What's the name of this type of dongle?

January 29, 2016 6:07 AM

I have speakers in my living room driven by an amp with one input. I want to plug both the TV and the media centre PC into the amp. What should I buy?

An audio mixer would I guess do the job, but costs >£50. Constraints:

• I don't need fancy fading and volume and things.
• If both inputs are playing, I don't mind what happens -- but...
• ...it should automatically switch between them, so I don't have to press a button or anything

I can get a 2-to-1 jack cable, but that seems... too simple. Or is it?

posted by katrielalex to Technology (11 answers total)

Best answer: Yes, the cable is too simple to do what you want.

You don't necessarily need automatic switching. If you use a cheap mixer to combine the TV and PC outputs, you won't need to switch them at all. If both devices are making noise at the same time, both will play out of your speakers, which maybe is not so useful, but perhaps you can just avoid doing that.

Here are a bunch of cheap utility mixers. These are much more suitable for your sort of use than mixers intended for DJs and sound engineers with sliders and lots of knobs. They're cheaper, too.

Make sure whatever you buy has stereo inputs (if it's meant for, say, mixing a mic and a guitar, then it is likely to be mono).
posted by ryanrs at 6:22 AM on January 29, 2016

I assume you want something with RCA jacks. Go to Amazon (or wherever) and search for "RCA A/B switch" or if you want to get fancy "RCA A/B fader". You should be able to find something for less than £10.
posted by adamrice at 6:24 AM on January 29, 2016

Agreed that you just need a switch. And agreed that they should only be a few dollars. Just be careful of the mono/stereo thing.

But of course you will have to push a button or select the source in some way. I don't understand what you mean by automatically switching between the sources. How would the device magically know what you want to listen to at any given moment?
posted by TinWhistle at 6:33 AM on January 29, 2016

Any auto-switching setup is likely to be problematic. There are devices that will auto-switch between digital signals, because with a digital signal (HDMI for example) the switch can tell the difference between signal/no signal and signal/quiet bit. A device trying to auto-switch based on line-in audio has to actually 'listen' to the audio and try to intelligently decide whether to switch. So you might turn on your TV and the switch says 'Aha! A sound! I'll switch to TV.' And then you get an email, or some other notification, and your PC goes 'Ding!' and the switch says 'Aha! A new sound source is active! I'll switch to that.'

I think your best option with an issue like this is to go for a switch with a remote, or just resign yourself to pushing some buttons. Or use the mixer option and just turn off the signal you don't want to hear.
posted by pipeski at 6:36 AM on January 29, 2016

I may be misunderstanding your requirement but if you genuinely don't care what happens if both inputs are playing, I can't see what's wrong with the 2-to-1 jack. In fact if you do have both going it's just going to... sound like both are going, isn't it?
posted by Segundus at 7:09 AM on January 29, 2016

Previously.

Short version: possible to damage one component or the other with a Y-cable.

This is closer to what you want.
posted by supercres at 7:23 AM on January 29, 2016 [1 favorite]

Best answer: what's wrong with the 2-to-1 jack

The outputs will fight each other. It's basically an electrical short-circuit, although you're not likely to break anything because the current levels are low-ish. But the quiet output WILL actively fight the one with sound.
posted by ryanrs at 7:23 AM on January 29, 2016

if you want to build a "safe" version of the Y cable, there's a simple circuit here that combines two inputs passively (without a switch). it only requires cables / connectors and a few resistors.
posted by andrewcooke at 8:37 AM on January 29, 2016

HD TV sound is 5.1 now, and it sounds like you want to plug it into a plain old stereo system. That's not really that good an idea in terms of the listening experience. TV particularly benefits from having a center channel. I'd replace your amp with a surround sound receiver and add some more speakers. You would get extra inputs as a side-effect.
posted by w0mbat at 10:21 AM on January 29, 2016

This really depends on whether you're doing analog or digital.

If analog audio is all you care about, you can just plug the audio out from the TV into the line-in on the media PC (using a 1/8" to RCA Y-cable or whatever), and set the PC to play back the input. On Windows 7+, this is in the audio properties for the line in device... check "Listen to this device".

You might be able to accomplish the same trick with digital, if your media PC has more than one HDMI connection and lets you use one as an input, but DRM would probably get in the way.
posted by neckro23 at 1:02 PM on January 29, 2016

Response by poster: So, uh, I just used a splitter and plugged them both into each other. It seems to work...

Thanks for the advice all!
posted by katrielalex at 7:41 AM on February 29, 2016