Educar has been involved with training salespeople on sales process and system design for many years. This space will address both the process of selling, and how to present new audio system technologies effectively.

It’s been the first part of a car-audio sale for decades. In the 80’s, we used compact-chassis shaft mount decks in the Toyota HiLux pickups when we could, to clear the right-side curve on the dash. In Volvo sedans, we used dual-cone 4” or a handful of coaxial with very-low-profile tweeters, so they could still clear the OEM grille. Navigating problems like this for the customer was the mark of professional.

Well, OEM systems today are giving us the question “what fits?” a new wrinkle.

The very first time I did an OEM audio integration, the signal was flat, full-range stereo – left and right had all the music, and the left and right were in phase with each other everywhere. Eventually I ran into some systems where the signal was equalized, but it was still stereo. Then I found some where the signal was actively crossover-filtered, and wasn’t full-range – but we could sum the channels back together and get back to stereo. Then I ran into some 7.1 upmixed systems, with center channels and two sets of rear channels – but I could turn off the upmixer in the tone-control menu and get back to good old “stereo”.

We can’t expect “stereo” any longer.

  • There are 5.1 and 7.1 upmixed systems which can’t have their upmixed function turned off. That means there are sounds attended in the left and right
  • There are systems using “Phase EQ” where the left and the right, or the high and the low speakers, aren’t in phase with each other at all frequencies.

Those types of stereo presentation are either very difficult, or impossible, to knit back to “stereo”.

So sell something that fits!


Simply put, high-performance upmixers are in cars to create a stereo presentation for more than one seat. I didn’t get that for years (Andy Wehmeyer finally rammed it through my head). Dolby, DTS, ELS, Centerpoint are examples of brand-name upmixers.

They often aren’t used to present stereo the way we expect it – there’s often an image inn front of each seat, but that result is not inherent in upmixers, and it can be corrected.

To upgrade an upmixed system, you will need to amplify the center channel and I recommend amplifying the second set of rear speakers as well (usually in the rear deck or D-pillar). Upgrading the rear door speakers – intended for rear-seat occupants – is strictly optional. Upgrading the sound of the center-channel speaker is crucial as well. That means EQing it better, or bi-amping the OEM mid and tweeter actively, or adding a tweeter to the factory mid and bi-amping it, or upgrading the center speaker completely! Once you have an upmixed music system with a center speaker, that becomes the most critical speaker in the system.

So, retaining and upgrading an OEM upmixed system requires more DSP channels, more amplifier channels, and more speakers?

Phase EQ

Stereo, by definition, is two channels which match in frequency response and are in phase with each other at all frequencies.

Phase EQ is performed with all-pass filters, and the purpose is to put two channels out of phase in the electrical-signal domain, so they are back in phase at the listener’s ears. Once it’s been performed, those signals aren’t in phase with each other at all frequencies, so summing them together results in cancellations. Also, once it’s been performed, applying delay doesn’t get you the results you expect. Most high-performance systems in the aftermarket use delay today, so that’s a conflict.

Upgrading a system with Phase EQ requires you to not use delay on any affected channels, to avoid summing affected channels, and to emphasize matching left and right levels and responses during the tuning process.

While Phase EQ is almost always present in Bose systems, it is found today in base-model deck-power receivers in many Toyotas, Subarus, Kias, and Hyundais.

Like upgrading upmixed systems, it often requires more input channels and amplifier channels. You may also want to use differently-sized speakers than you usually sell – especially if the only thing you usually sell for front speakers is a 6-1/2 and a tweeter with a passive crossover. Using speakers with similar sizes to the factory lets you use the crossover points used by the factory – and that means you don’t have to sum!

A word on “External Preamps”

Sometimes, there’s an “external preamp” available. Made by several suppliers, an external preamp plugs into the OEM audio system and “grabs” the signal on its way to the OEM amp. It applies typical preamplifier functions to it – volume control, tone controls – and adds in OEM functions such as chimes, nav voices, and handsfree audio.

They’re a great solution in many cases – but they aren’t available for every car when it comes into our bay, and they never will be.

How can we tell?

The best way to tell if a car is using one of these technologies is to listen to it. I like the Educar TestTune app for this, the Audiofrog Test CD in the UMI-1 mic kit is great, and you can use a signal generator app too. Playing a few simple test tones can help you determine what’s happening. Basically, if there’s a center speaker, you need to know if L or R comes out the center speaker.

If there’s no center speaker, you need to know if various notes – I focus on the mid bass – are in phase with each other with your head on the center line of the cabin.

Educar is introducing a course on this soon, with a checklist to help you remember what to do when you’re in the customer’s car.

How do we include this in our sale?

First off, you need to let go of your “5-channel amp, front comps, rear coaxes, sub box” square peg formula, because these cars are definitely round holes! Design a system for the car in front of you.

After I do my testing, I say something like:

“Good news – while your system can definitely stand improving, they are doing some really cool things that can help us!”

“While the amp is underpowered, there’s not enough bass, and the speakers are low-performing, they did build in some advanced technology that we can use!”

Then, design a system that fits what they’re trying to do. You can deliver two-seat stereo – something that many customers don’t even know they have – with better sound!

You can sell systems with more channels and more speakers and higher average tickets, with real benefits! You also can differentiate you and your shop from the shop down the street. This makes good business sense and it delivers concrete value to your customer.

It just means you have to know what fits.