Audiobus: Use your music apps together.

What is Audiobus?Audiobus is an award-winning music app for iPhone and iPad which lets you use your other music apps together. Chain effects on your favourite synth, run the output of apps or Audio Units into an app like GarageBand or Loopy, or select a different audio interface output for each app. Route MIDI between apps — drive a synth from a MIDI sequencer, or add an arpeggiator to your MIDI keyboard — or sync with your external MIDI gear. And control your entire setup from a MIDI controller.

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Pre-fader/Post-fader

What's the significance of having something pre-fader as opposed to post-fader? What's a good working example?

Comments

  • edited July 2018

    The volume on the effect send is independent in pre fader mode, they are linked in post fader mode. If you only wanted to hear the reverb on a snare you can turn down the original sound and the reverb won't be affected if using pre fader.

  • Pre-fader means the amount of signal going into an Effect or Send is unchanged when you move the fader. Post-fader means the amount follows the fader changes.

    For example, if you put a Reverb effect pre-fader then no matter what you do to the volume adjustment, the amount of reverb will be the same. Post-fader, the reverb will be louder and softer in proportion to the volume adjustment.

  • Another way of thinking about it is;
    When tracking, you may want to capture the raw audio signal regardless of the fader you set on the board/daw. Pre-fader is that signal.

  • Thanks! Y’all might have just helped me solve an AUM volume problem involving sends. I’ll hit the books!

  • edited July 2018

    You can use pre fader as send to bus, just ignore the volume fader and keep it at zero...
    On a traditional mixer pre fader ignores the eq/the volume fader /the other send ...

  • @JoshuaRex said:
    Thanks! Y’all might have just helped me solve an AUM volume problem involving sends. I’ll hit the books!

    Yep. Not sure if your problem is the same common newbie problem I had when I got started (feels like yesterday still), but it baffled me why I’d be able to hear a signal when I just clearly muted the track. The answer was, of course, my sends were pre fader.

  • If you have no idea what you are doing, just ignore pre fader,
    Post fader is what you want

  • Pre fader is useful for gain staging, whereby you look at the source level and try to trim the level of each channel down to quite a low level (ie, not hot, not maximised) to allow dynamic headroom and to allow a mix to ‘breathe’ when actually, you know, mixed. Pre fader metering in such a circumstance will tell you if you have a signal that is dominating at the point of the source, and therefore should have the gain trimmed back somewhat.

    You wouldn’t want to put a very hot signal into an insert effect, or chain of insert effects – you’re better off using somewhere between -12dB to -18dB at the point of source. If the source were normalised to hit 0dB, for example, during the maximum parts, that’d be too much in the mix (if all your channels were up there – you couldn’t even mix two such channels together without trouble unless you brought the levels down first), so you have a stage before the mix balancing where you adjust or trim the gains, to get them all down low.

    Once they’re all set to that lower gain, in your gain stage (or gain-trimming stage) of production, you may sensibly begin to balance your mix and pay attention to dynamics and the way certain things might need to be brought lower here and higher there, and so on. To do that, switch back to post fader (although I don’t, I should but I don’t, I leave it pre fader and just pay attention to the final mix output meter – I mustn’t be lazy and should switch it back when mixing).

  • @u0421793 said:
    Pre fader is useful for gain staging, whereby you look at the source level and try to trim the level of each channel down to quite a low level (ie, not hot, not maximised) to allow dynamic headroom and to allow a mix to ‘breathe’ when actually, you know, mixed. Pre fader metering in such a circumstance will tell you if you have a signal that is dominating at the point of the source, and therefore should have the gain trimmed back somewhat.

    You wouldn’t want to put a very hot signal into an insert effect, or chain of insert effects – you’re better off using somewhere between -12dB to -18dB at the point of source. If the source were normalised to hit 0dB, for example, during the maximum parts, that’d be too much in the mix (if all your channels were up there – you couldn’t even mix two such channels together without trouble unless you brought the levels down first), so you have a stage before the mix balancing where you adjust or trim the gains, to get them all down low.

    Once they’re all set to that lower gain, in your gain stage (or gain-trimming stage) of production, you may sensibly begin to balance your mix and pay attention to dynamics and the way certain things might need to be brought lower here and higher there, and so on. To do that, switch back to post fader (although I don’t, I should but I don’t, I leave it pre fader and just pay attention to the final mix output meter – I mustn’t be lazy and should switch it back when mixing).

    Holy cow, you say the words in my brain so much better than I do.

  • edited July 2018

    @u0421793 said: Pre fader is useful for gain staging,

    huh?
    it bypasses the eq
    the eq can have a big effect on how hot the level is (+/- 15 db)
    I would not recommend doing this like that
    its easy to clip the post sends at unity gain like this ...

  • @Max23 said:
    @u0421793 said: Pre fader is useful for gain staging,

    huh?
    it bypasses the eq
    the eq can have a big effect on how hot the level is (+/- 15 db)
    I would not recommend doing this like that
    its easy to clip the post sends at unity gain like this ...

    Do the same when you get to the EQ – look at how hot it is when it leaves the insert effect. Same with the Compression (in fact, that’s where I control the overall ‘energy’, by stepping the compressor make-up down where necessary) and so on. Each insert is a potential gain change, but rather than starting too hot, let each be satisfied with a reasonable dynamic range on the input, and let each deliver a polite amount as output to the next in line.

    As I say, I should pay more attention to post fade levels too, and I keep forgetting (mainly because I look at the automation instead).

  • @u0421793 hehe, we are old foxes with habits

  • Hi...I posted this a while ago and got no response...if anyone can shed any light I'd be grateful.

    It's great being able to use a midi controller to click fx on and off in Audiobus using 'bypass'. But the problem is that the bypass button is after the effect, so when you click the bypass ON, your lovely long reverb just gets chopped off. Most Au effects don't have their own input levels, or bypasses so you have to use your mixer, which in this case is Audiobus. In AUM there is an option to use effects post or pre fader. Can this be acheived in Audiobus I wonder?

  • @jazubon said:
    Hi...I posted this a while ago and got no response...if anyone can shed any light I'd be grateful.

    It's great being able to use a midi controller to click fx on and off in Audiobus using 'bypass'. But the problem is that the bypass button is after the effect, so when you click the bypass ON, your lovely long reverb just gets chopped off. Most Au effects don't have their own input levels, or bypasses so you have to use your mixer, which in this case is Audiobus. In AUM there is an option to use effects post or pre fader. Can this be acheived in Audiobus I wonder?

  • wimwim
    edited October 12

    I don’t see how pre/post fader affects this, and I don’t see how AUM would help. If you bypass an FX, it no longer affects the sound. Instantly. A reverb tail isn’t something that’s sent out of an FX and drifts away over time. It’s produced by the FX itself, so if you cut it off, it’s gone.

    Most FX do have a dry/wet control. I think what you need to do is fade the dry/wet control down to zero percent wet but still, the reverb tail is going to disappear no matter what you do.

  • @wim said:
    I don’t see how pre/post fader affects this, and I don’t see how AUM would help. If you bypass an FX, it no longer affects the sound. Instantly. A reverb tail isn’t something that’s sent out of an FX and drifts away over time. It’s produced by the FX itself, so if you cut it off, it’s gone.

    Most FX do have a dry/wet control. I think what you need to do is fade the dry/wet control down to zero percent wet.

    What he said

  • As a guitar 🎸 player, I have the ability to have reverb and/or delay naturally fade out OR get chopped off on my Line6 M9 FX unit.
    As @jazubon has already asked, Is the same thing possible on iOS? Would you have the midi controller assigned to the actual bypass button on the FX itself? I’m sure there are FX that are capable, I’ve just never really tried to use any like that yet. That’s why I have the hardware.. and most of the newer reverb + delay guitar pedals DO have this as an option (naturally fade out OR get chopped off).

    From the manual:
    The Model Select knob toggles between True Bypass and DSP Bypass. In True Bypass, mechanically switching relays route your signal directly from input jack to output jack, bypassing all circuitry, for absolutely no processing or conversion all FX are bypassed.
    If you’re playing back a loop, however, or you want your Delay and Reverb trails to be heard when bypassing all FX, you must use DSP Bypass.

  • @royor said:
    As a guitar 🎸 player, I have the ability to have reverb and/or delay naturally fade out OR get chopped off on my Line6 M9 FX unit.
    As @jazubon has already asked, Is the same thing possible on iOS? Would you have the midi controller assigned to the actual bypass button on the FX itself? I’m sure there are FX that are capable, I’ve just never really tried to use any like that yet. That’s why I have the hardware.. and most of the newer reverb + delay guitar pedals DO have this as an option (naturally fade out OR get chopped off).

    From the manual:
    The Model Select knob toggles between True Bypass and DSP Bypass. In True Bypass, mechanically switching relays route your signal directly from input jack to output jack, bypassing all circuitry, for absolutely no processing or conversion all FX are bypassed.
    If you’re playing back a loop, however, or you want your Delay and Reverb trails to be heard when bypassing all FX, you must use DSP Bypass.

    I think to get what you are after, you would put a bus send on your guitar channel that does to your delay/reverb channel. You can set up a MIDI control change to toggle the send. So, when you toggle the send off, it won't kill the reverb tail because the reverb is actually on its on channel. The reverb just won't receive any new guitar input until you toggle it back on. You could also set up something to turn the reverb on and off if you want it.

    There are tons of ways that you can go with it. A piece of paper and pencil can be useful for visualizing the signal flow that you want.

  • edited October 13

    @espiegel123 Thank you very much for that info.. it will get filed away in the "important iOS connections" repository.. and you're right about sketching out the signal flow.. It seems when I'm in "guitar" mode, I'm always thinking in a physical-pedal-kinda-way.. I know there is crazy power within AB3 + AUM + apeMatrix which I do take advantage of when I'm using synths + drum apps etc.. I just never seem to get as experimental when using my guitar in a similar setting.. yeah, I know.. I'm just in a different headspace when plunking away on 6 or 4 strings..

  • Finally! A question about something I care deeply about!

    I use several mixers in my hardware setups, and a prefader aux is always my preferred option. It allows me to route several instruments in different ways. I'll simplify...

    A drum machine and synth routed into my mixer. I can use the pre-aux to route either to an fx path AND have that path routed back into the mixer. If it was a post aux and you wanted to route it back to the same mixer, you'd get instant feedback.

    As a side note, the U420 mixer by Mackie has a STEREO pre-aux, which is an absolute rarity. My recommendation for the hardware world. In the iPad realm, we are very lucky to have so many options for routing internally.

  • edited October 13

    You wouldn’t want to put a very hot signal into an insert effect, or chain of insert effects – you’re better off using somewhere between -12dB to -18dB at the point of source.

    oh, please, not this gain staging nonsense again :((( It's myth which has nothing to do with reality in modern digital DAWs, which are internally processing all audio on 32bit (or even 64bit) floating point precision.

    Gain staging was important with analog mixing consoles. To gen enough headroom. In digital DAWs it's absolute wasting of time, nonsense and missunferstanding of how DAW processes audio...

    only place where you have to take a care about gain is AD and DA converter... not in digital domain inside DAW.

    period.

  • @dendy said:

    You wouldn’t want to put a very hot signal into an insert effect, or chain of insert effects – you’re better off using somewhere between -12dB to -18dB at the point of source.

    oh, please, not this gain staging nonsense again :((( It's myth which has nothing to do with reality in modern digital DAWs, which are internally processing all audio on 32bit (or even 64bit) floating point precision.

    people please stop repeating and spreading nonsenses, learn a bit how things really work.. i'm really tired of legends and hoaxes which originates in lack of knowledge.

    Gain staging was important with analog mixing consoles. To gen enough headroom. In digital DAWs it's absolute wasting of time, nonsense and missunferstanding of how DAW processes audio...

    only place where you have to take a care about gain is AD and DA converter... not in digital domain inside DAW.

    period.

    Like mentioned before, we all have our habits.
    I wouldn't recommend ignoring gain staging. Even though what you say is mostly correct - it won't hurt in most cases - it's just not a good practice to adopt. That way if you find yourself working with/chaining hardware you'll face less surprises. Also there are effects that work differently at certain gain stages - saturation, distortion, compressors. But in any case, it's not very wise to feed any fx with too hot signal.

  • edited October 13

    nonlinear effects (ovedrive for examole) are different topic and most of them do have internal "prefx" gain knob... if they don't have, of course you need to adjust gain before fx..

    i was reffering to widely spreaded myth that just plain gain staging (putting gain on all tracks to -xx dB) in DAW makes it sound better... Like putting gain to lower values to avoid too "hot" signal and eventually ovedrive when "VU" meter on channel is near 0 (or even above 0) on individual tracks (not master, this is different topic !) ... which is nothing but placebo in best case..

    here is very good video about this topic, that guy uses Reason, but fundamental principles which he explains can be applied to any DAW...

  • Yep, agree with everything you say and everything from the video. But imo gain staging isn't wasting time, but being aware of your signals.
    I'm sure you know exactly where to reach - or more importantly being able to recognise - when something isn't right, but when I see some demos here with limiter/maximizer on every channel I'm not quite convinced that "forget about clipping" is right message that will help/improve things.
    On the other hand, do what works for you. There is no wrong way really... "don't sweat it" :)

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