Ongoing documentation of audio upgrades to my 2011 G37x.


I purchased my G37x stock and the audio system is Bose with navigation. I don’t use the larger HDD for music (only have 1 CD ripped to it) and rarely use the navigation as Google maps is faster/easier. For audio I use either satellite radio or a 4th gen iPod connected to the USB input within the center console and controlled by factory radio.

My goal for the audio system:

• Enhance audio quality
• Keep stock components
• Keep it simple
• Add powered subwoofer
• Correct weak satellite signal
• Eliminate rattles/squeaks during the process

First, I’ll start by saying I like the overall sound of the stock Bose system.

When setting the stage for the driver, the imaging is greatly improved and I’m not interested in investing the time and money to replace the factory components and re-align the staging. I installed back in the 90’s and have learned time alignment with modern equipment has become quite advanced, however it’s a daily driver and I rarely sit still to listen to imaging.

The factory 10” drivers in the front doors produce an amazing amount of kick and low end for the front stage. I have Morel separates from the Accord Coupe I traded for this car and it would be difficult to get the same output from a 6.75” driver, plus there’s the depth issues in the door for larger drivers.

The factory system is loud enough for what I need. My days of chasing SPL are long gone and if the system plays loud and clean enough to be heard with the windows down then I’m happy.

This Bose system has great sound quality as it’s very neutral compared to many aftermarket alternatives. Those who discuss the system state that it’s flat sounding, is harsh, or are simply prejudiced because they’ve read online that Bose is inferior. The flat sound comes from its neutrality and lack of what I call “screaming tweeters”, harshness is real and addressed, and Bose, like all manufacturers, has advocates and opponents. What I’m not doing is shredding the factory components to add time alignment, components and 9+ channels of amplification. What I am doing is enhancing what’s already in the vehicle and adding an additional sub as I listen to bass heavy music (rap, dubstep, etc.) along with quality recordings such as Focal test discs.

There’s a review of the Bose Studio on Wheels and here on these forums a very comprehensive test and review of the factory system by @milosz that details and outlines many of the issues I will tackle. According to the analysis from @milosz , the midrange driver has significant cone breakup at higher frequencies lending to a “harshness” in the mids and highs which should be corrected by adding a passive crossover. The issues with mid-bass aren’t with the drivers themselves but can be attributed to lack of damping in the doors allowing the panels to continue to play (vibrate) after the music stops.

My game plan:

• Add additional damping to the front doors - possibly adding to the rest of the vehicle over time
• Address the effects of bass in the doors by adding absorption material to combat standing waves
• Add a passive crossover to the factory mids (squawkers) and tweeters
• Add powered subwoofer
• Ensure satellite antenna is properly grounded to improve reception, fix headliner noise at same time

I started this project in January of this year as outlined in my next post.

-Eric

 

unpossible.
XM sounds horrible in a car anytime i've tried it (ok for just talk shows i guess), and iPod sounds pretty bad as well, because none of the preset EQ settings do anything to make the Bose system sound better.

i've had the best results using a powered sub with sealed enclosure (i like tight and accurate bass), and a rooted Android phone with Viper4Android DSP app. next best is Jet Audio music player with 20 band EQ.

i can report that the Bose system in my Q60 is much improved over the one in my G37 ... far less tweaking needed to get it to sound good to my ears.

 

Thanks!

I read that Bose worked on the staging for the new vehicles and every generation of systems seem to improve on the prior configuration.

I don't use any EQ on my iPod and my source is typically FLAC to 320 MP3 to the iPod. I've read my CD player incorporates BB and I may do a one-to-one comparison of the iPod to the CD. I have a sealed sub from my Accord that I'll be using as I too enjoy tight controlled bass with a gentle roll off on the bottom end with a smaller enclosure.

-Eric

 

My goal for the front doors was to add a passive crossover to remove harshness and enhance the sound quality of the bass and mids.

Here’s a comparison of the factory system followed by one after my update to the doors, all using the original Bose components. Not a huge difference, but a better curve and a noticeable increase in low end.

Note: Pink noise is from 2005 IASCA test disc RTA test track using iPod with no EQ. I always keep balance/fader centered, treble flat, bass +2, staging set for driver. Software is AudioTool for Android, mic is Dayton Audio iMM-6 with calibration.



After updates:




More details to come.

-Eric

 

The first thing I wanted to tackle was the speakers in my front doors. I have a set of Morel separates and considered installing these but was concerned with loss of low end impact if I removed the factory 10” drivers and replaced with a 6.75”. Additionally, if I removed the factory speakers which are 2 ohm for the 10” and 4 ohm for the separates, I would probably need to bypass the factory amp to get the right balance and figure out a way to drive the center channel to the correct volume - I do have a 5 channel Zapco amp but that adds complication. And, Bose engineers had researched installing and adjusting the drivers to get decent staging and balance, and I want to keep this simple so I started searching for information.

I found the thread by @milosz where he pulled and tested the drivers from his 2013 G - I don’t imagine there’s a difference between his drivers and mine.

Here’s an overview of his findings:

• Bose used high quality drivers
• The overall frequency response in the vehicle was relatively flat
• The 3.5” mid suffers from cone breakup, tweeter to lesser extent
  • Causes system to sound harsh or excessive treble
  • Mid range overpowers the tweeter output
  • Adding a passive crossover might significantly increase the sound
  • Suggests 12 db 5 kHz high and low pass crossover
• 10” driver lacks punch as the doors are under damped, i.e. door keeps resonating after bass stops

To tackle the cone breakup, I started searching for components to create the 2 way crossover. As the speakers test at 4 ohms, I found components at Madisound to create a 12db Linkwitz-Riley (LR) centered at 5 kHz for $23 shipped. This consisted of a pair of 3.9 mfd Mylar capacitors and 0.25 mH air core inductors. I don’t use electrolytic capacitors for mids/highs as they don’t have the best sound and while I could have gone for cheaper electrolytic for the low pass using the same components for both crossovers is preferred. LR crossovers are flat at the crossover point and don’t have phase shift - very simple and popular crossover for most applications.







For the door damping, I knew what my plan was:

• Add butyl rubber peel and stick to deaden the panels and reduce resonance
• Add fiberglass insulation to the door cavity to enhance sound and minimize standing waves

Additionally, while I had the inner door skin and window regulator our, I took the opportunity to lubricate the regulator with lithium grease and use silicone spray on the glass channels.

The concept of adding deadener, such as butyl rubber, has been widely discussed over the years. The amount needed and type/brand are still debated, however I wasn’t adding it to reduce road noise. And, as the car is fairly quiet and I knew fiberglass would diminish outside noise, I was going after acoustic resonance in the panels and wasn’t interested in adding mass loaded vinyl (MLV) to the install. I had a roll leftover from when I added to my Accord Coupe so there wasn’t anything to purchase.

Next - adding fiberglass insulation to the door cavity.

**Note - breathing fiberglass insulation can be deadly. I don’t condone anyone doing this, I’m just documenting what I did. If you choose to do this - understand the risks and what you need to do to mitigate those risks

Fiberglass insulation is commonly used in a sealed enclosure to reduce standing waves along with other benefits. It’s not used in a ported enclosure as breathing in fiberglass (small glass fibers) is a health risk so it’s rarely used in an automotive application (I do have in my sealed sub enclosure).

I learned about the concept of adding it to a vehicle from a Honda Accord SQ build on a car audio forum as the poster is an acoustical engineers and outlines the benefits. I installed fiberglass in my Accord and noticed a significant improvement in sound quality and dramatic decrease in noise from the doors (road noise, rain, cars, etc.).

Here’s an overview:

• Purchase 2’ x 4’ ceiling tile from Menards
• Remove pebble backing and cut into sections large enough to fit between crash beams in door
• Wrap in thin plastic drop cloth to seal from moisture and trap glass fibers, seal with clear packing tape
• Attach to outer door skin using aluminum tape (HVAC)

Pictures and videos next.

-Eric

 

I am really interested to see how this plays out for you (sorry about the pun). My entry into the car modification world started with car audio, I preferred sound quality to just being loud. Audio modification used to be a simple task but with so much integration occurring these days it requires a great deal more thought. I have the bose system and its good and IF it was the only stereo I ever had I'd probably be more than happy with it as is. However once upon a time, having a car filled with Focal components and subs, Audison amplifiers, and so much sound deadener and foam filling the body panels, I found my ear drums distorted before the speakers did. I miss that stereo... Anyway fast forward about 10 years the stereo itch started again and I was pondering what I wanted to do to enhance the Bose or pull it completely and go nuts with either Focal or Morel. I figure I'll start with a subwoofer and make adjustments from there. I saw you start this thread and sub'd immediately. Keep the results coming!

 

the Bose speakers sound good with the Viper4Audio app when tweaked - its the EQ/DSP the Bose amp applies that make the bass muddy and the highs sound like a wet blanket is over the speakers. needs a powered sub, too, but that was easy enough to add. i really didn't feel like tearing everything out, especially since there's no good way to add an aftermarket head unit, and i'm more than satisfied with it now.

 

Can I ask what the general EQ settings are on the Viper4Audio app?

The low pass crossover I installed would cut output in the 1 kHz to 8 kHz range and should be down 3 dB at 3 kHz and 6 dB at 5 kHz dramatically reducing the output of the 3.5" mid-range.

-Eric

 

Thanks for your post!

My car audio experience started way back in the mid-90's when I was installing. Then we had to really focus on how drivers were installed to achieve any staging, and used rear fill along with center fill (tweeters in the back of mirrors). We often used single amps, i.e. 25 x 2 to compete in a 50 w class, so setting levels was manual with resistors and wiring to get things dialed in as the amp would run full range relying on passive crossovers to allocate the different frequencies. Seems today it's easy to run active crossovers, multi-channels of amplification, and have a DSP sort it all out.

I've been away from installing for a long time (20+ years) so things have changed and my ears have gotten older. My favorite system was a semi-competition system I had with a Denon CD player, Precision Power PAR-225, Phoenix Gold 2 way crossover, pair of Lanzar Opti-drive amps (original series) and Oz Audio mids/highs with 12" Oz Audio sub - this was back in 97?

I appreciate you tagging along and this is more for fun than anything. Many people (my wife) would say the factory system sounds just fine. My goal is to run with what @milosz found with the drivers and add a 12" Apline Type R sub in a sealed enclosure, driven by 2 channels of a 5 channel Zapco amp, leveraging my Audiocontrol LCQ-1.

Pretty simple and by no means a competitions system.

-Eric

 

The mid-late 90's was my intro to car audio, my best friend who is about 6-7 years older than me was an installer and taught me a ton along the way. We spent many of late nights reworking his stereo to go to IASCA events and entering in dB drag races. It was far from the wildest of setups, we were just there to have fun, not blow out windshields, but there was a great deal of math and science involved which I found fascinating. He was/is a huge fan of cerwin vega which comprised the base of his stereo setup along with Lanzar and SPL amplifiers. I learned that arcing a 1 farad capacitor results in a blackened finger and flying out of the back of the trunk (fortunately it was a learn from others type of situation and no real injury occurred). Lots of good times.

I don't have mega aspirations for whatever I do, for me it's more just about having something to tinker with and learn more about. It drives my wife nuts that I am always taking something apart and modifying it. My 8 year old daughter has become a total car girl and has been intently listening to me as I explain how things work. She first learned about continuity when she was 6 and I was chasing electrical gremlins in an Integra. Love it.

 

various things to tweak, or leave disabled if you want: Graphic EQ (don't remember actual settings for the G37 - that phone w/V4A is in my Q60 now), Bassboost, and the most important - Viper Clarity.
the Clarity setting really wakes up the Bose system - normally its dull-sounding, but turning up the treble just makes it harsh. the Clarity adds a crispness to the cound wihout being "ice-picky".

 

Below are some pictures and videos from when I installed additional butyl damping, fiberglass and the crossover components. I also took time to lubricate the power windows as I had access to the regulators and channels - removing the interior panel to get to the door skin necessitates removing the window glass. This was quite easy and I didn’t have any issues.

After listening to this for 4 months -

Pros

• Enhanced bass reproduction. Bass is more accurate (tighter) and appears to have lower extension (see RTA above). My theory is the fiberglass changes the enclosure (door cavity) and minimizes standing waves from coming back through the driver. Additional peel and stick, along with a general tightening of the screws securing the door panels together, adds further damping. Certainly not a quality speaker enclosure but better than before.
• Better reproduction from the midrange and tweeter. Previously, I could only hear the tweeter if I placed my hand over the midrange to reduce output - I can definitely hear the tweeters now. Harshness has been significantly reduced and this is evident in all types of music from electronic (i.e. dubstep), to jazz, vocals, etc. For example, the beginning to Love is Gone (David Guetta, Joachim Garraud & Chris Willis) was previously so harsh I needed to turn down the volume for the intro – it’s now better but still harsh and all music has better detail.
• Reduced exterior noise (road/rain/etc.).

Cons

• I’ve picked up some buzzing in the panels. When removing the doors, the clip securing the panel below the tweeter is so difficult to remove that I broke both wood trim panels (actually plastic). I did glue them in place, but now both buzz at different frequencies and I get some buzzing around the window switches. I can press on the area and the noise goes away so something I’ll address next time the panel is off.
• Some harshness still remains at higher volumes. There’s breakup in the tweeter at higher frequencies (above 15 kHz) according to the waterfall plot and I don’t know if this would impact me due to my age (51) as I probably have diminished hearing above 14k. I also don’t know if the factory Bose amp lacks headroom and is clipping at higher volumes. Replacing the driver or replacing the amp is beyond my goals however I didn’t install the high pass portion of the crossover and left the small cap in place. The capacitor is epoxied to the tweeter frame and I didn’t have time to dismantle it and re-wire. I can vouch for the crossover enhancements on the mid range and won’t know for a bit if the second part of the crossover will enhance the sound. Additionally, I have a 12 dB crossover on the mid and 6 dB on the tweeter most likely creating a phasing issue

The process for the doors was as follows:

• Remove the door panel and regulator panel/window to access outer door skin
• Add additional peel and stick to the exterior skin and regulator mounting panel (front and rear). I also found that several of the OEM pieces were loose - resecured and heated.
• Add fiberglass insulation to the outer skin. Cut ceiling tiles to size, wrapped in plastic drop cloth, sealed with packing tape, secured to skin between collision braces.
• Insert 12 dB low pass filter to midrange. The mid/tweeter are driven from the same audio channel with the tweeter paralleled off with an inline capacitor - still need to install the high pass. All components soldered and taped with 3M Super 33+ then zip tied to existing harnesses.
  

-Eric

Quick overview



Loose factory:







Crossover components.

 

Currently starting to investigate where to install my sub amp and crossover with remote level control. Components are Alpine 12” Type R sub (early series, SWR-1222D) rated for 500 watts RMS in a 0.9 cubic foot sealed enclosure, Zapco ST-5X amp and Audiocontrol LCQ-1. I’ll bridge two channels of the Zapco to deliver 300 watts to the sub and plan on leaving the factory sub in place and tapping the speaker level subwoofer output to feed the Audiocontrol.

The Zapco has a dedicated sub channel, however it delivers 300 watts to a 2 ohm load - the sub is dual 2 ohm coils so only gets around 200 watts wired in series at 4 ohm. I’m not using the other channels so will bridge 2 for 300 watts into 4 ohm.

-Eric

 

Nicely done! I haven't gotten into the door panels yet but that's on my to do list soon. Do you know the approx. thickness of your completed fiberglass inserts? I've been giving thought to using Noico Green and/or Foam (egg crate-like) sound proofing panels. Historically I'd always gone the dynamat route however at half the cost I picked up Noico butyl sound deadener. I lined most of the trunk space with it and I am impressed with the quality. Very comparable to dynamat extreme. I have also in the distant past used egg crate style foam padding to fill big spaces in rear quarter panels which I found to be fairly effective.

I am looking at getting a 10" Focal E 25KX paired with a Focal FPX 1.1000. It's dual 4 ohm so I can get about 700 watts out of the amp at 2 ohms which is right in the middle of the subs "happy" range. Looks like it would be happiest in a small sealed box 0.6-0.77 cubic foot, which is convenient given the coupe's smallish trunk.

 

Thanks!

According to Menards they're 5/8" thick.

Another option I'm considering is denim insulation to fill larger cavities where moisture isn't an issue. It's equivalent to fiberglass yet safer to use.

-Eric