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How To Use Pro Tune With A Harley Sound System


This article explains how to use our Pro Tune kit with an RTA app but all of this information is valid even without the Pro Tune kit. A smartphone is capable of improving your tune all on its own. This article was written specifically for Pro Tune users but most of the information also applies even if you are just using your phone without the kit. The Pro Tune setup and the functionality of the RTA app are often referred to as one in the same in this article. The Pro Tune hardware kit just makes it a lot more accurate, consistent, and easy to use. At American Hard Bag we believe in educating the public because it is good for the entire industry. Check out our other articles and tutorials here.  


We do not sell or support any RTA app. RTA apps are readily available for any smartphone. The Pro Tune kit is an accessory microphone kit that adds an additional level of accuracy and convenience to an RTA app because the kit includes a calibrated microphone which eliminates all variables inherent with your phones built in microphone. Additionally having the microphone remotely mounted is great because you can keep the microphone positioned properly while you use the app. The Pro Tune kit is only available with select speaker kits we sell and is not available for purchase as a standalone product. You can find our Velocity Speaker Design kits here.


Keep it simple. In my experience I have found that people tend to make all sound system related things way too complicated.

To set this kit up we will do four key things.

  1. Download a calibration file for your microphone (Pro Tune only)

  2. Download an RTA app to your smartphone or tablet

  3. Verify some settings in the app

  4. And position the microphone on the bike (Pro Tune only)

Do not make it any more complicated than that. Ignore all of the fancy apps that you don’t need. Ignore any settings in the app outside of what I detail here. 

Additional Items You Will Need

  • A selfie stick to hold the microphone in place. Get a selfie stick that has a suction cup attachment so that you can stick it to the tank or saddlebag lid of the bike. Holding the mic in the perfect position is key to the result. This one from Amazon is the one pictured and works great for $12.

  • 4 pole 3.5mm extension cable for the microphone (male to female). These are available for under $9 on Amazon. Make sure it is a 4 pole and not a 3 pole connector. Get a long one. 8 feet or more. This one from Amazon is the one shown in the images above.

  • Lightning to 3.5mm adapter if you have an apple device. Get an actual Apple adapter. The knockoff ones usually do not work with a microphone. 

  • 2 mobile devices (smartphone or tablets). You will use one to adjust your EQ and another for the RTA display. If your equalizer uses a computer to make adjustments then you will need a computer and just one mobile device. Don't try to do this with just one device. It is not practical.

I regularly use a second iPhone for the RTA app and it works just fine, but a tablet like an iPad is definitely easier to use for the RTA app if you have one available and you are working from a bench. The bigger screen is easier to glance at. Your hands will be busy with the device you are using to handle the equalizer. So it is nice to be able to set the RTA device down and not have to have it in your hands to get a good look at it. 

You will notice that in my videos I prop an iPhone up on a desk style phone holder and then stick that to the bikes gas tank with a gel sticky pad. This works great if you are sitting on the bike while you make your adjustments. If you already have a phone holder on your bars, use that. Sitting on the bike is ultimately the best place to be when tuning. Always do your listening tests while sitting on the bike. 


Pro Tune is an accessory kit for your smartphone that turns your phone into a Display that shows what adjustments need to be made to your equalizer in your sound system. This type of measurement and display system is called a Real Time Analyzer. Or RTA. Which is a very simple but powerful tool to have when tuning a sound system.


The display works in real time. So when you make an adjustment to your sound system you instantly see the result on the display. For example: The image above shows the equalizer of a Rockford Fosgate DSR1 digital sound processor. Adjustments that you make to the DSR1 are instantly reflected in the display of the RTA app above. 

The way this works is that you play a special test track that we have included on the thumb drive. The signal on the test track is a perfectly flat signal. If you were to feed this perfect signal directly to the phone the bar graph would display flat all across. Flat on the display would indicate a perfect reproduction in frequency response. When we play the test track through the bikes sound system though any deviation in the display from flat indicates a point that needs adjustment.

These deviations from flat are caused by everything between the thumb drive and the microphone. This includes the radio, the amplifier, the equalizer, the speaker wiring, and the speakers, as well as the environment and all noises around the bike.


The goal here is not to obtain a perfectly flat measured response. Because that's just not reasonable. That would be like trying to finish a drag race in zero seconds. But here is what we are going to do. We are going to use the RTA to identify problem areas and then use the equalizer and other adjustments in the system to fix those issues. The goal is to understand and see what is going on. The challenge is to make the right decisions and take the right actions to bring the system under control.

It’s that simple

Step 1

Locate the microphone serial number that is printed on the microphone container. Don’t lose this number!Go to Dayton Audio’s website ( and use that number to download the calibration file that is specific to your actual microphone. These microphones are all unique, and the file you download will not work with any other Dayton Audio microphone. Save this file to your phone or to some service that is accessible by your phone such as Dropbox or iCloud. This will be a txt file that is universally accepted by any RTA app.

Step 2

Download the app. Before we go any further we need to find and download a suitable RTA app for your phone. For iPhones we recommend the RTA app developed by Andrew Smith that you can find here. We don't have a specific recommendation for an Android app but there are literally hundreds of RTA apps out there to choose from and they all do the same thing. What is important is that the app has the ability to make use of the microphones calibration file to make it accurate and that the app is used in 1/3rd octave RTA mode. The ability for the app to use microphone calibration files should be in the app’s description.

Here is some app advice for you. Most of these apps have all sorts of fancy options that fall way outside of what we are trying to do here. But all we are concerned with is 1/3rd octave RTA mode. Nothing else matters when setting a 1/3rd octave equalizer. So ignore the other fluff and upsells that these apps usually have. And here is another piece of advice for you. Don’t make this part more complicated than it needs to be. Setup your RTA app like I am about to show you and you will be up and tuning in just minutes.

Step 3

Verify microphone settings in the app

  • Open the RTA app

  • Open settings

  • Open microphone setup

  • Add a new microphone

  • Give it a name such as Dayton Audio - Serial number

  • Add the calibration file you downloaded earlier. Use the import feature of the app to access the file.

  • Exit the microphone setup and find the RTA setting that allows you to set weighting and make sure that it is set to flat/off/or Z weighting which are all the same thing. Weighting is a feature that plays no part in the way we intend on using the Pro Tune RTA and it can mess things up if it is left on.

  • Check for microphone level settings in the app. Some apps will have level range settings for the microphone so that you can use the RTA at higher volumes. And we want to be able to make our adjustments at around 100 dB. You don’t want to clip (overdrive) the microphone when using it because that would skew the results on screen.

 Now we are about ready to have fun. Because all of the boring stuff is over!

Step 4

Setting up the microphone. The Pro Tune kit comes with a selfie stick adapter for the microphone. A selfie stick with a suction cup attachment on the bottom is the practical way to hold the microphone in place when tuning. The microphone needs to stay in one spot throughout the entire tune. The mic should be positioned pointing straight up at the sky and never pointed at the speakers. This type of microphone is not designed to be pointed at the speakers. Doing so will make your measurements invalid. The mic needs to be positioned at ear height when sitting on the bike and should be positioned from front to back right where your ears would be. The position of the microphone is important. The types of speakers that we use in Harley sound systems are very directional and not getting the microphone position correct will kill the accuracy.


When removing the microphone from the selfie stick adapter, be sure to push the mic out of the adapter and do not pull it out. If you pull the mic out of the adapter you run the risk of pulling the mic capsule off of the mic body and destroying the microphone.  


In this tutorial we assume that you have already fully installed your audio system and that you have already done the following before you start. The next several steps below are not necessarily specific to using an RTA. These are steps that are required for all bike systems, and commonly overlooked. Get the next steps right if you expect good results. 

  • Put your bike on a battery charger. Make sure that your bike is on a battery charger and not a battery tender. A fully charged battery is not good enough. You need the battery charger to be actively simulating your bikes charging system as if you were riding during your entire tune. You should use a fully automatic battery charger with at least a 30 amp capability. To make life easy on yourself you can make your charging connections at the starter motor and engine case instead of taking the seat off to access the battery. 

  • Set all of your speaker crossovers to the correct frequency for the speakers you are using.

  • Set all of your amplifier gains to minimum. If any of your speakers still play too loudly for the RTA tests with the radio at max volume even after turning your amplifier gains all of the way down, then you will need to find a secondary point in the sound system to further reduce the audio gain to those speakers. Your equalizer should have an input gain where this can be done globally to all speakers as well as output gains where this can be done to individual channels. 

  • Center all audio adjustments on your radio such as bass, treble, and fader 

  • Flash your radio. If you have a factory radio we always recommend flashing the radio with the Rockford Fosgate flash no matter what speakers and amplifiers you are using. And now is the time to do that if it hasn’t already been done. A flash tool can be rented from American Hard Bag if you need one and you are an existing customer.

  • If you have an aftermarket radio be sure to turn off or neutralize all audio features such as loudness, bass boost, crossovers (those should be done at the amp or DSP but not both), and equalizer presets. Any of those features that you may decide to use should not be applied until after you set your equalizer using the Pro Tune RTA 


  • Get your RTA mobile device plugged into the microphone.

  • Plug the USB drive into your radio and play the pink noise audio track.

  • Set your radio to infinitely repeat the track.

  • Set the playback volume


When using the RTA you want to measure just one pair of speakers at a time, and make adjustments to just one set of speakers at a time. The volume level of the speakers being tested needs to be louder than the background noise. With the radio volume turned down you can see the background noise level on screen. We want to be well above the background level but we do not want to exceed the microphone's maximum input level. You should shoot for around 80 dB as measured by the RTA. The exact volume level is not critical and there is no advantage to higher or lower levels as long as you are well above the background noise and well below the maximum input level of the microphone (120 dB).  Most RTA apps will let you know if you are clipping (exceeding) the max input level. A level that is comfortable for you to deal with for an extended period of time is a good idea. 


Factory radios have equalization built into them that is designed to compensate for all of the outside noises. This equalization is always in play below max radio volume. Even after flashing the radio. This makes the system sound a lot better at all volume levels. This is a good thing but you need to bypass it when adjusting your equalizer with an RTA. Here is how you do that.

  • Regulate the speaker output level with the amplifier gain controls and or the DSP.

  • Use the RTA only with the radio at max volume.

  • Don't allow the speaker volume to pass 80dB while using the RTA.

At max radio volume the factory equalization for road noise will be bypassed. Complete your EQ adjustments using the RTA and then reduce the radio volume and set your gains as normal. 


The information displayed on the RTA is all relative. An RTA is used to view the relationship amongst all 31 of the bands with each other and not any specific level. There is no specific target level that you need all of the bands to meet. What we are concerned with is relationships. The vertical represents volume level and the horizontal represents frequency. 

  • Look for groups of bands that are higher or lower than the average. Those groups of bands are areas that need to be adjusted. 

  • Always use the equalizers ability to cut bands for adjustments and only ever use the equalizers ability to boost any band as a last resort. There are many problems that come along with adding positive gain to any frequency band. 

  • Before you start making equalizer adjustments, look at the level for all bands and identify a reasonable common vertical (level) point that you can bring all of the bands down to. Use the horizontal lines to help you identify and keep track of this vertical point. In the end you will likely end up adding some positive gain to a few bands but these should be kept to a minimum. 

  • Refrain from using the equalizer to address sharp (narrow) spikes or dips. These are best addressed by ear instead of by RTA. Sharp spikes or dips are often times caused by factors more complex in nature than simple frequency response. Sharp problem points should be noted (write them down) and then revisited by ear while listening to music with vocals (no matter how high or low in frequency the band is). 


To effectively use an RTA you need to embrace some basic concepts about goals and strategy. 

  1. An RTA is used to identify problem areas that are not subjective in nature. For example: an area of the spectrum that is 12 db higher than the rest of the spectrum is factually too high and needs adjustment. 

  2. An RTA is not capable of identifying subjective characteristics of the sound system. For example: an entire range such as the 1khz to 5khz (upper midrange) may sound better when slightly elevated or lowered as a group with a gradual progression (hump or dip in the middle). These adjustments are better made by ear with music after the RTA session is over.

  3. RTAs should never be used to attempt a perfectly flat frequency response. Doing so will always result in a performance compromise. 

It is important to understand that the RTA is a tool that gets you in the ball park quickly and only after the RTA do you even attempt to listen to music and make subjective adjustments. Though the RTA can give you absolute feedback, an RTA does not hear or process sound in the same way as the human ear. So always have your quality music recordings ready to go so that you can make educated subjective adjustments. That is how the pro's get results.

Tip: Always make equalizer adjustments with left and right speaker channels linked together. There is never a reason for asymmetrical equalizer or crossover settings on a bike system.  


Please take the time to learn and understand the following topic. This is the single most misunderstood aspect of Harley audio that causes poor sounding systems. This topic is not that complicated but it is not widely known about largely because it is not generally an issue in car audio. But a bike is not a car. Bike systems are very prone to this problem. Always assume that your system needs to be checked. 

Baby Definition: After passing through the radio, amplifier, and equalizer the audio signal becomes unevenly delayed between channels and this causes the speakers to be out of sync with each other. The cones no longer move in the same direction at the same time. This causes cancellation and a bad sounding system. 

Phase is a critical aspect of a speaker system that can make or break the performance and it needs to be checked on every system. Not knowing about or understanding phase is a nasty pitfall that we see people fall into every day. The RTA is the perfect tool to use to quickly and accurately set channel phase. Channel phase is a critical adjustment that must be checked and accounted for before any equalizer adjustments are made. Channel phase is not the same as speaker wiring phase and should not be confused with how the bike is wired. Channel phase is the polarity of the audio signal on one channel in relation to the signal of any other other channel. Channels that are not out of phase and have no phase shift to begin with at the radio become out of phase (alignment) due to the radio flash (even the Rockford flash) crossovers and equalization in the radio, amplifiers, and DSP. Every channel of every bike audio system should be checked before any equalization settings are made and rechecked after equalization settings are made.


With just two speakers playing pink noise (lets say left and right fairing speakers), use the phase invert feature of your DSP to invert the phase of just one speaker channel. Note what inverting the phase on that channel does to the sound level on the RTA. Particularly the low frequency range for that speaker.


Find the phase setting that nets you the most low frequency output and ignore any output gain that you may or may not get at high frequencies. This is the correct phase setting for these two speakers. 


Ultimately you want to find the best phase combination that makes all of the speakers in your system perform in perfect harmony with each other. The way to do this is to keep adding speakers one at a time until you have accounted for all speaker channels. The end result will be an astounding jump in acoustic output power. Now you can move on to equalization channel by channel and then revisit the phase to make sure that the equalization process did not shift phase around on you. Reasonable equalization settings generally do not cause major phase shifts but dramatic equalization can definitely cause dramatic phase shift. 


In the example above we phase checked two identical speakers but phase is also critical amongst speakers that play in uncommon bandwidths such as tweeters and midranges or overlapping bandwidths such as fairing speakers and lid speakers. It is worth noting that all crossover and equalization settings should always be equal for speakers from left to right. 

Time Saving Tip:

Because we know that left and right side speakers should always have the same state of phase we can simplify our phase test procedure by muting all speakers on one side of the bike and then after we find the best phase combination to all speakers on the one side of the bike we then copy those same settings to the opposite side. This is a real time saver when dealing with a DSP that does not allow you to link the phase switch to left and right side channels so that you can invert speakers as pairs. 

But before you do that, you should always first phase check each left and right side speakers against each other in order to discover any accidental mishaps with speaker wiring. Left to right phase checking is really quick and easy as compared to phase checking dissimilar speakers. The results are much more obvious.   

View PDF

How To Use Pro Tune With A Harley Sound System

Step by step setup for the Pro Tune kit

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