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Adding Under Seat Subwoofer - Thoughts?

Teachmehowto20

Passed Driver's Ed
Hi all,
Searched for people dicusinng this and didnt find necessarily any clear thread titles. Apologies if this has been discussed before. But I have the stock navigation system in my car. (not sure model, the one with bluetooth though, i have a 2014 DE).
I am a baby audiophile, and honestly i am not unimpressed with the stock system. I find the bass to be nice and punchy, even at low volumes, and this is something I have always loved. My home setup has a powered sub and I dont need booming bass you find at night clubs, but i prefer a nice balanced sound, and especially a little bit of rumble at low volumes. Although i do like the stock system, anything over Volume 15 is noticeably distorted and hard to listen to.
My goal would be to have a small under seat sub help the bass to remain tighter at louder volumes. I know that may be a large ask of an under seat sub, but im wondering what are the different wiring options + accessories needed to make that happen? Ive seen something called an LC2 or seen speak of LOC's, not sure what these are though.
So can you help me with the following:
If i wanted to retain the stock nav system, what would be different ways i could integrate a powered or non-powered under seat subwoofer?
I apologize i dont know much about these systems, coming from an older car and everything was relatively easy back then.
 

gijoewoz

Go Kart Champion
Firstly, there isn't a ton of room under our seat, so you are going to be limited to pretty unimpressive sub woofers. You'll have a lot more options if you're willing to build something into the hatch area.

You will still have the issue of distortion at and above volume 15, that isn't going anywhere unless you replace the head unit (unless a vagcom tweak can help, but I'm not sure). The distortion is not from the speakers being pushed too hard, it's from the terribly OEM head unit.

An LOC is a line out converter. It takes the audio signal from the speaker level wires and converts them to low lever RCA's so you can connect it to a standard amp. You may find a powered amp that accepts speaker level inputs, and if so you won't need an LOC.

I haven't tested the rear signal, but I know the front has a LPF set at around 80hz (you may be able to defeat this with vagcom), so tapping into that won't do any good, since the sub frequencies have already been filtered out. I would imagine the rear signal is full-range, but again, I haven't checked.

So, you either need a powered sub (or amplifier) that accepts speaker level inputs, or a LOC. You will need to either vagcom the stereo to get a full range signal (if it's even possible), or check that the rear outputs are full-range and use those. You will be very limited with what will fit under the seat, so you may end up needing to run a separate amp somewhere in the car, and build a small box for a shallow sub that will fit under the seat. Again, space is tight, so working it into the hatch will give you many more options.
 

sterkrazzy

Autocross Champion
Firstly, there isn't a ton of room under our seat, so you are going to be limited to pretty unimpressive sub woofers. You'll have a lot more options if you're willing to build something into the hatch area.

That's what I did. I didn't even have to build anything. I just used the existing foam and cut out a spot for it.

 

Tony48

Go Kart Champion
Read through this thread which is the most definitive source of info for adding a subwoofer while retaining the OEM headunit and all functionality. Basically it involves tapping into your speaker wires, running that signal to an LC2i line-output converter, and running the output of the LC2i to your subwoofer amp. There's not enough room for a subwoofer under the seat which is why most add it under the hatch false floor or in the side cubby of the hatch.

Below is a pic of forum member veedoubleme's setup (under hatch floor) and my setup (amp under hatch floor, sub in side box). You can check out my build thread for more info and pictures of my setup.


IMG_20170106_163347_zpszbod3yvh by Tony G, on Flickr
IMG_20170106_163304_zpsnaszpjfm by Tony G, on Flickr
IMG_20170106_163407_zps685cgkcp by Tony G, on Flickr
 

gijoewoz

Go Kart Champion
You don't need a LOC if the amp/powered sub has speaker level inputs. A lot of amps do, so it's worth considering during the shopping phase so you don't have to buy unnecessary equipment.
 

Tony48

Go Kart Champion
You don't need a LOC if the amp/powered sub has speaker level inputs. A lot of amps do, so it's worth considering during the shopping phase so you don't have to buy unnecessary equipment.

You don't technically NEED a LOC but you need it if you want to see (hear?) any real gain in sound quality. The point of using the LC2i LOC is that it corrects the factory bass roll off at higher volumes. Otherwise your subwoofer output will actually decrease when you turn the volume up (this is to prevent the fragile OEM speakers from blowing). This is all detailed in the thread I linked to, with a very in depth write-up in post #51.

Also, shout out to OP, a fellow Maryland-er :w00t:
 

gijoewoz

Go Kart Champion
You don't technically NEED a LOC but you need it if you want to see (hear?) any real gain in sound quality. The point of using the LC2i LOC is that it corrects the factory bass roll off at higher volumes. Otherwise your subwoofer output will actually decrease when you turn the volume up (this is to prevent the fragile OEM speakers from blowing). This is all detailed in the thread I linked to, with a very in depth write-up in post #51.

Also, shout out to OP, a fellow Maryland-er :w00t:

You're much better off using vagcom (again, if possible) to get a flat fullrange signal, than you are to synthetically restore the bass. Audio Control is way down on the list of good DSPs, they're fine, but they are far from top of the line. Turning off the speed dependent volume on the head unit, and using vagcom would be a much better solution than to use the LC2i. You'd have less equipment to wire (and worry about), and the amp would see a real audio signal, instead of "restored" bass.

OP will need to decide what the best solution is, but I'd highly recommend avoiding the LC2i if possible.
 

Tony48

Go Kart Champion
You're much better off using vagcom (again, if possible) to get a flat fullrange signal, than you are to synthetically restore the bass. Audio Control is way down on the list of good DSPs, they're fine, but they are far from top of the line. Turning off the speed dependent volume on the head unit, and using vagcom would be a much better solution than to use the LC2i. You'd have less equipment to wire (and worry about), and the amp would see a real audio signal, instead of "restored" bass.

OP will need to decide what the best solution is, but I'd highly recommend avoiding the LC2i if possible.

The only way I know of to get a full-range signal from the OEM HU is to vagcom the head unit to the dynaudio option which outputs pre-amp signals. I agree with you that this is the best thing to do (and what I did in my car). The problem with that is you then have to amp all of your speakers which gets expensive and labor intensive really quick. Doesn't seem like OP wants to get into all that. I personally think the best bang for your buck is to tap into the rear speaker wires to grab a speaker-level signal and use the LC2i to a mono amp. Most people will be happy with this setup.

That being said, I personally went the more difficult/expensive route of vagcom'ing the HU to output pre-amp signals and amping all 4 speakers and a subwoofer from there. Was the added difficulty, install time, and expense worth it? I'm sure that depends on every person's opinion. It really comes down to how much work and/or money you're willing to put into the project and what your goals/expectations are.
 
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gijoewoz

Go Kart Champion
The only way I know of to get a full-range signal from the OEM HU is to vagcom the head unit to the dynaudio option which outputs pre-amp signals. I agree with you that this is the best thing to do (and what I did in my car). The problem with that is you then have to amp all of your speakers which gets expensive and labor intensive really quick. Doesn't seem like OP wants to get into all that. I personally think the best bang for your buck is to tap into the rear speaker wires to grab a speaker-level signal and use the LC2i to a mono amp. Most people will be happy with this setup.

That being said, I personally went the more difficult/expensive route of vagcom'ing the HU to output pre-amp signals and amping all 4 speakers and a subwoofer from there. Was the added difficulty, install time, and expense worth it? I'm sure that depends on every person's opinion. It really comes down to how much work and/or money you're willing to put into the project and what your goals/expectations are.

Doesn't the vagcom simply make them low level (I know a lot more about mobile audio than VWs)? It should turn the signal to low level (read RCA), so all you need to do is attach RCA ends and plug into an amp.
 

Tony48

Go Kart Champion
Doesn't the vagcom simply make them low level (I know a lot more about mobile audio than VWs)? It should turn the signal to low level (read RCA), so all you need to do is attach RCA ends and plug into an amp.

That is correct. But in VAGCOM you only have the option to make all 4 channels low-level, or all 4 channels speaker level. So, if you want to use a low-level signal for a subwoofer installation, you are stuck with low-level signals for all of your door speakers as well. Which means you have to provide an additional amp if you want to be able to use your door speakers.
 

gijoewoz

Go Kart Champion
That is correct. But in VAGCOM you only have the option to make all 4 channels low-level, or all 4 channels speaker level. So, if you want to use a low-level signal for a subwoofer installation, you are stuck with low-level signals for all of your door speakers as well. Which means you have to provide an additional amp if you want to be able to use your door speakers.

Understood, thanks for clarifying. I didn't really know what vagcom can/can't do.
 

Teachmehowto20

Passed Driver's Ed
Very much appreciate the useful information everyone.
I guess my fear is that once replacing the headunit, the stock speakers will lose a lot of that low volume, efficient bass output.
My last car was a 99 inifiniti and it came with a Bose system. The stock headunits were also considered trash by many, but again, i found that at low volumes, the completely oem system provided this glorious bass rich (without being overdone) sound. Once I moved to an aftermarket headunit, the same stock speakers had piddly bass output.

I am just worried that the same would happen here. If the easiest thing though is to switch to an aftermarket HU, and I would retain the low end tightness at low volumes, I would be very happy.

Because again, my goal isnt to blow anyone (myself included) away with loud sound. I DJ so im already doing most of my damage at gigs. I just want less distortion at volume 16-18 (realistically i dont see myself every going above 18 anyways)
 

gijoewoz

Go Kart Champion
Very much appreciate the useful information everyone.
I guess my fear is that once replacing the headunit, the stock speakers will lose a lot of that low volume, efficient bass output.
My last car was a 99 inifiniti and it came with a Bose system. The stock headunits were also considered trash by many, but again, i found that at low volumes, the completely oem system provided this glorious bass rich (without being overdone) sound. Once I moved to an aftermarket headunit, the same stock speakers had piddly bass output.

I am just worried that the same would happen here. If the easiest thing though is to switch to an aftermarket HU, and I would retain the low end tightness at low volumes, I would be very happy.

Because again, my goal isnt to blow anyone (myself included) away with loud sound. I DJ so im already doing most of my damage at gigs. I just want less distortion at volume 16-18 (realistically i dont see myself every going above 18 anyways)

Good bass at low volume is possible in 2 ways. One, OEM speakers usually have very light cones that move very easily with just a little bit of power. Most aftermarket speakers use heavier materials that need more power to produce the same SPL. Two, look into "equal loudness contours." Our ability to hear low frequencies (and highs) is reduced at low volume levels. Bass needs to be proportionally louder at low volumes to sound balanced. OEM head unit have a lot of processing built in that attempt to optimize the sound for the way most people listen. Most aftermarket head units have a feature called "loudness" that boost lows (and some highs) at low volumes so that at low to moderate volume levels the bass is still noticeable, but as you turn the volume up, the boost is defeated so that at higher levels the bass isn't overwhelming. Because of the way we perceive sound (equal loudness) you cannot have good bass at low volume that isn't overwhelming at high volume unless you have processing that well adjust the frequency response depending on the volume. Again, most aftermarket head units have a feature that will do this.

And again, the OEM source is the cause of the distortion, speakers won't change that. You can add an amp so that you can reach the volume levels you want before turning the head unit to 15, where the distortion starts, but the OEM head units are far from hi-fi.
 

zef

Drag Racing Champion

speeding_ant

Go Kart Newbie
I'm loving my under seat subwoofer. Used an LC2i, which did require a bit of tweaking, but overall it sounds great. I used a Pioneer TSWX120A and the cabling was relatively easy. There's a proper grounding point in the passenger footwell, and a little 'cow udder' for the power in the footwell also. I used the LC2i remote trigger for the subwoofer remote circuit. I didn't need to pull apart anything except for a little passenger side trim and of course removing the head unit.

I found the best sounding settings was to leave eq relatively flat in the head unit, shift the balance one back towards the rear seats, and increase the LC2i bass recovery until it sounds good. The Pioneer sub has a remote which I velcroed in the little cubby on the drivers side, but since tuning it properly I haven't needed to use it.
 
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