westdev Posted August 2, 2008 Share Posted August 2, 2008 Hi, This might sound like a silly question but I am trying to figure out how a connector I bought today works and if it is safe to use in the way that I want to. I have bought a phono 2 into 1 converter, so it allows me to place two mono phonos into one side and give me a single mono phono out. Now, I want to put a stereo signal in and get a mono signal out, will this do the job? Is there some circuitry inside to combine the two signals else surely you would short circuit the two live signals out? Any help would be much appreciated. Link to comment Share on other sites More sharing options...
Johnno Posted August 2, 2008 Share Posted August 2, 2008 If it's just a plain adapter it will be for getting two phono's out of a single input, the other way round to the way you are wanting to use it. If you want to join two outputs just insert a resistor in line with each channel and join their free ends together, 470 ohms 1/4 watt should do fine. Link to comment Share on other sites More sharing options...
westdev Posted August 2, 2008 Author Share Posted August 2, 2008 So if you tried to put to live signals in you would short them out? Link to comment Share on other sites More sharing options...
johndenim Posted August 2, 2008 Share Posted August 2, 2008 Can I please ask what this is for? John Denim. Link to comment Share on other sites More sharing options...
Johnno Posted August 2, 2008 Share Posted August 2, 2008 Joining low-level outputs together without a few ohms of resistance between them is generally not a good idea, but probably won't damage them. Can you give us a link to the item you bought or describe it more precisely? Link to comment Share on other sites More sharing options...
KevinE Posted August 2, 2008 Share Posted August 2, 2008 It will sound awful trying to just connect the stereo phonos just into one, as the signals will be also going back up into each other's output..as it were. If you want to combine a stereo feed into a mono then as already stated you need to join them with resistors (so the signal's mixed properly). I'd use 4.7k resistors in each leg in a Y-pattern myself. Link to comment Share on other sites More sharing options...
westdev Posted August 2, 2008 Author Share Posted August 2, 2008 http://www.maplin.co.uk/Search.aspx?criter...rce=15&SD=Y If you look at the bottom FAQ about the DVD player, that is similar to what I want to do but with a minidisc player, I want to convert L & R into one mono output. I wanted to check this with you guys because I am not sure if that is reliable information on their site. Link to comment Share on other sites More sharing options...
Johnno Posted August 2, 2008 Share Posted August 2, 2008 Hmm. That's a plain adapter for two outs from one in. Maplin's advice is a wee bit dodgy. It probably won't hurt your gear but should have resistance added to be electrically correct. Link to comment Share on other sites More sharing options...
westdev Posted August 2, 2008 Author Share Posted August 2, 2008 Knowing this I will take the adapter back, if used will the sound quality go drastically down hill? Even used on low level line devices surely this would eventually cause damage? I had a feeling that the guy in the shop had no idea what he was talking about, thanks guys. Link to comment Share on other sites More sharing options...
johndenim Posted August 2, 2008 Share Posted August 2, 2008 It's quite possible that the resistors will be integeral to this part. I'd suck it and see, I don't think you will damage anything, if it sounds bad don't do it! John Denim. Link to comment Share on other sites More sharing options...
Johnno Posted August 2, 2008 Share Posted August 2, 2008 The sound quality might be worse than it need be, hard to say. Low-level outputs have limited ability to supply current so are not likely to be damaged by being connected together. Also there may be capacitors in the output circuitry which will limit their ability to harm one-another by the worst case possibility of one output going positive while the other goes negative - the caps will stop the resulting direct short between the power supply lines. If you are at all worried don't use it. EDIT: I used to feed a laptop headphone output into a radio mic belt pack via a couple of resistors, all assembled on one of those plastic 12-screw strips. Link to comment Share on other sites More sharing options...
westdev Posted August 2, 2008 Author Share Posted August 2, 2008 Using a multi meter I tested the live one side against the live on the other and found no resistance, so they can't have put a resistor in the middle. Link to comment Share on other sites More sharing options...
Johnno Posted August 2, 2008 Share Posted August 2, 2008 It's quite possible that the resistors will be integeral to this part. John Denim. Unlikely. I think they'd mention the fact if there were and then charge more for it! If you have an ohmmeter you could measure it. EDIT I feel soooooo redundant ** laughs out loud ** Link to comment Share on other sites More sharing options...
KevinE Posted August 2, 2008 Share Posted August 2, 2008 It really isn't a good idea to use it as a combiner. Link to comment Share on other sites More sharing options...
djmatthill Posted August 3, 2008 Share Posted August 3, 2008 Knowing this I will take the adapter back, if used will the sound quality go drastically down hill? Even used on low level line devices surely this would eventually cause damage? Hmmm I really dont see the problem with using this adaptor . We often use similar adaptors to plug the stereo outputs from our cd players in to a mono line input on our mixer. The sound quality is fine for general PA use. Link to comment Share on other sites More sharing options...
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