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  #1  
Old 09-07-2005, 12:00 AM
sgladm sgladm is offline
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Default using outboard pre w/mbox - gain knob setting?

Hey,
I'm using an api channel strip these days (on loan) going into my mbox. (balanced trs line into mbox)
Trying to figure out the proper place for the gain knob on the mbox as not to increase noise, or 'double pre' the signal etc.
Happened to be talking to digitech about something else and asked him about it. What he said was interesting, i thought i'd pass it on.

He said on 002 the gain should always be dead zero (when using external pre).

On mbox however, he said 'it's around where one of the four dots are', and the way to calibrate it, is to set a track in PT, insert signal generateor on it with 1khz, leave it at -20, set output of that track to lets say output 1. then get a balanced trs cable going out of that output 1, going into lets say input 2 on the mbox, set an aux track (bussed somewhere else to avoid feedback), and set that aux tracks' input to input 2. the signal is going out and back in.
then press the button on on the mbox input 2 to 'line' and turn the gain knob until the led levels are the same on both tracks (both faders should be at unity).

Any thoughts?
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  #2  
Old 09-07-2005, 10:20 AM
superpenguin79 superpenguin79 is offline
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Default Re: using outboard pre w/mbox - gain knob setting?

Hmm... just a thought on this... I have never tried it on an MBox to be honest, but couldn't you use the TRS inserts to run your pre's into if you just had a couple instead of going through the normal channels on the MBox and having to fuss with the gain knobs? that way you should only have to set the level on your pre that is going into the insert. Most of the time those would be used for compressors, effects..etc. anyhow for a channel insert.. just a thought though.
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Old 09-07-2005, 10:48 AM
tele_player tele_player is offline
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Default Re: using outboard pre w/mbox - gain knob setting?

You CAN use the insert as an input - but it's an unbalanced input, so it might take some tinkering to use it with a professional preamp with balanced output.
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Old 09-07-2005, 02:49 PM
superpenguin79 superpenguin79 is offline
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Default Re: using outboard pre w/mbox - gain knob setting?

yeah, no easy way to break open the MBox and mod it to balanced inputs either... would definately be a non-Digi supported opperation. hehe
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Old 09-08-2005, 12:14 AM
tapani tapani is offline
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Default Re: using outboard pre w/mbox - gain knob setting?

Quote:
You CAN use the insert as an input - but it's an unbalanced input, so it might take some tinkering to use it with a professional preamp with balanced output.
Do I still need to 'tinker' if I go and get a cable from the store?

Thanks
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Old 09-08-2005, 10:10 AM
superpenguin79 superpenguin79 is offline
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Default Re: using outboard pre w/mbox - gain knob setting?

tapani: well, the inserts on the MBox are un-balanced so running a balanced cable into them is not going to make much of a difference actually. The reason you would want balanced inputs instead of unbalanced is basically for shock protection for your equipment for the most part. I know of pro engineers that run very expensive pre's un-balanced into units though and have no problems. I would just proceed with caution and unplug your cables when your pre's are not in use and you should be ok.
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Old 09-10-2005, 04:47 PM
albee1952 albee1952 is offline
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Default Re: using outboard pre w/mbox - gain knob setting?

Balanced out of the external pre into the line in on the Mbox using a TRS cable. Set the Mbox gain all the way down (which "should" be good for a +4 signal from the external pre line out.
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Old 09-10-2005, 06:56 PM
sgladm sgladm is offline
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Default Re: using outboard pre w/mbox - gain knob setting?

based on the 'calibration test' the digi tech told me to do, it's not when turned all the way down, rather pointing at the dot on the top right (around 2pm). He said it should be pointing at one of the top dots (he couldn't remember which one).
albee, what you say would be my intuition too, but conflicts with that the digi tech said. Do you have a good reason to assume that when the knob is turned all the way down is the level it should be at?
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Old 09-11-2005, 09:35 AM
albee1952 albee1952 is offline
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Default Re: using outboard pre w/mbox - gain knob setting?

I suspect you are correct. My idea of starting at all the way down is just safe. If the API pre has a meter to show output level, once you set that for zero, then you could ease up the Mbox gain till your track meter reads where you want it. In any case, there should be practically no difference in sound (if any) and I bet the API will drive quite a bit higher than +4 and still sound clean.
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