09 Sierra Audio Upgrade Complete

[BlitherinIdiot]

I recently purchased a 2009 Sierra SLT Crew Cab and decided to make a few upgrades to the factory audio system. I thought I would share a few pictures and details, hopefully it will help someone else considering a similar project. For reference, I am almost 40 years old and my main objectives were increased sound quality and a clean and factory looking installation when completed. I also wanted to maintain some level of storage space in the rear of the truck. I was not looking for an extraordinary amount of SPL, just a nice upgrade to the stock system.

 

I felt the factory Bose system had decent sound quality at lower levels but the quality was dramatically reduced as volume increased. I'm certain this is due to the processing taking place in the amplifier to reduce LF output when listening at higher levels in order to preserve the factory mid-bass drivers. The factory Bose "subwoofer" was totally inadequate. I should mention I have the standard 4-channel system and NOT the Bose system with the center channel.

 

I decided to keep the factory head unit for the short term and concentrate on new speakers for all four doors. I also added a subwoofer and amplifier. I added JL C2-650 components in the front doors and JL C2 525x coaxial's in the rear doors. The doors had Dynamat added during the installation. The amplifier is a 5-channel JL HD 900/5 with the JL Stealthbox under the drivers side rear passenger seat. I chose the amplifier because it has a good amount of power, should not stress the electrical system as much as an A/B dual amp configuration and it has a very small footprint. I went with the Stealthbox because I was able to get two 10" drivers without taking up all of the floor space in the rear of the truck.

 

Overall I am very happy with the results. It sounds dramatically better than factory and has plenty of headroom.

 

Pros:

 

Increased quality and headroom

LF levels no longer decrease as volume increases

Sufficient LF output for my requirements

 

Cons:

 

I don't like the placement of the amplifier. I had originally planned on having it on the floor almost to the rear wall, passenger side. Unfortunately there is not sufficient clearance between the floor and the bottom of the rear seat when it is in the down position. I could mount it on the rear wall but that would make access to the controls very difficult. I will be looking into other options in the near future.

 

I had Dynamat added to all four doors. I have read many comments for and against this product. I don't get any noise or rattles from the doors now at high levels so I suppose it is helping there but there doesn't seem to big a lot gained here outside of that.

 

The carpet on the Stealthbox doesn't match. My interior is the Light Titanium/Dark Titanium. The grey on the box is a little too blue to match. This is not a huge issue, just a minor issue when trying to make everything look more or less factory.

 

 

Here are a few pictures of how it turned out. These were taken on my phone. I may take better shots if someone would like them.

 

 

Front Door HF

 

 

LF Level Control

 

JL Stealthbox

 

JL Stealthbox

 

JL HD 900/5

 

 

Rear

 

 

 

Rear

 

[ap0352]

Whats your initial impression with the stealthbox? Been wanting one but was scared to spend the money.

[BlitherinIdiot]

Whats your initial impression with the stealthbox? Been wanting one but was scared to spend the money.

 

I was in the same position for the last two months. I have only been able to find one other review of this box in a great deal of searching but it was positive. I decided to go ahead and take a chance on it based on JL's reputation. I think it sounds very good and is very smooth. It is a sealed box so if you are looking for a significant amount of SPL, this may not be the box for you. I mostly listen to rock and it handles this very well with good impact and tight response. I did play Late Night Tip as a test and it was really loud but what may be loud to me may not be loud to others. I am feeding it 500 watts RMS from the 900/5 but it is rated for up to 1,000 RMS. It looks really good in the truck other than the color not being a perfect match. It also leaves room on the other side for storage with the seat folded up. It is bolted to the floor to couple it to the truck and for safety.

 

One other comment, the box looks as though it has a built in amp rack molded into the fiberglass. The 900/5 fits in this space but there is no room for the connections. I phoned JL today and was told this is actually part of the acoustical design of the box and not meant to be an amplifier mounting location. That was a bit disappointing because my JL dealer felt the amp would fit in this space neatly. I should have phoned JL directly before the installation but in the end I don't know that I would have done anything differently.

 

Overall I am very happy with the performance. There are certainly other alternatives that are less expensive but given the space limitations I felt this was the best compromise. The other prefab boxes I have seen that contain two drivers use the entire floor space under the seats. I bought the truck new and it wasn't cheap. I didn't mind spending an extra $350-$400 to get a fiberglass enclosure that was designed for the space. In the big picture, it isn't a huge difference IMO.

[Combat_Vet]

Excellent! Thats the exact route I'm going..

 

HU: Kenwood DNX9140

JL Audio front and rear speakers; however, I was going to keep the factory tweets as I didn't know what to do with the new ones in the pillar without messing everything up. Where are your crossovers for the components upfront?

JL Audio Stealthbox

JL 900/5

Misc modules for steering wheel controls, Onstar, XM, etc...

[Combat_Vet]

Chris,

 

I'll have a lot of questions for you as I save more money to prepare for the install. Somewhere around $6000 with headrest monitors, etc...

 

Hope you don't mind.

[ap0352]

What did you use to get the signal to the amp? cleansweep, etc?

[BlitherinIdiot]

Chris,

 

I'll have a lot of questions for you as I save more money to prepare for the install. Somewhere around $6000 with headrest monitors, etc...

 

Hope you don't mind.

 

 

I'm happy to answer any questions, especially for a veteran! Send me a PM if you would like to discuss by phone.

[BlitherinIdiot]

What did you use to get the signal to the amp? cleansweep, etc?

 

I had originally planned to use the Cleansweep. There are some great videos of how the unit works on the JL Facebook page. They go into detail and have the output on a spectrum analyzer so you can actually see what it is doing. I called the JL technical support line to get clarification on what exactly I needed and I was told that I did not need to purchase the Cleansweep for this truck. The factory head unit has a full range, unprocessed output to the amplifier. All of the processing for the factory speakers is handled in the amplifier. As long as you pull the signal from the output of the head unit, before the amp you should not need the Cleansweep. This is the case for the regular Bose system. I was told the upgraded Bose system with the factory center channel will require the Cleansweep because the processing is done in the head unit on those models.

[ap0352]

I wonder if the same holds true to the factory non-bose system..

Did you use a PAC to get the RCA signal from the speaker level outputs?

[tractionisovr8ed]

nice setup, very clean and professional installation. I'm about to help a buddy do a full setup in his extended cab 09 silvy and I'm gonna tell him about that JL 5 channel.

[BlitherinIdiot]

I wonder if the same holds true to the factory non-bose system..

Did you use a PAC to get the RCA signal from the speaker level outputs?

 

A speaker wire to RCA was used to get signal to the amplifier.

 

 

[Combat_Vet]

Chris,

 

I'll have a lot of questions for you as I save more money to prepare for the install. Somewhere around $6000 with headrest monitors, etc...

 

Hope you don't mind.

 

 

I'm happy to answer any questions, especially for a veteran! Send me a PM if you would like to discuss by phone.

 

 

 

 

I'll definately get with you when I get things ordered. I'm doing this on a spare cash flow option, so it may take a little bit to get everything together. This is exactly what I envisioned, with JL Audio in this truck plus the Kenwood nav will be awesome.

[ocean4200]

What are the original tweeters impedance? 2 ohms? 4 ohms?

[icetraxx]

do you remember what the color of wires were that you tapped into? Or how you figured out which ones?

[GMC_SD_08]

This may sound like a stupid question but how can you easily tell the difference between the standard bose (I believe the OP called it 4 speaker without the center channel) and the luxury bose with center channel. I have a 2008 Sierra Denali with Bose however no RSE package. I do see a speaker in the middle of the dash (thought that was the sub) along with the 4 main speakers in the doors and the two front A-Pillar speakers but I don't believe this is a 5.1 setup. Any input would be appreciated as the provided descriptions make it sound like with this scenario I may be able to tap in between the amp and nav head unit to receive an unfiltered signal. This would mean a JL Cleansweep would not be needed, right? Thanks in advance for any clarifcations.