TRRS adapter to take camera's audio output into cell phone's audio input for producer

BrandonT

BrandonT

Well-known member
I have a prospective job where I'll be field producer, with the in house producer on the phone with me the whole time. I'd like to use a TRRS adapter (see link below). I would have a 3.5 mm male to male audio cable. One side goes in the camera's headphone output (with a spliter on the camera side so I can also hear it). Then that goes into the microphone input on the TRRS adapter. Then my earbud for the phone call goes in the output on the TRRS adapter.

Do you all think this will work successfully?

http://www.amazon.com/StarTech-com-headsets-separate-headphone-microphone/dp/B004SP0WAQ/
 
No, I don't think this will work very well because the phone is expecting to be connected to a microphone and the camera is expecting to be connected to a headphone driver. You'll need to do some trickery with impedance matching to attenuate the camera signal down to something the phone can accept. You may also need some kind of transformer arrangement if the phone is trying to power the microphone. Also, how will you talk to the producer? You'd want to mix another mic in downstream of the camera output, wouldn't you?

UPDATE: Look what I found, it's a cable with an attenuator built in, this is more what you're after:
http://www.kvconnection.com/product-p/km-iphone-2trs-a22.htm
 
Yes as said the phone will use the impedance load of a mic or other source to switch from it's internal mic and you will need an attenuator for it too, I have a cable made up with an TRSSS plug to male and female XLR and then use a transformer DI box to drop the level by around 40db and provide the correct loading.

There are better solutions to this and what you are basically wanting is a coms and IFB system.
 
As Rick has said JK Audio make excellent tools for this work. A "Daptor Two" or "Daptor Three" would work for what you are doing. You might find a "Two" used on ebay.
 
the two issues that I see are first, what everyone else has said about impedance, though I doubt if it's a mic switching issue since that is probably mechanical. A headphone out is stronger than a line level out and you would be feeding it into a mic in so you will need some really big attenuation. But the mic in will also be sending plug-in power to the headphone jack and that may be a problem. A head phone out put does not expect to have voltage coming IN so you should probably block that with some small capacitors.

As a practical matter it's going to be a PITA to get levels right since they will be interactive unless you have a variable attenuator on the jump to the phone.

BTW the adapter above with the attenuation looks like it will knock the signal down enough and it may even block power (or they have found that plug-in power isn't a problem?).

The JK Audio stuff is great but I'm guessing if your first instinct is to go for a $3 splitter a $700 box is out of the budget range.
 
Certainly on the i-phone it is the resistive load of the mic that switches the mic from internal to external not the plugging in of the TRSS jack.
 
Interesting. I had to check but your right.

OK so that is a worry also, sorry for the misinfo.
 
Awesome, lots of good info here. Thanks, everyone. Know that I may not even get the job. But after thinking it through and drawing a wiring diagram, I wanted to see if it was possible, any way.

The phone would be a Samsung Galaxy S4. As far as talking to the producer-- I could just unplug it when I needed to.

I had thought about the line vs mic issue. So looks like the $32.50 KV cable would work as far as that goes.

And yes, the $150 to $700 boxes would be out of budget, because the job would only max out around the $700 range. It's not something that I would see using regularly, but would be a good little tool to have in my bag for freelance jobs, just in case they want it. Just a little extra selling point.

I had not thought about the phone trying to power what it thinks is a mic, and that going into the headphone jack on the camera. Sounds a bit dangerous on the camera side. Another option is to take it from the RCA white & red output with a cable that goes to 3.5 mm on the other side. It would still have the power coming into the camera, though.




How about if I added a Zoom H4n into the mix? So the audio comes out of the camera (from either headphone or RCA), and into the H4n (either into the 3.5 mm input jack on the H4n, or one of the inputs that is both XLR and 1/4"). Then on the side of the H4n, it has a headphone/ line output. There are lo cut & comp/limit options in the menu, if that would help anything. And of course, I can control the levels. Then bring that into the KV adapter.

Another potential option: if we worked over Skype on a laptop. I have a Macbook Air, which has the one audio port, that is both input and output. So there's similar issues there. But instead, use the H4n as a USB input device. Do the output from the camera into the H4n, and make OS X/ Skype use the USB input as the default input source.

Thanks again! I'm not really an audio guy, but I often have to interface with a mixer when covering events, and often run into some problems to work through. So even if I don't use this info now, it's helpful just as a mental exercise.
 
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That adapter is supposed to do pretty close to exactly what you want so as I mentioned before I'm guessing they are either blocking the voltage, which is not hard to do, or they have found that it isn't an issue. There isn't a lot of voltage involved and very little current so my worry is not really damage but possible noise or audio problems because of the voltage. Like a big DC offset. The power is normally terminated in the mic and blocked out at both ends. With some phantom power misss hookups you could damage things but Plug-in power was always a consumer thing and I'm sure there are all kinds of limits internally because people will stick in anything that fits and will be really pissed off if that breaks something.
 
I would rent the proper gear. A JKAudio box and a good quality mixer in front of that for mic-pre's and routing audio where you need it.
 
Well, the $6 cable that I originally posted worked great. The attenuation was definitely a consideration, though. The adapter only brings in the left channel on the mic input. So I turned down the left channel on the camera to about 10 or 20%. And then I had the right channel at the normal 50 or 60%. In post, I would just mix the right channel to both channels. And then on the phone, I was also able to hear the person speaking on the other line through the headphone jack on the adapter. Note that for a situation where the volume would have to be normalized, it would be too loud. In that case, I suspect that the KV cable would work.

Thanks, again!
 
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