[XtremeRevolution]

Edit: This thread is obsolete. The thread remains for historical purposes. Refer to the SQ Car Audio V2 thread: http://www.cruzetalk.com/forum/36-gen1-audio-electronics/11204-sq-car-audio-thread-v2.html


This is going to be the mother of all SQ car audio threads.

In this thread, I'm going to show you how to install a full-fledged SQ based sound system in your Cruze that you could probably compete with. Some of this may go over your head, but with a bit of research, questions, and learning, you'll be able to do what I'm about to do.

This system will be based on Sound Quality (SQ), not SPL (sound pressure level), although it will reach SPL levels capable enough to cause hearing loss with prolonged exposure. The goal is to create a system that sounds as good as a system can possibly sound on a modest budget. I will explain all of the decisions I make so you can learn more about car audio as well as help you make your own decisions with your own installs. This will probably take a month or two for me to finish.

This initial post will be dedicated to outlining concepts I will use while documenting this project. Let's start.

What makes a good SQ system?

​

Balance
Ever heard a bass thumping ride rolling down your neighborhood? That's not what we're going to do here. If you sat in that car, all you'd hear is bass. If you're competing in SPL competitions or trying to impress some kids, that's fine, but if you want to enjoy your music the way it was recorded, you're going to need to learn how to accept bass in moderation. SPL gets old after a while. Almost every car audio enthusiast I've known eventually passes the SPL phase and spends his/her time in SQ. We need a balance between bass and front sound stage. When you get in your car and turn the radio on, you shouldn't be able to tell that the sub is in the trunk. It should sound like it's everywhere, it should be tonally accurate, and most of all, it should blend well with the front stage.


Sound stage
There are two approaches to car audio. The first is the "more speakers are better" approach. This train of thought implies that the more speakers you have, the more "full" and "rich" the system will sound. The truth of the matter is that this isn't true. Your goal is to reproduce the recording as true to it's source as possible. If you can reproduce a live sound stage, you're even better off. Home theater companies sell you on this with 5.1, 6.1, 7.1, and beyond, implying that more speakers are better. For movies and surround effects, the point can be validly argued, but for music, you need a front sound stage, not a surround sound stage.

This system will focus all energy and resources on the front speakers in an effort to reproduce a realistic front sound stage and not blow the budget. We don't want an "in the club" feel, but we do want the sound to be rich and full. This will be an upgrade to the non-pioneer system. The rear deck will remain empty, while the front speakers and tweeters will be replaced, and the door speakers will remain, but with high pass filters designed to cut off bass frequencies to prevent distortion. The only reason I'm leaving the rear doors in is so that my rear passengers have something to listen to. Otherwise, I'd remove those as well as they will be faded out when I'm alone in the car. Once you hear a well-designed sound stage in a car, you'll always feel like something is wrong when listening with rear speakers playing.


Frequency Response
Component speaker kits are designed with passive crossovers to tame midwoofer cone breakup and protect the tweeter from playing too low of a frequency. These however do not have any reasonable equalization, phase alignment, or time alignment capability. In order to achieve a reasonably flat frequency response around the Cruze, we need to go digital. This system will use a MiniDSP digital processor and purpose-selected speakers to achieve my goals. The MiniDSP allows me to select any crossover point and slope up to a 4th order LR on both the tweeter and midwoofer, as well as provides me with a 31-band equalizer. The speakers will be measured with a Dayton MM-6 measurement microphone with an M-Audio microphone pre-amp in order to get as flat of a frequency response as possible.

The subwoofer's box will be designed with JBagby's WBCD and BDS spreadsheets to predict and model cabin pressurization gain, boundary loading, and apply those to the sub's frequency response based on it's T/S parameters. This way, we don't need to spend money on a PEQ for the sub amp and can get a reasonably flat frequency response out of it.


Deadener
This is undeniably one of the most important and most under-estimated aspects of a car audio install. You need to reduce vibrations, reduce noise, and separate your midwoofer's back waves from the front waves in order to give you a strong midbass presence, but without fatiguing resonances and distortions. The doors, trunk, and trunklid will be effectively treated with deadener, and I will teach you how to do that.



​

Compromises​

Stealth vs Axis Response
Our first compromise will be in favor of stealth. I live in the Chicago area, and the last thing I need is people knowing there's a system in my car when I take my friends and family downtown during visits. For this reason, I will not be making custom pods for the tweeters to be mounted to the pillars. This is a compromise because tweeters perform best when listened to entirely on-axis, near ear height, directed at you. It is my biggest compromise, but I need this to look completely factory through the windows without any indication that there's something worth stealing inside. For this reason, the factory head unit will also remain and a GM-specific PAC LOC will be used. My tweeter choice will help alleviate the impact of this compromise.

Cost vs Sound Quality & SPL
Naturally, I could spend more money on better midwoofers, a second subwoofer, and newer amplifiers, but let's face it, I drive a Cruze Eco. This system will touch on some of the bare minimums of what one can spend to get world class sound quality in their Cruze. ​

 

[R1XSTA]

Hey man. Quick question.

If i gave you sub details and spec's. Could you design a box??

 

[XtremeRevolution]

Hey man. Quick question.

If i gave you sub details and spec's. Could you design a box??

I've designed over 130 sub boxes in the past couple of years alone, all for free and in ways I've never seen anyone else do it. I can predict exactly what it will sound like in your car, so short answer is yes, and I'll be glad to. Post the T/S parameters (fs, qes, qms, vas, sd, xmax), and answer the following questions:

1. what amp do you use and does it have a subsonic/high pass filter?
2. what's your goal? SQ, SPL? Smallest box possible?
3. what types of music do you listen to primarily?

 

[Mick]

I guess I was wrong, I thought I wanted sq but I want to be surrounded. Not feel like I'm at a stage. I know I definitely don't want sp sound.
I don't want to be able to pin point where a sound is coming from, although I do want to be able to pin point sounds (instruments).. If that makes any sense.
I'd also like to hear bass (depth) not feel bass (vibrations) if that makes any sense. I'm thinking 6x 9's over sub and tweets up high would be a better option for me. What you think?

I had a buddy back in the day that had some pioneer 6x9 speakers and a pioneer 12". When the sub was off the bass sounded exactly the same but you couldn't feel it or hear rattle. And sitting in the back sounded almost exactly as sitting in the front.

 

[XtremeRevolution]

I guess I was wrong, I thought I wanted sq but I want to be surrounded. Not feel like I'm at a stage. I know I definitely don't want sp sound.
I don't want to be able to pin point where a sound is coming from, although I do want to be able to pin point sounds (instruments).. If that makes any sense.
I'd also like to hear bass (depth) not feel bass (vibrations) if that makes any sense. I'm thinking 6x 9's over sub and tweets up high would be a better option for me. What you think?

I had a buddy back in the day that had some pioneer 6x9 speakers and a pioneer 12". When the sub was off the bass sounded exactly the same but you couldn't feel it or hear rattle. And sitting in the back sounded almost exactly as sitting in the front.

Sit in my 95 Regal and I can guarantee you that you wouldn't ever know that there aren't any back speakers. The truth is that cars have so many reflective surfaces that the sound is always everywhere. If it's designed correctly, it will sound just as rich, full, and immersive.

Describing sound stage is very difficult until you hear it for yourself. In a well designed sound stage, you'll never pinpoint where the sound is coming from because of those reflections, so don't get the impression that you'd be able to identify two separate point sources; that's not what we're doing here.

If you want to pinpoint instruments, you'll need a flat frequency response and good phase and time alignment. I'll describe this briefly. Say you are sitting in front of a home theater speaker, something that looks like my recent design:

Now, say you're 3 feet away from the speaker and everything is at ear level. The woofer and tweeter are equidistant from your ears. Now, put the speaker on the ground and stand 3 feet away from it. What happened? The woofer is now farther away than the tweeter. The critical issue with this is in crossover overlap. In order to prevent a woofer from sounding distorted by playing too high of a frequency, you need to roll off frequencies above that point. In order to protect a tweeter from playing bass frequencies, you need roll off frequencies below a certain point. Here's the crossover sim for the above speakers. Click to enlarge:

The thick black line is the total frequency response. It's pretty **** flat in the usable range. the thick blue line is the woofer's frequency response after the crossover has been applied, and the thick red line is the tweeter's frequency response after the crossover has been applied. Those two overlap from 1000hz to 6000hz in order to "sum" and create the continuous black line. They are time and phase aligned for the sound to reach your ears at the exact same time when you're sitting directly in front of them, aka on-axis. Now, if you are off-axis and the woofer is farther from your ears than the tweeter is, what happens? The sounds from both tweeter and woofer in the "summed" range reach your ears at different times. The result is a sound that is not as clear, crisp, or detailed as one would like.

Now, take this concept and multiply it by 10 and that's the problem you have in car audio. You cannot possibly time and phase align both your front and your back speakers in order to have the same clarity you would in a home theater with two speakers at ear level. Furthermore, the reflections of the back speakers create destructive interferences that actually over-boost some frequencies and cancel out others, creating peaks and dips in the frequency response. The more speakers you have, the worse this problem becomes.

In the end, you're best off using two front speakers. The car's cabin will reflect sound from enough surfaces to create enough ambient noise in the back of the car to make up for what you think you've lost. The result will be the clarity you're looking for.

As for the bass you're looking for, I could spend a LOT of time going over this, but I've written up an explanation before so I'll just forward you to it instead. A lot goes into sub box design that most people have absolutely no clue about. To get that transparent bass you're talking about that just feels right, you need both a well designed sub and a well designed box.
Why sub boxes are important

Sit in my 95 Regal and you won't be able to tell that the sub is in the trunk. It will just be everywhere and it will be tonally precise, accurate, and musical. Now that's a word you have to hear to understand. Hearing a truly musical sub like the Image Dynamics IDQ15 I've chosen for this project will give you one **** of an "aha" moment followed by a "holy sh!t" moment, followed by speechlessness.

 

[XtremeRevolution]

Driver Choices
​

In this post, I'll outline my choice of speaker components and explain why they were chosen.

Tweeters
I will be using Morel MDT-44 tweeters, which will replace the tweeters in the pillars. These were purchased used but in mint condition in their original box for $60 shipped and are discontinued. Their replacements cost $118 per. These may require some modification on my part, but such modifications can be made with these without affecting frequency response.

Morel MDT-44 1-1/8" Compact Soft Dome Tweeter 277-042

An ideal front sound stage would consist of a 3-way speaker system comprised of a tweeter, midrange, and woofer. The reason for this is axis response. Speakers in general will have a much better frequency response when listened to on-axis as higher frequencies are very directional. You may notice that a subwoofer's location in a home and in a car is not easily pointed out. The higher the frequency, the more directional that sound wave. The goal here is to play as much of the frequency response through the tweeters as possible so the midwoofer in the door doesn't have to since that's pointing right at your feet, and last I checked, our ears are not at our feet. A particularly excellent characteristic of this tweeter is its ability to play with a relatively flat and smooth frequency response off-axis, which will be excellent for this environment my tweeter mounts in the pillars are not pointing directly at me.

This particular tweeter will be crossed between 1000 and 1500hz, which is generally very low for a tweeter. This is a particularly robust tweeter with an incredibly high power handling of 120W RMS. By comparison, most component set tweeters won't play below ~3000-3500hz. Bringing more of the sound on-axis improves clarity and raises the sound stage so it doesn't feel like it's coming from your feet. It also creates a better ambient atmosphere in the car and allows it to sound more "airy."

The other reason for having a tweeter that can cross as low as this is in order to create a crossover point as far away from the vocal range as possible. In an SQ based system, you need vocals in music to be as clear and crisp as possible, and the lower you can cross, the farther away from the critical vocal range you will be.

This specific tweeter was also chosen due to size. While frequency response is important, getting the teeter to fit in the pillars is another challenge altogether. These are extremely small for the amount of performance they provide and should fit in the pillars without any real problems.



Midwoofers/Midbass
While the choices for tweeters that will fit in our pillars and play low are very small, the choice for midbass drivers is fairly large. I would have wanted to fit an 8" midwoofer in these doors, but the factory grill on the door isn't large enough for that. My recommendations for midbass have changed to the Silver Flute 6.5" 4-ohm driver:

http://www.madisoundspeakerstore.co.../silver-flute-w17rc38-04-ohm-6-1/2-wool-cone/


When choosing a midwoofer, there are some variables you need to consider. First is the ability to pick up all of the frequencies below that the tweeter will not smoothly. Since I'm crossing at 1500-2000hz, this midwoofer needs to be able to play up to 2000 cleanly, and this woofer does just that.

The second variable you need to consider is that of excursion. The idea here is not only to play the midwoofer up to where the tweeter drops off, but also drop this off low enough for the subwoofer to pick up. This is something called midbass; a frequency response region that is difficult to correctly achieve and even more difficult to play with authority, typically in the range of 100hz and 700hz. I have yet to hear a stock system that can play that frequency range with authority. In order to create bass of any frequency, you need to do two things; move air, and separate the back waves from the front waves so that they don't cancel each other out. I'll go into the second item in my post on deadening.

In order to move air, you need two things: cone area and excursion. A speaker's excursion capability is measured using two variables; xmax and xlim. Xmax is the maximum electrical excursion that a driver can handle before the voice coil leaves the magnetic gap. Typically, you can exceed this by about 10% without much audible distortion. Some speakers have an xmax rating specifically at what is measured as 10% distortion, so care must be taken when comparing speaker drivers to determine if the xmax rating is derived based on measured distortion or magnetic gap. Xlim is the maximum mechanical excursion that a speaker driver can handle before the voice coil physically bottoms out and hits the backplate. What we're concerned with here is xmax, and this driver has a decent amount; 5mm.

Why is this all important? Because my goal is to have an SQ system, and in order to do that, I need to achieve a good sound stage and bass that blends and integrates well. In order to do that, I need to have this midwoofer playing at least down to 90hz. Bass becomes less and less directional as you go lower in frequency. Typically, this is around 100-125hz, so in order to prevent the sub from playing those frequencies, this midwoofer needs to play down to ~80-90hz with authority. The result will be a perfect blend between the front sound stage and bass from the subwoofer.



Subwoofer
This is an area of great debate and subjective listening. There has always been and will always be great amounts of arguing on car audio boards over which subs provide the best sound quality. Some say that the ones that measure the best with the least distortion (underhung, lambda, and xbl^2 come to mind) but others note that those subs sound lifeless, bland, and cold. Regardless of what some may say, I've chosen what I believe to be the best SQ sub for this job, the Image Dynamics 15" IDQ15 V2 D2. This was purchased on ebay for $125 shipped.

(not my picture, I found this on google images as it shows both sides of the sub)

True car audiophiles will recognize and greatly respect the Image Dynamics brand, and SQ competitors will fear the IDQ V2 series. The pair of IDQ10 V2 drivers I have in my home theater were purchased from a member on anothe audio board who won the MECA State Class A SQ championship with them. These subs are arguably the absolute best SQ subs for the money and compete with the likes of the $800 Morel Ultimo. These sound transparent, musical, and clean, with incredible transient response.

What makes a great SQ sub? To start, you need transient response. You need to be able to play a 30hz tone and immediately play a 80hz beat/pulse with no delay, lag time, or blend between those notes. In order to do this, you need both good motor strength and low moving mass. The latter is something you won't find in many subs. Most manufacturers now over-design their subs with heavy cones so they can be abused. This sub will definitely bottom out when pushed to it's limits and is not designed to be abused. These subs need to be treated like musical instruments. This particular subwoofer has a very low moving mass but a very rigid cone. It has a healthy xmax of 13.5mm, but a relatively limited xlim that encourages listeners to keep the sub within it's distortion-free range.

This sub will be wired to 4ohms for efficiency, as the amplifier I'll be using is significantly more efficient at 4 ohms than it it 2 ohms. It has a 400W power handling, and will be provided with 500W RMS. These also happen to do excellently in small sealed boxes. It will be installed in a sealed box at around 1.3 cubic feet. The box will be heavily braced and will have double thick front baffle with a recess for the sub in the outer layer.

I opted for the 15" as I wanted both SQ and a bit of punch when I felt like rolling down the windows and blasting some music. With a cone area of 840 square cm, this sub will move a lot of air. Consider that typical 8" subs have ~210 square cm, typical 10" subs have ~310 square cm, and typical 12" subs have ~520 square cm, and you'll get an idea of how capable this subwoofer is.

 

[CruzeTech]

I wont go 15. Probably wont even go 12. I had 4x 8s in one of my cars and it was amazing. Of course that was with McIntosh equipment. I dont have the 8s anymore, but I still have the McIntosh stuff. This may be going into my Eco. Im also looking at the Pioneer DEX-P99RS as a head unit since I dont have a decent one anymore.

 

[XtremeRevolution]

I wont go 15. Probably wont even go 12. I had 4x 8s in one of my cars and it was amazing. Of course that was with McIntosh equipment. I dont have the 8s anymore, but I still have the McIntosh stuff. This may be going into my Eco. Im also looking at the Pioneer DEX-P99RS as a head unit since I dont have a decent one anymore.

What's the difference between one 15 and 4 8s? About 0-50 cm^2 of cone area, which when you're already over 800 cm^2 is pretty insignificant. The idea is not to have massive output, but to get to decent levels musically and without distorting. If I had a 10 and I wanted to play a linear bass note down to 30hz for example, it would take a good amount of excursion. I want all of that excursion to be within the subwoofer's xmax and under 10% distortion. I chose this particular 15" sub because it works amazingly in 1.55 cubic feet sealed. For a 15" sub, that's a pretty small box, and that's on the larger side of what you'd need as the sub will also work well in 1.35 cubic feet. At 1.55 cubic feet, the sub has an in-cab F3 of 14hz! Talk about linear...

The problem with smaller subwoofers is that it's more difficult to dig down into the sub-bass frequencies due to a typically higher resonant frequency. It usually doesn't make a difference as that resonant frequency is typically in the mid to high 30s or low 40s, but you won't have the ability to play the same sub-bass harmonics as something like a 12" sub would.

What I have with the IDQ15 is a recipe for excellent sound quality. Low excursion, low moving mass, high cone area. The high cone area allows me to have incredible efficiency, which also means that I can get a lot of bass out of very little power, thus also reducing distortion from the amplifier. High cone area also means I get a whole lot of sound out of very little actual excursion, which helps me keep distortion way down at moderate and even higher volumes. A lot of thought went into deciding to use the IDQ15 instead of the two IDQ10 subs I also have.

I think you should definitely get your stuff installed in your Cruze. No point in having awesome equipment just sitting around. Put it to use!

 

[XtremeRevolution]

Deadening and Door Treatment
​

Today I'm going to talk about Deadening and Door Treatment. This is probably one of the most underestimated, overlooked, and misunderstood aspect of car audio. It's importance cannot be overstated. However, for some reason, most people won't so much as give it a second thought when they're considering upgrading their car audio. Most people will start with a budget, find a way to fill it amplifiers and speakers, and see sound deadening as an afterthought. In reality, it should be the first thing that's budgeted. I will be putting a great deal of effort and time into ensuring that my install is well deadened, but before I start, I'd like to explain why this is so important.

For my install, I've chosen to use the products sold by Sound Deadener Showdown, which is run by a great guy named Don. His knowledge of deadening eclipses my knowledge of car audio as a while. He can be contacted at [email protected]. His website is: Sound Deadener Showdown - Your Source for Sound Deadening Products and Information

I've chosen his products because they outperform anything I've ever used before. At one point, I would argue with him profusely that multiple layers of flashing tape like Elemental Designs eDead or DynaMAT would match the performance of his product, but after testing with my measurement microphone, I failed in proving that and instead proved him correct. Repeatedly. These are purpose built materials that outperform anything else I've seen on the market and are very affordable.

Door Sealing
Going back to the concepts mentioned earlier, in order to produce bass, you need to separate the front waves from the back waves. This is the #1 reason why subwoofers are placed in boxes. From the factory, most cars don't come with anything more than a sheet of semi-transparent or white plastic covering the door with some sticky butyl rope around the edges to hold it down. This serves as a very poor sound barrier, and your plastic door trim isn't going to be enough. This plastic sheeting is designed to block road noise coming from the outside as well as to block some of the back waves of the speaker from cancelling out the front waves. This is primarily important with bass, as these frequencies have a much greater tendency to "wrap" around the speaker. In home theater, this behavior is directly correlated to baffle diffraction. Sound waves will generally wrap around an object that is creating them. This sound wave rendering demonstrates this concept:

Sound wave renderings - pjay speaker building peter smith

When a front sound wave that is in-phase and a rear sound wave that is out of phase wrap around a speaker and intersect, they cancel out that frequency. Thus, one of two orders of business is to prevent that wrap so that every bit of sound that is being produced by your midbass driver is heard. Achieving this requires the use of a better barrier than the plastic sheet used from the factory. For my particular install, I will be using one layer of Closed Cell Foam, backed by a layer of Mass Loaded Vinyl.

Sound Deadener Showdown - Your Source for Sound Deadening Products and Information

Sound Deadener Showdown - Your Source for Sound Deadening Products and Information

Together, these will not only prevent the MLV from vibrating, but will block virtually all sound inside the door from penetrating into the car's cabin. Not only does this serve our purpose of preventing the cancellation of sound waves, but it also effectively prevents the entry of road noise into the cabin, which will allow me to actually hear every detail that my SQ system can produce with reduced outer interference. Most people will give up on SQ systems because once you start picking up speed, road noise essentially overshadows all of the hard work you've put into hearing every last detail. This is the solution to that problem. For those that are curious, I have indeed attempted to cover an entire door with flashing tape-type sound deadeners, and my results were that I increased the weight of the door unnecessarily, spent more than I should have, and the stuff was not as effective as I would have hoped.

One 36"x54" sheet of CCF and MLV will cover both doors. A roll of Extruded butyl rope will also be needed. I'll be using the 1/8" CCF.


Controlling Panel Resonance
The stock speakers in the Cruze don't do a terribly good job at producing midbass frequencies due to both the weakness of the speaker and the inadequate sealing of that sheet of plastic. However, it is a known fact that a metal panel will have a specific resonant frequency at which it will "hum" or "buzz." Typically, this is around 300-1000hz. Play your music a bit louder one day with some midbass presence and crank it up a bit, and you'll hear what I'm talking about. While you may have difficulty identifying this resonance, you will have absolutely no difficulty noticing that it's gone once you eliminate it. The result will leave you astounded.

The fundamental function of a speaker is to vibrate in order to create sound. If that vibrating speaker also causes the metal door panels to vibrate, they too will create sound, only that will be sound in addition to what is commanded by the amplifier, also known as distortion. In an effort to ensure that we have clean, accurate, and detailed sound, we need to control these panel resonances. This is another area where Don's product is superior to anything else I've ever used. It would take at least 5 back to back sheets of Dynamat to even come close to the performance of one CLD tile.

Sound Deadener Showdown - Your Source for Sound Deadening Products and Information

While other products I've used in the past will have an extremely thin sheet of aluminum foil over a small layer of adhesive butyl or asphalt rubber, this product uses a solid piece of aluminum that retains it's shape when bent and will easily cut your hands if you aren't careful. I'll let his website speak for the effectiveness of this product, but I will stress the importance of using it in my car. This will be installed on the outer door skin (on the inside of course), and on the inner door trim to effectively eliminate panel resonance. These will also be installed on the rear deck, trunk lid, and trunk floor to prevent those from resonating when the subwoofer's bass beats hit. All in all, I will be installing about 24 CLD tiles in my car.

It is common for one to spend more on sound deadening than they would on the speakers in the car, and after working with deadening over the last several years, I can certainly see not only a benefit, but a requirement for it when attempting to achieve any level of sound quality. If I was on a budget, I would install CLD tiles as a minimum. One note I'd like to make is that this stuff is permanent. You can remove it (with difficulty) within the first ~24 hours after you install it, but if you wait too long, you'll never get it off without a scraper and some solvents.

What point is there in achieving the absolute best sound quality out of a set of components only for those efforts to be drowned out by road noise and panel resonances? If anything, this should be the first step someone takes in an effort to improve their sound system. I will be measuring this panel resonance both before and after the CLD tiles are installed to demonstrate the difference.

 

[CruzeTech]

What's the difference between one 15 and 4 8s? About 0-50 cm^2 of cone area, which when you're already over 800 cm^2 is pretty insignificant. The idea is not to have massive output, but to get to decent levels musically and without distorting. If I had a 10 and I wanted to play a linear bass note down to 30hz for example, it would take a good amount of excursion. I want all of that excursion to be within the subwoofer's xmax and under 10% distortion. I chose this particular 15" sub because it works amazingly in 1.55 cubic feet sealed. For a 15" sub, that's a pretty small box, and that's on the larger side of what you'd need as the sub will also work well in 1.35 cubic feet. At 1.55 cubic feet, the sub has an in-cab F3 of 14hz! Talk about linear...

The problem with smaller subwoofers is that it's more difficult to dig down into the sub-bass frequencies due to a typically higher resonant frequency. It usually doesn't make a difference as that resonant frequency is typically in the mid to high 30s or low 40s, but you won't have the ability to play the same sub-bass harmonics as something like a 12" sub would.

What I have with the IDQ15 is a recipe for excellent sound quality. Low excursion, low moving mass, high cone area. The high cone area allows me to have incredible efficiency, which also means that I can get a lot of bass out of very little power, thus also reducing distortion from the amplifier. High cone area also means I get a whole lot of sound out of very little actual excursion, which helps me keep distortion way down at moderate and even higher volumes. A lot of thought went into deciding to use the IDQ15 instead of the two IDQ10 subs I also have.

I think you should definitely get your stuff installed in your Cruze. No point in having awesome equipment just sitting around. Put it to use!

Oh, I HAD 4x 8s. Installing something now, I wouldnt go with more than 1 or 2. Maybe even 1 x 10. And I may do something flush mounted into the hole I already have in the floor. Something I can pickup or pull out to get to the pump. I think it would be worthless to use my amp and keep the stock deck in there. I dont have a head unit anymore, thats why I was looking at that Pioneer setup. Id like to put the Mcintosh H/U in there, but I just dont think it goes well with the lines of the dash, which is semi important to me.

Also I see in your tutorial, you referred to these as being better than Dynamat. How much does this stuff weigh? As you know, Dynamat is extremely heavy.

 

[XtremeRevolution]

I had a couple of neo 10" Tang Band subs I recommended to a guy that would work very well in the space in that cavity. Search the electronics section for recent threads.

I'd get a new head unit, but with the MiniDSP, it's really not necessary. These are worlds better than the head units in older GM vehicles. There simply isn't enough benefit to spending another few hundred dollars on a head unit and factory integration modules, and it kills the whole stealth thing I'm going for. Depends on where you live and work I guess.

What material are you referring to? The CLD tiles? The reason why Dynamat weighs so much is that you need so much of it to serve the same purpose that some CLD tiles. As Don puts it, you need the right tool for the job. You shouldn't be covering every square inch of metal surface with the damper, and you shouldn't be using it to seal air holes. That's what the MLV is for. One product that's meant to do everything will do nothing particularly well. All of the SDS materials I'm using are purpose built for a specific goal. The CLD tiles for damping, the CCF and MLV for sealing and sound blocking.

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[CruzeTech]

Im not familiar with the miniDSPs uses. Are you saying they offer the same or similar qualities as a high end head unit out of the stock stereo? I'd hate for the head unit to be the single point of failure. Id really like the stealthiness of the stock unit as well. Im not all that familiar with the different equpiment that come in these cars. I have the Eco as you do, but I have the standard head unit. I dont have the upgraded setup, 9 speaker or whatever the next upgrade is. I honestly went out and bought the car because a friends sells them and I liked his. I trust him, Ive known him for almost 30 years. I didnt plan it, I didnt review the car, I didnt read about what options were available. I bought what was on the lot, I didnt add any options. I guess I should look at that stuff. Its more of a hobby of owning cars. I thought it looked nice, its not my primary car, I do like to drive it though and find myself grabbing the keys more than my other cars costing 2-3 times the money. So I would like to put a nice setup in it.

 

[XtremeRevolution]

Im not familiar with the miniDSPs uses. Are you saying they offer the same or similar qualities as a high end head unit out of the stock stereo? I'd hate for the head unit to be the single point of failure. Id really like the stealthiness of the stock unit as well. Im not all that familiar with the different equpiment that come in these cars. I have the Eco as you do, but I have the standard head unit. I dont have the upgraded setup, 9 speaker or whatever the next upgrade is. I honestly went out and bought the car because a friends sells them and I liked his. I trust him, Ive known him for almost 30 years. I didnt plan it, I didnt review the car, I didnt read about what options were available. I bought what was on the lot, I didnt add any options. I guess I should look at that stuff. Its more of a hobby of owning cars. I thought it looked nice, its not my primary car, I do like to drive it though and find myself grabbing the keys more than my other cars costing 2-3 times the money. So I would like to put a nice setup in it.

I was going to wait until I made a post specifically about the MiniDSP like I did for the other components I've chosen so far, but since you asked, I'll explain how it works.

The MiniDSP
The way I see it, the head unit serves a few purposes in a system like this. First is to control your music inputs. Previously, I would buy one for the aux input as well as a USB input for a flash drive. The Cruze has both, in addition to bluetooth, steering wheel controls, and XM. The only real question there is how good is the pre-amp inside the head unit? From what I've been hearing, it's good (which can't be said of the kind you'd find in a 1995 or 2000 w-body for examaple), which is all I'm really concerned with. What I will be doing is hooking up that PAC LOC that basically gets plugged in between the radio's harness and the radio itself and provides me with 2 sets of RCAs. One of those sets will go to my sub amp, and the other set will plug directly into the back of the MiniDSP.

You then plug in the remaining two sets of output RCAs to two individual 2-channel amps (or one 4-channel). What you now have is 4 channels of sound; a tweeter left and right, and a woofer left and right. So here's where the magic happens. The MiniDSP a digital sound processor. You give it power, hook it up to your laptop via USB, and using their software, you see something that looks like this. Here are the two more important screens available, among many others.

The first screen basically allows you to select a cut-off for the tweeter and then for the woofer. This makes it so I don't need a physical crossover; it's all digital. We don't want the tweeter playing bass frequencies or the woofer playing treble frequencies. You can figure out where to select this cut-off based on the tweeter and woofer you chose by looking at the specs and the frequency response charts. All good tweeters and woofers will have these available. In my case, with a tweeter that has a resonant frequency of ~700hz, I can probably hit 1000-1500hz as a cutoff. I'll have a section that allows me to adjust gain/sensitivity as well.

The second screen then gives me a 31-band equalizer. Keep in mind, this can all be adjusted in realtime. What I do then is I hook up my measurement microphone and I play a few averaged log sweeps that record the frequency response of the system. I observe where peaks and dips are, and I adjust the equalizer on the MiniDSP, and I take another measurement, then repeat until it measures well. Once it looks good, I have a listen with some real music, slowly increasing volume. If the treble starts sounding harsh or strained, I'll know I'm crossing the tweeter too low, so I'll adjust the crossover frequency a bit higher. Then, I'll adjust the equalizer to suit my own personal preferences. For example, I like a little extra "sparkle" in my tweeters above 10,000hz, and a little less treble between 2000-6000hz (similar to the "BBC-Dip" - google that one).

Basically, so long as the sound quality coming out of the amplifier is good, this MiniDSP will make it so the frequency response is completely flat. Of course, there's also the ability to configure time delay in .002ms incremements for phase/time alignment purposes, but I could spend the whole night explaining that one.

Once you have the system calibrated and adjusted, you don't need to make changes unless you don't like something. A good SQ system will sound amazing with all types of music so you won't need constant adjustment of the equalizer. Knowing all of this, what then is the purpose of a new head unit? A touch screen? Navigation? An SDCard slot? Those are the only features I can really find that this system wouldn't have, but good luck finding a head unit with a 31-band equalizer.

 

[CruzeTech]

Pioneer Stage 4 DEX-P99RS This has some pretty impressive specs. Based on the specs of this unit, can the miniDSP duplicate, to a degree, what I would be able to get out of this unit? I know the 24bit AKM DACs dont come in but 2-3 head units.

 

[Survivor058]

very nice write up on everything. ill be doing a post hopefully next week on a kicker setup ill be doing on my crude that will be replacing the 9 speaker pioneer system. i will be using some of these methods but different parts. also only going with one sub and its not the L7. will probably be using a 5 channel amp but details to follow great write up!

 

[XtremeRevolution]

Pioneer Stage 4 DEX-P99RS This has some pretty impressive specs. Based on the specs of this unit, can the miniDSP duplicate, to a degree, what I would be able to get out of this unit? I know the 24bit AKM DACs dont come in but 2-3 head units.

It will give you the MiniDSP. As far as the rest, it will be whatever the head unit has. Honestly, you're comparing a $150 MiniDSP with a factory head unit to a $1200 Pioneer deck. WAY out of the scope of this thread. I guarantee you that you would get better sound if you even went with a $500 Pioneer deck and added a MiniDSP to it.

The problem you have is that the Pioneer head unit you posted is not a crossover processor, it just provides some fancy signal. In the end, you still need to plug in speakers that will have their own crossovers or use a MiniDSP along with this in order to get select your own crossover points and slopes.

very nice write up on everything. ill be doing a post hopefully next week on a kicker setup ill be doing on my crude that will be replacing the 9 speaker pioneer system. i will be using some of these methods but different parts. also only going with one sub and its not the L7. will probably be using a 5 channel amp but details to follow great write up!

Please, please don't use Kicker stuff. The only good components they make are amplifiers. Their subs sound like crap and do not even belong in the same sentence with SQ. Even their SPL "just plain loud" subs are horribly inefficient, underperformed, and overpriced. If you want SPL, go Digital Designs or Sundown Audio. If you need some advice on parts, feel free to ask. I guarantee you that there are infinitely better parts on the market than what you can buy with a Kicker label.

I feel like I'm being a bit of an ass since you complimented my writeup, but I'm trying to do you a favor here. Just trying to help you get the most out of your money.

 

[CruzeTech]

I read a few reviews on that Neo 10" most people gave it good reviews and commenting that it actually fit under their seat in a box. But there were a few people that said it was too noisy to be good. And mentioned it was in the high end of noisy for a sub. And that connecting it to a tone generator you'd know it right away.

"I hate to go against the trend of positive reviews here but
just connect this thing to a tone generator and listen. It's just a little noise
box! I didn't bother with distortion measurements because it was clearly not a
driver I would have any use for due to the excessive noise. I would very much
like to find a low profile driver like this with good performance but this
simply isn't it.
I ran it up and
down from 10 Hz to a few hundred. Above a couple hundred Hz the noise audibly
goes away but I'm sure it's still there and would be measurable.

A lot of woofers
are noisy. In fact it's very difficult to find one that isn't. I have to say
this one was right up there with the worst of them however. If you are going to
put this in any kind of box, vented or sealed, you may not notice the noise so
much but it's there and destructive to sound quality. Forget putting these in
open baffle, at the low end all you would hear is noise!

Monte"

 

[XtremeRevolution]

Keep in mind, not everyone knows how to build sub boxes. A sub can be considered noisy if it's mounted to a box that's not sealed well. A small air leak will make the sub sound extremely noisy. I certainly haven't ever heard of a sub that sounds "noisy."

Since he said it goes away above a couple hundred hz, that makes me believe that the noise is excursion related and that he either had a leaky box, or he ran it free air. Free air, most subs will have suspension noise, but that will not be audible because the primary purpose of a box is to separate the sound created inside the box from the sound created outside. Otherwise, the back waves created by the sub would cancel out the front.

In this particular case, where we're considering installing these in a sealed box, this will be a non-issue.

 

[CruzeTech]

I just dont want a 100 pound box in my car. To me the car is light enough. I dont want to add that kind of weight in the trunk. Something that I only need a few cu ft for is what I want. The question is. 1x10 or 2x8?

I may go 2x10s but that depends on how big the box needs to be.

 

[XtremeRevolution]

I just dont want a 100 pound box in my car. To me the car is light enough. I dont want to add that kind of weight in the trunk. Something that I only need a few cu ft for is what I want. The question is. 1x10 or 2x8?

I may go 2x10s but that depends on how big the box needs to be.

There are a lot of subs out there that will fit in very small boxes under 50 pounds . The Alpine 8" Type R can be used in under .5 cubic feet. The dayton HO 10 fits in well under 1 cubic foot sealed. I can't recommend a good sub without knowing what your goal, budget, and listening preferences are.

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