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Old 21st August 2007, 01:51   #16
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MX is a good brand that make some good cables, but there are other factors that could help create this problem as laid out by souljah & LBM.
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Old 21st August 2007, 08:43   #17
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Which MX cables did you buy? There are many models.
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Old 21st August 2007, 08:44   #18
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Quote:
Originally Posted by clipto333 View Post
there is a fuse in the HU which blows when one is careless with the wires. this happens when the hot pin i.e. the inner pin of the rca jack comes in contact with the ground.

the wire you see is the solution to this problem or you can get the hu checked and replace the SMD fuse or bypass it.
That is correct. My installer has corrected the problem same way, but he has used the wire. Where can I get the actual fuse? I prefer to have everything pukka.
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Old 21st August 2007, 08:48   #19
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If that really is the problem, how about using an audio isolator? That would be a better way of doing it, wouldn't it?

I don't think running the wires around RCA female sockets is a great idea when we're spending thousands on the RCA cables, IMO.






Construction:
A ground loop isolator contains an isolation transformer for each channel. The transformers generally have a 1:1 ratio which neither boosts nor cuts the audio level. The audio is magnetically coupled through the transformer's core. Since DC can not flow the transformer, the DC path is cut and the noise is eliminated.


Taken from here:

Ground Loop Isolators

More here:

Audio isolators


I would however, first suggest that you check for any leaks in the RCA and the grounding of the amplifiers first.

Last edited by rocksterraghu : 21st August 2007 at 08:52.
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Old 21st August 2007, 12:11   #20
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MX-797 ,Sam.
It came in the CD-case kinda packing.
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Old 21st August 2007, 12:22   #21
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Quote:
Originally Posted by nitrous View Post
MX-797 ,Sam.
It came in the CD-case kinda packing.
Is that the "digital" series? Im not sure.. I had got a bunch of these for my friends. The case is funky no, I might still have it lying around will check.

Even though its for home/dvd entertainment it would be a double shielded cable so interference shouldnt really be concern.
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Old 15th December 2007, 21:37   #22
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Hello BHPians,

I have a newbie question on the ground loop problem. Would appreciate if the gurus can answer:

In a setup using unbalanced output (from the HU), and an unbalanced input (say, to the amp), what is the outer wire of the RCA cable used for? Is it:

a). used for providing a common reference point for ground across the HU and the amp? If so, can the ground loop problem still show up in the setup? My reasoning is that if the outer wire of the RCA cable is the common ground point, then any difference in the quality of the electrical ground at the HU and the amp would not cause a ground loop problem, because the audio input jack of the amp would be isolated from the amp's ground anyway. So no current flow (apart from the audio return) can happen between the amp and the HU on account of variation in the quality of ground.

OR

b). used to provide insulation from RF interference (instead of being in the audio signal return path). If this is the case, the ground of the amp, and the ground of the HU would be connected to each other via the outer shield of the RCA. Any interference would be shorted to the ground (presumably in the direction of the lower potential). However, if the quality of the grounds in the amp and the HU is even slightly different, then current would begin to flow through the outer shield of the RCA cable, and would induce a corresponding voltage in the inner wire of the RCA cable. Is this scenario true for car audio, and if so, is this the precise cause of the hum.

Like I said this is a newbie question as my fundamentals are not strong. Any input would be appreciated. If there are other scenario, please tell me.

Last edited by adya33 : 16th December 2007 at 01:49.
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Old 3rd December 2009, 13:59   #23
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Quote:
Originally Posted by s0uljah View Post
Pioneer HU na?

Nitrous anna, all you need to do is ground the RCA jacks to the HU. Will post the pic shortly.

A Simple copper wire around the rca jacks of the HU to a screw on the back of the HU will suffice.

MX cables for the win



another testimonial to souljah's recommendation.

My car hit a bad bump and alternaterot whine started.
I remoevd the RCA and the whine stopped so diagonised that the whine was due to the HU .
Tried the above contraption and the whine disappeared.

thoroughly recommended for pioneer HU suffering from alternator whines.
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Old 3rd December 2009, 14:04   #24
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Yes, this solved it for me.
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Old 3rd December 2009, 14:29   #25
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Unbelievable, but believe it, it's true.
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Old 3rd December 2009, 15:57   #26
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Will this not SHORT circuit the HU? Are my eyes seeing right?!

All the 4 RCA jacks have been shorted?!

After a recent mess - the last 0.5m of my audio setup (connected to battery) was rewired and new fuse put. Now there's a SOLID whine (everything else is same!). trying soulie method tonight!
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Old 4th December 2009, 12:02   #27
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Default Hissing & 'Thup' sound

Hi all,

I had an issue with alternator whine and got rid of it when I decided to change my entire wiring with good Ground Zero RCAs & wires. However, I am still getting a hissing sound which is very audible at low/zero volume. It is also more prominent when I switch on my headlights. I also get a very minute 'tick' sound from the speakers when I brake.

I addition I also get a 'thup' sound, which is similar to a sound emitted when an electronic item short circuits. This sound is emitted only when I turn on the switch of my headlights. It also happens when I turn off the headunit. I am using the Pioneer 6950!

I have been told that this is due to a fault in the headunit & usually occurs when RCAs are connected to the headunit with the system on during installation. This leads to a shorting of some component in the headunit and hence the 'thup' sound.

Is the above true? How can these issues be resolved?
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Old 4th December 2009, 12:14   #28
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Quote:
Originally Posted by Epic View Post
I have been told that this is due to a fault in the headunit & usually occurs when RCAs are connected to the headunit with the system on during installation. This leads to a shorting of some component in the headunit and hence the 'thup' sound.
I've read the same - a search for "pionner HU pico fuse" shows this result. Grounding the RCA's (like the picture shown above) seems to be a band aid kind of fix. Getting the HU serviced might be an option.

The problem is that most installers hot swap RCA cables (i.e. plug them in when the system is powered up). I've seen them do that on their own cars (with pioneer HU's)!

Ignorance on their part or is this pico fuse thing an urban legend ? Experts please pitch in.
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Old 15th December 2009, 06:20   #29
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My alternator whine issues have been resolved now. Grounded the wires like in souljah's recommendation above.

Now its only a mild hiss if I start car with radio ON!
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Old 15th December 2009, 12:01   #30
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Quote:
Originally Posted by phamilyman View Post
Now its only a mild hiss if I start car with radio ON!
you'll fry up your ICE this way!
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