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robogun
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Joined: 10 May 2005
Posts: 3

Post audio processing Reply with quote
I've been broadcasting on FM for the past year. My signal is mono and I'm using a 7W transmitter from PCS and a 40W amplifer. The system is working great! I've got folks from the community coming in and doing shows on a regular basis now. I would like to get some basic audio processing. I should have done this along time ago but funds didn't permit. My biggest problem is getting the audio from the mic at a descent level compared to music. Any suggestions? Someone suggested behinger composer. Oh and and some kind of switch for the mic would be good. Fiddling with the knob on the mixer is a pain.

thanks
Sat May 06, 2006 7:29 pm View user's profile Send private message
cliffyk
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Joined: 28 Sep 2005
Posts: 43
Location: 87.9 to 107.9
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Post Reply with quote
Anything from Behringer is top-notch, many of the "composer" units can do exactly what you wish to do--poke around at their website and you will learn a lot...

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Sun May 07, 2006 5:31 am View user's profile Send private message Visit poster's website
cons44
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Joined: 21 Mar 2006
Posts: 23
Location: Zamboanga City, Philippines
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If you're on a tight budget... there are software solutions...

Sound Solution is one of them... some settings can mimic omnia and orban processors...
Sun May 07, 2006 11:53 am View user's profile Send private message Yahoo Messenger
cliffyk
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Joined: 28 Sep 2005
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PC sound card based solutions are really neat, and there's a lot of very competent freeware stuff out there, however there are a couple of issues to be aware of:


They can be inexpensive IF you have a PC with a good quality sound card that you can dedicate to the job (depending on your hardware, certain CPU intensive activities like disk I/O can cause glitches and/or dropouts in the audi stream).


Most consumer grade soundcards have significant levels of high frequency noise and switching transients** from the DAC's in their output--these signals are inaudible however they can rob power in a mono FM signal (depending on the nature of the exciter's audio path they can end up being "pre-emphasised" to even higher levels).

In a stereo path they should be filtered out by the encoder's 15 kHz brickwall, however thet might still create problems (the 15kHz filter in many DSP applications only affects the actual audio signal, the soundcard's ultrasonic artifacts will be unaffected by any software based filter).


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** In fact it is these transient's that contribute most to measured distortion+noise in PC sound card generated signals...

My SB 24-bit USB external "card" measures 0.12% THD+N at 1kHz with a wideband analyzer, if I filter the signal with a simple RC filter with a 10 kHz "corner" (3 dB down at 10 kHz, 6 dB/octave, passes up to the 6th harmonic with negligible effect) this drops to the floor of my analyzer at <0.006%.

With a 26 kHz filter it's still less than 0.01% THD+N--the major contributor to the noise is a 3rd harmonic of the 48 kHz samplling rate.

BTW--Even the cheapest 16-bit soundcards are capable of <0.1% THD+N (which is better than most bench grade function generators) when the ouput is filtered.

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Sun May 07, 2006 2:14 pm View user's profile Send private message Visit poster's website
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