Combine(via Y cables) two RCA outputs into one input okay? - AVS Forum
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post #1 of 21 Old 12-03-2009, 07:43 AM - Thread Starter
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Is it safe to combine(via Y cables) two RCA outputs into one input? I have run out of RCA audio inputs on my receiver and want to connect both my DVD and XBOX to the same RCA audio input (via two Y cables). I would likely never have them on at the same time, but may by accident. The guy at Radio Shack said this should be safe, but am looking for a second opinion. Thanks in advance.
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post #2 of 21 Old 12-03-2009, 08:10 AM
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Quote:
Originally Posted by fzone View Post

Is it safe to combine(via Y cables) two RCA outputs into one input? I have run out of RCA audio inputs on my receiver and want to connect both my DVD and XBOX to the same RCA audio input (via two Y cables). I would likely never have them on at the same time, but may by accident. The guy at Radio Shack said this should be safe, but am looking for a second opinion. Thanks in advance.

It may be safe and it may work but it may not. Why not just get a simple 2way switch from RS for this and be certain?

Kal Rubinson

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post #3 of 21 Old 12-03-2009, 08:14 AM
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buy a cheap 2x1 switch!

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post #4 of 21 Old 12-03-2009, 10:34 AM
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It could overload the input if you have both on at once. Even worse, it could overload the output (power amp input) if the gain (volume) is high.

I wouldn't do it. It is a disaster waiting to happen, and easily solvable with a switch as others have said.
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post #5 of 21 Old 12-03-2009, 11:26 AM
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The switch suggestion was the best and the switches are cheap.

On the other hand this can be done with a little work and more than a Y cable. Usually people want to mix L&R from a single device into a mono input such as a portable PA system playing back a CD or such., but your requirement is not too dissimilar.

The best way to do this w/o a switch is to open the Y cable and insert a 10k resistor in series with each of the hot legs into the common output. This will require some wire work and soldering, but the 10K isolation between channels will buffer the outputs from each other. You can do this with the Y cable itself or with 2 short RCA to RCA cables plus a Y cable. Be sure the shield is intact and that the resistors are insulated from the shield.

This is a VERY common practice and works. The only major codicil is that the two signals be line level outputs and neither one should be a speaker or headphone level as overloads can occur.
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post #6 of 21 Old 12-03-2009, 11:54 AM - Thread Starter
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Quote:
Originally Posted by penngray View Post

buy a cheap 2x1 switch!

Are there any switches that are automatic?
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post #7 of 21 Old 12-03-2009, 12:04 PM - Thread Starter
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Quote:
Originally Posted by Gizmologist View Post

The switch suggestion was the best and the switches are cheap.

On the other hand this can be done with a little work and more than a Y cable. Usually people want to mix L&R from a single device into a mono input such as a portable PA system playing back a CD or such., but your requirement is not too dissimilar.

The best way to do this w/o a switch is to open the Y cable and insert a 10k resistor in series with each of the hot legs into the common output. This will require some wire work and soldering, but the 10K isolation between channels will buffer the outputs from each other. You can do this with the Y cable itself or with 2 short RCA to RCA cables plus a Y cable. Be sure the shield is intact and that the resistors are insulated from the shield.

This is a VERY common practice and works. The only major codicil is that the two signals be line level outputs and neither one should be a speaker or headphone level as overloads can occur.

Are there any off the shelf Y cables I can purchase that already of this done?
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post #8 of 21 Old 12-03-2009, 12:04 PM
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Quote:
Originally Posted by DreamWarrior View Post

It could overload the input if you have both on at once. Even worse, it could overload the output (power amp input) if the gain (volume) is high.

That's not the issue. The issue is that the two outputs (presumably of low impedance) will shunt each other. The overload issues are unlikely and subject to human control.

Kal Rubinson

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http://www.stereophile.com/category/music-round

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post #9 of 21 Old 12-03-2009, 02:51 PM
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Non-resistant y-cables (wye-cables) are for splitting signals, not combining them. See this Ranenote for some of the technical details of "Why Not Wye".

Either a switch or resistive combiner (as was previously described by Gizmologist) are the correct & safe approaches. Commercially available combiners are commonly called 'DI boxes' and in my opinion to pricey for such an application. I have seen automatic switchers for video (composite) but don't recall seeing ones for audio, although they may exist.

Personally I use one of the little plastic project boxes from Fry's or Radio Shack along with surface mount RCA jacks, 10K resistors & a little bit of soldering. For an average DIY'er with basic soldering skills it'll take 15-30 minutes to put it together. It takes me about an hour to do one of these but I have visual acuity challenges that slows up the work.

If you do decide to do it yourself, here's a more simplified circuit diagram than what the Ranenote had and it should meet your needs.

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post #10 of 21 Old 12-04-2009, 09:15 AM
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Quote:
Originally Posted by fzone View Post

Are there any off the shelf Y cables I can purchase that already of this done?

This is probably the closest thing you're going to find. It would require cutting the cable ends off and connecting the internal wires straight to the combiner. Much easier (and probably cheaper) to just go with the switch.

Regards,
Wayne A. Pflughaupt

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post #11 of 21 Old 12-04-2009, 09:32 AM
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Quote:
Originally Posted by Gizmologist View Post

On the other hand this can be done with a little work and more than a Y cable.

The best way to do this w/o a switch is to open the Y cable and insert a 10k resistor in series with each of the hot legs into the common output. This will require some wire work and soldering, but the 10K isolation between channels will buffer the outputs from each other. You can do this with the Y cable itself or with 2 short RCA to RCA cables plus a Y cable. Be sure the shield is intact and that the resistors are insulated from the shield.

Quote:
Originally Posted by FTWMike View Post

Personally I use one of the little plastic project boxes from Fry's or Radio Shack along with surface mount RCA jacks, 10K resistors & a little bit of soldering. For an average DIY'er with basic soldering skills it'll take 15-30 minutes to put it together.

A neat trick you can do is use Switchcraft #3502 RCAs. They have a hollow tip, so if you use a 1/4 or maybe 1/8-watt resistor, it's small enough to slide inside the tip. Solder the resistor in-line with the center conductor and drop the resistor inside the hollow connector tip. The resistor's lead with stick out the end of the tip. Just solder the end of tip and clip the excess. Voila, normal-looking cable, no project box needed.




Regards,
Wayne A. Pflughaupt

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post #12 of 21 Old 12-04-2009, 09:35 AM
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WE just got the impression from the OP that he wasn't too sure about the process and didn't have the parts/desire to do this.
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post #13 of 21 Old 12-04-2009, 10:05 AM
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Understood, which is why I didn't address my comments to him. Just thought you and/or Mike might find the tip useful.

Regards,
Wayne A. Pflughaupt

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post #14 of 21 Old 01-05-2010, 05:47 AM
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Hey everyone...I have this same exact issue as the OP (which I've never had before), and I just want to be sure I'm getting the appropriate switch.

I found this on the RS website - will it suffice? (I'm new here, so it won't let me paste the URL)

2-Way Audio/Video Selector Switch
Model: 15-1982 | Catalog #: 15-1982

Is $16 a reasonable price, or are there cheaper?

Thanks!
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post #15 of 21 Old 01-06-2010, 10:48 PM
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Quote:
Originally Posted by Siciliano View Post

Hey everyone...I have this same exact issue as the OP (which I've never had before), and I just want to be sure I'm getting the appropriate switch.

I found this on the RS website - will it suffice? (I'm new here, so it won't let me paste the URL)

2-Way Audio/Video Selector Switch
Model: 15-1982 | Catalog #: 15-1982

Is $16 a reasonable price, or are there cheaper?

Thanks!

If you're needing to switch both stereo audio & composite video, then yes the item you noted will work perfectly. If you only need to switch one of those (just audio OR just composite video), then that RS switch is a little bit more than you need, it'll still work though. As to price, it seems to be within a dollar or so to a similar switch at Target.

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post #16 of 21 Old 01-07-2010, 12:26 PM
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Quote:
Originally Posted by Kal Rubinson View Post

That's not the issue. The issue is that the two outputs (presumably of low impedance) will shunt each other. The overload issues are unlikely and subject to human control.

So then if they shunt each other, what happens? The output devices on the source units see a load change and are at risk? I would think the input voltage ratings on the receiver would be exceeded, which could be a bad thing....? No?
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post #17 of 21 Old 01-07-2010, 10:22 PM
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Shunting the two will result in reduced voltage at the input of the following device or, at worst, damage to one of the sources.

Kal Rubinson

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http://www.stereophile.com/category/music-round

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post #18 of 21 Old 01-07-2010, 11:05 PM
 
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Quote:
Originally Posted by DreamWarrior View Post

So then if they shunt each other, what happens? The output devices on the source units see a load change and are at risk? I would think the input voltage ratings on the receiver would be exceeded, which could be a bad thing....? No?

No.

how can the output voltage increase?

The source impedance of one device will 'partially short' (shunt) the other .
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post #19 of 21 Old 07-25-2011, 12:32 AM
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I have been trying to find an answer to this question since my 10-year old Kenwood is on its last working digital audio input.
I found my answer with this Phono Y-adapter from Radioshack:
search this product ID on RS =2104065
This will work to combine two DIGITAL audio sources to one digital audio source. I am using it currently to run external audio from my Scientific Atlanta DVR as well as my newly purchased Blu-ray player. As long as both are not on at the same time, this should work. Mine works sweetly!

PS: I would have made the link to RS a hyperlink, but it looks like I am being prevented from doing so unless I have made three or more posts.
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post #20 of 21 Old 07-25-2011, 06:33 PM
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Quote:
Originally Posted by sublimemystic View Post

This will work to combine two DIGITAL audio sources to one digital audio source. I am using it currently to run external audio from my Scientific Atlanta DVR as well as my newly purchased Blu-ray player. As long as both are not on at the same time, this should work. Mine works sweetly!

Sorry to burst your bubble but just because something like this seems to work does not mean that it is working as you think it is nor does it mean that it's not causing damage to the outputs. I could be mistaken but all the reasons noted above your post of why you should not do this kind of thing with analog audio apply to your digital audio jacks as well. Y-adapters are for splitting signals never for combining them, even if only one is active at a time.

Mike

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post #21 of 21 Old 10-31-2014, 12:05 PM
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I had exactly the same problem and found a solution.

1. There are many manual switch options but I'm not interested. I want remote control from bed.

2. Then I considered auto sensing switches.
The Auto-sensing A/V Switch 5-in/2-out from Amazon is only $6.71 but it senses video signals only.

The Sonance AL-1 Automatic A/B Source Selector Line Level Switch from ebay is about $20 and seemed to be a perfect solution.

3. But I found a better solution. I used two Y splitters. I have two sources, one airport express, the other TV. when the airport express is on, the sound from TV is very low. So I used a remote power switch socket (about 20 bucks from amazon. I had it already) to turn off the airport express when I want the sound from TV. The solution is the simplest for my use and works flawlessly.

Another option I considered: use a blue tooth music receiver for TV. My vizio TV can connect to it and there should not be delay of audio.

If you use a difference source than TV and don't mind delay, you may also use two airport express.

Or, if both of your sources can do airplay or blue tooth, you can use one airport express or bluetooth music receiver to turn your speaker system wireless.
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