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#85087 - 03/04/2002 06:38 constant crackling interference
crewe
member

Registered: 12/01/2001
Posts: 114
Loc: London, UK
When I power up the empeg I get a constant crackling sound (even before the engine is running). It doesn't get any louder as I turn up the volume, so I can disguise it somewhat by turning up, but it's still there and very noticeable during quieter songs or when I lower the volume. It is a constant sound, not altered by revving the engine or anything else.

I have searched the board all day and found a few leads, but was hoping you guys could help.

My amp (McIntosh MCC446) is grounded to bare metal in the car's boot (trunk). The empeg itself is not grounded to bare metal directly - I think it's just fed into the vehicle's wiring, which is then grounded as normal. Should I attach a wire from the empeg's metal sled to the car's chassis, behind the empeg? Should I insulate the empeg sled or the RCA jacks with tape?

The problem seemed to only start after I had my crossover installed (McIntosh MEN455). Perhaps this needs to be grounded as well? (I really don't know whether it is or not as it was installed at the audio place).

I also get a loud pop sound when the empeg and/or ignition is turned off, although I think this could be the classic 'negative spike' problem, and I have emailed support to get a diode to fix this.

I also still get (athough rarer now) the little battery symbol flashing up, and sometimes the empeg cuts out for a few seconds if I use my electric windows. This was a huge problem last year, but since then I fitted a vastly uprated alternator and a stonking great big modern day BMW battery (bear in mind this is an MGB!). I should have more than enough juice to power everything at once, not suffer audio cut-out's just because I flash my lights! Perhaps this is also to do with the negative spike bug though.

Hope you can help!

Thanks
Sally

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#85088 - 03/04/2002 11:08 Re: constant crackling interference [Re: crewe]
tfabris
carpal tunnel

Registered: 20/12/1999
Posts: 31565
Loc: Seattle, WA
Interesting series of noise-related problems. Sorry to hear things aren't all peachy with the MG.

The battery icon appearing is covered here. The crackling might be related to one of the things in that list, too.

The pop may be the diode thing, but it also might be all tied into the same problem (crackling and battery icon). Cleary something is not right with the power or the wiring that supplies your stereo system, and it should be checked out.

Maybe the fluid is just low in your battery? (Not kidding, check it, assuming you have the kind of battery that needs fluid)
_________________________
Tony Fabris

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#85089 - 03/04/2002 12:24 Re: constant crackling interference [Re: tfabris]
crewe
member

Registered: 12/01/2001
Posts: 114
Loc: London, UK
Hi Tony,

Thanks. Yes, I'd seen the riocar.org stuff, that's where I read about the Negative Spike Bug (which incidentally sounds *exactly* like a problem I have).

The battery is brand new, (it's condition has been checked also). The battery icon problem happened before the new battery / new alternator, and has happened since then although it did go away and then come back. It went away right before I upgraded the charging system, but we upgraded anyway. It stayed gone, but came back a few weeks ago (the upgrades were made last year).

Strangely enough, the first time I drove the car after starting this thread, there was no interference whatsoever! Typical, eh? But still, this (and the battery icon) have been problems that come and go. Fine for a few weeks, then back worse than ever. This is what makes me think it's some kind of loose wire behind the empeg. These problems are the worst!

Can anyone give me a firm answer on whether or not I should ground the empeg sled to the chassis? And if so, how?

Thanks

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#85090 - 03/04/2002 13:28 Re: constant crackling interference [Re: crewe]
tfabris
carpal tunnel

Registered: 20/12/1999
Posts: 31565
Loc: Seattle, WA
This is what makes me think it's some kind of loose wire behind the empeg.

That is a possibility. There were some of the sleds that had bad crimps on the connector and the wires would tend to pull out of the connector block. I'd definitely check that first, it could account for everything.

Can anyone give me a firm answer on whether or not I should ground the empeg sled to the chassis?

There's no firm answer on this as it'll vary from car to car as to whether or not it's needed.

In theory, it should only need the ground from the sled unless there's something else in the system causing a ground loop. Sometimes ground loops can be solved by grounding to the chassis, sometimes they are solved by isolating the ground from the chassis. You never know, really, until you get into it.

But before worrying about that, I'd triple-check all the wiring, because the way you describe the problem being intermittent really does make it sound like a simple loose wire.
_________________________
Tony Fabris

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#85091 - 03/04/2002 14:15 Re: constant crackling interference [Re: tfabris]
crewe
member

Registered: 12/01/2001
Posts: 114
Loc: London, UK
Hi Tony

Received my spare sled from empeg today, so I'm going to swap the sleds around (inc. wiring harnesses) tomorrow and see where that puts us. Empeg are also sending me a spare sled wiring loom (to replace the dodgy one currently in my car). Then I'll have 2 working units. (The 2nd one is for my brand new Miata that arrives in June ) Yes it's true, but don't worry, I'm not getting rid of the MG. Just putting her into semi-retirement as I lost my garage and parking her on the street is evil. Quite happy to park a new Miata on the street though! ?

Incidentally, I got my tweeters installed into the dash top, so my install is complete now. Will post some pics tomorrow.

So... guess I should start asking Miata install questions. New thread I think...

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#85092 - 04/04/2002 10:30 Re: constant crackling interference [Re: crewe]
crewe
member

Registered: 12/01/2001
Posts: 114
Loc: London, UK
Update: it's totally fixed !!!

Just ran a simple wire from the back of the empeg car mount to the chassis behind the dash, and the crackle totally vanished. I am now the proud owner of a totally clean sounding system.

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#85093 - 04/04/2002 11:10 Re: constant crackling interference [Re: crewe]
tfabris
carpal tunnel

Registered: 20/12/1999
Posts: 31565
Loc: Seattle, WA
Cool. Makes me wonder what's wrong with the ground wire on the docking connector, though.
_________________________
Tony Fabris

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#85094 - 04/04/2002 20:43 Re: constant crackling interference [Re: tfabris]
msaeger
carpal tunnel

Registered: 23/09/2000
Posts: 3608
Loc: Minnetonka, MN
we had to do that on my roommates too
_________________________

Matt

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