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Sonic Restomod: Retrofitting A Classic Loudspeaker With Modern Technology

Restoring and modifying an Eastern Acoustic Works (EAW) KF750 three-way concert loudspeaker from the 90s with modern components.

By Bernie Broderick October 4, 2018

A photo taken by the editor many years ago provides a look at a KF750 array configuration.

Readers who are mechanically inclined will certainly understand the term “restomod.” But for those who aren’t familiar, the concept is simple – take the shell of an old car or truck and completely restore (or retrofit) it with modern components.

What you end up with is a vintage shell but with a modern, reliable engine, fuel injection, disc brakes, air conditioning and even a modern dashboard with all of the bells and whistles. From the outside it looks all original but from the inside, a lot has been changed.

As a mechanic and former racer (and current race dad), I’ve found a way to apply my love of anything automotive to pro audio. HotRod, a division of the Truth In Audio (TIA) organization that I launched earlier this year, allows me to get my hands dirty, throw sparks, and create things that have never existed before.

The goal of restomodding an Eastern Acoustic Works (EAW) KF750 three-way concert loudspeaker, originally introduced in the 1990s, is something that I’ve had in mind for quite awhile. In fact, I first thought of doing it more than a decade ago but couldn’t really justify the effort.

But in discussions with the organizers of Live Design International (LDI), I discovered that the organization is celebrating its 30th anniversary at its trade show later this month (October 15–21) in Las Vegas and wants to commemorate it with a 1980s theme. Although the KF750 system was released a bit beyond that timeframe, we decided it still qualifies so the project I’m describing here will be presented at the LDI: Live Outside event.

The EAW KF750

The plan is relatively simple but to pull it off, I’ve enlisted the help of some veteran (and very clever) audio professionals, including David Gunness (who worked on the original 750/755 product line for EAW), Martyn “Ferrit” Rowe, Robert Scovill, Pepe Ferrer and a man we can only refer to as “Agent X.”

We’re renewing this loudspeaker system with everything we can throw at it, not because there was anything particularly wrong with the original, but maybe there wasn’t anything particularly wrong with the brakes on that ’69 Camaro either?

With the overall plan in place and much to do in a compressed timeframe, we leveraged the help of several industry brands to supply the necessary parts.

First came the actual acquisition of a KF750 rig, generously contributed by Chris Anderson of Anderson Audio (Harrisburg, PA), followed by performing modern software prediction to understand where improvements could be made and estimating how effective they’d be.

The specific aspects we’re addressing include:

Weight. Loudspeaker driver technology has come a long way over the past three decades; performance has increased while weight has dropped with the application of neodymium magnetic structures. We reached out to Beyma, which graciously agreed to provide us with the low- and high-frequency devices needed for the project. After careful consideration, we chose the Beyma 12P80nDV2, 12-inch cone driver, due to its broad, flat response, and the CD10nD/N, a 1-inch neodymium compression driver, for its extended HF capability. (KF750 owners may find this part confusing but hang with me for a minute.)

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About Bernie

Bernie Broderick
Bernie Broderick

Bernie Broderick is the founder of Truth in Audio and a veteran of live production with nearly 30 years of experience from sound company owner, pro-touring FOH, systems technician to 17 years as an educator for EAW. He was also one of the initial collaborators of the ADAPTive line of products and has worked intimately with hundreds of shows and numerous tours that utilize the product line.

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