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#1
Posted to rec.audio.pro
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Routing a stereo out to a mono input.
I played a gig using my laptop to play backtrack MP3s.
The MP3s were recorded in stereo. I was running out my laptop's headphone out jack via a cable that converts 1/8" to 1/4'. I ran that to a direct box and then to the board. It seemed that some instruments were missing. Would I be right to theorize that I would have been losing one of the two speaker's in the stereo field via this routing? If so, how would I be able to ensure that both stereo tracks would have been routed to the mono signal? |
#2
Posted to rec.audio.pro
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Routing a stereo out to a mono input.
Ludwig77 wrote:
I played a gig using my laptop to play backtrack MP3s. The MP3s were recorded in stereo. I was running out my laptop's headphone out jack via a cable that converts 1/8" to 1/4'. I ran that to a direct box and then to the board. It seemed that some instruments were missing. Would I be right to theorize that I would have been losing one of the two speaker's in the stereo field via this routing? If so, how would I be able to ensure that both stereo tracks would have been routed to the mono signal? One of two things could have been happening: You used a mono plug and indeed lost one side of the stereo signal...or you used a stereo plug and combined the left/right signals out of phase. Either could account for your missing instruments. The proper way (one at least) would be to use two DIs, or a stereo DI. Lots of stereo 'av' DIs will properly sum the l/r channels and then output to one balanced out. Otherwise, two DI's--with the proper cables to split l/r--would work (into two channels of the mixer). I've used this one very successfully: http://www.directproaudio.com/product.cfm?directid=61283 but it's pretty pricey. Otherwise, you could use a summing network ahead of your single DI to combine the l/r channels in a fashion that won't upset the stereo output of your lappie. Many (most) don't like l/r to be just connected together without some resistance to isolate them. Distortion is the usual result. A couple of 1k ohm--1/8 watt resistors is probably enough to make your output happy. Connect one end of each in series with the left and right outputs and tie the other two ends together. Where they're tied together is your summed mono out. You can build that into the housing of a 1/4" plug.... jak |
#3
Posted to rec.audio.pro
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Routing a stereo out to a mono input.
Ludwig77 wrote:
I played a gig using my laptop to play backtrack MP3s. The MP3s were recorded in stereo. I was running out my laptop's headphone out jack via a cable that converts 1/8" to 1/4'. I ran that to a direct box and then to the board. It seemed that some instruments were missing. Would I be right to theorize that I would have been losing one of the two speaker's in the stereo field via this routing? That's certainly a valid theory. You need to figure out how the cable you have is wired. Most likely it has the tip and ring contacts (left and right channels) of the mini plug connected in parallel and wired to the tip of the 1/4" plug. That should work. But if it's a "balanced-to-unbalanced" cable, the two plugs would be connected tip-to-tip and the ring of the mini plug would be connected to the sleeve (ground). That would effectively short out one channel. If you have an ohm meter or other continuity tester, you could check out your cable. Or you could make a test recording on one channel, then the other channel, and play it back to verify that you get both channels. Another possibility is that some MP3 encoders do strange things with the phase relationship between the two channels which could make a hole in the middle of the stereo image and, in mono, make some things drop out. Does your mixer have line inputs? If so, that makes it easy to experiment - just connect the headphone output directly to the line input, using the appropriate adapter. If, during your shows, the mixer is located at some distance from your MP3 player, then using a DI is a good idea for making that long cable run, but if it's within reach, you can eliminate the DI. That won't solve your missing instruments problem, but it will simplify your hookup and you won't sacrafice any sound quality. -- If you e-mail me and it bounces, use your secret decoder ring and reach me he double-m-eleven-double-zero at yahoo -- I'm really Mike Rivers ) |
#4
Posted to rec.audio.pro
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Routing a stereo out to a mono input.
On Mar 29, 1:53*am, jakdedert wrote:
Ludwig77 wrote: I played a gig using my laptop to play backtrack MP3s. The MP3s were recorded in stereo. I was running out my laptop's headphone out jack via a cable that converts 1/8" to 1/4'. I ran that to a direct box and then to the board. It seemed that some instruments were missing. Would I be right to theorize that I would have been losing one of the two speaker's in the stereo field via this routing? If so, how would I be able to ensure that both stereo tracks would have been routed to the mono signal? One of two things could have been happening: You used a mono plug and indeed lost one side of the stereo signal...or you used a stereo plug and combined the left/right signals out of phase. *Either could account for your missing instruments. I was actually using a stereo cable 1/8" on laptop end to 1/4". The 1/4" side had a stereo adaptor. This end went into the DI box for XLR conversion. Since I first posted, I confirmed that I was only getting the right speaker from the stereo field. Could I simply solve this problem by using a 1/8" to 1/4" mono convertor? Would a mono convertor route both speakers' mixes? |
#5
Posted to rec.audio.pro
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Routing a stereo out to a mono input.
Ludwig77 wrote:
I played a gig using my laptop to play backtrack MP3s. The MP3s were recorded in stereo. I was running out my laptop's headphone out jack via a cable that converts 1/8" to 1/4'. I ran that to a direct box and then to the board. It seemed that some instruments were missing. Would I be right to theorize that I would have been losing one of the two speaker's in the stereo field via this routing? Yes. One channel is tip, and goes to your output. The other channel is ring, and goes to ground. If so, how would I be able to ensure that both stereo tracks would have been routed to the mono signal? You can make an adaptor with a TRS plug, with T and R both wired through 1K resistors to the T of your 1/4" TS plug. I make a similar adaptor with 47 ohm resistors for my wife to listen to headphones, since she has only one working ear. Or, you can set it all to mono in software, which seems like the easiest solution. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#6
Posted to rec.audio.pro
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Routing a stereo out to a mono input.
On Mar 29, 8:49*am, Ludwig77 wrote:
On Mar 29, 1:53*am, jakdedert wrote: Ludwig77 wrote: I played a gig using my laptop to play backtrack MP3s. The MP3s were recorded in stereo. I was running out my laptop's headphone out jack via a cable that converts 1/8" to 1/4'. I ran that to a direct box and then to the board. It seemed that some instruments were missing. Would I be right to theorize that I would have been losing one of the two speaker's in the stereo field via this routing? If so, how would I be able to ensure that both stereo tracks would have been routed to the mono signal? One of two things could have been happening: You used a mono plug and indeed lost one side of the stereo signal...or you used a stereo plug and combined the left/right signals out of phase. *Either could account for your missing instruments. I was actually using a stereo cable 1/8" on laptop end to 1/4". The 1/4" side had a stereo adaptor. This end went into the DI box for XLR conversion. Since I first posted, I confirmed that I was only getting the right speaker from the stereo field. Could I simply solve this problem by using a 1/8" to 1/4" mono convertor? Would a mono convertor route both speakers' *mixes? It really depends on what is inside the mono converter. As others have suggested, you could sum the signals through a resistor. An alternative would be to mix down the tracks to mono and use them instead. You might find the second approach gives you more control over the balance of different instruments by adjusting the channel levels before mixing. It is a little surprising that the left channel was missing since the tip is the left channel. If the DI were mono, only the tip would be connected. |
#7
Posted to rec.audio.pro
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Routing a stereo out to a mono input.
Ludwig77 wrote:
I was actually using a stereo cable 1/8" on laptop end to 1/4". The 1/4" side had a stereo adaptor. This end went into the DI box for XLR conversion. You really need to be clearer about your terminology. A "stereo adaptor" is unclear. Does the 1/4" plug have three metal pieces, like a headphone plug, or two pieces like a guitar cable plug? If it's like a headphone plug, you're still only connecting one channel to the DI. Forget the bits about resistors. You need to connect the two outputs of your MP3 player together and connect THAT to the DI box. Assuming you're in the US, go to your friendly local radio shack store and buy, or at least look at the following two parts: Catalog #: 42-2545 http://www.radioshack.com/product/in...ductId=2103863 and Catalog #: 42-2540 http://www.radioshack.com/product/in...ductId=2102972 Plug them together and you'll have what you need. You can get a longer version of the 1/8" plug to two RCA plugs cable. -- If you e-mail me and it bounces, use your secret decoder ring and reach me he double-m-eleven-double-zero at yahoo -- I'm really Mike Rivers ) |
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