Nagra Reference Tone


Newbie using 2.3.0, Windows 7

My input is a reel-to-reel tape recorder that I have connected to a Behringer U-Control 202 (for analog-digital conversion.) The tape contains an -8db reference tone generated by a Nagra tape recorde (tapes are for a movie, synch sound) Do I need to adjust the Audacity record input level so that the tone displays at -8db. If so, how?

I’ve got the IDT Audio Manager up to max (that’s the system volume control I think on my PC) - it affects volume rather than the Audacity record level. I’ve also tried using the Audacity gain boost but I can’t get the meter to move up to -8db for the tone. How important is this?


Assuming that the levels on the tape are accurate, that “-8dB” tone should be 12dB below the maximum recording level of the Nagra.
Recordings on tape generally push the recoding level as high as possible to maximise the available dynamic range. This is not the case with digital recording.
The dynamic range of digital recording is massively more than tape, so there is no need to max-out the recording. Furthermore, maxing out a digital recording is very risky because digital recording is extremely unforgiving about going over 0 dB.

If the tape recording uses all of its dynamic range, then the maximum peak level will be +4 dB. Attempting to record +4 dB digitally will create nasty and permanent distortion.

I’d suggest that you adjust your recording level so that the test tone is a little below -12 dB.
Note that Audacity’s recording meter can be dragged and resized with the mouse. Dragging it to full screen width makes it easier to see the signal level.
Then do a test recording and ensure that the peak level of the actual recording remains below 0 dB at all times and sounds free of distortion.

We generally recommend aiming for a maximum peak level of around -6 dB when recording, though if the Nagre reference tone is accurate, then it should be safe to go a little higher than that.

Yeah… After recording, if you wish you can run the Amplify or Normalize effect to bring the digital peaks up to 0dB.

…If you were do to that with analog tape, you’d boost the tape noise along with the signal, but with digital there is no tape noise.

I don’t think you should be dealing with the tone at all.

The Nagra pilot tone is there so a Nagra can play the tape back with surgical precision to match the completely separate movie camera, also running with surgical precision. Nothing good can come if you have that tone. If you have a mono Nagra tape, it’s a three channel recording with the tone in the middle. I don’t remember if the top and bottom channels are out of phase or not. I could have that backwards, but those are not normal tapes. If you read only one channel, then you automatically have a 6dB noise penalty over an Actual Nagra.

Without the tone management, the tape could be running off speed.

If you have a regular tape, then hope to goodness that someone else had a Nagra and used it to correctly to play the tape and make a good dub. In that case you may have a 3dB noise penalty from dubbing. If they didn’t have a Nagra, it could be even noisier and be running off speed.

I think that’s the list.

Those are rare beasts. How did you get Nagra Work/or/Tape? More importantly, what are you trying to do to it?