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Some audio files are garbled and unusable


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This is my first year running a musical show. A very simple 16ch system with an fm transmitter. Playing the show from my laptop to the controller. The music files I am using were recorded in Audacity and saved as .mp3 at constant bitrate and 128k. When I was sequencing the songs the music was fine. When a certain few files run in a show the audio is garbled and unusable. The sequence seems to be controlling accurately but sound is bad. This has happened to only a few of the files, the others seem fine even tho they were recorded and saved in the same way. Also, when I re-open the SE and play back the files that did not play well, the sound is good but when those certain files run in a show it all goes bad. 

In  my troubleshooting I have tried going back to audacity and re-exporting the mp3 to a different file name. Then assigning that new media file to the sequence and re-saving the sequence as a different name. When the new sequence is played in the show the problem persists.

Any other ideas or suggestions? My next guess is a windows media player problem.

Thanks for any input


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             Sounds like some of the MP3 files may be recorded at a very high volume level. They sound good in the se but not good when you transmit them to the radio.

A lot of folks on here use a free program called MP3 Gain. It is a great volume leveling proggy. You can use it in batch mode also. That is my first guess at your problem.

The next thing would be to re rip the songs if you ripped them. If you purchased them see if you can down load them again.

Hope this helps you out. Also make sure the volume level on your laptop is not set too high. That would over drive your transmitter.

Edited by Joe Polenchar
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Not sure exactly what you mean by bad, the lights or the audio. However if the audio is distorted, mos likely the level is too high and is over modulating the FM trans. Reduce the volume in the Windows mixer and see if that helps, and if so reduce the volume of the offending songs in Audacity or try MP3 Gain.

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Thanks guys. I will double check the gain structure tonight after work.

It does seem to me that in my troubleshooting I pulled the audio cable out of the pc to verify that it was not the transmitter causing the problem. When I did that it still sounded unrecognizable through the laptop speakers. I just don't understand why when it is played in the SE it would sound fine and then through the show it is not even understandable. It makes me think the player is causing issues.

Well it is a simple enough thing to do so I will give the gain thing a try and let you know how it goes.

Thanks for the quick responses

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I think you will find that SE and the show player both have their own slider in the Windows Mixer so they may be set differently. The SE slider will probably only appear when the program is open. Similarly fro the show player. Of course they should not normally be open at the same time.

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GOT IT!!!!

The cable that came with my cheap transmitter was some how incompatible with my laptop. I noticed that when I pulled the jack out of the socket on the pc just a little then everything would sound fine through the transmitter. So, I swapped the 3.5mm stereo audio cable with one I had on hand and it sounded perfect!

I had done a ton of work making new audio files, normalizing levels and saving new sequences and nothing I did seemed to fix it. After a while I noticed that the files that had problems were mono, the ones that worked were stereo. This lead me to chase any stereo possible causes. Knowing that some laptops have weird sockets for other devices I tried pulling the jack out part way and bamm! That was it! 

What is weird is that I can see no visible issues with this cable...... It looks identical to other 3.5mm TRS jacks I have. It tests fine for continuity and is pinned correctly. It did have a ferrite bead clamped on it but that shouldn't cause an issue.

Well all is good now and if nothing else at least now all my sound files are properly normalized.

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