Cacophony Forums

Unofficial Mackie User Forums => The Mackie Forums Refugee Camp => Topic started by: celticexplorer on May 25, 2013, 12:04:57 AM

Title: profx12 HELP!!!
Post by: celticexplorer on May 25, 2013, 12:04:57 AM
I'm trying to connect a pair of headphones to the the monitor trs output for onstage monitoring purposes, but the sound is coming through on one ear only, what I need to know is, can this be solved by using a mono 1/4 inch to 1/8 inch adaptor, It's kinda money saving experiment, thank you
Title: Re: profx12 HELP!!!
Post by: RoadRanger on May 25, 2013, 01:58:07 AM
You need a 1/4" mono to 1/8" stereo adapter like this:
Hosa GPM-179
http://www.ebay.com/sch/i.html?_nkw=Hosa+GPM-179&_sop=15
Title: Re: profx12 HELP!!!
Post by: celticexplorer on May 25, 2013, 07:44:56 AM
Thanks man, didn't think it would be that simple,, take it thats the difference between balanced and unbalanced, was the reason I was getting a mono output, also take it it would be a mono balanced signal
Title: Re: profx12 HELP!!!
Post by: Greg C. on May 26, 2013, 04:06:29 PM
Thanks man, didn't think it would be that simple,, take it thats the difference between balanced and unbalanced, was the reason I was getting a mono output, also take it it would be a mono balanced signal

Actually no. The difference between balanced and unbalanced lines is that in a balanced signal line, the hot and cold lines have common source impedance relative to ground. While it's true that active balanced topologies have signal riding on both the hot and cold lines, it's not a requirement of balanced signal lines. Also, if that output was actually active balanced, the left & right of your headphones would be in opposite polarity and wouldn't sound correct. Lastly, I don't care what anyone says on this forum or any other - you are not supposed to drive headphones with a line output. The circuit is not designed to handle it. The result is distortion and possible damage to the output circuit due to excessive current being sourced through the circuit to drive the relatively low impedance load (headphones). A lower impedance output is always supposed to drive a higher impedance input. Connecting line outputs to headphones does the opposite.
Title: Re: profx12 HELP!!!
Post by: RoadRanger on May 26, 2013, 04:35:17 PM
Yup, Greg's correct. If you do use a headphone amplifier you also need some sort of limiting to prevent that inevitable LOUD feedback from instantly frying your ears - especially if using earbuds. The outputs on the board probably don't have enough "oomph" to fry your ears. I'd rather see you fry the board outputs than your ears but YMMV ;) . I use cheap $175 wireless IEM's that have built-in limiting, the Galaxy AS900 .