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New IEMs - Issues

Discussion in 'Live Sound [BG]' started by xk49w, Feb 10, 2014.

  1. I tried out my new 1964Ears IEMs last gig using a Rolls PM351. I inserted (is that the right term?) the IEMs and plugged in the cord to the PM351 - "POP". A HUGE pop and not good. I looked at the schematic for the PM351 and see that the output side of the coupling caps is floating so a huge portion of Coulombs was waiting to be delivered once I plugged in the 25 ohm loads. This could be fixed but the transient was so alarmingly loud that I do not want to use it anymore.

    However. With the other problems I had with the rig, and the various cables, wall warts, and considering how much I have invested in this setup so far I want to consider a wireless headphone gadget. I want to keep what hearing I still have and not incur any more tinnitus inducing volume (that was the point of this effort), so I insist that it shall protect against deafening transients in the user's audio stream.

    So what are the options? I have looked at a few of the offerings. So, I am looking to the vast TB user base to provide any real-world experience with respect to:
    - transient protection
    - real-time volume limiting
    - RF connection stability
    - good behavior when the link is lost
  2. ggunn


    Aug 30, 2006
    Austin, TX
    Um, turn them on and plug them in before putting them in your ears? When I used them I used to do that for the very reason you stated.
  3. Really? You plugged a socket for your earphones into a set up that is on, turned up, with your buds in your ears?

    Am I reading this correctly?

    You have to liken this to plugging your bass in with your amp turned up and speaker connected.
  4. Somewhere along in the chain you ought to have a limited. Many wireless packs have these built in to protect against unruly spikes and pops.
  5. If anyone knows of a quality, half-space stereo brick wall limiter suitable for IEM use please post it...
  6. Almost. The PM351 was powered, the gains were off, buds were in the ears and I attempted to plug in. If the PM351 were designed differently (I might say properly), this would not be a problem because the output jack terminals would be at ground potential rather than at half the supply voltage due to the floating output cap. 47uF had to charge to 6V through about 35 ohms. That's a big current spike.

    Were this fixed there will still be the risk of power surges and dropouts which could cause the same thing, also other sources of clicks and pops, maladjusted faders, etc.. A limiter, or something with a limiter is essential.
  7. Plug every thing in. And I mean EVERY LAST THING. Have it on and ready to play before connecting the IEMS the audio source and putting them in your ears. Every time something is turned on, turned off, plugged in, unplugged, there will be some level of popping.

    Think of it this way, if it were on in the house speakers, and you did something that made a noise, it will come through IEMS. If you unplug mid set and don't mute your signal, POP!

    Your IEMS should be the absolute last thing you put in before doing sound check or playing. Everything else should be set prior to that.

    A limiter is always a good idea even if you never use it. It only takes fluke to blow out your ears.