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joshie75
Advanced Member
Joined: 09 Nov 2010
Posts: 235
Location: Illinois
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 Posted: 19 Feb 2012 06:58:04 pm Post subject: Merging L and R audio |
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| If I want to take the L and R from a 3.5mm audio jack, and merge the connections, I need to add in some resistors right? |
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comicIDIOT
Guru
Joined: 01 May 2006
Posts: 5108
Location: SFBA, California
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| Posted: 19 Feb 2012 08:38:08 pm Post subject: |
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You want to go from stereo to mono audio using hardware, correct?
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christop
Power User
Joined: 09 Mar 2011
Posts: 385
Location: Arizona, USA
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| Posted: 20 Feb 2012 12:10:01 am Post subject: |
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Resistors shouldn't be necessary if you're just converting stereo to mono. All you have to do is connect the left and right wires together.
Or you could treat one of the sides as ground and leave the real ground wire disconnected so you get a mono signal that is the difference of the two channels. But that's probably not what you want to do.
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joshie75
Advanced Member
Joined: 09 Nov 2010
Posts: 235
Location: Illinois
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| Posted: 20 Feb 2012 01:57:53 am Post subject: |
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I was talking to a friend, and he said if there are no resistors there could be a short. I don't understand how though, because if hooked together, the LR are both flowing in the same direction.
@Comic
That is exactly what I would like to do;
@Chris
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Kllrnohj
 PH34R |\/|3
Joined: 24 May 2005
Posts: 8189
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| Posted: 20 Feb 2012 02:22:13 am Post subject: |
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| joshie75 wrote: | | I was talking to a friend, and he said if there are no resistors there could be a short. I don't understand how though, because if hooked together, the LR are both flowing in the same direction. |
Well, technically it is a short - but that's what you want.
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There are only two kinds of programming languages: those people always bitch about and those nobody uses. (Bjarne Stroustrup) |
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ParkerR
Member
Joined: 15 Nov 2010
Posts: 135
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| Posted: 20 Feb 2012 02:24:02 am Post subject: |
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| I never thought of that being a short. But yes I can confirm crossing the left and the right wires and then connecting those to a speaker + and the ground to a speaker - does work. |
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joshie75
Advanced Member
Joined: 09 Nov 2010
Posts: 235
Location: Illinois
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| Posted: 20 Feb 2012 03:23:41 pm Post subject: |
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| Why is it considered a short? Thanks guys |
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Aes_Sedia5
Minor Calculator Deity
Joined: 01 Sep 2011
Posts: 1002
Location: Where Nightmares end and Dreams begin
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| Posted: 20 Feb 2012 03:25:43 pm Post subject: |
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It is a short because you are crossing your hot and cold lines, which is technically, a short, although a non harmful one.
iirc
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KermMartian
Site Admin
Joined: 14 Mar 2005
Posts: 55764
Location: Earth, Sol, Milky Way
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| Posted: 20 Feb 2012 03:28:40 pm Post subject: |
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| joshie75 wrote: | | I was talking to a friend, and he said if there are no resistors there could be a short. I don't understand how though, because if hooked together, the LR are both flowing in the same direction. |
Your friend is mistaken. The resistors won't prevent the current flowing backwards, just attenuate it. Not to mention decreasing the volume on both channels.
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joshie75
Advanced Member
Joined: 09 Nov 2010
Posts: 235
Location: Illinois
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| Posted: 20 Feb 2012 05:25:35 pm Post subject: |
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Oh I understand now.
@Kerm;
The current flowing backwards, that won't harm the input device, right? |
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benryves
Cemetech Expert
Joined: 12 Aug 2008
Posts: 1359
Location: London, United Kingdom
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| Posted: 20 Feb 2012 05:39:01 pm Post subject: |
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I'd personally connect a smallish resistor and capacitor to each side (left and right) and join those together to avoid putting undue strain on the amplifiers.
Code:
0.1uF
L o--[100R]---||---.
+---o Out
R o--[100R]---||---'
0.1uF
I use a similar circuit (albeit with much larger resistors) to mix stereo to mono and to attenuate the signal so I can use it to connect audio output to a microphone input. |
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joshie75
Advanced Member
Joined: 09 Nov 2010
Posts: 235
Location: Illinois
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| Posted: 20 Feb 2012 08:04:10 pm Post subject: |
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| Now as Kerm mentioned earlier, wouldn't those resistors lower the volume on the channels? Do the capacitors just make sure there is no backwards flow, if not, what do the caps. do? |
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Kllrnohj
PH34R |\/|3
Joined: 24 May 2005
Posts: 8189
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| Posted: 20 Feb 2012 10:12:14 pm Post subject: |
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| joshie75 wrote: | @Kerm;
The current flowing backwards, that won't harm the input device, right? |
Where is this "backwards flow" stuff coming from?
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There are only two kinds of programming languages: those people always bitch about and those nobody uses. (Bjarne Stroustrup) |
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joshie75
Advanced Member
Joined: 09 Nov 2010
Posts: 235
Location: Illinois
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| Posted: 20 Feb 2012 10:19:33 pm Post subject: |
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| Well there is none, I thought Kerm was saying backwards flowing current can be prevented. I looked at my circuit and there is no backwards flowing current so I'm good there. |
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benryves
Cemetech Expert
Joined: 12 Aug 2008
Posts: 1359
Location: London, United Kingdom
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| Posted: 22 Feb 2012 06:31:31 am Post subject: |
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Adding the resistors will indeed attenuate the signal (and 100R is probably a bit high - 22R is probably more appropriate) but would protect the amplifier outputs and reduce distortion.
May I ask why you need to do this? |
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