Nakamichi spezifische Messkasetten

[Jürgen Heiliger]

Hallo Jungs,

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Nakamichi Calibration Tapes
The service manuals for most Nak decks mentions only 7 calibration tapes.  They are listed below.  The prices listed are from the Nak Retail Price List from 1988-89.  As far as I know they are no longer available from Nak.

DA09001 - 20 kHz Playback Frequency Response Tape - This tape has an accurate -20 dB level signal of 20 kHz.  It is used to verify playback frequency response.  $95
DA09002 - 15 kHz Playback Frequency Response Tape - This tape has an accurate -20 dB level signal of 15 kHz.  It is used to verify playback frequency response.  $76
DA09003 - 10 kHz Playback Frequency Response Tape - This tape has an accurate -20 dB level signal of 10 kHz.  It is used to verify playback frequency response.  $70
DA09004 - 15 kHz Azimuth Tape - This tape has a 15 kHz signal recorded on it and is used for aligning the PB head azimuth.  $130
DA09005 - 400 Hz Level Tape - This tape has a very accurate 0 dB tone of 400 Hz recorded on it.  It is used to calibrate the output balance/level and meter level.  This tape should be used before doing any kind of tape level/bias adjustment.  $50
DA09006 - 3 kHz Speed & Wow/Flutter Tape - This tape has an accurate 3 kHz signal recorded on it.  It is used for adjusting the decks captan motors and for measuring the decks speed error as well as wow/flutter.  $60
DA09007 - 1 kHz Track Alignment Tape - This tape has a 1 kHz signal recorded on it, but, it's recorded on either side of the tracks center.  It is used for adjusting the PB head height.  When using this tape the PB head is adjusted for minimum signal out, NOT maximum like the 15 kHz azimuth tape.  $90
DA09008 - EX (Normal bias) Reference tape.  $12.34
DA09011 - Tape Travelling.
DA09012 - Track viewer.  $200 back picture
DA09013 - Torque Gauge
DA09021 - EXII Reference tape.  $9.14
DA09025 - SX (CrO2 Bias) Reference tape.  $32
DA09092 - is not a tape, but, rather a gauge for adjusting record and playback head height

The DA09001-9003 are only used to verify the frequency response.  They are not needed to do a calibration on a deck.  They will tell you if your azimuth is off, but, you shouldn't adjust your heads azimuth to these tapes.  While the azimuth has got to be pretty close, these tapes are most likely not produced on the precision equipment needed to make an actual azimuth tape and therefore aren't guaranteed to be acurate.

The DA09004 15kHz Azimuth Tape is one of the most important tapes for calibrating you deck.  Although a genuine Nak tape would be nice, any of the Azimuth tape will be fine, even the Emtec 10 kHz Azimuth tape.  With this lower frequency adjusting for maximize output level might not work as well.  There are two things you can do to get a more accurate reading.  Adjust for maximum level on a VTVM, then fine tune by adjusting for minimum phase shift on a scope.  Another way is to again adjust for maximum level on a VTVM, then short the Left and Right outputs together and fine tune for maximum level.  When the phases are the same the signal is a maximum.  When the phases are opposite, they cancel and the output is a minimum.  I used to use this method with a Dorrough stereo test set which had a switch on the front to sum L & R.

The DA09005, 400 Hz level tape is another important one.  There is some question about what is considered 0dB.  I think the Nak tape is 400nW/m (nanoWebers per meter), but, other cal tapes may use a different flux level (magnetic strength) for 0dB.  Try to use a genuine Nak cal tape.

The DA09006, 3 kHz Speed and Wow/Flutter Tape is another generic tape.  Any similar calibration tape can be used.  The DA09007, 1kHz track alignment tape is a really special one.  Only Nakamichi has it.  Other calibration tapes can be used to aligning the cassette decks playback head height, but, DO NOT use the procedure in the Nakamichi service manual.  It won't work.  What other cal tape manufacturers do is record a narrow stereo signal down the center of the audio tracks and then you adjust for maximum signal out.

Here are a couple links to Non-Nak Calibration Tapes
http://www.almedio.co.jp/cassette.html
http://www.teac.co.jp/testmedia/cas.html <--Link no longer works
http://www.jrfmagnetics.com/basftapes.html

There is a calibration tape for sale by Electronix.  DON'T BUY IT.  It is utter crap!

There is a guy on ebay (User ID:  el355) selling a calibration tape that he claims is a genuine Nakamichi calibration tape for NAAC.  Personally I don't believe it.  He says the P/N is DA-09005X2.  I've never seen a tape with that number before, I've never seen any Nak service manual reference any special calibration tapes specifically for the NAAC system and I've never seen a Nak cal tape in a TDK MA-R shell (alluminum alloy frame with clear side covers).  It's a nice shell, but, Nak cal tapes are in generic black shells.

Ok, I need to say one more thing about Cal tapes.  Most of the non nak cal tapes are recorded using using the IEC 1981 standard.  Most Nak decks do not use this standard, they use the earlier one.  As far as I know the MR-1B, MR-2B, later CR-7A's and everything after the CR series uses the IEC 1981 standard.  Everything before uses the IEC 1976 standard (I may be incorrect on the year).  The IEC 1981 standard came about because of the crappy heads the other guys were using.  They didn't perform well at high frequencies.  The IEC 1981 standard introduces a bump of a few dB in the high end during recording.  When a tape is played back the bump is eq'd out.  Since Nak heads were so good they didn't see the need
and did not conform to the new standard until much later (when people started complaining that their tapes sounded dull to everyone else decks and their tapes sounded overly bright when play back on Naks.)  The disadvantage of the IEC 1981 standard is reduced headroom in the high end.  So really the older standard is better, but, only if played back on another Nak.  You can convert your older Nak deck to the newer standard, but, it requires modification in both the record and playback equalization circuits as well as a complete calibration using IEC 1981 cal tapes.  The Nakamichi calibration tape part numbers I wrote in my earlier post are for the earlier standard.  Not IEC-1981.

Luis Peromarta is making his own calibration tapes with his Dragon. While I'm not a fan (because I have genuine Nak cal tapes) a lot of people seem to like them. He is in Spain and sells them for 75 Euros plus 5 Euros shipping to western Europe and 10 Euros for shipping elsewhere. He has a nice web page for them Luis' Calibration tapes

Vielleicht für den einen oder anderen NAKA Liebhaber nicht uninteressant.......