Audio Upgrade Guide, Part 1: It All Starts with the Source

PART 1: It All Starts with the Source.
a.k.a. Why you should always upgrade the head unit first.

There are a lot of people who own Nissan Frontiers that eventually get that audio itch. They want to upgrade to better sound, but many try to pinch the budget by coming up with all kinds of methods to keep some components from the OEM system to save a few bucks – and generally, it’s always the head unit, as in they want to keep the OEM head unit and upgrade to better speakers or something. For the uninformed, it’s easy to want to keep the OEM Nissan head unit, especially the more recent iterations. I mean, look at how good they make it seem! They even call it smart, giving you a head unit that’s all high tech with a fancy touch screen and satellite radio and other cool apps and stuff:

The problem with this is that the basic rule of dependency applies to car (truck) audio as well:  every stereo system is only as strong as the weakest link – and unfortunately, the Nissan Frontier’s OEM head unit is that weakest link (yes, even that Rockford Fosgate system you paid extra for when you picked a Nismo/Pro-4X).

Even Basic Aftermarket Sounds Better
To quickly illustrate just how bad the Frontier’s OEM Nissan head units are, take a look at this super inexpensive, simple aftermarket stereo as an example – I present to you the Dual XDM270:

Yes – the current price (quoted from Crutchfield as of this writing) of the simple little aftermarket head unit shown above is less than $25. It doesn’t have a fancy touch screen, it doesn’t have Apple CarPlay or Android Auto, and it doesn’t do SiriusXM or Pandora. But when it comes to sound quality, guess what? This $23 basic head unit is capable of producing much better audio quality than your fancy OEM Nissan head unit!

“How can that be?” you wonder? Let’s take a step back from parts shopping and rewind to the basics. Diagram A below shows the four components of car audio and the direction that your music will take. We’ll call this the “Path of Audio”:

The path goes in only one direction (left to right) with the head unit being the “source” (or origin) of the audio signal – whether it’s AM/FM radio, CD/DVD, on-board music files from your connected phone, or streaming music from the Internet. The signal then optionally gets processed by a DSP (Digital Signal Processor, if equipped) or an EQ (Equalizer, if equipped), or even basic tone controls (i.e. “Bass/Treble” knobs, or “Hi/Mid/Lo” adjustments). From there it gets amplified (makes the sound louder), and finally the signal comes out from the speakers in your truck in the form of actual sounds that your ears hear.

Diagram B, below, shows what the audio path looks like in the OEM Nissan audio systems; note that while the standard system (B1) has the source, processing, and amplification all built into the OEM head unit, the premium-level Rockford Fosgate system (B2) features an outboard, separate amplifier in between the OEM head unit and OEM Rockford Fosgate speakers:

Volume Limiting: The Worst Thing You Can Do to Audio Signals
Alrighty, so what’s so bad with the OEM Nissan head unit? Two words: Volume Limiting. Though this guide focuses on Nissan Frontier owners, a majority of OEM Nissan head units (yes, even the “Rockford Fosgate” and “Bose” systems in almost ALL Nissan/Infiniti head units since the late ’80s) have a built-in “don’t blow the speakers!” safeguard in where the head unit reduces the highest (high pitch tones) and lowest (bass) frequencies when you turn up the volume. Here’s a visual of what I mean:

The blue line above shows the frequencies as they are being played by your OEM Nissan stereo at low volume. When you raise the volume, you get the red line. Notice that while the middle portion of frequencies (a majority of the music and voices) go higher in volume level, the lowest audio frequencies and the highest audio frequencies (circled in yellow) get left behind. This is your head unit actively limiting the highest and lowest frequencies. Yes – it’s purposely giving you weak bass and nonexistent highs by design.

The reason why they do this is simply to ensure you don’t blow the OEM factory speakers (that alone tells you that your OEM speakers are inferior). Without diverting too far from the current topic, know that your OEM factory speakers are not meant to be powered by more than about… 2-watts. Because of this, when you raise the volume, not only do you have a smaller range of frequencies going to the speakers, but chances are since the OEM speakers themselves are very basic in producing a good sound, the result is loud – but bad quality – sound. Remember what I said about the “Path” of car audio? If your source is bad, nothing you do afterward will make it as good as it should be, like so:

The Head Unit is the Key to Sound Quality
So full circle now, remember that sub-$25 basic aftermarket brand name car audio head unit I mentioned at the beginning? That aftermarket head unit does NOT do volume limiting. That aftermarket head unit will produce a complete audio signal from the lowest lows to the highest highs, no matter what you set the volume to, and regardless of whether your speakers can handle the signal or not. Aftermarket head units offer a wider frequency range to produce higher quality, richer-sounding audio. When you turn the volume up with brand name aftermarket head units, this is what the frequency response looks like:

Once again, the blue line above shows the frequencies as they are being played by an aftermarket head unit. In contrast to what the OEM Nissan head unit does, here when you raise the volume, you get the red line… and the signal curve is identical. ALL frequencies go higher in volume level, and nothing gets left behind.

Beware the “No Name” All-in-one Trick
You might have noticed that I used the term “brand name head unit” earlier. This is because these days there are so many off-brand head units that seem to have the same features as the brand-name models but at a ridiculously low price. Beware of these, because the saying “too good to be true” applies. For example, one of the more popular 2020 “flagship” models (I won’t name the brand) touts a feature list that seems incredible for just $250: Custom software interface, double-DIN Full HD touchscreen, built-in GPS, Spotify, RCA pre-outs for use with external amplifiers, etc. Sounds great, doesn’t it?

Except it isn’t. What you’re really getting for $250 is a heavily skinned mid-grade Android tablet in the shape of a car audio head unit. That “custom software interface? It’s just a themed Android 8.0… which a phone and tablet operating system that came out in 2017! The “Full HD” touchscreen (1024 x 600) isn’t even HD at all… it doesn’t even reach HD 720p resolution (1280 x 720) and is nowhere near Full HD resolution (1920 x 1080). The built-in GPS? It’s just the Google Maps offline app. In fact, the Spotify feature and any other “connected’ feature of these head units actually rely on tethering to your smartphone for real-time updates and functionality. What about those RCA pre-outs? They’re barely 2-volts, which is half of what most aftermarket head units produce. And finally, when it comes to audio quality, they won’t tell you output frequency or sensitivity or sampling rates or signal-to-noise ratios – common specs you’ll find on any brand-name head unit. Why? Because the reality is that you’re getting a low-end mobile device audio chip that was originally designed for use with… earbuds.

On the contrary, when you go with brands like Kenwood, Pioneer, Alpine, Sony, or even budget brands like Dual or Axxera you know you’re getting a good source unit. Most of these brands have many different models to fit your budget, with the main difference being the number of features included for the price. As far as the audio output goes, any model in their lineup will produce the same wide-range frequency signal for clean, complete audio.

This is why aftermarket head units almost always are superior to OEM, and thus for the final time, we bring up the “Path” of car audio: If your source is good, you can ensure that anything you do afterward won’t be held back.

In Part 2 of this series, I’ll discuss why it’s easy to pick the wrong aftermarket front speakers for your Frontier. Hint: Without separation, you’re just wasting money.

Links to All Parts of the Audio Guide
Intro: Your OEM Stereo Sucks.
Part 1: It All Starts With the Source. (this post)
Part 2: Speak(er) the Right Way.
Part 3: You Don’t Drive From the Back Seat.
Part 4: Dogs Underwater
Part 5: Less is More
Part 6: More is Less?
Part 7: Separation Anxiety
Part 8: Time Travel… While Standing Still
Part 9:Partial Means… You’re Not Done
Part 10 Finale: At the End… Here’s 10 (Things to Know)