Tech Talk: An In-Depth Look at the JBL PRX ONE Column PA Loudspeaker

Tech Talk: An In-Depth Look at the JBL PRX ONE Column PA Loudspeaker

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The JBL Professional PRX ONE all-in-one powered column PA features a powerful new acoustic package and is fully loaded with a 7-channel digital mixer, DSP with presets, Automatic Feedback Suppression, Bluetooth 5.0 functionality and JBL Pro Connect universal app control.

Contributing HARMAN Insights Editor, Sarah Jones, sat down with Brandon Knudsen, JBL’s Portable PA Product Manager, to find out more about the innovative new technologies driving this incredibly versatile sound system.

Can you share a little bit about the PRX ONE design backstory?

From the beginning, the acoustic solution has been the most important aspect, because if you’re spending $2,500 or more on sound reproduction, you’re expecting high-quality sound reproduction. Any included feature becomes an added benefit.

That said, we wanted to build a product that serves a broad range of customers. A lot of the PA systems in this price point are geared toward a single-use case, whether that be singer/songwriters or DJs/event entertainers. We saw an opportunity to make a product that could resonate with both and would have relevance with corporate and education customers.

For singer/songwriters, we added inputs and outputs and audio effects, so that they can travel with a powerful system that’s going to suit their needs but bring less gear along. You look for the best ways to streamline your setup because nobody likes making multiple trips and nobody’s helping you push your bass cabinet or guitar amp. You begin to realize that your back is a finite resource

Brandon Knudsen, JBL Professional Product Manager for Portable PA and Loudspeakers.

From a DJ perspective, we knew that they typically weren’t going to use things like reverb and delay, but that giving them a powerful woofer package, the ability to really dial in EQ, and adding niceties like automatic feedback suppression, would really resonate.

Then we said, what kind of features does a corporate presenter need? We know that people who use a PA for speech reproduction at a corporate event are often not audio-savvy people. They want to plug in, turn on, and be done. So we implemented very easy-to-use presets such as a compressor that will help keep your speaking volume at a nominal rate and a gate that will limit plosives; the presets also compensate for things like smacking the microphone around in someone’s hand. Users can activate these presets via the PA’s onboard LCD to get up and running quickly.

Ultimately, we said, let’s cram as many features as we can without overloading the package. And then let’s make it as easy as possible for everybody to use so that they can leverage those features in a smart and effective way.

JBL Professional PRX ONE All-in-One Powered Column PA

Is there a sizeable challenge with portable PAs in balancing performance and form factor?

Absolutely, especially with a column form factor, which is almost exclusively chosen for its more elegant approach than a point-and-shoot box. A point-and-shoot system is big, bulky, and cumbersome, whereas a column can fit into your surroundings. With a column, the form factor is tremendously important to people. And if you can optimize your acoustic package within those form-factor constraints, you can begin to come up with something that’s really impactful and powerful.

But a column PA brings design challenges: anytime you stack a bunch of transducers on top of each other, it becomes problematic from an acoustic perspective. You begin to get things like phase cancellation and terrible off-axis response.

Each manufacturer approaches these issues differently. Some use tons of DSP and some use waveguides.

 

If we were to put a waveguide on the PRX ONE, the array would be twice the size that it is now. We’re talking about a speaker that already weighs 50 pounds. If you’re adding waveguides to that, it’s now into the 60 to 70-pound range – who wants to carry around a 70-pound speaker?

We solved this issue through A.I.M., or Array Inumbration Mechanics, basically geometrically optimized array-shading technology. In simple terms, we send specific amounts of audio signals to specific speakers so they can more evenly distribute the frequency response.

How is that different from a crossover?

It essentially is a crossover. But a crossover focuses on frequency dependencies: Usually, you’ll see a crossover between a woofer and a high-frequency transducer and that crossover will say, send anything 500 Hz and below to the woofer and send anything above 500 Hz to the high-frequency transducer.

With A.I.M., we’re sending more signal to some speakers and less signal to other speakers, which gives you a smoother frequency response from the front to the back. This is essentially a passive crossover. But it’s not a frequency-dependent crossover, it’s a signal-dependent crossover. So as you move back from the speaker, the only difference that you experience is in SPL, as opposed to frequency response. We’re making it so that the drop-off is more consistent with the way our brains want to perceive it, versus how our brains actually perceive it.

In-Depth Walkthrough and Demo Video

So you’ve got custom-engineered drivers and array technology working together?

Yeah, the whole acoustic package is actually custom-designed for this solution. We wanted to make sure there were congruencies and that components got along. For example, woofers are great at reproducing low frequencies because the acoustic theory behind low-frequency reproduction is the bigger the woofer, the more air you can push.

High frequencies are simple to reproduce but very easy to get wrong. Our ears are naturally attuned to high frequencies, with a sweet spot at 1 kHz. So as a designer, you don’t have to work hard to get 1 k to sound good. But you do need to make sure that your whole system is working together. With these high-frequency transducers, we’ve added a copper cap that helps us in the very-high-frequency range, like the 5 to 7 k range; if you don’t nail that, the speaker can sound very harsh.

The work that we’ve done on the copper cap to lower inductance really just gives us a smoother and more accurate high-frequency response. This speaker reproduces everything almost like a flat-tuned recording monitor.

Artists have spent years, maybe even decades, crafting their tone. They don’t want to plug into something that’s going to change that. We’ve given them a blank canvas with speakers that breathe and perform naturally. And then you can tell this canvas what colors you want to paint, as opposed to saying, here’s your green canvas, paint something green.

The 2½-inch tweeters give us very good frequency response down to 250 Hz. That helps us better align our crossover so that the woofer is focused on what the woofer does best, which is low-frequency reproduction.

How does that translate to what someone hears?

We don’t have to overly process the woofer to get the bass response that we want. From a listener’s perspective, you can easily tell when something has too much DSP on it because as you turn it up, the woofer will start to “huff.” It sounds like it’s struggling to breathe. Because we didn’t take that approach, our woofer performs much more naturally in those low frequencies.

We’ve geared this system toward allowing all of the speakers to perform naturally. We’re able to do that because of the custom high-frequency transducers. It’s actually not a feature of the woofer itself, it’s a feature of the high-frequency transducers being able to extend so low and reproduce frequencies accurately in a low range. When we’re able to dial in the high frequencies to help cover where the woofer can’t, we don’t have to counteract that with DSP.

PRX ONE is powered by a custom-designed, 2,000-watt Class D amplifier. We know that Class D amps are lightweight and efficient; how does this particular amp optimize the power performance of this PA?

This custom amp will, from a burst power perspective, get us up to 3,200 watts of power, but we don’t need that. From an optimization standpoint, we’ve given the system exactly the amount of power it needs to get the perfect amount of headroom available to the transducers so they don’t power compress or clip.

That reduces the overall distortion rate and power compression—when a PA isn’t optimized from a power perspective, the power begins to overdrive speakers, and you get distortion, clipping and transients that begin to hurt your ears.

There are a lot of misconceptions out there about the relationship between power and SPLs.

People are starting to become savvier about power optimization and moving away from wanting bigger power, a bigger power amp. Ten years ago, people were selling PAs based on sheer wattage, but that power doesn’t mean anything if you can’t actually execute it from a transducer perspective.

We have a smaller power amp that’s giving us more headroom. We said, here’s what our specs need to be, here’s what our acoustic package needs to be. From there, we need x amount of transducers, and to power those transducers without running into any under- or over-powering situations, we need a power amp that does x right.

Can you share a little more about the industrial design?

Absolutely. Anytime you have a column array, you’re stacking weight on top of a base. If you don’t have a solid base, the system can sway. So we’ve got our connection points set up so that the array has a male connection with a long plastic piece that slides into a female receptacle in the woofer cabinet. That gives us optimal mechanical integrity without adding additional moving parts like a locking mechanism.

The other thing that we’ve done is maximize the height of the array, because the higher you go, the better you can control the frequency directivity and aim sound where people are listening, which is at ear level.

This unit is about six-foot-seven. It’s really taking advantage of frequency directivity and the control of that directivity. The goal here is more consistent response. Anytime you move off-axis, a speaker is going to sound slightly different

“What kind of features does a corporate presenter need? We know that people who use PAs for corporate events are often not audio-savvy. They want to plug in, turn on, and be done. So we implemented very easy-to-use presets to make it simple.”

We wanted to play with your brain a little bit so that as you move off-axis, your brain doesn’t notice as much of a tangible difference as you might on other systems.

Are you also driving the sound electronically?

It’s many things. The A.I.M. technology helps with our vertical and horizontal directivity. The height of the array helps mostly with vertical. So combining the height with the A.I.M. technology helps us get a better spatial picture.

We said: “It’s fine to understand that when you move off-axis, you’re going to get a different response. But what we don’t want is a pronounced difference; we don’t want to be at 10 degrees and hear something completely different than we would at 20 degrees.

How did you make sure these PAs are ready for prime time?

We put them into our test chamber and hit them at max capacity for 100 hours, deliberately trying to break them. We go far outside typical use cases—we want to know what our users can get out of this PA even if they use it in all the wrong ways.

When you’re building something, it’s important to know how to break it. Then we can put preventative measures in place, like a hard system limiter that doesn’t allow users to get there.

Any system is going to have limitations, period. We want to understand those limitations so we’re not fighting against them. Gearing a solution so an end-user doesn’t bump into those limitations just builds a product that’s going to last the test of time.

WE’D LOVE TO TALK TO YOU ABOUT YOUR INTEREST IN PRX ONE

If you are a rental house, buyer, technology manager or anyone interested in speaking to our Audio Solutions Team to learn more about how we can best support you with the PRX ONE or any JBL Professional product or solution – we’d love to talk.