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The Complete Guide to Using your Stock Car Stereo as a Legitimate Engineering Tool.

My Multi-Use Mixer Stand Project
July 4, 2016
The Green File Debacle in Windows.
December 1, 2016

Bass: -4
Treble: 0
These are the settings I use for my 2013 Mazda 3’s stock stereo. If those settings are a surprise, then this blog post is definitely for you.

I spend a lot of hours on the road between Los Angeles and Bakersfield. Each round trip is 250 miles and I can almost navigate the drive “by braille” because I am intimately familiar with where all the potholes are on the interstate. I usually like to kick my shoes off, pop open an Orange Rockstar Recovery, set the cruise control and then commence audio consumption.

When I purchased the Mazdarati, I got it because it was inexpensive, reliable and was going to be friendly on the wallet for my commutes. The stock stereo wasn’t anything special but I had already decided that I wasn’t going to install an aftermarket system like I’ve done with many of my vehicles from the past.

As an audio engineer, it’s purely second nature to want to try and optimize the sound of a system and push it to its limits to see what it’s capable of. It’s not so far off from what a mastering engineer might do to fine-tune a song to its maximum potential and get it sounding the best it possibly can. The Mazdarati didn’t offer much in the way of tone controls – only separate “Bass” and “Treble”, plus your typical balance and front-rear fader levels. What you have in your own vehicle doesn’t really matter. It’s all about finding the “sweet spot” of the system.

Finding the sweet spot is a bit of subjective process and how you arrive at what the ideal settings are for your system is going to vary from user to user and car to car but the principals are pretty similar and the practices that surround your quality control will serve you well.

For me, I started with what anyone naturally would – the volume knob and an FM radio station. Let’s see how this thing sounds from the factory without any tweaking at all. The Mazdarati factory audio experience was not very impressive I must say. As I turned the volume up, the bass was too muddy and the mids/lo-mids were slightly too boomy/boxy. Because of this, the treble seemed buried.

Note: if you’re going to try this with your own stock stereo system, I would recommend that you set all of the tone controls flat in the middle so nothing is being boosted or cut. Balance and fader to flat as well. Basically “reset” the system to factory settings so you have a consistent base line to work with.


Now, we all know (or *should* know as audio enthusiasts) that FM radio runs everything through a brick wall limiter (among other things) to smash the audio so it’s LOUD and to prevent the level from crossing a specified threshold and over-modulating the station’s transmitter (which is illegal, if I remember correctly). All you need to know is that radio is a terrible medium to use as reference material for your system.

The Aux Input is what you need to be concerned with.

Plug your phone into it, find some music you are familiar with and let it play. The more you know how this music sounds on other systems (like in your control room or on your headphones) the easier it’s going to be to try and match that sound in your stock system. Kendrick Lamar’s GKMC is an album that I am intimately acquainted with. I’ve listened to it 200 times easily and studied it intensely. Even though it may not be the greatest engineered album of all time, it’s still one of my desert-island reference pieces. Everyone, and I mean EVERYONE, who is an audio professional should have a collection of reference material that they rely on.

So now I have Kendrick bumping and I am starting to tweak the system. My main objective is to get the album sounding “right”. Since the factory stereo is putting out too much bass, I have a couple options. I could boost the treble to try and equal them out but doing this made the album sound too brittle and bright. The other option is to CUT the bass. -2 ended up sounding about right until I turned the volume up so I finally settled on -3 for my bass. This setting gave me a smoother sounding and more accurate low end and it also helped with the lo-mids that were a little boxy before. Because I don’t have a midrange control, the volume knob becomes the only thing that can affect it when I’m listening so the trick is to balance the bass and treble to the fixed midrange. On my system, adding ANY treble makes the high end too bright compared to the midrange and bass so treble stays flat at ZERO.

Note: If you’re one of those people who automatically boosts the bass and treble on your car system, that *might* not be the optimal settings for the system in question. If you think it sounds dull when you return those controls to flat, turn them down even farther (all the way) and then back up to flat and then it may sound a little more reasonable to your ears.

Now that I have Kendrick sounding pretty good, I check a few other reference pieces. Steely Dan’s Aja is one of my favorite albums of all time and revered in the industry as a production and engineering masterpiece. It’s not a bass-heavy album so I don’t expect it to hit like a modern Hip Hop album would and in the Mazdarati, it sounds optimized with the bass at -1 which is what I would have expected. The thing to note here is that once you find a globally optimized setting for your system, you LEAVE IT THERE PERMANENTLY. This allows you to compare apples to apples, and eliminates variables (which complicate any assessment process). Nicolay’s City Lights albums are also some of my favorites to reference with. After listening to quite a few sources I decide on Bass:-3 and Treble:0 as the final global setting for my factory stereo.

Now I need to find the optimal volume setting.

It’s not a good idea for an audio engineer to blast music at loud volumes (especially for extended periods of time) but we do need to find the point where our system clips and starts to distort so that we can specify the exact level that we should be listening to in order to compare and assess different songs in the listening environment. Bump the Kendrick again: Money Trees. I get the volume up so that the kick starts to distort, then I back it off to where it has a little bit of headroom and sounds clean. It’s “33” on the volume knob but there’s an issue that needs to be addressed. My iPhone.

Because I am using the headphone jack on my mobile device, I need to find a volume setting for it that will be the DEFAULT setting I use when I feed the Aux In on the factory deck. Now, MANY devices operate on the unity gain principal for their audio outputs. That means that there is a level on the volume knob where the audio is neither being amplified, nor attenuated. This is the level we want coming out of the phone. One of the things I was taught in audio engineering school is that most devices are at unity gain when they are at roughly 75-80% of their full volume. This holds true for my iPhone 6s back to my iPhone 3s: Full volume, minus two clicks of the volume down button = 80% roughly.

A couple things happen if I ignore this level coming out of my phone. One of them is distortion. Even if it’s slight, it adds a variable to our system that prevents us from making the best informed decision about what we’re hearing.

“But my phone doesn’t distort even when I have it at maximum volume.” You might be right. OR… your phone is using an automatic built-in compressor/limiter that keeps it from distorting at high volumes, which is a feature of MANY mobile devices. The problem… it’s messing with the dynamic range of the audio – another variable. If your ears aren’t trained to hear this gain reduction tool, then you’ll be trying to make assessments on your latest mix and not understand why it doesn’t sound right. The best practice to take away from this is to set your volume around 75% and ALWAYS use that level to eliminate variables.

So now that my phone is set at the correct volume, Kendrick at “33” is too loud for my stock stereo. I dial it back a few clicks and after some additional extended listening“29” is now the OPTIMUM level to audition songs.

The Mazdarati has another setting on my deck called ALC which I assume stands for “Auto Level Control”. It basically turns the volume up when the car goes faster (and has more road noise to contend with) and turns it down when the car slows down. I don’t need this in my life. I am an audio engineer and I want constants, not variables.

Speaking of variables, let’s talk about apps for a moment. The apps you use to listen to music introduce variables. Spotify, Pandora, YouTube, Apple Music, Amazon – each one uses a different algorithm and data compression scheme for their platform. Some may have EQ curves you can apply to your music (Jazz, Rock, Pop, etc). Using these complicates your ability to compare apples to apples - unless you listen to your mixes using the same app that you listen to other music with. For me, I use Amazon Music’s cloud player. It stores all the albums I’ve purchased but it also lets me upload my own MP3’s to add to the library. I upload a mix and can then make a fair comparison about how things are sounding compared to all the other reference tracks that are in my Amazon Music library. For *you*… this might be iTunes. Or maybe it’s listening to a track right from your email inbox. The key here is to use the same “app” or method when you critically listen to music so that you eliminate variables that exist from using multiple platforms.

So in the Mazdarati, everything at this point is now SET IN STONE as far as settings go on all devices/apps and I am working with a constant set of variables. This allows me to open a mix I just worked on and know IMMEDIATELY if the low end is too much. It lets me know if the song is too bright. It lets me know if the song is over-compressed or limited too much and thus, too loud. I can get a clearer picture of how everything is balanced in the mix and what could maybe use some minor tweaks back in the control room. It’s become a legitimate assessment tool that I use as an audio engineer for my clients. One final note to leave you with… Because I bought my car used, I assumed the previous owner played enough music so that the factory speakers were broken in. They weren’t. Over time, they loosened up which increased the bass response fairly significantly and I had to compensate by adjusting my Bass to -4 where it’s been now for more than 18 months. If your stereo speakers are new, it wouldn’t be a bad idea to burn them in before you start trying to optimize your system. There’s plenty of resources online that tell you how to do this – it’s the same process for new headphones (which you should consider doing when you buy a pair).

Thanks for reading!


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