grutter

iTrader: (1)

I hope this helps someone out...

After upgrading my system, I had a noise coming through the tweeters that I 'thought' was alternator whine. Drove me nuts checking grounds etc., to no avail.

Then I discovered that I only had the noise if my AC control was on. I realized that the noise I was hearing was likely the high frequency pulses for the car's AC LAN Control System.

Somewhere during my troubleshooting, I suspected the routing of my RCA cables (Power was run down the passenger side channel, RCA's down the center console).... so I had some old (and cheap) RCA's that I connected from my output converter directly to my amps.. and pure silence !

So at this point I new the problem was in the RCA cables... but what could be wrong with my high-dollar STINGER cables, that a cheap set fixed.?!@#$

The STINGER cables I used are "directional"... meaning that the signal conductors are a twisted pair, and the shield is connected at only one end. The "cheap" cables that eliminated the noise had only a center conductor and outer shield.

So I dis-assembled the ends of the STINGER cables at the amplifier (the end with the shield NOT connected), and re-assembled with the shieild connected.... and PURE SILENCE !!

Lesson learned -> don't use directional cables! The only thing I can think of is that the outputs may be floating, not necessarily grounded. So with the shield connected to one end, it acts like a big antenna, coupling high frequency signals INTO the signal pairs.

LS350Z

I think the lesson learned is to know what you're working with... Seriously, directional cables are great to use in high end installs but if you install them wrong you can't really blame that on the product . My $0.02 anyway...

grutter

iTrader: (1)

I wasn't trying to slam the product. Stinger makes great stuff.. but the directional cables weren't the right product for my installation. Wasn't a question of installing them wrong.. I checked all the arrows on the cables. They were installed correctly.

I was just trying to caution other members that using directional cables can actually introduce noise, especially if all of the inputs and outputs are isolated... and I would expect that high end systems would have isolated interfaces.

Normally when you see posts about noise, the only advice you get is "check the grounds"... and fix the problem rather than try to mask it with isolators and/or filters. I agree with fixing the problem, which is why I posted my problem and what I found to solve it.

I bought high-quality cables because I didn't want noise, so checking the cables was the last thing I tried.

MacGyver

Those cables are designed to prevent ground loops from ocurring...something that should happen with quality equipment to begin with. YMMV...

grutter

iTrader: (1)

Sorry, but you are incorrect.

In an RCA connector, you only have 2 connections: the center pin and outer conductor. If both the source and destination equipment used a chassis ground reference, then the signal (on the center pin) would use ground as it's reference. A ground loop could occur if there was a slight difference in ground potential between the different components, in that the outer interconnect conductor would act as a current carrier trying to bring both units to the same ground potential.

However, most quality electronic components today are floating, and the signal is derived from the difference between the signals on the center and outer conductors.

So if you have an interconnect that has three conductors (twisted pair + outer shield), you still have only two places to terminate these three conductors. If the shield is connected at only one end, then the shield can act as an antenna, rather than a shield because it is not tied to chassis ground. The signal that it picks up winds up being amplified because the amps are amplifying the signal that is the result of the difference between the outer and inner conductors.

If you weren't dealing with RCA connectors, you could tie the shield to ground and eliminate noise. The reason "twisted pair" interconnects are effective is that any noise induced in one conductor is equally induced in the other... essentially cancelling the noise. Again, the amps are looking to amplify the difference in the signal on the center and outer conductors... so if the same 'noise' signal is present, then it will cancel out.

I hope this makes sense.... please don't make me draw a picture.

MacGyver

No need for a pic...I misread your original post and had a different image of what the cables were. You're correct...

grutter

iTrader: (1)

We should keep in mind that these forums are here to help each other out.

The sole purpose of my post was only to let other forum members know that I found a problem (and solution) that might help them out if they also get stumped by a noise problem... they might want to check out their interconnects... regardless of how 'high quality' they might be.. that they might not be the right cables for the application.