Engine Noise from GPS

[Bigfish]

Garmin 2720 has bad engine noise coming through earplugs.

 

Got power to my GPS last night.

 

I connected the audio from the gps as follows:

 

2.5mm/3.5mm adapter, 3.5mm extension plugged into dual isolated autocom device then into Aux2 of autocom.

 

I also have my V1 plugged into the dual autocom.

 

V1 in audio A and GPS in Audio B = GPS volume @100% very low output. When I switch the GPS to A and V1 to B, the volume is loud @ 100%. Both instances produce bad engine noise.

 

Any suggestions from you fine folks on the board?

 

Thanks.

[John Bentall]

Garmin 2720 has bad engine noise coming through earplugs.

 

Got power to my GPS last night.

 

I connected the audio from the gps as follows:

 

2.5mm/3.5mm adapter, 3.5mm extension plugged into dual isolated autocom device then into Aux2 of autocom.

 

I also have my V1 plugged into the dual autocom.

 

V1 in audio A and GPS in Audio B = GPS volume @100% very low output. When I switch the GPS to A and V1 to B, the volume is loud @ 100%. Both instances produce bad engine noise.

 

Any suggestions from you fine folks on the board?

 

Thanks.

 

What Autocom unit are you using?

What dual isolated adaptor part number are you using?

Are you using in ear monitors?

 

Start by unplugging all the audio inputs and check what noise you get using the Autocom in "intercom" mode (talk into it and check the side tone).

Then start plugging in the Audio devices and see when the noise starts. Try re-routing the wire around on the bike to move them away from electrical noise generators like the alternator and coils. Even a little change in position might have a significant effect.

 

The isolating transformers in the "dual autocom" do reduce volume - no doubt about it - but if it really is a dual-isolated unit I would expect the volume to reduce by the same amount whether it was plugged into input A or B. Can you check on this please?

 

In-ear monitors are absolutely ruthless in highlighting engine interference. Try without just as a reference point.

[Bigfish]

What Autocom unit are you using?

Pro-7 Sport

 

What dual isolated adaptor part number are you using?

Autocom Part #1317

 

Are you using in ear monitors?

Arizona Al's acoustical air tubes via speakers.

 

BTW, since my PC8 has mini fuses, I have removed the in-line fuses that were attached to the power leads from the GPS and V1.

 

More info:

I installed the PC8 from Easternbeaver.com

Ran two separate looms. Right side has ground loom and left side has power leads.

 

The V1 is working fine with no noise.

I purchased my gps used but did not get any part to connect the 2.5mm to the 3.5mm input into part #1317.

 

I guess I could try a different wire ( both ground and power ) that connects back to the PC8.

 

Thanks for helping John

 

Will look forward to your suggestions.

[cali_beemer]

check your ground wire. I know with car stereos a bad ground can give identical results. Dont just eyeball it, see if you can use a good multi-meter. Also check how good your ground wire to connectors are. If not using some ferride beads at each end of the cable will fix it. The noise you hear is from interference and as noted by another, moving its location can help. However, using a ferride bead should remove the noise and is always a good idea to use. If you want to go one step further, you can route your wires in a shielded sleave as well.

[John Bentall]

What Autocom unit are you using?

Pro-7 Sport

 

What dual isolated adaptor part number are you using?

Autocom Part #1317

 

If you are using #1317 then port B is not isolated according to my information. You have checked this out already when you said that the GPS only lost volume into one of the 2 ports (port A in this case).

#1317 was perfect for mixing the input from a bike-powered RT radio with a battery-powered iPod.

The twin-isolated equivant would be #56, that later turned into a #1281.

 

Top Gear still appear to be selling them.

 

 

[UberXY]

I used an $18 noise filter from Crutchfield to eliminate the ignition noise when I used an Autocom on my RT. It worked great. I have since ditched the Autocom for a Wirevo/Scala Bluetooth setup with my Zumo, and thereby eliminated the need for the filter.

 

Noise filter

 

And BTW if a part is $18 on Crutchfield, it is probably $9 on eBay, and $50 from Autocom.

 

[Bigfish]

Thanks John.

 

Just picked up a 1281 off ebay. Will give that a try and hope it solves the issue. I'll keep you posted. Probably be a couple days before I receive the item.

 

Thanks to all for the suggestions and input.

 

For now, Visual only - No Audio yet

[Bigfish]

Got my Autocom part #1281 and it has fixed my engine interference noise issue.

 

However, the volume on GPS 2720 is set to 100% and I can barely hear the voice commands.

 

Any Suggestions?

 

Do I need the special Autocom audio wire?