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Logic 8 Having signal routing issues...

Discussion in 'Logic 8' started by intchr, May 18, 2009.

  1. intchr

    intchr New Member

    Hey gang, first post here and I'm stoked to be here. I've had Logic Express 8 for about a week now and am having an issue with trying to reamp a clean guitar signal. To preface, I'm using a Focusrite Saffire Pro 40 for my interface and a Line 6 PODXt for my effects pedal.

    The way I've got the signal chain is like this -- I've got my guitar routed into Logic via input 1 on the saffire, and I've got the routing on the track strip set to route that signal out to outputs 3-4. Then I'm routing output 3 (and I've tried output 4 as well) into my Line 6 pedal, and then sending the stereo outs on the Line 6 back into the audio interface via inputs 5 and 6. Then I've got another track strip that's grabbing the signal from inputs 5-6, and then sending that signal out to the master.

    When I play live I can see the levels bouncing on both the clean strip and the effects strip, and when I record into the clean strip that part is going ok, but on playback for whatever reason the audio doesn't get bounced through the Line 6 and back into the effects strip. :brkwl: I don't understand why the recorded audio's not bouncing properly to my effects pedal, the audio should be following the preset signal flow correct?

    If anyone has a clue as to what's going on that'd be awesome -- I really appreciate it!

    EDIT: I forgot to mention, the I/O plugin doesn't seem to remedy the situation either :(
  3. JumpingInFire

    JumpingInFire New Member

    Out of curiosity, why are you routing it this way? I have a PODxt Live and a Pro 40. I just run my guitar through the POD then into my interface for a short, clean, and simple signal flow.
  4. intchr

    intchr New Member

    I do it this way because I record clean into my DAW, which allows me to play around with settings on my PODXT Live and also audition different effects configurations. That way, if I'm not happy with the amount of reverb I used I can simply change the reverb without having to re-record again. This technique is referred to as Re-amping, and where this comes in real handy is when you're not the guitarist and you'd rather have a perfect source file to work with instead of calling the guitarist back into the studio. And as for me, I'm not a strong guitarist so it's better for me this way, since I'm not really guaranteed to get that perfect take right again without spending hours recording and scrubbing. :D

    Edit: I also figured out what I was doing wrong -- the I/O plugin under the utilities folder is the way to make all that happen. It records the guitar dry, then routes the signal out of the Saffire and back in again. I route out via output 3 (mono signal) and route the Line 6 back in through outputs 7-8 (stereo). I hate to say it as well, my Vox AC50CP2 has been collecting dust since I got this Line 6, the mic and amp emulators are that convincing. :)
  5. Peter Ostry

    Peter Ostry Administrator Staff Member

    itchr, I am not sure if I understand your reasons correctly, but your routing looks a bit awkward. You route the live signal through Logic and afterwards through an amp. If you don't use Logic effects on the signal this makes no sense, it just gives you a remarkable latency.

    Reamping is usually done with the dry signal. Means, you record dry and send the signal through an amp afterwards, after you edited/comped the takes. For this you would split the guitar signal with a DI box, send the balanced output to the interface and Logic, the link output to an amp to hear the sound while you play.


    If you don't need the sound, you can record without the amp and monitor the dry sound via the audio interface.

    You can of course record the amp sound also while you play, on a second track. But you say you need a couple of takes to get a good one. In this case you would need to edit/comp always two tracks at once and this is a terrible job. Depending on the amp sound (reverb, tremolo etc) it might not even be possible.

    For reamping a recorded dry Logic track, the I/O plugin is, as you say, the tool of choice. Expect to adjust the position of the recorded region, there is no latency compensation for outboard gear.

    But although reamping is fine, keep in mind that you send a line signal to the amp. This is not the same as the interaction between a guitar pickup and the input stage of an amp. If you are very picky about your sound, you might consider to record the amp with a mic. But it is a good idea to record the dry signal also.
  6. intchr

    intchr New Member

    Hi Peter,

    You're definitely right, and I've actually had troubles using my amp because of the dramatic difference between a line signal and the guitar's signal. That's not to say that they can't be worked out, but matching the signal strength of a passive electric guitar is a process of trial and error, and yes it is tedious.

    I should've been more clear on my routing in my reply -- having just come from Ableton Live as my choice of platform, the only way to route with a dry signal was to set up a strip to record the dry guitar on, change the output channel to one going into your guitar rig and then set up a strip to receive the signal after it's been processed. This was my mode of thought when switching to Logic this month, that I would have to do something similar to attain similar results. It would've been more clear of me though to say in my reply that I've actually abandoned trying to do crazy routing through the strips in Logic...

    But you're inevitably right Peter, a DI box would probably improve things substantially on my end. Maybe I should take your advice instead of constantly fighting levels, S/N and unintended gain and drive issues from having to crank my signal. Do you have any recs for a good one?
  7. JumpingInFire

    JumpingInFire New Member

    Well a cool thing about the Saffire MixControl software is that you can send any input to any output without hitting Logic first. You don't need the I/O plug for this interface.

    For example, in MixControl, set output 3 to spit out your analog input 1 directly from your guitar.
    In Logic your direct guitar track will record from input 1.

    Route output 3 from the Pro 40 to the input of your Podxt.
    Route the outputs of your Podxt to inputs 7/8 on the Pro 40.
    In Logic your processed signal will come from inputs 7/8.

    You will have zero latency when monitoring through the MixControl software for either the direct or processed signals. Not so when monitoring through Logic.

    The only possible issue is that the Pro 40, I believe, will be sending a line level signal to your Podxt instead of an instrument or amp level signal. Is this bad? Idk, perhaps someone else here may know for sure.

    Another PITA is that you would have to play back the direct signal in real time after changing settings on the Podxt and record back onto the processed channels.

    So back to the original post . . .
    As long as you have the output section of Saffire MixControl looking like the attachment, there shouldn't be a problem getting the signal to the Podxt while recording.

    And btw intchr, if you'd like, I can send you a .pro40 set-up for this. Just PM me.

    Sorry, forgot to mention that you must switch output 3 from sending the analog input 1 to whatever you have the recorded direct guitar playing through. This is where the I/O plug is helpful!!!

    Attached Files:

  8. Peter Ostry

    Peter Ostry Administrator Staff Member

    Not zero but little. Sound goes in, A/D conversion, sound is routet, D/A conversion, sound goes out. There is the latency of the two conversions and I think a small buffer. Not much overall, many people are happy with this method.

    Yes. This is always the case with monitoring through interfaces or mixers. You can un-balance the signal after the output if you get a problem but you will not get the low impedance of a pickup and not the interaction between a pickup and an amp.
  9. Peter Ostry

    Peter Ostry Administrator Staff Member

    In passive DI-boxes the path for recording goes only through a transformer to the balanced output, the transformer is responsible for the signal loss and the signal quality.

    The best passive DI-Box I have is a German product, Millenium DI-Pro, it has a Haufe transformer. Poorly built, cheap jackets, but very little signal loss and great sound.

    Cordial has a good passive DI-Box with two channels. It loses about 4 dB, quite normal for passive boxes.

    Palmer is kind of a standard but I was not happy with active Palmer DI-boxes. Can depend on my instruments, don't know.

    If you want a big box for almost everything I can recommend the active Alto DI-4.

    I have no other recommendations, sorry. If you prefer an active box you have to try it with your instrument. They are very different. If you go for a passive one, ask about the transformer since this is the only thing that counts. Active boxes have also transformers but additional electronic which colours the sound.

    Passive boxes are more universal. You can use them in either direction, so you can also un-balance a signal between a balanced output and an unbalanced (mono) input.

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