[lil_weg]

To get started, car audio may look confusing with all the numbers flying around to the uninitiated, but its really quite basic once you get your head into it. I admit I am an engineer so this kind of stuff just clicks with me but if you need help on your own car I'm just a PM away!

So the I30 has an okay stock audio system, but its not going to win any awards so I quickly got to work. In previous cars it was simply replace the headunit, which gives you RCA low level outputs to fronts, rears and a subwoofer, which made installs a breeze! Since the I30 has such a beautiful (limiting in audio adjustability still) headunit, there are a few things to consider.

It is possible to simply put speaker level inputs into amplifiers these days but I cannot stress enough how this is not the best way to feed a signal to your amplifiers. The high level speaker inputs are noisy and any noise from power wires, the alternator and other electrical sources will be 10x worse once amplified.

The better way and industry standard is either an audio processor (see Audison Bit Ten) or a line level converter, which takes high level speaker inputs and gives you a clean low level RCA output to feed your amps. I'm not talking about the cheap line out converters either, Audio Control make excellent products for this job, with level adjustability and safety features to help you prevent distortion and restores bass to the signal as many factory radios remove bass at higher volumes to save their rubbish stock speakers. Depending on the model you get, there are different perks:
LC2i - Gives you accubass bass restoration adjustability, bass output, main output (amplify speakers)

LC6i - Allows 6 channels in, has channel summing (ie if one speaker has full range audio, the LC6i can feed all outputs this signal) and allows level adjustability

LC7i - basically the LC6i with accubass bass restoration

For my task I bought the basic LC2i on ebay for $80 (RRP $150-200) and it worked wonderfully. Tapping into the front speaker channels (I found these to be a good full range signal (as in 20Hz to 200kHz) but an RTA would confirm this which I may end up getting later on as i perfect the system)

The front speakers are a pain in the ass due to the door loom, unlike other cars I've worked on, this car isnt a series of wires running through a boot to the door, its literally a boot running to a plug, so the door can be swapped easily which made things difficult. I ran a wire through the boot and into a grommet near the door, hiding the wires as best I could and then ran them to the boot. The wires were tapped into the factory speaker wiring to give a left and right signal from the fronts to the LC2i.

There is a guide already on running power wires for amplifiers so I won't go into detail, but I ran two sets of 8 gauge power cables I had left over from a previous setup to the boot ( a single 4 gauge would’ve been cleaner). I then ran a set of 8 gauge grounds from one of the rear seat brackets and sanded the contact point to ensure a good ground.

 
I made this neat amp rack to sit on the rear floor, under the boot floor level which worked really well! See I have mounted the subwoofer amplifier on the left, LC2i in the middle, and a 4 channel JL audio XD400/4 to amplify all the speakers later. The great thing about the JL amp is it allows a 2 channel input (say from the main out of the LC2i) and then doubles this to a 4 channel output, meaning I can have front and rears speakers off the main output of the LC2i with ease.

I then built an enclosure, suited to the volume requirements of the subwoofer within 50ml of the required volume in litres. I chose a JL audio 8W3v3-4 (250w RMS 4 Ohm) subwoofer for this, as I've used a 10W3V3-4 and 12W3V3-4 in other cars and they're a quality woofer. The 8" required 8.5 Litres of volume and the box was designed to fit the angle of the rear seat snug, and allow for restraint by a strap on the rear D tying point of the floor. Added in some battery connectors from my drone racing hobby to allow for easy sub removal and the job was done.


I'm not 100% finished, the wirings a mess but its a proof of concept (and I was too excited to get it done after work to be neat lol)



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[Crustycottage]

Looking good, 
Its so frustrating car manufacturers just skimp on the RCA line level outputs from the head units. really would it be that difficult ??? 

[lil_weg]

T-line enclosure coming... Not going to have much of a boot lol


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[Cookie Thumper]

Yep, that'll eat up a heap of boot space !

[lil_weg]

All I can say is you'll never hear a lower hitting 8"

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[Cookie Thumper]

Is there any special requirement/parameters for the sub that goes into a transmission line box or will any old sub work ?

[lil_weg]

Each sub has a different reasonant frequeny and cone size which determine the dimensions, but most any sub can be used in a design

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[Cookie Thumper]

Each sub has a different reasonant frequeny and cone size which determine the dimensions, but most any sub can be used in a design

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cool, it is an interesting design and as I'll be taking the new gear I purchased my my i30 with me th Thailand I might have a play with a t-line rather going sealed.... is there some sort of calculator to work out box dimensions ?

[lil_weg]

It goes like this,

Sound travels at 343m / sec

to calculate length of Freq Devide 343 / (freq)  say 30hz

343/ 30 = 11.43m long Full wave length But we need to divide this by 4 - for 1/4 wave which equals 2.8m long

Pretty long huh, to have a true T-line, you need to keep the port/tunnel/line - a Line, that equals Cone area, or pretty close to it. If you have a 10" The average  SD/Cone area is about 0.033sq meters (to find SD in inches, you measure the cone, by useing a tape measure, and measure from middle of surround, to middle of surround on opposite side)

That is your Port AREA.

So, a Tline for a 10" with a Fs of 30hz, and a cone area of About 0.33 sq meters, will be about 2.8m long

This is why I chose an 8, my line was 2.4m long,and fit neatly in  box 800Lx340Dx250H

I would say it hits every note down to about 35hz at the same volume, and doubles the volume compared to a sealed enclosure, so worth it

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[Cookie Thumper]

niceone, thanks for the explanation.

[butters7388]

i30 specs have just been update, SR models now come with 7 speaker Inifinity premium sound system as standard.

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[lil_weg]

I'd still 100% rather my setup than a crappy factory sub!

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[Dazzler]

i30 specs have just been update, SR models now come with 7 speaker Inifinity premium sound system as standard.

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Jeepers! I heard you the first time.. You don't have to rub it in! 

[Crustycottage]

i30 specs have just been update, SR models now come with 7 speaker Inifinity premium sound system as standard.

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Jeepers! I heard you the first time.. You don't have to rub it in! 

That's the problem with buying the new cab of the rank. I still think my own set up when finished will surpass the updated infinity setup with sub. It is still built to a cost although will probably sound 100 X better than 2017 PD stereo

[Crustycottage]

GDay Lil Weg
After some advice, just purchased Audiocontrol LC7i off Fleabay and will mount it similar to u in lower boot between sub amp and pioneer 4 channel amp. I already have Morel coaxials rear speakers & components in front door & tweeters installed.

I ran power cable down the left hand side trim from battery & have tapped off both rear door speakers and ran cables into boot for high level input into existing sub amp which is working very well TBH. 

 I now want to feed front speakers high level into lc7i in the boot which to me is running 2 runs of speaker cable, 1 from front door speakers to lc7i in boot, short RCA lead into 4 channel amp then another set of speaker cables from amp back to front speakers down both left and right hand side of car. 

However, the issue is where & how to feed the front tweeters as don't have wiring diagram. Are tweeters fed direct back to stereo unit to connected to front door speaker cables somewhere? I could leave the tweeters powered by stereo alone but unsure if this impair sound quality.

I am also concerned about running 2 sets of speaker cables alongside the power line into the boot which may cause interference.

Any advice would be helpful