Direction of signal flow on interconnects

On3s&Z3r0s

All the interconnect questions recently reminded me that I have one. Why is it that some RCA interconnects have an arrow indicating what direction the signal is supposed to flow? When it's just a male-to-male RCA I use them the way the arrow points... no reason not to. But I don't understand what makes the direction important and the downside of using them the other way.

The reason I ask is I have some RCA Y-splitters (1x male-to-2x female) that are apparently really supposed to be a combiner (combining L/R stereo channels into a subwoofer input I think). The signal flow arrow goes from the 2 female ends to the single male RCA. I want to use them to split a single channel instead and am wondering if this will work.

steveinaz

Sometimes signal direction is shown because the shielding is only connected on one end. Sometimes it's done to show the preferable direction of flow, to go "with" the grain of the copper.

On3s&Z3r0s

steveinaz wrote: »

Sometimes signal direction is shown because the shielding is only connected on one end. Sometimes it's done to show the preferable direction of flow, to go "with" the grain of the copper.

Cool, thanks for the answer. I can't say I totally understand how it works. I found some older threads discussing this and don't really understand them either (I guess I need to read up on what a drain wire in an interconnect is supposed to be doing). It sounds like it's mainly to avoid ground loop hum, but since most of my gear isn't grounded maybe that doesn't apply in my case. Anyway, it doesn't sound like this "combiner" couldn't also work like a splitter. Worth a try anyhow.

gfong

Here is some background from Atlas Cables of Scotland, they manufacture entry level to high end cables.

http://www.atlascables.com/index.php?id=75

Nice article and explains a lot about cables. Section 6.5 starts to answer your specific question but the entire article is a good read.

On3s&Z3r0s

That is a good read... the pictures helped some. So, it sounds like all directional interconnects are "pseudo-balanced" interconnects with the return conductor connected to the shield at one end. Unfortunately, I don't fully understand the practical implications of these statements:

"This type of cable design minimizes noise interference, while still allowing shielded inter-connection between single-ended components, and provides the signal with electrically equivalent going and return conductors."

And,

"this interconnect is recommended for analogue interfaces such as that between a turntable and pre-amplifier or between pre and power amplifier where RCA sockets are provided. Pseudo balanced interconnects are always directional - the screen and return path must be connected at the 'source' end for them to work best."

That last quote actually seems to contradict what I got from some of the posts on the other threads on this topic in terms of where the shield/drain connects and why. And none of it really explains the downside of flipping the interconnect around. I guess it's just a sort of try it and see situation. I do appreciate the help, though... I know more about interconnects than I did yesterday for sure!

quadzilla

The point of the shield is to absorb EMI including RF. If you dump that into your pre or your power amp, it gets amplified along with the signal. So you dump it back into the source where it's grounded and doesn't interfere with the signal.

On3s&Z3r0s

quadzilla wrote: »

The point of the shield is to absorb EMI including RF. If you dump that into your pre or your power amp, it gets amplified along with the signal. So you dump it back into the source where it's grounded and doesn't interfere with the signal.

That definitely makes sense... just not for the splitter I have in front of me. The way they're put together, the two female Y ends are the source. The single male end is at the arrow head end. But the more I look into it, the only answer is that the splitters are wrong. I'm guessing Monster wasn't paying attention when they manufactured them. These are no longer listed on Monster's website and are now unavailable from Amazon where I bought them (although the product page for THXAIYM is still up).

The reviewers all describe using them to split a signal normally, so best case, the cable jacket is just pointing the wrong way, making them mislabeled or worst case Monster actually built them incorrectly. I'm not sure if there's any way to tell with a multimeter or anything like that. In any event, yet another reason to not buy anything with the word Monster on it. I can't believe they're still in business.

quadzilla

No, that's fine. A splitter shouldn't be directional. So you plug the cables into the female ends, the male end goes to your actual source, and it still ends up being directional when considering the entire assemblye as the splitter will still provide a drain the EMI/RF noise back to the real source.