A New Framework for OEM Upgrades, using Audison AF Forza

I started in the car-audio business in 1986. I’ve been focusing on OEM integration since 2004, and have spoken at many educational events on the topic over the past 15 years.

The biggest problem with making OEM upgrades sound good has always been not knowing what signals we are starting with. What has already been done? Have some notes been emphasized, or attenuated? Are some channels out of phase with others, at some or all frequencies? Have any channels been delayed? OEM suppliers want to earn a long-term contract, so they will find ways to improve the sound which are consistent with the requirements of the OEM automaker (these constraints don't just limit current draw, weight, and cost - they often mandate similar performance in multiple seats).

If our aftermarket upgrade doesn’t sound the way we want, it’s often a puzzle as to why - a long, difficult, time-consuming, and often unprofitable puzzle. Unfortunately, many techniques which OEM suppliers use to make systems perform slightly better interfere with techniques we use when installing higher-performance sound system upgrades. Those of us who have invested in signal analysis tools, and who have analyzed every system before we started, have avoided many surprises - but we spend time and money to be certain, and many installers don't. Many shops aren’t comfortable with the expense and the time required to do this on each job.

A few years ago, I started working with elettromedia, doing some training and a bit of product development support. Starting in early 2020, I was allowed to participate a bit in the development of the company’s 4th generation of Automotive DSP products - AF Forza. I was pleased to find so many advancements and innovations already designed into this product. With some additional input from myself and others, the AF Forza product line incorporates everything I have ever wanted in OEM Integration. We can eliminate surprises and provide transparency into the OEM sound processing we must handle.

With AF Forza, it’s easy to identify the input channels, it’s easy to identify clipping, it’s easy to identify frequency content, it’s easy to test for relative time and phase alignment, so it’s easy to know exactly what you’re starting with - all without any 3rd-party tools or test equipment. It’s all in there!

Every AF Forza bit amplifier has the same OEM input arrangement:

• Eight native analog speaker inputs with up to 20V of capability
• The option for four more with up to 34V capability (using the F4 IN card)
• Each of the 12 inputs have 12 bands for EQ , Notch filters, and Phase Manipulation, along with a Delay buffer
• USS?automatic speaker loading prevents automated channel muting due to speaker-detect circuitry in many OEM systems
• The eRTA input analyzer lets each input channel be examined in detail, or in conjunction with any other input channel. This not only allows us to make de-equalization as precise as we like, it allows us to readily detect the presence phase-and-time processing - and counteract it!
• There is a fully-controllable mixer with switchable polarity inversion to route the proper signals from the input channel to each output channel. Multiple signals can be completely or partially summed together, or common information can be attenuated.
• The ability to manage multiple bit amplifiers at the same time (for the most complex systems with +12 input channels) is supported.

This input section lets you be very confident that AF Forza can give us visibility into any OEM system we come across, and then respond in an effective manner.

A New OEM Framework

Based on the AF Forza architecture, and our recent research, we are introducing a new OEM system analysis tool which sorts OEM systems into three types.

Type A uses an amplifier inside the deck. That's what the 1984 Honda CRX used.

99% of these systems are essentially full-range and 4-channel (front and rear, left and right).? If there are tweeters, they are not on their own individual amplifier channels, they share an output with a woofer and use a passive series capacitor as a crossover filter. There are a few corner conditions, such as the Honda systems which a 5th subwoofer channel, or the Porsche systems with front highpass, rear highpass, and front-door lowpass outputs. Regardless, Type A systems are increasingly using a combination of EQ, delay, and phase manipulation which only a few years ago was reserved for premium sound packages! AF Forza allows quick analysis and correction of these systems without any 3rd-party tools.

It’s unheard of to find a new Type A vehicle system without EQ applied to the signal. Beyond that, we estimate that there are more than 100 different US vehicle models using phase manipulation (Toyota, Hyundai, Kia, GM, etc.). A higher number that that use delay, at least on the rear speaker channels. It's a simple matter for AF Forza to return these signals to flat, time-aligned, phase-aligned front and rear pairs.

Type B uses an amplifier external to the deck.

Many of these systems are not full-range - there is often a subwoofer, and sometimes the multi-element speaker systems use active channels with electronic crossover filtering. AF Forza supports managed summing, so that these channels can be knit back together into full-range, time-aligned, phase-linear channels if desired. These systems often incorporate EQ, delay, and phase manipulation within the OEM amplifier. Type B systems may include a center speaker, but generally only has one set of rear speakers.

Most Type B systems can be handled by the eight native speaker-level inputs with their 20V thresholds. In a few cases, the voltage exceeds 20V - in these cases, the F4IN adds four inputs with a threshold of 34V, so OEM subwoofer channels can be handled with ease.

Type C uses an external amplifier with upmixing processing.

This means there is always a center speaker, and usually there are two sets of rears (one primarily for rear occupants, the other for ambience effects). These systems ironically often use less signal processing than Type B, after the upmixing algorithm is taken into account?(Bose is an exception). Upgrading these systems require flexibility in signal routing, and the algorithm’s operation can often be improved with judicious tuning decisions. There are various algorithms - Centerpoint and Panaray from Bose, Logic 7 and QLS from Harman, Symphoria from Fraunhofer, DTS Neural from DTS, and Dolby Pro Logic II. In addition, any Atmos-equipped sound system includes Dolby Surround upmixing for two-channel content, and so Atmos systems can be addressed as Type C systems.

The availability of the F4IN input expansion card makes Type C upgrades more manageable than ever before. The completely-flexible mixer in AF Forza allows us to re-route audio as needed to retain what we need, or delete what we don’t.

Here’s an extreme example - let’s say someone plans to use a 5-channel DSP amp in a Honda Civic audio upgrade - but it turns out this Honda Civic has the 12-channel, fully-active DTS system. You can turn DTS off, use the AF Forza 5.11 bit amplifier and the F4IN expansion card, and run all 12 channels in. You can sum the tweeters and mids, the center, and the surrounds, and deliver a traditional 5-channel front/rear/subwoofer system that sounds great - and includes all the chimes and non-entertainment sounds you need.

But what if the vehicle owner likes the idea of DTS upmixing and its stereo presentation to multiple occupants, and just wants better sound? In that case, we can use one of our AF Forza 8-channel bit amplifiers for front, rear, surrounds, and center, and add a subwoofer amplifier. Or we could use our AF Forza 12-channel amp, and retain a fully-active architecture.

Maybe the idea of a 12-channel amplifier in a Civic system sounds unrealistic (even though it seemed like a good idea to Honda and Panasonic). Let’s talk about BMW. We have helped dozens of people use the AF M12.14 bit amplifier and the F4IN sound card in BMW systems with h/k and Logic 7 upmixing. We have improved on the sound with more power, better tuning, and often better speakers, while retaining? the Logic 7 upmixing to deliver great 2-seat sound.

We’ve done dozens of Bose upgrades in Chevy trucks, without a 3rd-party interface - both passthrough systems using our wideband speakers, and traditional upgrades where we get the lefts and rights and highs and lows back into phase, and then we use delay the way we expect to. We’ve even upgraded the new premium Centerpoint systems in the top-of-the-line trucks!

AF Forza - the family is all here!

The introduction of AF Forza was a staged process, due to component shortages that we all remember from a few years ago. We started here in the US with one 5-channel AF Forza bit amplifier. We now have an entire family of AF Forza products available - it honestly can be thought of as an “ecosystem” - and we are helping dealers sort out how to use this family of products to best advantage in their businesses. We have five bit amplifiers (soon to be six), we have four companion amplifiers, we have a remote controller (soon to be two), we have plug-in cables to eliminate RCAs between AF amps, Bluetooth streamers for Full DA sound, and we are launching a smartphone app to allow those with the Bluetooth streamer to use their phone as an additional remote control for these systems!

Audison isn’t done. We have even more advances and innovations planned for these amps, this software, and for future products. This is OE integration with the efficiency and transparency that we have wanted and needed for many years. Do yourself a favor and check it out.