DON’T SCRAP YOUR NAGRA 4S

THERE’S LIFE IN THE OLD GIRL YET

Comments on NagraMaster

compiled by Peter V Meiselmann CAS

Recording on NagraMaster is admittedly a political issue. You have to convince production that running at 15ips is worth the extra expense in tape stock. Tape stock is the cheapest link in the production chain, and as humiliating as it is to have to argue about it, it is well worth the effort.

The following statements should clear up some of the confusion and remind Nagra IV-S users and post production people of an existing superior recording equalisation.

Dan Dugan of Dan Dugan Sound Design, San Francisco

 Most Nagra users ignore the second 15ips position on the 4S speed switch labelled NagraMaster. NagraMaster is a special equalisation which gives a greatly improved signal-to-noise ratio at 15ips compared with NAB standard. With current high level tapes like Quantegy 480, it compares favourably with DAT recording.

Recording at the standard dialogue speed of 7.5ips requires a substantial treble boost (pre-emphasis) inside the recording amplifier. This is to compensate for losses in the recording process. This treble boost reduces the high frequency headroom. It is possible to record all the way up to +4 modulation at the lower frequencies, but by the time you are up to 10kHz, the boost has hit the ceiling, so though the frequency response is flat at low and moderate levels, high treble levels will saturate.

The maximum recorded level at 10kHz with today’s tapes is 5- 10dB lower than the low frequency maximum. This is no problem with voices or classical music because the peak energy spectrum of these sources also roll off at higher frequencies. Also at 7.5ips there is no complementary roll-off in the playback, as there is in the RIAA disk equalisation, so the overall phase shift with frequency, called ‘group delay’ is an inherent sonic limitation of 7.5ips recording.

At 15ips, no treble boost is needed. Indeed, with today’s tapes, a small amount of treble roll-off is required. This makes the 15ips NAB record EQ good for recording hot cymbals or synthesisers, or treble rich sound effects like hissing steam, that would have to be turned down to avoid the treble saturation at 7.5ips. Not having the pre-emphasis at l5ips also means much less group delay.

Kudelski’s trick with NagraMaster EQ is to use the 7.5ips treble boost for recording at 15ips. Then a complementary treble roll-off is used in playback to restore flat frequency response. This makes a dramatic decrease in the tape noise level. and furthermore, shapes the noise spectrum to a

velvety hush rather than an intrusive hiss. This has to be heard to be appreciated. NagraMaster is more like digital than any other analogue system, in my opinion.

There are two disadvantages to using NagraMaster. First, you have to be aware of the possibility of high frequency saturation due to the pre-emphasis. This is no problem if you are used to recording at 7.5ips. The pre-emphasis is the same, so the same recording level habits will serve. The second problem is confusion at the transfer house. You have to make sure that everybody down the line knows how to handle NagraMaster before you use it for a project. NagraMaster tapes must be transferred either from a Nagra (IV-S or T-Audio), or from a standard NAB machine followed by a NagraMaster roll-off EQ. Recordists “in the know” about NagraMaster have achieved spectacular results.

Will Harvey, Head of the Film Dept,

The Music Annex, San Francisco

NagraMaster recording is a straight analogue path without any noise reduction to degrade the signal. For ease and simplicity, the format cannot be equalled. Using the NagraMaster format in production yields superior analogue performance and sound quality on a robust and common format.

Agememnon Andrianos, Production Sound Mixer, San Rafael

 I used NagraMaster on The Absent Minded Professor starring Robin Williams. Robin Williams never does a take the same way twice and very often would add or enhance his performance with vast changes in level or action. NagraMaster gave me the cushion needed to capture his spontaneity on the tracks.

The greater dynamic range of NagraMaster allows you to under-record a little, providing greater headroom for sudden level changes, from screams to whispers. You can record with confidence and tape noise is exceptional for quiet scenes.

NagraMaster allows for a quieter recording. measuring about 5dB better signal-to-noise ration than 15ips NAB. However it sounds better than that due to the frequency spectrum of the tape noise. It

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