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Thread: EDM FM Transmitter and J-Pole Antenna - Sound Quality Help

  1. #1
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    Default EDM FM Transmitter and J-Pole Antenna - Sound Quality Help

    I'm trying to figure out how to improve the sound of my show. It comes through on the radio but the quality is terrible. i have an edm transmitter that connects to a FPP using a J-Pole antenna tuned to 87.9. Not sure what else to do at this point, as it seems like it should at least produce acceptable sound. Unfortunately, it does not.

    Any help?

    UPDATE: Seems something is up with my J-Pole antenna, as a little antenna i attached works and sounds much better. With that said, the playback, while clear, is very choppy. any ideas why this might occur?
    Last edited by corydorning; 10-14-2018 at 02:22 PM.

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    Default Re: EDM FM Transmitter and J-Pole Antenna - Sound Quality Help

    Are you possibly over driving your transmitter? Try turing down the input a bit and see if that clears it up.

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    Default Re: EDM FM Transmitter and J-Pole Antenna - Sound Quality Help

    i messed with both of the adjustments and still no luck :/

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    Default Re: EDM FM Transmitter and J-Pole Antenna - Sound Quality Help

    Both adjustments? There is only one adjustment on the FPP.

    When we say turn down the signal on the EDM input we mean go to the audio source (FPP in this case) and reduce its output. The EDM uses a line level input. Many people connect that to their source via a headphone jack (not line level). That gives less than ideal quality and you need to reduce the "volume" of that output until it is within the acceptable range of the EDM.


    2018 - Moving and going to visit my Daughter in New Zealand. Most likely I will be dark or nearly dark, Some static stuff that is simple to put up.

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    Default Re: EDM FM Transmitter and J-Pole Antenna - Sound Quality Help

    So i feel like what you are describing may be my issue, but i don't fully follow what you are saying. i currently connect my pi (fpp) with a 3.5mm to rca inputs on the edm. are you suggesting something different?

    I did turn down the sound on the fpp from 100 to 50 but now i can barely hear it.

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    Default Re: EDM FM Transmitter and J-Pole Antenna - Sound Quality Help

    when i hook my edm up to my mac and play my show from within xlights, it sounds MUCH better.

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    Default Re: EDM FM Transmitter and J-Pole Antenna - Sound Quality Help

    oddly enough, i swapped antennas and it sounds MUCH better. i am experiencing some choppy audio though.

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    Default Re: EDM FM Transmitter and J-Pole Antenna - Sound Quality Help

    Quote Originally Posted by corydorning View Post
    So i feel like what you are describing may be my issue, but i don't fully follow what you are saying. i currently connect my pi (fpp) with a 3.5mm to rca inputs on the edm. are you suggesting something different?

    I did turn down the sound on the fpp from 100 to 50 but now i can barely hear it.
    The 3.5mm jack on the PI is a headphone output. The EDM expects a signal generated by a 'line' level output. The headphone jack works but you have to turn it down so you do not swamp the EDM.

    I run my PI audio setting at 80%. I have a PI Audio DAC (HiFiBerry Pro) that is generating the Audio signal (I gave up on the built in audio on the PI).

    FYI: It is fairly common to have choppy audio from the PI. It uses a simulated Digital-to-Analog Converter (DAC) that, when you have a good transmitter, can sound pretty poor. The built in PI 3.5mm audio output also suffers from processing artifacts (CPU gets busy). Look at the HiFiBerry or PiFiBerry (chinese knockoff). They plug on top of the PI (aka Audio PI Hat) and give very good audio quality. They also have both 3.5mm (headphone) and RCA (line) outputs. Best quality is RCA-to-RCA but 3.5mm-to-rca works almost as well.

    My first year, I had a horrible buzz in my audio. It was because I used a cheap cable from my 3.5mm jack to my FM02 transmitter. I upgraded the cable and added a toroid coil at each end. Buzzing went away. Later, when I added a PI Hat and EDM, I switched to RCA-to-RCA with a good quality cable, I did not find the need to insert the coils.

    Next, your antenna and the cable running to it can be a real problem. My first year I used an old TV coax cable as the lead to the antenna. I also had a crappy transmitter. However, when I looked closely the transmitter wanted a 50 ohm cable. I was using a 75 ohm cable. Swapped out the cable and my simple j antenna sounded much better (still not good but better) and my range went way up. Next year I switched to the EDM with the same antenna. No better quality. Built a ground plane antenna with some left over wire, got good quality lead wire and had an exceptional level of audio quality.

    The moral of the story is that there are lots of places where you can lose a bit of quality. Add them all up and you get a poor audio experience. My EDM has been working great. Any time I am having an issue it is usually because some other point in the chain has degraded or failed.
    Last edited by MartinMueller2003; 10-14-2018 at 05:46 PM.


    2018 - Moving and going to visit my Daughter in New Zealand. Most likely I will be dark or nearly dark, Some static stuff that is simple to put up.

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    Default Re: EDM FM Transmitter and J-Pole Antenna - Sound Quality Help

    Also the Pi's audio quality is known to be poor, a lot of users will get a USB Audio device to drive the sound for their show/radio.
    Matt

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