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Discussion Starter #1 (Edited)
Thread will be closed until my initial posts are completed.

Scope:
Due to many requests and high demand for system design in this car and the MX-5, I've decided to get a thread on a proper audio build going. The purpose of this thread is to take you along my process for designing, tuning, and installing a mobile audio system in the 124 Spider, with consideration for constraints and specific goals. This thread will provide recommendations for equipment but is ultimately intended to give you the information you need to design your own mobile audio system. Since some of the components I'll be using may be discontinued by the time you are reading this, the focus will be more on the "why" as opposed to the "what." That being said, I will publish my tune specifications for the components I'm using as well as making recommendations for currently available components. I expect that most people will follow my component recommendations to guarantee the same results I achieved.

This thread does not assume that the components I am using are the best on the market or that you couldn't achieve better results with better equipment. The focus will be on bang for the buck within a reasonable price point consistent with the price point this car sold for, but without sacrificing key quality requirements.

Before we continue into technical audio discussions, it will be greatly beneficial for you to have a fundamental understanding of acoustics. For this, I have four articles written on my website to give you a crash course: http://xtremerevolution.net/category/home-car-audio/audio-101/
 

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Discussion Starter #2 (Edited)
Constraints & Requirements:
This is one of the most important aspects to a mobile audio install. It is important to understand the environment you're working with and its specific acoustic challenges before you dive head-first into mobile audio. One of the biggest mistakes people make in mobile audio, and a mentality that is perpetrated by much of the mobile audio industry, is that you can get better results by just throwing more money at it. While there is some ray of truth to getting better results by using better components, everything has to be used correctly.

Since audio installs tend to be highly subjective with a great deal of brand bias/loyalty, it's important to establish the constraints around which this system was designed and built. Without constraints and requirements, we don't have an objective manner in which to design the system. With constraints and requirements clearly defined, we can narrow down our options. Here are the constraints and requirements I've set for this showcase project:

Space: This is the most obvious of our constraints. The car is small, so the components used will have to be as well. Multiple considerations will be made for component location, which may involve some unusual and unconventional install locations for components. This will inevitably make install more difficult, but will better utilize already extremely limited space. Folks, it doesn't get much more limited than this. Despite this limitation, the goal is for this system to not take away any functional space from the interior or storage of this vehicle. Every effort possible will be made so that the trunk, storage compartments, and interior space will remain the same as stock.

Budget: As I noted before, this isn't a Ferrari, so I will not be installing Focal or Morel speakers, Hertz amplifiers, or Audison digital processors. That's not to say you can't get good results with those, it's simply difficult to justify components of that caliber with my budget and the noise floor we have to deal with. I am setting a target budget of $1,200 USD for this project. .

Noise Floor: Because this is a convertible, no matter what you do, the car will not be suitable for ultimate sound quality. That being said, sound quality is not the only goal of an upgraded system. Most people following this thread will be looking for louder and less fatiguing sound under top down driving conditions, as well as clearer sound with the top up. We won't be chasing every last bit of distortion away, and I won't be spending money on high dollar amplifiers to get rid of that last 0.1% THD. You're more than welcome to your adaptation of this build, but I don't feel that the extra cost of high end amplifiers justifies the comparably minor sound quality improvement. This will make it easier on our budget while also allowing us to set reasonable expectations. I'm going for loud and clear with low fatigue.

Complexity: Because we have some pressing constraints, that increases the complexity of our install. This is more of a compromise than a constraint, but it goes without saying that this will not be as simple as in larger vehicles. For example, while I might be able to get away with more easy to use drivers like I did in my Cruze, this car may require some unconventional approaches to driver choices. That being said, I am setting a requirement for simplicity.

Because I want world-class sound to be accessible to everyone, I will make the following efforts to reduce complexity:
- I will be doing all of the tuning for free. That means I will spend several hours in my car with a measurement microphone precisely tuning the in-cab response, adjusting crossover with 3rd order harmonic distortion, and setting time alignment so all you have to do is download the file, upload it to the DSP, and hook it all up. The only drawback to this approach is that the tune will be specific to the speaker drivers I end up using.
- I will only use a 5-channel amplifier in order to eliminate wiring and reduce component cost.
- I will provide a power cable kit with hydraulic terminal crimps specifically measured for the 124 Spider's cabin so all you have to do is run the cable, hook it up, and you're done. You'll have good, true AWG OFC cable for power and ground with proper crimps.
- I will use factory integration wiring to effectively eliminate any cutting or splicing of factory wiring and allow you to revert the entire car back to stock without any trace of anything having ever been done.

Factory Integration:
I don't like splicing into wiring; it damages the casing and exposes it to corrosion long-term. As a result, I have spent hours of research finding factory integration modules. As a result of these efforts, if everything fits according to plan, there will be no need to cut or splice any factory wiring, resulting in a clean, easy install that anyone can do on their own.

LFE (Low Frequency Extension): Basically, bass; how low can you go? Not that we need earth-shaking bass that can be felt from a block away, but we do need tonal accuracy and the capability of the lower frequencies to keep up at louder volumes. For that, we need a subwoofer, and this system will have a subwoofer! I have not decided if it will be an 8" or a 10". I am 90% confident that we can fit a 10" sub, without using the trunk or any cabin space that is currently available for driver or passenger.

Advanced Tuning:
We're not just going to slap a pair of component speakers in and call it good. I have a level of sound quality that I won't compromise on. This system will include time alignment, frequency response tuning, and precisely measured crossover slopes to allow the best sound stage this car can possibly have.

Stealth:
Nothing says "rob me" more than fancy high dollar equipment that you can see plain as day. We will build everything into this car in hidden or factory locations so you won't even be able to tell anything has done, aside from the preset controller on the DSP.
 

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Discussion Starter #4
Thread unlocked. If anyone has any questions about what I've said so far, or where I'm headed with this project, please let me know.

Today I reached out to a friend of mine for help with this build. As a pioneer in the mobile audio industry, he has a great deal of experience and has agreed to support my project, which will ultimately benefit everyone in the 124 Spider and MX-5 community. With his expertise and experience, I am entirely confident that this will be an affordable world-class audio install to set an example for what can be achieved in this platform with a bit of planning, patience, and methodical design.
 

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One more item for your Scope is which system you are upgrading - non-Bose or Bose, and whether your recommendations will apply to both, or not. I'm actually pretty pleased with the sound emanating from my non-Bose system in my Classica, and most of the complaints that I've noted actually seem to come from those with the "premium" Bose system (audio-pilot is a waste of 4 headrest speakers!).

I'm open to easy upgrades though ;)
 

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Discussion Starter #7
One more item for your Scope is which system you are upgrading - non-Bose or Bose, and whether your recommendations will apply to both, or not. I'm actually pretty pleased with the sound emanating from my non-Bose system in my Classica, and most of the complaints that I've noted actually seem to come from those with the "premium" Bose system (audio-pilot is a waste of 4 headrest speakers!).
This should apply to both. I would assume that anyone who wants to upgrade will be pretty much gutting the factory system.

I have no intention to utilize the headrest speakers. Those will remain connected, and the system will be faded forward.
 

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One more item for your Scope is which system you are upgrading - non-Bose or Bose, and whether your recommendations will apply to both, or not. I'm actually pretty pleased with the sound emanating from my non-Bose system in my Classica, and most of the complaints that I've noted actually seem to come from those with the "premium" Bose system (audio-pilot is a waste of 4 headrest speakers!).

I'm open to easy upgrades though ;)
What does this "auto pilot" do anyway?
 

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This should apply to both. I would assume that anyone who wants to upgrade will be pretty much gutting the factory system.

I have no intention to utilize the headrest speakers. Those will remain connected, and the system will be faded forward.
This is exactly the kind of solution I am looking for!.
Leave the headrest speakers the way they are, and probably tap into the audio at the output of the TAU.
I would happily replace the Bose speakers and amp. I already have an Alpine and a Hertz 4 channel digital amps sitting around new in boxes ready to devote to the project and will consider a subwoofer upgrade if it can be done without compromise the trunk space.

Sitting on the edge of my seat,.....:)
 

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I'm going along for the ride on this one for sure! I usually just lurk around on various forums gaining what info I can (this is what, my 3rd post this year anywhere. LOL) but I remember seeing a pic of a MX-5 with the interior removed so you could see the area between the trunk and interior. I'll see if I can dig it up so we'll get a better look at available space there.
 

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Hey Guys, just did some investigation of space in the car and, as XRev pointed out, there's not much. Not sure what size the components will be, so I'm just pointing out some nooks and crannies of space. There's a fair amount of space in the rear quarters in the area above the side marker lights. That's about it for the trunk area. The center (rear) console and cubbies behind the seats take up all the area behind the seats up to the "rectangle". Still trying to figure out if there's anything under the "rectangle" that the roof sits on when it's down. If nothing else, here's what the trunk looks like for anyone who hasn't gone exploring yet.
 

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Also found this pic which appears to show that the deck behind the seats is pretty much flat into the trunk area, so maybe there is a hollow under the "rectangle" that the retracted roof sits on/above. Unless there is something mounted here, it may be some valuable space that could be utilized.
 

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Discussion Starter #17
Also found this pic which appears to show that the deck behind the seats is pretty much flat into the trunk area, so maybe there is a hollow under the "rectangle" that the retracted roof sits on/above. Unless there is something mounted here, it may be some valuable space that could be utilized.
The area under the top, when it's down, is utilized by the two cubby holes and the center console. I don't mind re-purposing the cubby holes but the center console is valuable space I'm not going to mess with. Keep in mind that any amplifiers we put back there will need at least *some* ventilation.

I'll do some more digging tomorrow.

If I can't find a place to fit an amplifier, I might just compromise the trunk for a *thin* but long amplifier. That wouldn't be too much of a loss, but I won't be dropping in a sub box.
 

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The area under the top, when it's down, is utilized by the two cubby holes and the center console. I don't mind re-purposing the cubby holes but the center console is valuable space I'm not going to mess with. Keep in mind that any amplifiers we put back there will need at least *some* ventilation.
Just wanted to point out the "rectangle" again. You can see the backs of the cubbies (felt) and center console (hard plastic with a bumper on top so I think the roof actually rests on this when down) and then there's the molded "rectangle" behind these. You can feel it if you put your hand right to the back of the cubbies. If there is a void under the "rectangle", this would be some serious space (at least for this car). Just looking to see if a total "stealth" installation is possible. :)
 

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Discussion Starter #19
Just wanted to point out the "rectangle" again. You can see the backs of the cubbies (felt) and center console (hard plastic with a bumper on top so I think the roof actually rests on this when down) and then there's the molded "rectangle" behind these. You can feel it if you put your hand right to the back of the cubbies. If there is a void under the "rectangle", this would be some serious space (at least for this car). Just looking to see if a total "stealth" installation is possible. :)
I checked that out and it feels solid underneath. I pulled the panels out of the trunk and the space there is pretty limited. I might end up sacrificing some space at the bottom of the trunk in the sunk in area for an amp, but the sacrifice will be minimal for the gain.

The cubbies will be good for something like a DSP or other signal processor.

In other news, I am going to fit a sub in this car, and it won't take up any extra space. I don't want to spoil the surprise yet but it's going to be absolutely incredible.
 

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Discussion Starter #20
Oh and side note, if anyone wants to cut down on some road noise, the bottom "pan" area of the trunk resonates LIKE CRAZY. I'll take a video soon so you can see and hear what I'm talking about. I'm actually really baffled that FIAT didn't do any sound deadening there. That's a huge miss.
 
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