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Pre-Fader vs. Post-Fader Quick Reference: Long story short Use pre-fader aux
sends for monitors What is the difference? - Signal flow (a critical concept if you're serious about this) Here we go... A pre-fader aux send takes its feed from each individual channel BEFORE (pre) it goes thru the fader for that channel. Thus the term "pre-fader". This means that the pre-fader aux send is completely unaffected by the channel fader. You can turn the fader all the way up or all the way down and it won't have any effect at all on the pre-fader aux send. Pre-fader is ideal for monitor mixes where you want your stage monitor feed(s) to stay where you put it, even if you make changes to the front of house (FOH) mix - because you will ! The point is: If you want to send something (like a separate mix) out of the console (from multiple channels), set the volume, and leave it there... then you need to use a pre-fader aux send. Next: When using effects, remember that what you send out of the board goes somewhere and gets turned into an effect. Then you have to get it back into the board somehow in order to hear it. This us usually done by connecting the outputs of the effects device back into channel inputs on the board (stereo channels are great for this), or by using dedicated "effects return" channels. A post-fader aux send takes its feed from each individual channel AFTER (post) it goes thru the fader for that channel. Thus the term "post-fader". This means that the post-fader aux send is dependant upon the channel fader. Once you set the aux send; if you turn the channel fader up, the aux send goes up. If you turn the channel fader down, the aux send goes down. If you're wondering why you can't hear your effects, make sure your channel fader is not completely off. Post-fader is ideal for effects sends to devices like reverb generators, digital delay units, and anything else generally considered an audio effect (chorus, flange, phaser, etc.). The idea is that once you get your channel fader where you want it, then you set up your effects - using the aux send knob for a specific channel to control the amount of effects FOR that channel. There is a nice balance (hopefully) between the original audio signal (the "dry" signal in the fader), and the effect (usually called the "wet" signal), controlled by the aux send (the post-fader aux send in this case). Once you set this balance and have it the way you like it, it would be a shame to screw it up. SOOOO......... When you turn the fader up (this is your dry signal), the effect goes up with it. When you turn the fader down, the effect goes DOWN with it. Ahhh - nice. Your effects stay proportionally in balance with your channel volumes even when you make changes to your FOH mix. If this is all a little fuzzy, then read it again. Try it on your mixer. Plug a mic or a signal of some kind into your board and send it thru both a pre-fader aux send, and a post-fader aux send. Listen (PFL or Solo) to your aux send masters (if your board will let you do that - because some cheaper boards won't), and see what happens when you change the fader with a pre- vs. a post-fader aux send. Experiment! That's the best way to learn. Just don't experiment during a show! Experiment on your own time - prepare. There are some exceptions to every rule. Here's an interesting one. Pitch-shifting... Assignment - you want to run a vocal mic into a pitch-shifter and shift your voice down a few steps to get that cool "angry demon" sound for Halloween, or maybe you want to pitch it up a few steps so you can sound like the Chipmunks. Either way - nobody wants to hear your original voice along with the effect. So... You need to hear the effect WITHOUT hearing your original voice... You can do this in one of two ways. (1) Un-assign your mic from all of the busses including the stereo bus (if your board doesn't have bus-assign buttons, then this won't work for you). With the un-assigned fader up, your post-fader aux send will still be sending signal even though the channel fader isn't going anywhere. This will achieve our goal of being able to hear the effect without the original signal. (2) Go against the "rules" and use a pre-fader aux send for your pitch-shift effect. You don't have to worry about un-assigning anything. Just pull the fader down, and turn the pre-fader aux send up (assuming you have plugged the pre-fader aux send into your pitch-shifter). Now your dry signal is down, and your wet signal is up. You can hear the pitch-shifted voice, but not the original. Just what we wanted. The best way to learn these concepts is to play with them on a real mixer. You can probably find one at your school or church, or you can buy one these days for under $100. Just make sure you don't mess with anything you can't put back the way it was before you got there. Ask someone to help - tell them you're learning. Churches typically set the board up once and then never touch it again. So don't mess up something they can't fix. Once the light bulb goes on and you finally "get it", you will probably want to use more effects. Some day you'll be doing more than just one or two monitor mixes as well. If you stick with this - it's bound to happen to you - YOU'RE GOING TO RUN OUT OF AUX SENDS !! (Insert Psycho strings sound FX here) That's why they make bigger boards. Larger consoles have more aux sends - some have up to 20 or more for a professional monitor console. Larger format consoles also have nice features like better EQ's and smoother faders, better mic pre's, etc. |
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