Honda Element Owners Club banner

Ground Loop problems?

5K views 7 replies 2 participants last post by  brendan 
#1 ·
This is the text of an article I posted to the empeg.comms.net support board, but perhaps one of the Element owners here might have a suggestion as to the problems, as they occur even using just an aftermarket CD headunit. Thanks for looking.

--------------------------------

ObRTFM: I've gone over the FAQ and believe I've got everything wired to the same ground potential, but the sonic evidence indicates otherwise. Any additional advice would be welcome.

Vehicle: 2003 Honda element EX.

Factory System: Double-DIN head unit with standard Honda wiring loom, plus three additional connectors: antenna, subwoofer line-out and auto-detect aux-port input (for the in-dash 1/8" connector). Headunit, however, only puts out line-level, as there is a separate OEM amplifier in the passenger kick panel that does 4-channel plus subwoofer amplifying (4x50W max, 1x70W max, not sure of the RMS). The equipment was all manufactured for Honda by Alpine.

The factory system is 100% noise-free. It also plays CDs noise-free even if three of the four "extra" harnesses are detached (antenna, subwoofer, aux-in socket), leaving only the standard Honda/Acura in-dash harness connected (checked that just in case there were ground requirements for the other harnesses).

I replace the OEM headunit with Pioneer DEH-750MP connected through 2 (cheap) two-channel speaker-level to line-level converters and a honda-compatible mating harness. Slight noise ( when headunit's amps are on). Thumps a little bit when amps turn on of off. If I disconnect the eight speaker-side wires, no noise but no music. If I disconnect the "system remote control" (as labelled by Pioneer) from the amp turn on (not labelled), again, no noise but as expected, no music.

Important: Originally, I had the output polarity of the line level converters reversed. They had RCA outs, and I cut off the RCA connectors and wired each shield to the channel's positive and each center conductor to the channel's negative, but the noise was tons (unbearably!) worse then. I took the harness inside, uncrimped, reversed the polarity, recrimped, went back out and hooked it up and, for a moment, I thought I had fixed the issue entirely. But then I noticed the noise was still there, just substantially quieter. I was unsure if that was the 'right' fix or if I should have been swapping the polarity of the inputs to the converters instead, but the wiring up to the converters seemed to be wired with correct polarity. Might have to try swapping the polarity of both the inputs and outputs this time. Or, more likely, replacing these with higher end units? Could this be a channel ground vs. common ground thing?

To be sure, switched back to the OEM head unit, yup, no noise.

Switch back to the Pioneer + converters, yup, noise. I can hear the CD spinning up, alternator whine, etc.

Add the empeg MkIIa (riocar) to the system by plugging its ISO plug into the ISO socket supplied with the unit and wired in parallel with the pioneer harness. This adds substantially more annoying noise (harddrive, processor, etc), regardless of whether the empeg's line level output is connected to the head unit or not.

Add the Parrot CK3000 to the system, by patching it in through the ISO plugs/sockets (described below): symptoms are even worse! Grr.

Pull it all out and put the OEM unit back in. Leave the dash, subwoofer cover, glove box, etc. all in pieces. Sweet music. Fall back, regroup, live to fight another weekend.

My approach on the wiring was to do things as modularly as possible, with no cutting of the OEM or any product's wiring. In order to support the CK3000, I needed to use the speaker-level outs of a new headunit to feed the ck3000, then attenuate the output down to line level before feeding that to the OEM amp. It also required including a conversion of the OEM wiring to ISO plugs, and a conversion of the headunit/empeg's wiring to an ISO double-socket.

[cont]
 
See less See more
#2 ·
[cont]

While I felt this next item may be important regarding the noise problem adding the empeg, it doesn't explain the above problem with using just the new headunit: the empeg's power/control harness is wired in parallel with the headunit's harness to the double ISO-socket using the extra ISO plug included with the empeg. I've checked the connections of the ground, power and ignition wires connections (all three ways) with a multimeter, while wiggling, all seem to be good and resistance free.

I've done whole system continuity tests from the 'to OEM-wiring' end to the 'to empeg' or 'to pioneer' ends. No problems. How concerned should I be regarding the other wiring vs. chassy grounds or the line-level adaptors above?

Here's a (helpful?) diagram (without Parrot CK3000):

http://brendan.org/element_wiring.txt

-brendan
 
#3 ·
I installed an older Pioneer model (P5200) which initially had noise due to my bad wiring and the use of a line-level convertor (which is inherently noisy).

Here is what I got out of your 2 posts. The only things you installed are 750MP headunit and the line-level convertor. You are using the factory amp, speakers and subwoofer. Here is where you lost me;
Important: Originally, I had the output polarity of the line level converters reversed. They had RCA outs, and I cut off the RCA connectors and wired each shield to the channel's positive and each center conductor to the channel's negative, but the noise was tons (unbearably!) worse then. I took the harness inside, uncrimped, reversed the polarity, recrimped, went back out and hooked it up and, for a moment, I thought I had fixed the issue entirely.
What RCA outs are you cutting and wiring?

My first recommendation is; WHY ARE YOU USING LINE-LEVEL CONVERTORS? Sorry for the caps but your headunit has 3 sets of RCA outs. There is no need for you to use line-level convertors unless you want to add noise into your system. I had to use it because my old model HU only has 2 sets of RCA outs. Lordy man stop making more difficult than it needs to be.

All I did was to use the Metra harness I bought and twist pairs of speaker wires from the harness and soldered it into RCA plugs. Once I had the 4 channels I just plugged them into the HU and line-level convertor. In your case skip the convertors and just plug directly into the HU.

You didn't mention how you attached your HU to the subwoofer wires. Here is where I messed up. I was lazy and used cheap RCA wires that come with your VCR and the like. I cut off a section and spliced that into subwoofer wires. The wire just didn't work and the sub sounded weak and it added a hiss into my system whenever the CD spun up. I ripped that wire out and made a good RCA cable with some twisted 20 or 18 gauge wire. I reattached this with splice and all the noise went away.
 
#4 ·
[quote:641f4b8ea9=" "]Here is what I got out of your 2 posts. The only things you installed are 750MP headunit and the line-level convertor. You are using the factory amp, speakers and subwoofer.[/quote:641f4b8ea9]

Exactly.

[quote:641f4b8ea9=" "]Here is where you lost me; [quote:641f4b8ea9="brendan"]Important: Originally, I had the output polarity of the line level converters reversed. They had RCA outs, and I cut off the RCA connectors and wired each shield to the channel's positive and each center conductor to the channel's negative, but the noise was tons (unbearably!) worse then. I took the harness inside, uncrimped, reversed the polarity, recrimped, went back out and hooked it up and, for a moment, I thought I had fixed the issue entirely.[/quote:641f4b8ea9] What RCA outs are you cutting and wiring?[/quote:641f4b8ea9]

The 2 two-channel speaker-to-line level converters I got had 4 wires input and two RCA cables output. Since I needed to wire the RCA line level out into the metra harness, I had to chop the connectors off. I had thought about chopping up some RCA wiring, but the converters were $3 each (no-name, but rated for 50W max), so I chopped them up instead. In case they are the (or a) problem, I've ordered the OEA-4 Scosche 4-channel converter to replace them (it gets good write-ups and is adjustable).

[quote:641f4b8ea9=" "]My first recommendation is; WHY ARE YOU USING LINE-LEVEL CONVERTORS? Sorry for the caps but your headunit has 3 sets of RCA outs. There is no need for you to use line-level convertors unless you want to add noise into your system.[/quote:641f4b8ea9]

The reason is that the bluetooth speakerphone system I'm installing needs to be wired at the speaker-level, and not line-level! And it inserts itself in the stream of all four channels (but only outputs in the front two when active). I really wish they'd added an option to work at line level. Sigh.

When it mutes the system, it actually outputs high-power (speaker-level) signal directly into the harness facing the amp. If I fed that into the amp directly, without the converters, it wouldn't work (and would possibly smoke the OEM amp).

This product is the entire reason I added the headunit->ISO and ISO->Metra parts of the wiring, since it's europe-market targeted, and ISO connectors are all the rage over there.

[quote:641f4b8ea9=" "]I had to use it because my old model HU only has 2 sets of RCA outs. Lordy man stop making more difficult than it needs to be.[/quote:641f4b8ea9]

Really, I'm trying to keep it simple. :)

[quote:641f4b8ea9=" "]All I did was to use the Metra harness I bought and twist pairs of speaker wires from the harness and soldered it into RCA plugs. Once I had the 4 channels I just plugged them into the HU and line-level convertor. In your case skip the convertors and just plug directly into the HU.[/quote:641f4b8ea9]

Wish it could be so. :(

[quote:641f4b8ea9=" "]You didn't mention how you attached your HU to the subwoofer wires. Here is where I messed up. I was lazy and used cheap RCA wires that come with your VCR and the like. I cut off a section and spliced that into subwoofer wires. The wire just didn't work and the sub sounded weak and it added a hiss into my system whenever the CD spun up. I ripped that wire out and made a good RCA cable with some twisted 20 or 18 gauge wire. I reattached this with splice and all the noise went away.[/quote:641f4b8ea9]

I haven't connected up the subwoofer yet. I did a quick test of connecting the non-fading out using a chopped RCA cable, it seemed to work "OK", but I plan on using something more substantial to do the job. I've read the sub is a dual-voice coil: does it require two signals from the head-unit? Should I combine the stereo out using a y-cable, or just use left or right? what's the 3rd pink wire on the connector?

Also: thanks so very much for taking the time to wade through my long double-post, Silk. I seriously appreciate the help, big time.

-brendan
 
#5 ·
LOL all of this for speakerphone. Boys and their toys.... I have the Scosche and it works fine. It has a built noise circuitry and a ground. I would only advise you to adjust the levels on the Scoshe unit carefully before you put everything back together.

As for the sub even though it is dual voice coil, it is still a mono sub. You only need to hook it up to one of the non fade channels. Don't think it matters but I think it was the left channel according to the Pioneer diagram. The infamous 3rd wire question I can not answer but if you do find out the answer please let me know. Good luck.
 
#6 ·
[quote:354f14c3b8=" "]LOL all of this for speakerphone. Boys and their toys.... [/quote:354f14c3b8]

Heh, yeah the toy aspect lead me to that particular bluetooth integrated w/ stereo model. But the idea of a speakerphone is also an important safety issue for me. I see way to many near-misses with people on the their phones these days.

[quote:354f14c3b8=" "]I have the Scosche and it works fine. It has a built noise circuitry and a ground.[/quote:354f14c3b8]

Oh cool, hadn't realized it had those built in.

[quote:354f14c3b8=" "]I would only advise you to adjust the levels on the Scoshe unit carefully before you put everything back together.[/quote:354f14c3b8]

Will do. I'll have everything piled on the dash or center console and tested (except the upgraded speakers) before mounting. And then I'll retest.

[quote:354f14c3b8=" "]As for the sub even though it is dual voice coil, it is still a mono sub. You only need to hook it up to one of the non fade channels. Don't think it matters but I think it was the left channel according to the Pioneer diagram. The infamous 3rd wire question I can not answer but if you do find out the answer please let me know. Good luck.[/quote:354f14c3b8]

Ok, left side it is. Will see what I can do with that wire. Thanks for the above.

-brendan
 
#7 ·
[quote:49aebf9895="brendan"][quote:49aebf9895="Silk"]I have the Scosche and it works fine. It has a built noise circuitry and a ground.[/quote:49aebf9895]

Oh cool, hadn't realized it had those built in.[/quote:49aebf9895]

Scosche OEA-4 came today. I popped open the case and, yes indeed, it has capacitors inline on the headunit side for both the signal and ground lines, all eight of them. Should be no ground loop issues on those eight wires, anyway, when I get around to trying again this weekend.

The unit doesn't have a ground itself: perhaps you were thinking of the SLC-4?

-brendan
 
#8 ·
[quote:b1173486bb="brendan"]Scosche OEA-4 came today. I popped open the case and, yes indeed, it has capacitors inline on the headunit side for both the signal and ground lines, all eight of them.[/quote:b1173486bb]

Did the wiring part of the install tonight. The OEA-4 solved the ground loop problem entirely (that's what I get for cheaping out on the no-name adapters). Everything works and sounds great, even the bluetooth carphone adapter, which is zip-tied on the left side of the left mounting bracket. It even pauses the empeg and mutes both the empeg and the pioneer. There's a huge amount of room behind the environmental controls and driver-side dash for overflow wiring to go, thank goodness.

However, some things are still in the half-a, er, half-done stage:

1. The carphone mic wiring comes out of the top-right of the glove box and then is taped along the dash, a-column, rear-of-passenger-sunvisor to its spot on the rear-view mirror mount. At a minimum, it should snake up inside the a-pillar. I'm wary of pushing it up into the gap between the top of the glass and the ceiling, due to the element glass issues.
2. The carphone pickup/hangup button module's wire is also taped along the edge of the center console. Might simply replace the tape with some black and gray strips of double-sided foam.
3. The "dash-kit" isn't here yet, so neither of the 2 din units are bolted in and there's no pleasing frame covering the hole they are in. Grr.

[I don't have cars up on cinderblocks, I swear.]

Ok. Other things to remedy:

1. Speaker installs, since all the equipment is here. Probably the 4 easy ones this weekend, then the a-pillar ones in december, during which time I'll reroute the car phone mic a bit as well.

2. The subwoofer works when wired in, but I didn't have any dependable way to do that other than cutting the honda wiring. I might still do that, but add some bullet connectors to both parts, and then wire the honda sub signal lines to a bullets-to-RCA wire. Before I do that, I'm looking through my junk pile for some pin-headers with the right spacing I could use instead.

3. I still want to wire the aux-port in to the Pioneer, in parallel with the empeg. Just because.

-brendan
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top