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  #1  
Old 06-12-2007, 04:44 PM
Mark The Frog Mark The Frog is offline
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Default Pre-amps/Signal Flow question on DIGI 002 rack

Hey!
Does anyone know if the pre-amps are totally bi-passed (True-Bypass) when using the line channels 1 trough 4 on a Digi 002.
Do they become line-level channels like inputs 5 through 8???
How does the signal flow???

EX:
Exterior Pre-Amp ...to... Line Input
or
Exterior Pre-amp ...to... Digi 002 Pre-amp Bypassed ...to... Line Input

Any infos would be greatly appreciated!!!!

Thanks
Mark
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  #2  
Old 06-12-2007, 05:00 PM
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Park Seward Park Seward is offline
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Default Re: Pre-amps/Signal Flow question on DIGI 002 rack

I'd like to hear the story from Digi but since the input impedance is different on the jacks:

Inputs 1-4 (XLR): 2 kohm
Inputs 1-4 (1/4"): 10 Mohm

I suspect the mic pre is bypassed.
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  #3  
Old 06-12-2007, 08:08 PM
Mark The Frog Mark The Frog is offline
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Default Re: Pre-amps/Signal Flow question on DIGI 002 rack

Yeah I guess it would mean it's bypassed.

Thanks!
Mark
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  #4  
Old 06-13-2007, 06:38 AM
stoneinapond stoneinapond is offline
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Default Re: Pre-amps/Signal Flow question on DIGI 002 rack

Quote:
Hey!
Does anyone know if the pre-amps are totally bi-passed (True-Bypass) when using the line channels 1 trough 4 on a Digi 002.
Do they become line-level channels like inputs 5 through 8???
How does the signal flow???

EX:
Exterior Pre-Amp ...to... Line Input
or
Exterior Pre-amp ...to... Digi 002 Pre-amp Bypassed ...to... Line Input

Any infos would be greatly appreciated!!!!

Thanks
Mark
There is a simple test. If you select line, but the gain control still works, the preamps are not bypassed, merely padded.
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Old 06-13-2007, 09:31 AM
Pepo Pepo is offline
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Default Re: Pre-amps/Signal Flow question on DIGI 002 rack

Are you shure? Most mixers can bypass the preamp (going line in) and you can still use the faders.
Pepo
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Old 06-13-2007, 10:15 AM
stoneinapond stoneinapond is offline
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Default Re: Pre-amps/Signal Flow question on DIGI 002 rack

Quote:
Are you shure? Most mixers can bypass the preamp (going line in) and you can still use the faders.
Pepo
I am NOT talking about faders. I am talking about the gain trim pots.
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Old 06-13-2007, 11:05 AM
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Default Re: Pre-amps/Signal Flow question on DIGI 002 rack



[/QUOTE]

There is a simple test. If you select line, but the gain control still works, the preamps are not bypassed, merely padded.

[/QUOTE]

No. that is not necessarily true. Take a look at some audio mixer signal path line drawings. By switching to another jack, like switching between an XLR and 1/4", you can easily bypass the pre amp stage and send the 1/4" directly to the make-up gain stage.
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Neumann U-47, Tab V76 mic pre, RCA 44BX and 77DX, MacBook Pro 9,1, 2.3 Mhz, i7, CBS Labs Audimax and Volumax.
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Old 06-13-2007, 11:33 AM
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Default Re: Pre-amps/Signal Flow question on DIGI 002 rack

The pre-amp is not bypassed when using the line inputs 1-4 - the pre-amp stage is the same between both, with only the gain and impedance being different.

If you need a true line input, you should use inputs 5-8.
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  #9  
Old 06-13-2007, 11:41 AM
stoneinapond stoneinapond is offline
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Default Re: Pre-amps/Signal Flow question on DIGI 002 rack

Quote:

There is a simple test. If you select line, but the gain control still works, the preamps are not bypassed, merely padded.

[/QUOTE]

No. that is not necessarily true. Take a look at some audio mixer signal path line drawings. By switching to another jack, like switching between an XLR and 1/4", you can easily bypass the pre amp stage and send the 1/4" directly to the make-up gain stage.

[/QUOTE]

You are missing the point. If you have two discrete inputs, where the line input joins the channel strip after the preamp, then yes, you have a true line input.

However, these days, and particularily in the low end of audio, the line input is simply wired behind the microphone input jack, with a pad to allow a line level in. It's a cost issue.

In this case, you are still going through the preamp. And since the trim pot is part of the preamp, the "line" signal is also attenuated using this control. Which will reveal to you whether or not you have a true line input.
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  #10  
Old 06-13-2007, 09:32 PM
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Park Seward Park Seward is offline
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Default Re: Pre-amps/Signal Flow question on DIGI 002 rack

Quote:

You are missing the point. If you have two discrete inputs, where the line input joins the channel strip after the preamp, then yes, you have a true line input.

I don't believe I am missing anything. The combo Neutrik jack has different connections (two discrete inputs) for the XLR and the 1/4 part of the jack, just like two different jacks would. One goes to the preamp, the other after the preamp. You are making different connections to different circuits. The difference in input impedance shows that.
Quote:

However, these days, and particularily in the low end of audio, the line input is simply wired behind the microphone input jack, with a pad to allow a line level in. It's a cost issue.

In this case, you are still going through the preamp. And since the trim pot is part of the preamp, the "line" signal is also attenuated using this control. Which will reveal to you whether or not you have a true line input.
True for some implementations. However, there are two jacks in one connector. Check out the Neutrik wiring diagram.
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The Transfer Lab at Video Park
Analog tape to Pro Tools transfers, 1/4"-2"
http://www.videopark.com
MacPro 6 core 3.33 GHz, OS 10.12.1, 8 GB RAM, PT12.6.1, Focusrite Saffire Pro 40, PreSonus DigiMax, MC Control V3.5, dual displays,
Neumann U-47, Tab V76 mic pre, RCA 44BX and 77DX, MacBook Pro 9,1, 2.3 Mhz, i7, CBS Labs Audimax and Volumax.
Ampex 440B half-track and four-track, 351 tube full-track mono, MM-1100 16-track.
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