[stochastic]

First let me state I'm writing this up for a couple different forum audiences (will likely post in diymobileaudio.com as well as i30ownersclub.com) so if some aspects seem obvious, it may be interesting to those on the other forum.  Also, as I go, feel free to question and ridicule me - I'll try to do the same to your posts in return   Really though, it's a fun learning project for me any suggestions/tips/new perspectives you can throw at me are really welcomed.

After my first drive in my first car (a 2010 Hyundai Elantra Touring)

 I noticed how muddy the stock system sounded in the midrange with poor bass performance - a new system was required.  I also have found this car to be a touch high on road/engine noise in the cabin, so that was also a goal of this project.  After looking over the speakers at the big-box electronics outlets accompanied with lame sales pitches and poor service, I decided I could do a better job than anything they offered - plus it would be fun.  I didn't really start the project for a few months - just started reading/surfing and getting acquainted with car audio - but during a month away from work for apprenticeship schooling (chef training) I had enough time to dig in.  Let me also state that I'm not doing this to compete in car audio competitions, I'm doing it for my own enjoyment of music as well as a quieter ride - though I'll probably show off the final result at a local competition or two provided I'm happy with the results.

First I decided the roof should be tackled as it would involve nearly no electronic components (thus allowing me more time to make the best purchase decisions after more research).  To my pleasure, there was a substantial space gap to work with between the headliner and the roof.

  I began by adding some CLD to the metal to dampen the vibrations, then I added in a drop ceiling of 3/8" baltic birch plywood.

  The wood ceiling serves dual purpose: sound proofing, and more natural sounding resonances in the cabin interior (I like the sound of wood over the sound of plastic).  On either side of the drop ceiling I put ~1/2" pads of Roxul RXL60 rigid fiberglass board insulation that I had leftover from previous acoustic projects.  This stuff absorbs sound and is cheaper than acoustic foam - comes in 2" thickness so I cut it down to ~1/2" slabs.  At this stage - before even putting the headliner back in, the audio in the car became much richer and fuller sounding - still missing the detail that I crave, as the speakers still suck, but the spectrum has a nicer balance.

I wanted to hear the resonance of the birch rather than the cotton/fiberglass/foam headliner, and the Roxul absorption pads work best when you expose them to the cabin space, so I decided to put speed holes in my headliner Who doesn't love some speed holes in their car!?  This process was pretty intensive as I originally attempted to not remove the fabric, but merely cut out sections of the fiberglass backing but that was too tedious for the results, so I ended up stripping the cotton/foam layer off the headliner, leaving two layers of fiberglass on either side of a foam core.

  I then cut some speed holes in a binary array that scatters audio reflections of various wavelengths (a diffusion pattern).  YAY SPEED HOLES!!!  I repeated this pattern in a couple places varying the sizes and will also include some other sections of holes/diffusion to aid in the acoustic transparency of the headliner.

  I have also selected the stretchy acoustically transparent fabric that I plan on re-upholstering the headliner with - tried to keep the look as stock as possible in this choice.


After a bunch of research I finally decided on what speakers I'm going to run.  I went to Bob Reimer's shop (he owns and runs Creative Sound Solutions    great shop, great products ) to listen to a few drivers yesterday just to confirm my selection and to get a better understanding from a professional.  I also thought that dropping by to pick thing up would save me a chunk of cash on postage.  I went with a pair of Mark Audio Alpair 10 full-range drivers for the main front sound-stage.  Although I wanted the new generation two models, Bob made me a phenomenal offer for the last two of his old generation one stock.  I also purchased one of his CSS SDX10 subwoofers as I knew I wouldn't be able to get a box big enough for the Alpairs to hit 20Hz into my car.

  My plan is to create pods for the Alpairs in the dash corners where the windshield and the A-pilars all meet, and probably put the SDX10 in re-built centre console sealed box next to my gear shifter and e-break.  Currently I'm breaking in my Alpairs (on about hour 30 right now) with progressively louder, more rhythmic bass, etc.. and as I go, I'm pleasantly surprised by the clarity in tone across the spectrum. I don't plan on using a crossover on the Alpairs, just a lowpass on the sub.

More updates to follow.

[AlanHo]

Congratulations - that SOUNDS very good...........................

[Shambles]

I'd like to be in that cab with a symphonic track playing - something from Sibelius or Thomas Tallis. I'm guessing it would sound awesome.

Nice work

[Dazzler]

Should be great when you are finished.. Just one thought though .. Where you want to mount your front speakers will that create a blind spot or effect the operation of the curtain airbags??

[stochastic]

Should be great when you are finished.. Just one thought though .. Where you want to mount your front speakers will that create a blind spot or effect the operation of the curtain airbags??

They may create a minor blind spot, I'm toying with the idea of cutting into the dash to mount them lower.  As for the side curtain airbags, no.  They only travel partially downward into the a-pillar (less than half way) and I'll be placing the pods at the base of the pillars.

[Dazzler]

 

[Phil №❶]

I'd like to be in that cab with a symphonic track playing - something from Sibelius or Thomas Tallis. I'm guessing it would sound awesome.

Nice work

Nah

Pink Floyd - Great Gig In The Sky   for me 

[beerman]

Pfft everyone knows that speed holes are done by sniper fire. The only acceptable DIY method is via the use of a pickaxe.

Also they are done for the purpose of making a car go faster, not sound better.

Worst thread ever!

http://www.myspace.com/video/downnoutdubin/speed-holes/59946858

For those playing at home.

In all seriousness, looks good.

[syecadelic]

This should be very interesting

[stochastic]

This update is merely a hardware/planning update, I've yet to do much more in the way of install or fabrication - bad weather outside is preventing it, but in the coming days I'm itching to get my roof finished - so now I just plan.

First step was to check what the output voltage of my factory headunit is as this is a piece I don't plan on replacing any time soon (too many nice features, plus the added security benefit of having OEM looks).  I pulled out the HU and refferred to the manual on the electrical system, plugged in my multimeter and turned the volume up.  The most I registered on the multimeter was just over 4V peaks in an excessively loud sound test.  You'll notice on the diagram that there's no sub-out on my HU - this is a tricky pickle I need to work around (more on my stereo-to-mono box design below).



I did decide on an amp.  It was a local used Memphis ST-1300D (or Big Belle as it's often called).  Very pleased with the look, specs, and deal I got on this one.  5 channels total, four@75W, one@300W - THD>0.03% S/N<92db  This amp will take care of the whole system, two channels for the Alpair full range drivers, two channels for my rear-fill, and one sub channel with built in LPF and sub-sonic HPF - problem is that it's a mono input for that channel. 



I was cleaning the chrome heatsink, so I took the guts out and washed the heatsink, so for anyone interested in what the amp guts look like:


I plan on mounting this beast in the trunk/boot in the shelf just above the spare tire.  Since this area has no air flow (as it's covered by the floor of the trunk) I picked up two quiet 12VDC fans to push air through the cavity - I plan on putting slotted vents on either side of the amp to allow this air flow.


The only piece (other than wiring and box building) that's required is a means of hooking the sub into the system.  My current plan is to design (or get someone else to help me design) a proper stereo-to-mono sum box.  A Y-cable is no good as if a drum hits on the far left, the signal will travel through all points on the Y including a path back toward the right out on the head unit.  A single channel input (i.e. just using the left channel output) is no good since I need to split off the signal from the four outputs that are all being used - this will create a 6db (or half power) reduction in the channel I split off from.  In the end I realize I need to get some circuitry made, and since a proper rear-fill centre removal and time delay is required anyway, why not plan to put it all in one tidy custom box?

I just so happened to have a sweet looking box that likely has enough room, and some excellent feeling potentiometers on the front - my Altec Lansing NT1201-8a crossover (from a woofer I have in storage and don't plan to use anytime soon).  I figure there's enough free space in there to leave the somewhat valuable Altec circuitry in place but also hide my own custom board on the opposite interior wall.  If anyone knows a good audio electrical guy that enjoys projects, send him my way




While I was at the electronics stores planning some of this stuff out, I came across this sweet looking retro fader control (and I mean the box was even unopened from the 60's sorta retro).  I already have a fader control in the HU, but I'm sure I can use this plate for some delay control.


Also, I got the brilliant notion that as I'm planning to soundproof the firewall, I'll need to take the dash apart.  During that time it'd be really nice to add in some VU meters in my instrument cluster - there's some space for them just below the tachometer and speedometer.  I'll need to back-light them some how and create a nice looking way of mounting them there, but I love VU meters, they're sexy.


Oh, and here's a better pic of the exterior of the car.  Just took this on a recent trip.


Now hopefully the weather improves soon so I can start building more and spending less. 

[Ugly Mongrel]

Thanks for the update, mate.

[Shambles]

Good pics - you're getting there, tho I'm not so sure about that retro fader control - looks like it fell off a Ford Anglia 

[Doggie 1]

Good pics - you're getting there, tho I'm not so sure about that retro fader control - looks like it fell off a Ford Anglia 

I have very fond memories of Ford Anglias.
My dad used to have Ford Anglia panel vans as company cars from a milking machine company he used to work for in England, called Fullwoods.
I have fond memories of spending days with him at work during the 60's, travelling from farm to farm in the north of England.

[stochastic]

Quick update: I've gotten my headliner back in the car now.  Upholstered after stage 1 of design.  I'm now calling this stage 1 because it was about a 4/10 on the success scale.   This post is going to concentrate mostly on the issues I had along this stage of the process.  I'm already working on solutions because I love how it sounds.

I finished the diffusion in the headliner, finished the absorption roof, reupholstered the headliner, and re-installed.

The diffusion pattern has three binary sections of various sizes, and three free-hand MLS-style diffusers (yes, I know free-hand diffusers are a silly idea but I needed to open the space up to the absorption more to prevent causing a helmholtz resonation.

When I went to apply the fabric that I originally picked out, I noticed that the fiberglass bumps, cracks, frayed-ends, diffusion holes, etc... all showed through as texture on the very stretchy (think swimsuit) material.  It had been the most breathable, and looked very 'stock' for the car so I had purchased it without this consideration in mind.  I did quickly run to the fabric store and get a very thin stretchy black layer that I thought might fix the issue, but in the end it did essentially nothing but waste money.  I'm thinking a dark color of a less stretchy fabric will hide these issues better.  I'm toying with the concept of lengthwise pinstripes.  This stretchy fabric also had a handful of glue bleed-through points where the fabric got wet with the glue during the application process and is noticeably discolored though most of these are hidden by complex curves and shadows around the sun visors and passenger handles.




Currently this is the image I plan on showing the fabric store saleswoman:   Any thoughts on that style in an i30?

The birch suspended interior was finished off and I glued some 1" thick slabs of roxul fiberglass insulation onto it.  This is acoustic absorbent that hopefully won't see moisture sucked into it over the years (I may end up installing a dehumidifier in the car if it becomes an issue - I'll probably be getting a deep-cycle battery eventually anyways).  My neighbour commented at this stage as he stuck his head in the open car "It'll be like listening to music in a giant earmuff!"



In the end, after installing back into the car the centre large diffuser obviously took too much structure out of the headliner.  The middle of the headliner buckled and is now 'installed' but collapsing above the rear middle passenger (it's stable and could probably remain there for a number of years if I didn't care how it looked - but I do).

The positive is that the sound in the car (keep in mind I'm still using 100% stock equipment on this install - the aftermarket stuff has yet to be put in) is absolutely miles above what it used to sound like.  There is a widening of the soundstage by about 6" on either side of the front door windows and the overall area of the interior sounds more spacious.  I feel like there's a crispness in the upper-mid range (say 6KHz-ish) that certainly had never been there before.  No measurements have been taken, so this could be a placebo, but it's my ears that I care most about on this build.

I plan on taking the headliner out, re-enforcing the structure with some steel mesh bent into shape, adding some thin foam to the underside to smooth things out, and probably choose a different fabric.

Also, in relation to the fader knob that has found critics in this thread - I think it's a silly idea since there's no other chrome on the interior.  Though there's lots of chrome near the amp rack, so it's possible that it will find a home somewhere...

[Dazzler]

Thanks for the update stochastic  (I don't mind the pinstripe material)

Be mindful of your Jargon (you might need to explain some of your technical terms for us lay people) 

[stochastic]

As far as jargon is concerned.  If you need anything clarified let me know (or ask wikipedia for a clearer explanation  )  I am writing these updates (as stated in my first thread) for a few different forums and then posting them all at once so sometimes sections may be more directed at a certain audience.  If this gets too clouded with jargon (I assume words like diffuser and helmholtz resonation are what you're talking about) poke me and I'll dumb it down upon posting here.

[Dazzler]

Sorry  I forgot you were writing it for a few different forums.... but yes they were the words I had in mind. A short bracketed summary of what they mean inserted after the word would save us having to head for wiki half way through your post 

[stochastic]

diffuser - sound scattering.  These objects scatter reflections of sound.  Everything does this (bookshelves are quite good at it), but smooth surfaces give very directionally scattered reflections which tends to be bad for listening areas.  A designed diffuser will hopefully scatter evenly in all directions (but nothing is perfect).

helmholtz resonator - an enclosed space that has a narrow opening.  Think of an empty pop (or wine) bottle.  The size of the opening and the size of the enclosed space determine what pitch the resonant frequency sits at.  In the case of the headliner, I wanted to make sure that there was enough open space to the above area that I didn't create an audible (above 20Hz) resonant frequency.

[Shambles]

My head Hertz

[Dazzler]

diffuser - sound scattering.  These objects scatter reflections of sound.  Everything does this (bookshelves are quite good at it), but smooth surfaces give very directionally scattered reflections which tends to be bad for listening areas.  A designed diffuser will hopefully scatter evenly in all directions (but nothing is perfect).

helmholtz resonator - an enclosed space that has a narrow opening.  Think of an empty pop (or wine) bottle.  The size of the opening and the size of the enclosed space determine what pitch the resonant frequency sits at.  In the case of the headliner, I wanted to make sure that there was enough open space to the above area that I didn't create an audible (above 20Hz) resonant frequency.

Thanks..

[stochastic]

I picked up some clear flexible 1/4" vinyl tubing at the hardware store and ran it through my door weather stripping.  I picked this idea up from UNBROKEN on diymobileaudio.com and thought it would be a great way to increase the STL (sound transmission loss) at a clear weak point in the car.  The door clasp now pops open when opened, but that's a minor issue that I expect will slowly disappear with time (as the tubing gets more squished into place).  Update: Sure enough, a week or so after install essentially all effects (other than the reduced sound transmission) have disappeared - though if the door is closed too lightly it does not fully close (as is common amongst most cars, just slightly more so).


The car comes with a false floor storage area above the spare wheel already and my amp fits nicely into the lower section, leaving space for a processor and carputer.  It also happens to fit my cooling fans quite nicely.  The only problem is that it's made of moulded styrofoam and an amp that's bolted into styrofoam can easily be ripped out.  So I need to add in a layer of wood, and probably some means of securing it to the vehicle itself.

I came up with a design where I upholster the styrofoam in some black cloth I have lying around, then put a birch ply floor in the insert, then a chrome trim around the birch to match my chrome amp.  I'll figure out how to secure it to the body of the car later, but probably won't post it here for the world to see due to obvious security reasons.




I took some time to sound deaden the hatch.  I also found large cavities of space in the rear corners of the car that would work perfect for bass traps (yes I plan on soaking up the excess bass that cabin gain gives me) or for a sub enclosure if the centre console idea turns out to be a bust/too complex/etc...


I also happened upon some heat and noise reduction paint on sale at the local tool store.  Made by Al's Liner, which makes products for truck bed liners and is designed for hot-rod applications for firewalls - similar to the Second Skin Spectrum paint that others might be familiar with.  So as I was changing the tires from winter back to summer, I lathered a good coat on each wheel well interior.  It's tough to judge the effectiveness as summer tires are normally quieter than the winter tires, but yeah there was a reduction overall in noise transmission. I'll take a look later to see if I can reach my firewall with this paint - though maybe I can tackle it from the interior when I go to put in mass loaded vinyl.


Oh, and I fixed the headliner by putting some 1/4" steel gardening mesh on the upper-side to re-reinforce the weakened structure, some vinyl-coated polyester mesh on the lower-side to smooth out the speed holes, and finally re-upholstered with thicker cotton to hide more of the modifications.  It doesn't look perfect, but I can live with it for the life of the vehicle.  Next time I won't destructively edit any pieces of the original vehicle - lesson learned.  Too much work for what that was worth.  I'll post a pic of it installed when I can.

[Dazzler]

Stochastic, you are doing a great job.. thanks for the write up and pictures..

[asathorny]

Amazin 

[syecadelic]

Definitely some hard working going on here. Much credit to you. Shall have to update my own audio build thread when I get it finished, taking some time

[stochastic]

I'm at an impass with one part of this project, hopefully people around this forum might have some ideas.  I was running my amp's power wire yesterday but I can't find a place for it to run through the firewall.  It's a 4AWG wire, so about 1/2" diameter.  The spot where most wires go through is directly above the dead pedal on my driver's side (left-side) and runs at a very strange curve into the engine compartment in a very crowded section.  There is probably space in this area for the wire, but I couldn't get it to go through for all my trying.  I was looking for other grommet spots that things like the hood release cord go through, but I couldn't find anything.  The last resort is probably to drill my own hole, but I'm a bit scared of the repercussions of possibly drilling into a brake line or worse...  So to recap: I think there's three options 1) fit the wire through the main wire grommet (any ideas how to snake it through?) 2) find a new grommet that would fit the wire 3) create my own hole/grommet for the wire.  What are thoughts on this?

[Phil №❶]

Given the lengths that you are going to with this project, I would imagine drilling a new hole through the firewall would be a simple task for you. To miss fuel or brake lines, locate a suitable place in the engine bay to drill through, use a metal punch to make a suitable mark & if necessary, carefully drill from the footwell inside the car into the engine bay using your mark as the drill point. Be extremely careful to insulate the power cable adequately, as due to it's size, it can obviously carry a lot of current. 

[Hati]

If you decide to drill, make sure that the section you pick is not double skinned on the cab side. They often use metal pressings for strengthening, especially when it comes to crash ratings and stopping the engine to end up on your lap after a head on. Measure multiple times and cut once, but I'm sure you already know that
Best place to go for is near an existing grommet, preferably checking how thick the firewall is at that section. 

[syecadelic]

I'm at an impass with one part of this project, hopefully people around this forum might have some ideas.  I was running my amp's power wire yesterday but I can't find a place for it to run through the firewall.  It's a 4AWG wire, so about 1/2" diameter.  The spot where most wires go through is directly above the dead pedal on my driver's side (left-side) and runs at a very strange curve into the engine compartment in a very crowded section.  There is probably space in this area for the wire, but I couldn't get it to go through for all my trying.  I was looking for other grommet spots that things like the hood release cord go through, but I couldn't find anything.  The last resort is probably to drill my own hole, but I'm a bit scared of the repercussions of possibly drilling into a brake line or worse...  So to recap: I think there's three options 1) fit the wire through the main wire grommet (any ideas how to snake it through?) 2) find a new grommet that would fit the wire 3) create my own hole/grommet for the wire.  What are thoughts on this?

Dont drill anything!!!

take off your wheel at the side of the battery (driver side in your case) ?

(now this worked on mine, im a RHD but should be the same for yours providing everything is the same place)

anyways

Take left front wheel off, same side as battery. Undo all the wheel arch lining plastic.  On the inside strip off the kick panels . all being well you will see where the wiring loom comes into the car. there is a black bit of plastic which sort of clips in. Pop it out, and you will see a spare grommet which leads to the wing/arch of the car.

If you run your power wire from the battery and down the side of the battery, you should be able to get it  dangling down the wing. Think it slips under the tray, you'll see yourself. Just look for light from the wing.

From the outside of the car you will see the grommet which leads into the cabbin, at your foot well. If i remember correctly its at the top of the wing, near the place were it meats your sill.

Feed the wire through, and cable tie the power wire to the plastic tubing at the top of the arch, which holds the existing car wires. Once your wire is in the cabbin, you may have to cut some of the black plastic thing away to allow it to sit flush once the wire is in place.


Lift all your plastic trim from the carpet away and feed your wire As you can see in the pictures, the wire comes down from behind the glove box.

EDIT: Found pics of when i done mine. I now have a 0 gauge wire running down the side of battery, not into the wing as  pictured here with the 4 gauge

Grommet is at the more top end of the wing. apologies. power wire runs down the whole on the wing... see pictures:


Black conduit tubing is the power wire, not connected to the battery.


Power wire after coming through grommet




Grommet power wire goes through, poke a whole with a screwdriver, knitting needle etc. dont stab yourself!

if its not looking possible on your driver side (LHD) try the other side,

EDIT: added captions

[Dazzler]

Good one Sye 

[Phil №❶]