that the passenger side of the box is different than the drivers side. DOH!!! Oh well. No biggie. Got the drivers side of the box glued into position.

The first time I looked under the driver seat I noticed this large bracket. In my LX, all this bracket is doing is holding the seat belt sensor and air bag wires out of the way. This bracket appears to be a mount of some kind for the power seat models. Since this is such a large bracket, I am VERY tempted to remove it. Removing the bracket would allow a taller box to be built, and it would also give more clearance for the subwoofer when the system is cranked up. Both subwoofers that I am looking at(the shallow mount Cadence 10” or a Massive Audio 8”) have just over 1” of peak to peak excursion. This amount of excursion requires adequate room above the box so the sub does not hit anything. Removing this bracket would allow at least an additional 1”-2” of room. The bracket is only held in place with 2 small welds. So removing it would not be too hard. The main question is this;

Is removing the bracket going to help that much?

The answer to that question eludes me at the moment. So, it is time that I sit down with pen, paper, and a calculator to see the air space differences with and without the bracket. Once I have this information, then I will be able to make an informed decision.

One other item that is slowing progress on this is a recent move to a new house. During the move, I misplaced several tools. A pneumatic brad nailer, all of my C clamps, a counter sink drill bit, metal straight edge, and all of my screws. Once I find all of this, progress will improve greatly.
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post #20 of 63 (permalink) Old 02-14-2019, 12:30 PM Thread Starter
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Alright, after putting pencil to paper and taking some more measurements, it looks like my answer is pretty obvious.

With making the box 6” deep total between the seat frame rails, it would leave me with 0.315 cubic feet of air space. This is exactly 10% smaller than the minimum recommend air space and target minimum of 0.35 cubic feet.

If I remove the bracket, it looks like it would free up an additional 2” of total height to 8”. This would give an air space of 0.438 cubic feet. Once you take into account the air space lost due to the structure of the subwoofer inside the box, it would still be ok.

So, the bracket has to go.
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