Ground Loop?

[danp129 10+ year member]

What voltage do you get after you set it by ear?

 

[IDSkoT 5,000+ posts]

What voltage do you get after you set it by ear?

I just realized it was my fuse that was blown. So I switched the fuse in my DMM and it blew again >=| So I went to RadioShack and got new fuses (For free, thankfully) and now I'm gunna go do it again...

 

[Haunz 10+ year member]

The wire around the RCA terminals is better than any ground loop isolator or protector.
The isolator/protectors will only cover up the problem ... the wire is re-grounding the RCA's; This is the source of the issue.

Signal ground from the deck is not ment to be rigged up to power ground.. this can even induce more noise in some cases...

The problem with ground loop stems from the fact that many amps and decks have poor isoltation between signal ground and power ground... grounding the RCA can work, but IMO is a ghetto fix...

A good quality isolator is a better fix IMO.. the transformers inside break the direct connection for a loop, so I don't see how it's a 'cover up'... the problem with cheap GLI's is their transformer windings act as a low pass filter in the audible frequency range...

There are several other fixes for goung loop; the absolute best being an isolated 12v/12v power supply with floating ground for the deck & processors...

 

[IDSkoT 5,000+ posts]

So I think there's something wrong with either my math or my DMM.

I replaced the fuse, unplugged all my speakers, put the 1K Hz Test tone on, turn to 47/62 volume and probe the right channel. At full gain it was only 32.44 Volts... My math says it's supposed to be 40 volts (For a JBL GTO75.4 II w/ 104x4 @ 4-ohms)

 

[ultimate157 5,000+ posts]

Signal ground from the deck is not ment to be rigged up to power ground.. this can even induce more noise in some cases...
The problem with ground loop stems from the fact that many amps and decks have poor isoltation between signal ground and power ground... grounding the RCA can work, but IMO is a ghetto fix...

The reason the Pioneers develop the alternator whine is the HU has a "Picofuse" on the PCB for the ground on the RCA's. If the rca's are played with when the system has power, it is very easy to pop this fuse and wipe out the proper ground on the RCA. Grounding the shielding to the case is indeed a ghetto fix, but its a free one.

I'm not sure whether or not the RCA's ground is totally disconnected when the fuse blows, but if it is then an isolator wouldn't work since there isn't a complete circuit.

So I think there's something wrong with either my math or my DMM.
I replaced the fuse, unplugged all my speakers, put the 1K Hz Test tone on, turn to 47/62 volume and probe the right channel. At full gain it was only 32.44 Volts... My math says it's supposed to be 40 volts (For a JBL GTO75.4 II w/ 104x4 @ 4-ohms)

Turn your HU volume up to 55 or 60 ... Pioneers don't clip until 62/62.

 

[IDSkoT 5,000+ posts]

Turn your HU volume up to 55 or 60 ... Pioneers don't clip until 62/62.

Will that give me the right voltage?

Oh: And BTW- if anyone's gunna do the stripping wire thing and wrapping it around the RCA's... a really good tool that you'll definitely need is tweezers. They were so **** helpful. e_e

I tried with my fingers and only my fingers before, and it took me like an hour to do. Wit hthe tweezers it took like 5 minutes at most.

 

[Haunz 10+ year member]

The reason the Pioneers develop the alternator whine is the HU has a "Picofuse" on the PCB for the ground on the RCA's.

From my understanding it's not a fuse for the RCA.. it's a fuse for the OP amps signal ground... and pioneers will ground loop anyway...

 

[ultimate157 5,000+ posts]

From my understanding it's not a fuse for the RCA.. it's a fuse for the OP amps signal ground... and pioneers will ground loop anyway...

Could be; I'm not positive on the schematics //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

My pioneer never developed the whine until I messed with the RCA's with the unit on (Long before I knew what I know now)

 

[ultimate157 5,000+ posts]

Will that give me the right voltage?

It will increase your RCA output voltage closer to its rating and should raise the output potential of the amp. I didn't have good luck at all with my volume lower than 50 when setting the gains.

 

[IgnoreMe 5,000+ posts]

hey, ultimate157 it looks like there isnt much room for the rcas to "seat" on the connection. is the rca suppose to basically touch the wire as you slide it on, or is the wire suppose to wrap AROUND the actual rca shield when you put the rca on?

 

[dman4486 5,000+ posts]

From my understanding it's not a fuse for the RCA.. it's a fuse for the OP amps signal ground... and pioneers will ground loop anyway...

never had any problem with ground loops on my pioneer until i popped the pico, layed a wire across it(using the pico's weld points) and haven't had problems since. any noise i have ever seen from a pioneer hu's rca's is due to the picofuse breaking

 

[ultimate157 5,000+ posts]

hey, ultimate157 it looks like there isnt much room for the rcas to "seat" on the connection. is the rca suppose to basically touch the wire as you slide it on, or is the wire suppose to wrap AROUND the actual rca shield when you put the rca on?

It appears that way in the picture, but once you push the RCA's on, they're on there very tight. You also don't need to use as large a wire as I did, I just had it lying around.

I would do it my way instead of wrapping the RCA's around the shielding once the RCA's are on. This way the wire is secured in a pressure fit instead of just wrapped around.

 

[rumple4skin 10+ year member]

The wire around the RCA terminals is better than any ground loop isolator or protector.
The isolator/protectors will only cover up the problem ... the wire is re-grounding the RCA's; This is the source of the issue.

he is right man half those isolators are built like shit, i watched a buddy return 3 untell he got one that kinda worked when all you need is some scrap wire.