I've got a head-scratcher here and I hope some of you guys who really know your mobile audio can help. Since this is about the mp3 player on my Zumo 450 mounted on my Road Glide, I hope it's not too far off the "touring" topic.

I don't want to wire my Zumo audio output directly to the "aux" jack on the bike's stereo. (If you're familiar with roadglide fairings you understand the difficulty with running wires out to the fairing) So to facilitate this, I bought a wireless FM modulator. My plan was to connect my Zumo to the modulator, set a radio button for 87.9 and poof, I have my mp3 library coming through a preset on my radio. Which I do, except there's this HUMMMM. Here are the facts about the situation:

*The hum is independent of the Zumo volume control. The music gets louder and softer, but the noise is constant.

*When I take the plug out of the Zumo and and insert it into any other electronic device, the modulator signal to the radio is clean.

*When I plug some good headphones directly into the Zumo, the audio to the headphone jack is clean.

*But when I hook the Zumo to the modulator--it's a steady hummmmmmmmmm. It doesn't drown out the music if I crank up the Zumo's volume all the way, if I were looking at a VU meter I would guess the noise is about 40%.

I'm sure it's not wiring-related, and besides, it works fine on any source but the Zumo. In fact, it's so steady and constant that I could be hearing some sort of feedback.

Does anyone have any idea why both the Zumo's mp3 player and modulator would work correctly seperately, but not together?

 

Did you try to connect the Zumo to the AUX with a patch cord to see if that worked? Any cord that works with an I-Pod will work.

Why do you want to use a FM Modulator? You still have to tune to 87.9 so it's not like you still have access to the radio while using Zumo and wire will give better sound results. You don't have to run the wire out under the failing unless you want too and it really is not at all hard to do. What's the difference aesthetically between having the modulator strapped to the bars vs a patch cord. With the cord you will still have a preset on the radio, it's the AUX and you don't need to reach over to the radio to select it, just flip the right handle bar toggle.

On the other side, your problem could be a "ground loop" problem. If it humms with the patch cord then you'll need a cord with a choke on it. Check out the www.zumoforums.com site and do a search. I've seen something on it just recently.

If it is a ground loop problem, her's a cable to take care of it.
http://www.tesseractcorp.com/product...tingPatchCords

 

On a Road Glide, the fairing is attached to the frame, not to the handlebars like an ultra. If I ran the audio from the bar-mounted Zumo to the aux input up on the fairing, the cable would have to hang across the space between the bars and the fairing so that's not an option. Secondly, the audio line from the zumo will run along the frame back to the modulator attached to the inside one of the saddlebags, not strapped to the handlebars. I'm not sure where you got that.

Thanks for the link but that doesn't appear to be the problem according to the site: "...the newer models with a satellite radio, MP3 player or other stereo audio source built-in use a standard 3.5mm jack and do not need isolation."

Any mobile audio pros out there?

 

Try a 1/8" male to 1/8" plugfrom the Zumo audio out to the HD Radio Aux in.
(It's a $3.99 test) Do you still get a hum?

I tried the FM modulator approach the first time I did it.
https://www.hdforums.com/fb.asp?m=2818922

I removed theFM modulator and added an AUX input to the back of the HD radio.
I did this for a bunch of reasons better sound quality, no components to fail, interference on FM stations, no wiring etc. Now, I don't have to be concerned about picking up an FM station in my travels and it sounds real clean.

I found the instructions on CVOHarley.com. GREAT JOB!
"How To" Aux Input Jack Moved to Back of Radio
http://www.cvoharley.com/smf/index.php?topic=7674.0 and here
06 and up http://www.cvoharley.com/smf/index.php?topic=10044.0

Boy am I glad I did it! It was really easy! The additional AUX input took less than 20 minutes.
What a much better sounding system now!

Here is the entire project post.
https://www.hdforums.com/m_2812645/tm.htm

It was much much easier to connect an additional AUX input than it was to hook up the FM modulator.

Hope this helps.

 

Merlini: My good friend Kevin (pirateeye on HDF)wired his Zumo 550 by adding an AUX IN on the back of the HK radio using the info on the CVO forum I provided to him--he's very, very pleased with the install.

BG: Not trying to hijack your thread and regret that I have no solution to offer, but this post will bump your request to the top of the page for a bit--hope you get a solution from an audio pro.

 

Thanks!

My whole issue with hardwiring is running the wire from the handlebars to the fairing. I don't want it strung like a telephone line! Merlinii, I see from your sig that you ride a RG--how did you run the wire to the fairing and keep it concealed?

PS: I emailed Garmin tech support and they suggested that there may be an "incompatibility issue" between the zumo and the modulator. I asked them for clarification and I'll post any reply I get in this thread.

 

Yes, I am aware that the fairing is hard mounted. If you're going to string 8 feet of wire back the frame and across to a saddlebag then why not just drop down the front tube and follow the wiring harness that the factory uses to carry all the electrical wiring to the gauges and radio in the fairing?

Let's see, where did I get the ideat that you might hang the FM modulator on the bars? I've seen it done and it looked like ****!

Any mobile audio pros out there?

 

I ran mine thru the black plastic piece around the forks. I can't see it.

 

I'm not a mobile audio expert, but on my buddie's '06 EG Classic with the Zumo connected at the rear of his HK radio, that wire runs with the handlebar harness to a plug; the Zumo has a very short plug that he plugs into it when he has the Zumo on the bike; when the Zumo is off the bike the wiring and plug are invisible, figuratively speaking of course.

 

The best test to see if a system would benefit from an isolated power supply is to temporarily power the component with a small 12 Volt DC motorcycle battery. If the noise goes away and the component performance improves with the motorcycle battery, then the isolated supply should be considered. An isolated power supply is not an in-line filter. The supply actually generates its own energy and when installed correctly, acts like a small motorcycle battery that never needs to be charged.