Class D AMPS and FM reception issues
Outstanding HDF Member
Joined: Mar 2012
Posts: 2,843
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From: Michigan
I would suspect that the components that disrupt FM are being used because they are either inexpensive, or because amps are usually not located as close to the head unit as we install them and the manufacturer never tested them in this way.
Supporter
Joined: Apr 2014
Posts: 19
Likes: 0
From: new york
i have a 2014 sg with the 4.3 ss 520 amp and hertz speakers 6.5. and harley hidden antenna. i lost fm reception. took hidden antenna out and put stock antenna back on. was a tiny bit better reception.
stumbled across the ferrite core thread and bought some. wrapped wires through core,2 loops,both power and ground and got my reception back.
then put cb in and hid the whip antenna behind bag and up through fender support and under seat. now my reception is spotty kinda comes and goes when it feels like it.
gonna fab a bracket so i can move cb to right side where it belongs and put radio antenna on left.
but the cores worked for me before cb install
nick
stumbled across the ferrite core thread and bought some. wrapped wires through core,2 loops,both power and ground and got my reception back.
then put cb in and hid the whip antenna behind bag and up through fender support and under seat. now my reception is spotty kinda comes and goes when it feels like it.
gonna fab a bracket so i can move cb to right side where it belongs and put radio antenna on left.
but the cores worked for me before cb install
nick
Tourer
Joined: Jul 2008
Posts: 436
Likes: 5
From: Northern Virginia
Old thread but some new data. I have a Rockford Fosgate T400x2ad amp mounted in fairing on bracket above stock HK HU. Shorty antenna on the tourpak. Based on reviews I was hoping I wouldn't have EMI issues, but I have interference on both AM and FM radio bands. Will be trying some ferrite core beads next time the fairing is off to see if they help.
Last edited by Gnarl78; May 16, 2015 at 07:36 AM.
Grand HDF Member
Joined: Nov 2012
Posts: 3,784
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From: Pasadena TX
My current amp is a Power Akoustik RZ4-2000D. I also use the cheap ebay hidden antenna http://www.ebay.com/itm/Hidden-ANTEN...88e599&vxp=mtr. Last week I swapped a Sony DSX for a Sony MEX head unit. With no other changes my FM came back to a degree. I had no FM at all, now I easily pickup the 100,000 watt stations.
Road Warrior
Joined: Aug 2013
Posts: 1,505
Likes: 31
From: Las Vegas
Old thread but some new data. I have a Rockford Fosgate T400x2ad amp mounted in fairing on bracket above stock HK HU. Shorty antenna on the tourpak. Based on reviews I was hoping I wouldn't have EMI issues, but I have interference on both AM and FM radio bands. Will be trying some ferrite core beads next time the fairing is off to see if they help.
Tourer
Joined: Jul 2008
Posts: 436
Likes: 5
From: Northern Virginia
Do you have any suggestions I should try to restore my radio reception? One of the main reasons I went with it was based on your test results showing no loss of FM. I really want to make this amp work for my setup as it sounds great powering the BT7.1's up front.
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Extreme HDF Member
Joined: Nov 2007
Posts: 14,670
Likes: 139
From: East of the Sun, West of the Moon
my rule of thumb is
always expect some if not all FM degradation from any Class D amps. There are manufacturers out that that swear up and down their Class D amps don't interfere but there are plenty of customers out there to say otherwise.
This doesn't mean you will have FM signal loss, you just need to be prepared for it to be gone.
I've installed some SS, NVX, PA, Kicker, HT, etc. amps with no FM signal loss whatsoever, then again I've also installed those same amps on other bikes where FM is degraded or gone completely. I think it's the luck of the draw as to whether you'll get one that kills FM reception.
You might try moving your power and ground wires from inside the wiring tray and simply lay them on top of the wiring tray instead of being inside it.
always expect some if not all FM degradation from any Class D amps. There are manufacturers out that that swear up and down their Class D amps don't interfere but there are plenty of customers out there to say otherwise.
This doesn't mean you will have FM signal loss, you just need to be prepared for it to be gone.
I've installed some SS, NVX, PA, Kicker, HT, etc. amps with no FM signal loss whatsoever, then again I've also installed those same amps on other bikes where FM is degraded or gone completely. I think it's the luck of the draw as to whether you'll get one that kills FM reception.
You might try moving your power and ground wires from inside the wiring tray and simply lay them on top of the wiring tray instead of being inside it.
my rule of thumb is
always expect some if not all FM degradation from any Class D amps. There are manufacturers out that that swear up and down their Class D amps don't interfere but there are plenty of customers out there to say otherwise.
This doesn't mean you will have FM signal loss, you just need to be prepared for it to be gone.
I've installed some SS, NVX, PA, Kicker, HT, etc. amps with no FM signal loss whatsoever, then again I've also installed those same amps on other bikes where FM is degraded or gone completely. I think it's the luck of the draw as to whether you'll get one that kills FM reception.
You might try moving your power and ground wires from inside the wiring tray and simply lay them on top of the wiring tray instead of being inside it.
always expect some if not all FM degradation from any Class D amps. There are manufacturers out that that swear up and down their Class D amps don't interfere but there are plenty of customers out there to say otherwise.
This doesn't mean you will have FM signal loss, you just need to be prepared for it to be gone.
I've installed some SS, NVX, PA, Kicker, HT, etc. amps with no FM signal loss whatsoever, then again I've also installed those same amps on other bikes where FM is degraded or gone completely. I think it's the luck of the draw as to whether you'll get one that kills FM reception.
You might try moving your power and ground wires from inside the wiring tray and simply lay them on top of the wiring tray instead of being inside it.
been doing a lot of testing with Hog Tunes products over the last couple months, couple of thing I have found out on Class D EMI was coming from the Output wires from the hog tunes amp, try wrapping your hands around your output wires and see what happens you should see fm reception improvement. Also found if you can separate the amp from HU problem gets better need about a 3" buffer zone between amp and head unit. Also make sure the wires from output and input are twisted. twist all your speaker leads - and + as they go to your speakers. I have now tested the NCA 70.2. and the new version 200 amp class d version. They are still having having EMI/RFI issues. another trick I found was to check routing of the antenna wire and the power wires under fairing keep them separated.
Non Class D amp can have problem too as we are seeing on some Harleys up to 10 volts AC @2500 rpm is leaking through regulator to the DC circuity and the amp pick it up causing momentary cut out of sound usually above 2500 rpm.
I am getting ready to try to build a shield system for the amp very much like the Guitar guys do for feed back. I have just order in some copper tape to wrap output wires in and also put a layer between the amp and the HU to build emi shield. I will keep you posted
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Tourer
Joined: Jul 2008
Posts: 436
Likes: 5
From: Northern Virginia
Yes, that would be a good idea. You might want to get some of the EMI chokes that Radio Shack sells in hand when you do your test in the likely event you have EMI interference and see if the chokes help. They will cost you less than $10 and you just snap them over your wires. If you have interference put them on the input and output wires to/from your amp. You might need larger ferrite cores for your power and ground wires. Try to get 2 wraps around the cores for the power and ground. I got about 85-90% of my FM reception back using these EMI reducing techniques with my RF T400x2ad amp.
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