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Installation Guide

How to Tune Compression Horns in a Harley Sound System

How to Tune Compression Horns in a Harley Sound System

Kenneth Saguban |

Systems with compression horn tweeters require an extra level of attention when it comes to the tuning process. This is because horns are wildly efficient but that big boost in output comes directly at the expense of frequency response. When used with a good DSP in the right hands though you can easily achieve both great frequency response and extreme levels of output. When left unequalized though or tuned incorrectly, it is not reasonable to expect the system to sound good or last very long without burning something up. Just think about horns like a turbocharger. There are tons of performance benefits but an extra level of control and tuning are required. So, if you want to play with the big boys, it’s time to learn the basics of tuning systems with horns. 

 

THIS VIDEO COVERS PART ONE OF A TWO PART TUTORIAL

In part one I lay out the basics that need to be understood about balancing amplifier power between horns and mid range speakers using both amplifier gain as well as equalization. In part two of this tutorial I will demonstrate with a live tuning session exactly how to go about equalization on both passive crossover systems as well as full active systems. It’s quick and easy when you know how to do it.Part two of this tutorial is running behind schedule and will be released when it is complete.

THE FOLLOWING IS A TRANSCRIPT OF THE ABOVE VIDEO

Today we're talking about horn loaded tweeters, why we use them on bikes, and how you should tune your system. To make the most of this amazing technology. Hey, this is Rob from Americanheartbag.com. In today's video, I'm going to explain how to get great sound out of your compression horn tweeters, and how to get your entire system to play louder without blowing up. I'm going to show you how to use your equalizer to quickly get a killer tune with accuracy the first time. And I'm going to do all this using real world equipment on one of my own bikes. So be sure to stay tuned as I explain some of the basics. And then we'll step right into how to actually perform a tune on my own bike a little later in the video.

See, horns are a purely mechanical device that allow a tweeter to perform as if its diaphragm was much larger than it actually is. Just like a turbocharger allows an engine to perform as if its displacement was quite a bit bigger than it actually is. But also just like a turbocharger, horns come with their own bag of characteristics that you need to know about when you're tuning the bike.
 

The very first thing to know about horns is that they are much more efficient than all of the other speakers on the bike. No matter what speakers you have, no matter how big and how powerful they are, the horns are always going to be much more sensitive. The second thing, and probably the most important thing to know about horns is that horns by themselves do not sound loud. This throws a lot of people. I just said it's the loudest speaker in your whole system. And now I'm saying that horns don't sound loud by themselves. And it's true. In order for a horn to work properly, it has to work in tandem with a mid range at about the same level. If the horn is playing at a level that's much higher than the mid range, it will not sound loud because the bulk of the energy of even the highest frequency instruments resides with the mid range. The midrange has to start that process, and then the horn fills in the rest of it. It makes it sound loud when the two work together. But by itself, it's not going to be loud. It's just going to sound horrible if it's not playing at the right level. So something that's really important to understand whenever you're tuning a system that has horns is to understand the power relationship between the midrange and the horn. The horn naturally plays at a higher pressure level given the same power than a midrange. But a midrange is capable of absorbing a lot more power than a horn can. A typical midrange might be 200 watts, and a typical horn is 50 watts.

A really typical situation that plays out with horns when someone doesn't understand the power relationship between the midrange and the horn is that they'll play a horn and a mid range off the same channel, which is fine, you can totally do that, but they don't do any equalization, they don't level that horn out to the same level as the mid range. Consequently, they play that mid range to its max. Let's say it's 200 watts, 400 watts, it doesn't matter. It's a lot more than what the horn is. So they play the midrange to its physical max limitations and now the horn is expected to keep up with that, except for the horn naturally plays at a much higher pressure level than the mid range. So the horn is past red line goes thermal, and people blow up their horns and they don't understand. The first assumption from a lot of amateurs is, “that horn didn't handle enough power”, “or that horn wasn't loud enough”, or “it's a cheaply made horn”, but what they don't understand is what they did.
 

But there's good news, because horns are great and they thrive and they're spectacular in really high sound pressure situations. So when the bike is tuned properly and the horns are brought down to the same level as the midrange, the horns are operating at a small fraction of the power of the mid range. And that's how it's supposed to be. You want to leverage the horns efficiency instead of just cramming a bunch of power down its throat that it can't handle. So when it's done right, the horn can keep up with the mid range. And the mid range, you can max that guy out. And it's damn near impossible to blow up a horn because a horn is capable of playing so much louder than the mid range can. It's just at a different power level.

So now the question that any reasonable person would ask is, how do I go about getting the level of my horns down to the mids so that everything sounds its loudest? And of course, if your horns are on their own amplifier channels, you have the gain that you can go up and down with, but you still want to do some equalization on top of that. Just gain with most horns is not enough. If the horns in the mids are sharing the same channel, the way that you go about it is completely through equalization, because both speakers are sharing one gain control. It's easy enough to do. You go to your equalizer and you find the frequency bands that correlate to your horns frequency range. And the easiest way to do that is to get yourself what's called an RTA app. It's a real time analyzer app. Looks like this, looks just like an equalizer, has the same amount of bands, has the same frequency points on it as a 31 band equalizer. But this shows you what's actually happening. So it's really simple. Might look complicated, but it's not. You play a special test track called Pink Noise and that's something you can find free. It's available all across the Internet. We supply it with some of our products. We put it on a thumb drive for customers so they have a good recording to work with. And you get this app that I think I paid $5 for this one, but there's a lot of free ones. This one, I think, even has a free version. And you just fire up the app and you play the test signal. And if your system is tuned properly, these bars are going to be almost flat all the way across the top. There's always going to be some variations, but the goal is to get them all level with each other. Now, anytime you have horns in a system, the highest frequencies which are on this side are going to be up a lot higher than the rest of the bandwidth. And so you just want to use those sliders on your equalizer to bring that range down. And when the bars are all around the same level as each other, you've done it. Your horns are now playing at the same volume as your midranges. Now you can start going and get in, critiquing your tune and getting into little tiny details, but the system is going to sound a lot better and a lot louder than it did before.
 

Now, on the topic of using an RTA app on your smartphone to make adjustments to your system, it's a big topic, I won't lie to you. And making equalization changes is also a really big topic. But the important thing to get from this is don't make it complicated. Get yourself an app, maybe a free app. Put it on the phone that you've already got. Don't buy any extra hardware. Fire it up. Start taking a look at it. You'll figure it out. When you play with your equalizer, you're instantly going to see changes on the RTA app. It's not rocket surgery. Get started. Because these topics are so important to getting your system right, I wrote a detailed article at americanheartbag.com on how to use an RTA app on your phone. Go to the installation and guide section and look for the Pro Tune article. How to use Pro Tune. Pro Tune is an RTA accessory hardware kit that we include with some of our better speaker systems. But you don't necessarily need the hardware to be able to use the app and get a lot of benefit from it. Of course, if you have the Pro Tune kit, it's a lot more accurate and a lot more convenient to use. But the important part is figure out how this works so you can make the best decisions for your system. Want the perfect audio system for your Harley Davidson Bagger?

Whether you're looking for guidance on how to best customize your audio system based on what you already have, or if you're looking to start a fresh build, look no further than American Hard Bag. Call us now at 1888 311 0016, our friendly and knowledgeable team located in Northern California. can get you the parts and the answers that you need. So call us now at 1888 311 0016.

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