More tape "theory" - the dolby symbols on the meters...

[jbeckva]

Ok, so I've figured out that for some decks the "Dolby Level" is -1 db, while for others it's +3 db. And it's marked as such on the meters.

My question... Why have the mark on the meters in the first place? Is it because when Dolby is being used, we shouldn't exceed that level or ???

One of those questions I've always wondered about....

BTW.. I have a MA-XG with the peaks set right at the "mark" and with Dolby S on the Teac... sure sounding good...

 

[orange]

It's not an absolute limit-it's a calibration level. In many case it is a good reference to average your peak levels to as well. Engineers originally set this level in an area where distortion was the least and the most robust testing could be found.

With improvements the levels rose and the same manufacturer may have more than one standard.

 

[rtp_burnsville]

With my Sansui 9090DB the marks were used with the built-in test tone for setting the correct dolby levels. I don't remember the procedure at the moment but do remember using the oscillator and meter marks to get everything set.

Robert

 

[nakdoc]

Levels in tape decks are arbitrary ( see the definition for Vu, volume unit). I suspect it was mandatory to put dolby level indicators on the meters as a condition to use the circuit. If you have a dolby reference level test cassette, the playback level would be set at the dD mark. Beware, however, many decks had separate record and play VU meter calibrations, so knowledge of the set up and an external reference AC voltmeter must be used in these machines.