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Digitizing NAGRA 4.2 Audio ?


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#1 Aaron Hultin

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Posted 30 December 2007 - 05:28 PM

I have been using a NAGRA 4.2 to record sound, and I'd like to know if there is somewhat of a easy way to digitize the audio myself (rather than sending out the reels to someone else). I have a DAT, which is connected to my computer. So I am hoping to run the audio from the NAGRA, through the DAT, and into Adobe Audition. I haven't had any luck so far hooking the two up, I even tried a 1/4" jack to XLR cable in the headphones socket, but its too noisy. The other option I tried was a banana jack from the output socket to xlr, but this too produced horrific results.


Curious what the REAL way to do this is?

Thanks.
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#2 Hal Smith

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Posted 30 December 2007 - 06:04 PM

I have been using a NAGRA 4.2 to record sound, and I'd like to know if there is somewhat of a easy way to digitize the audio myself .............

Playing the Nagra directly into Audition in your computer digitizes the audio. When it comes time to save it, use the "Save As" option and decide what digital format to save it as. I recommend .wav since that's an uncompressed format unlike .mp3, etc.

I strongly recommend using a dedicated soundcard, not any on-board unless your computer is one of the rare ones with an on-board Creative Audigy. One of the best cost effective soundcards around currently is the M-Audio Q-44 PCI card with an outboard input/output adapter with professional style balanced audio connections. The Q-44 has a control panel that allows you to select input and output levels, with the Nagra, +4dBu would be best.

If you do use the onboard soundcard, its line level input will be much too sensitive for the Nagra's output, you'll need to pad down the Nagra's output approximately 25dB (or so).

See: http://amps.zugster....les/attenuation for pad info. That article is written specifically for musical electronics but the principle is the same.

An afterthought: There's a special M-Audio hardware only Academic version of ProTools that goes for around $190. It's more than the LE version but not as much as the full professional version but at that price it's a steal.
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#3 Aaron Hultin

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Posted 30 December 2007 - 10:19 PM

I have a sound card that has all kinds of inputs, but what kind of connection should I use to run it into Adobe? The problem with the NAGRA is that it doesn't really have 'proper' outputs. It has no XLR out, no 1/4" out (other than the headphone jack), so I'm wondering what kind of connection I should use, also - I have tried outputting through the banana jack (as described in the manual), but it does not seem to work correctly, as there is way to much noise to be useable.
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#4 Hal Smith

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Posted 30 December 2007 - 11:27 PM

I have a sound card that has all kinds of inputs, but what kind of connection should I use to run it into Adobe? The problem with the NAGRA is that it doesn't really have 'proper' outputs. It has no XLR out, no 1/4" out (other than the headphone jack), so I'm wondering what kind of connection I should use, also - I have tried outputting through the banana jack (as described in the manual), but it does not seem to work correctly, as there is way to much noise to be useable.

Unless your soundcard is a professional model, its "line" input is designed for a -10dB unbalanced stereo input. The banana plug output is spec'd at 4.4 volts RMS at 0dB on the Nagra's meter at a 600 ohm load impedance. It's sourced by a transformer which means driving a unbalanced input one terminal is "hot", the other is "ground". But that 4.4 volts output is +15dB therefore overdriving the soundcard by +25dB from what it's designed for. My guess is you're turning down the output of the Nagra so far that you're hearing nothing much more than the noise generated in the Nagra's line output amplifier. Your best options are either a 25dB L pad designed for 600 ohm input, or much better a reasonably professional soundcard with balanced line inputs. Even a pro card would be best with an 11 dB "T" pad to bring the Nagra's output down to +4dB which is current standard practice professional audio line level. The Nagra was designed in the era where a lot of mixing boards were broadcast derived and built for very hot input and output levels. The Nagra's "mixer" output has more friendly levels but you may have trouble finding the matching plug.

If you want to experiment with L pads, use a 560 ohm series input resistor and start with around a 33 ohm shunt output resistor for your current soundcard. That's a voltage divider ratio of 18:1 = 25dB and should put you in the ballpark, additionally it's a pretty close impedance match for the Nagra. Audio gear with transformer outputs needs to be impedance matched for best performance. The soundcard will have a high input impedance without a transformer and impedance matching there can be ignored.

Tie the soundcard right and left channel "hot" inputs together to hook up to the "L" pad's output to record equal levels in both Audition channels.

To adjust the attenuation, adjust the output shunt resistor. RadioShack sells an assortment of 500 resistors for $13 or so which has those two values in it plus a bunch more. If you have a real electronics distributor close to you buy a couple of the 560 ohm resistors and a collection of maybe 10 resistors in values between 5 and 47 ohms for experimentation. If they have small metal film resistors, get those, they're better for audio but not essential for your use.
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