The Jazz Guitar Chord Dictionary
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  1. #26

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    OK... let me give this a shot.

    The virtual instruments in logic, in your case I'm assuming pianos, horns, flutes, or even drums, are audio sound files stored on your hard drive. They differ from virtual synthesizers in that they reproduce sampled audio files. In other words, they are "virtual samplers" with a vast library of sampled real instruments. That's why logic pro X is a 75 gigabyte download. These sounds are not reproduced by the DSP chip in any sound card. They are loaded FROM disk INTO memory (RAM) and played back as needed, by the MIDI controller keyboard in your case. That is why audio interface latency is not relevant in this instance.

    I mentioned the included sound card because to play instruments in this manner, no special hardware is needed. The included sound card in any modern computer will reproduce these sounds adequately with out latency.

    To have a rock solid virtual instrument performance system, it is more important to have tons of RAM in your system, in the recommended mirrored pair configuration, to have the quickest access to the samples possible.

    The realtime effects, on the other hand, will be affected by the latency in your audio interface, but the actual work of processing reverbs, delays, etc, is usually taken care of by the computer's CPU. Some sound cards, like the Apollo I mentioned, have a special DSP chip that works with SPECIAL PLUGINS that can process the sound in realtime with out impacting CPU performance. For what you describe:

    a live singer
    a live guitar
    a midi keyboard (organ or piano samples)
    maybe a sequenced drum track

    Any modern computer with a good quality audio interface should be able to handle that and even more. In realtime, with imperceptible latency. There will always be latency in a digital audio system. ALWAYS. But for what you describe, it shouldn't be something to worry about.

    So, for example, you have the Apollo Twin, or an Apogee DUET, or an RME babyface (all three are comparable products). you have your guitar connected to input 1, going to a channel in Logic, This channel has an amp simulator as an insert (the included amp modeling in logic is superb BTW). A singer connects his/her mic to input 2, which is going to a second channel in Logic that has a little reverb and delay to "sexy" things up a bit. A third channel in Logic has a virtual instrument loaded (its a MIDI channel, not an audio channel) and is controlled by the midi controller keyboard. Additionally, a third track of audio drums can be used to play back and sync everybody if needed.

    Does this help? I'm in a bit of a hurry, so I may have left some things out. Let me know if something isn't clear and I'll try to answer you later tonight.

    K

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    The Jazz Guitar Chord Dictionary
     
  3. #27
    Thanks K,

    That is very very helpful.

    Yes, you could imagine that our little trio is recording in real time tracks to go with some existing tracks already in Logic (some drums, some bass, some marimba, maybe a guide vocal). The really most important thing is to have tiny latency for the singers. The second most important thing is small latency for the guitar. I kind of figured that a good DSP would take care of that. But then I got to the whole issue of MIDI and Logic horns and flutes and I was trying to figure out how to get them into the DSP for real time monitoring.

    So your explanation was very good, except I still don't exactly follow the (low latency) path from the MIDI controller to the singer's headphones. I assume it goes: controller>USB>somewhere in the mac>hard drive>RAM>somewhere in the mac>interface/DSP>output>headphones. So I am assuming that the DAW is nowhere in that direct low latency path and that it is just forks off at some point.

    And I still don't understand whether I should get an interface with MIDI (Babyface) or whether it is fine just to send the controller in via USB (since the Apollo doesn't have MIDI).

    As I said, the really important thing is the vocals and to a lesser extent the guitar. I have been admonished that professional singers will not tolerate latency, so I need to elimitate it. And this stuff is very intricate vocally. So that is really really important. But in actual fact, the MIDI stuff isn't that critical. I will put most of that in via Finale by hand rather than by controller. But since I need to make a decision about whether to get an interface with or without MIDI, I figured I better learn how MIDI works since I will want to put some stuff in via a controller (probably some drums at least), so why not imagine doing it live with the singer and guitarist at least as a thought experiment. I don't want to find out later I could have avoided some MIDI latency by getting the Babyface instead of the Apollo.

    I have a virgin mac sitting here and I'm slowly trying to figure out how to connect it to other stuff.

    Thanks.
    Last edited by jster; 03-26-2014 at 12:58 PM.

  4. #28

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    Quote Originally Posted by jster
    But since I need to make a decision about whether to get an interface with or without MIDI, I figured I better learn how MIDI works since I will want to put some stuff in via a controller (probably some drums at least), so why not imagine doing it live with the singer and guitarist at least as a thought experiment. I don't want to find out later I could have avoided some MIDI latency by getting the Babyface instead of the Apollo.
    In the old days, MIDI meant a specific communication protocol and implied a specific physical connector. MIDI jacks look like this:

    Thunderbolt for interfaces-midijacks-png

    Today, however, most MIDI functionality is the communication protocol, but sent over any capable (digital) wires, usually USB. When an audio interface (RME, Apollo, etc.) says it has MIDI input/output usually what they mean is that the device has the actual old-school jacks on it, to support old-school equipment (DX-7 anyone?). However, if your keyboard is a USB MIDI keyboard (extremely common in recent years), then you don't really care about the old-school jacks. Your DAW should be able to handle MIDI input/output over USB, in addition to, audio input/output through your interface. I say "should" since I don't know every capability of every DAW, but this is fairly basic stuff. In fact, a lot people into various 'electronic' music, who only use USB MIDI controllers (keyboards, e-drums, etc.) don't need any interface device.

  5. #29
    Thanks again. I think I'll be able to get a MIDI controller today. I'm hoping I will be able to get one that just runs through my RME (I got the UCX). I would prefer to not install any software and I'm thinking if I just go through the RME as opposed to USB I won't need to. One reason is that there are often driver issues with older controllers and the latest mac OS. Another is that I don't need anything on the software. So avoiding USB I'll avoid extra software. Really, the newer controllers look like driver nightmares. I just want velocity and aftertouch, so I'm bidding on a somewhat older keyboard. I'm hoping that will work straight into the RME.
    Last edited by jster; 04-05-2014 at 06:49 AM.

  6. #30
    I am using the RME babyface and route a keyboard through it into the DAW (Cubase), never had a problem.

    Latency can be an issue with respect to the use of midi instruments within a DAW, eg when you use a virtual organ such as in Hauptwerk, where one virtual instrument may need more than 16GB RAM, or when you address a whole orchestra through multiple tracks. However, if you use the 'normal' stuff available in DAWs (eg a piano, some drums, double bass in a jazz context), latency from your playing of the midi keyboard (via interface, DAW, midi instrument, back to singer) is hardly audible.

    However, latency does play a role if you record the singer into the DAW. Recording continuously flowing audio into a computer requires a good amount of RAM buffering, and you should think of upgrading your computer in this regard. Dont buy from Apple, you can get excellent RAM eg from Crucial for half the price (installing the RAM is a piece of cake): http://www.amazon.com/gp/aw/d/B008LT...110_SY165_QL70

    With 16 GB RAM you should be able to run any DAW seamlessly, adjusting accepted latency in the DAWs parameter to a minimum. If you do this with 4GB RAM and record a singer and say a guitar simultaneously in 2 tracks, the system may begin to clip.
    Last edited by Phil in London; 05-25-2014 at 04:41 AM.