Phono Question

[Matt Riley]

I'm with kevin. I was teching a presentation at uni a couple of years ago and the only input to the crestron controlled system to do the sound was a mono XLR intended for a podium mic. I was running a bit short on time, so bodged it using a Y lead, which is basically what you're proposing and some XLR-phono adapters.

 

It was a very embarrassing moment for me. Nuff said that since we were playing a dvd clip then bad things happened.

 

Now I propose everyone has a good old read at: http://www.rane.com/note109.html before considering the answer to the question. Funnily enough one of my projects this morning was to build a magic laptop lead (stereo minijack to mono jack combiner) for use when you just don't have enough channels!

 

M

[thetechguru]

I'm with kevin. I was teching a presentation at uni a couple of years ago and the only input to the crestron controlled system to do the sound was a mono XLR intended for a podium mic. I was running a bit short on time, so bodged it using a Y lead, which is basically what you're proposing and some XLR-phono adapters.

 

It was a very embarrassing moment for me. Nuff said that since we were playing a dvd clip then bad things happened.

 

Now I propose everyone has a good old read at: http://www.rane.com/note109.html before considering the answer to the question. Funnily enough one of my projects this morning was to build a magic laptop lead (stereo minijack to mono jack combiner) for use when you just don't have enough channels!

 

M

I'm afraid the problem you created was not related to 'Y or not to Y'. You were driving a line level signal into a mic input which probably had phantom power sitting on it. Mic inputs are for mic level ( -60db to -40db approx) line inputs are for line level( nominally 0db )ie 60db above a dynamic mic output.

[Andrew C]

I'm afraid the problem you created was not related to 'Y or not to Y'. You were driving a line level signal into a mic input which probably had phantom power sitting on it. Mic inputs are for mic level ( -60db to -40db approx) line inputs are for line level( nominally 0db )ie 60db above a dynamic mic output.

Of course, the REAL problem here is that the input was a balanced one, and you were sticking stereo into it. That will react REALLY badly.

 

I've been hitting a similar problem over the last week with some projector installations. Wall plate has 2x phonos for "AUX" and 3.5mm jack for "PC". Now we all know that your typical AUX is a DVD or VCR with a 10kR impedance and a PCs headphone socket is 600R. Does it work? Nah; not really!

[Matt Riley]

I'm not sure about both your suggestions. If I was driving line into a mic input (the volume pot was tres low at this point) then I'd hear clipping. If there was a phantom power issue then probably I'd have let the smoke out of something somewhere, and phantom would be no more. It was two phonos with their plus wired to pin 2 of an XLR and their minus wired to pin 3 of the XLR. The other tell tale sign was that when I unplugged one side, the sound got a lot better.

 

M

[bruce]

. The other tell tale sign was that when I unplugged one side, the sound got a lot better.

 

That's what you'd expect if you had the 2 phono pins connected to 2&3 on the XLR.

[Matt Riley]

I don't want to be too annoying but I'm not sure how this could have happened - I basically used clicky with a couple of these clicky again and then one of these into the laptop?

 

So you guys are saying that there was a wiring fault, and somehow I'd in effect used a 3.5mm balanced jack to XLR lead in a very very wrong way?

 

M