RCA Y-Splitter => Joiner?

[sjaguar13]

If I have 2 RCA jacks that need connected to 1, would the Y-splitter work? It's to make a left and right audio signal into a single, mono plug. Would I be better off just using the right or left signal instead of trying to combine them?

 

[audioguru]

A Y-splitter shorts the two outputs together. Some outputs blowup if they are shorted together. It is best to use series resistors with the end shorted together. The resistors become a resonable load for each output and their combined output is mono.

 

[jtallent]

I agree with Audioguru completely. One should NEVER use a "y" to combine two signals. In addition to what was mentioned previously, audio outputs are typically fairly low impedance sources that are expecting to see a relatively high impedance load. A good rule of thumb for easy calculation is that the load impedance should be at least 10x the source impedance and as you try to "y" two signals together this way, the load impedance seen by the source is much lower than it should be. The best way to accomplish this is with an active device that combines the two signals - similar to a audio mixer. There are some manufacturers that make two channel devices for this purpose or you could make one if you are so inclined. The next best thing is what audioguru suggested, using a resistor to passively combine these signals. Check out this application note for more info - it's pretty good, and gives some good examples of passive combiner circuits for both balanced and unbalanced (your RCA's) sources.

 

[jtallent]

I know this doesn't realy apply to your situation but I wanted to add that as long as the rule of thumb mentioned (10:1 load to source impedance ratio) is followed you can use "y's" to split signals as much as you want.

As for your question about being better off using either the left or right signals, keep in mind that when stereo audio tracks are mixed, many of the tracks (or instruments) are frequently hard panned to either the left or right side, leaving your source void of many of the instruments if you were to simply ignore either the left or right side.

 

[Sceadwian]

Why not just use two resistors on each of the mixed lines? A 1k 5k or 10k resistor on each input line could be used to adjust for various impedances. If you want to get 'advanced' you could use a pot on each line and ballance each line indepedantly as required to maintain proper signal levels. Then only problem with using resistors to mix signals like that is you're going to attenuate the signal a bit, and add a little bit of noise from the thermal noise of the resistor itself. This is usually managable if not disregardable.

 

[sjaguar13]

Is this what I would need to make the two become one?

**broken link removed**

 

[Nigel Goodwin]

Is this what I would need to make the two become one?

**broken link removed**

Yes, but you don't need the third resistor (the one down to ground).