March 4, 2015

Manually adjusting azimuth when playing and transferring cassette tapes

One difficulty encountered when transferring cassette tapes to a digital medium is the issue of proper azimuth alignment. Essentially, this boils done to differences in the direction the play head in the machine is aligned with when tape is passing over it. The goal is to have the same alignment as the original machine which made the recording. This will not be possible in 99% of cases, unless you are using the same deck. 

Here is one excellent article and a fine video on this subject. Anyone who is very serious about helping to preserve recorded musical culture will hopefully be motivated to take a few minutes to read a couple of other articles as well. 

YouTube video on how to manually adjust azimuth


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  2. Hi Richard - I'm really impressed with the quality of your analog to digital conversions. I recently procured a large number of Raag Sangeet cassettes, but do not know the first thing about extracting good quality digital music from analog tapes. Can you provide some pointers on how to get started without spending a crazy amount of $$ on equipment? My primary objective is to create high quality digital files from tapes that go back to 1980s. At the moment I have a latest gen Macbook Pro device. Any tips are highly appreciated!

    1. Hi KIran: probably the most important thing is to get the best analog signal to begin with. Obtaining a decent (not amazing, just decent) cassette player is very important. Even if you have to borrow one. It's not easy finding good quality cassette decks these days. There are few if any being manufactured. The used ones on eBay and etc are often in terrible shape. The word "refurbished" can mean anything. I would expect a long detailed list of what was done to the unit if I were purchasing a refurbished deck. Check out this page (and especially at the bottom where he explains what sorts of things can go wrong with a used cassette deck):

      And as i have said before, aligning the azimuth is easy and can be done without any special tools other than a very small screwdriver and your ears. You twist the screw back and forth and you will hear the high frequencies disappear and reappear. You leave it where the high frequencies are the best.

      I use a portable recorder as my Analog-Digital converter and then slide the SD card into my MacBook Air. It is certainly possible to buy an inexpensive ADC such as this one:

      I would use the free software program Audacity. There are a lot of youtube video tutorials for Audacity and a large online community of people answering questions on forums dedicated to audacity.

      Once recorded, I find one of the most useful effects is the one called "AUParametricEQ" -- it comes with the software and will allow you to change the EQ in a gentle way and listen to the results in real time as the track plays. The easiest trap to fall into is too much use of EQ. The end result should both highlight what you think might be missing from the cassette (such as the high frequencies or low frequencies of a vocal) but still sound natural.

      Thanks and good luck! The record industry is unreliable and fickle in their tastes, current musicians are mostly asleep at the wheel when it comes to recording their performances -- it is the music lovers who will need to preserve a lot of the music recorded between 1906 and 1996.

      If you have more specific questions just ask and include your email -- I won't publish it and will respond as best I can.


    2. One more thing that I have learned from being a paying customer of audio engineers: when listening to a track, try to mentally break up the sound into five zones: 1) highest highs 2) mid-to-high zone 3) middle zone 4) mid-to-low frequencies zone and 5) lowest lows. Once you get used to dividing up the raw sound that way, pay attention to each "zone" in whatever order you like (I usually listen to the mids then work my way to the outer zones). That way you won't get caught up just listening to one "zone" all the time and ignoring the others.