Ahh, the beloved cassette...where do I begin?
Perhaps the best place to start is to suggest that the cassette was
originally thought of as a dictation and general purpose format, not a
high-fidelity format. Considering the tolerances involved and the skill
of mass-producing precision machinery back in the day when it was
introduced it is a miracle that it worked as well as it did.
With assistance from Jay McKnight of Magnetic Reference Lab and a few
others, I have written to blog posts on some of the ambiguity in
high-frequency response. This was in response to the widely held myth
that Nakamichi violated the equalization standard in order to make the
cassette sound better when, in fact, it appears that they actually
upheld the printed equalization standard while Philips et al made
calibration tapes that did not meet the actual printed standard. This
ended in an unspecific "Prague Compromise". The bottom line is a 4 dB
ambiguity at 16 kHz.
Jay links to some of his papers within his quoted reply in the second
blog post above, but his website is here
As to EQ, references are provided in the 2010 blog post and Jay has
material about EQ on his website.
A great reference (and order your copy now while a few inexpensive
copies still exist) is Marvin Camras's "Magnetic Recording Handbook"
ISBN 0-442-26262-0. I just ordered the copy from Better World Books,
there are others. The best place to find the deals is www.fetchbook.info.
As to azimuth, I've done my best to attempt to describe and show the
effect of badly adjusted azimuth here:
You might find some useful information at this page
This might be of some interest but is not directly related to cassettes
This refers to aligning a tape recorder, but note that MRL does not make
cassette calibration tapes
While not describing how bias really works (which is currently not
properly described in most publications including Camras, according to
McKnight and others) here is a sampling of bias frequencies.
This discusses issues of mono cassettes and stereo reproducers
and was updated just now
This relates to azimuth and azimuth wander in 1/4-inch tapes. There are
similar issues in some cassettes.
This applies to reels, but may offer some insight to the geometric
issues that also somewhat apply to cassettes.
This provides some insight into gap loss, but is not enough for a
Another cassette issue:
You might enjoy this travesty
Another annoying cassette
Issues with old machines
As to your last question about who should do it, any task worth doing is
worth doing well and that means that experienced professionals should do
the work. You have to start somewhere, so becoming an experienced
professional is possible, but giving the work to an uninterested and
inexperienced clerk is a certain invitation to failure, especially if
there is no technical supervision. I know of one project that was
supervised by someone who made it her business to learn and then had a
bunch of volunteers actually coming in. She trained them as to what to
listen for and when to call if they needed assistance. Thousands of
tapes were successfully digitized. She started out by hiring me to
assess the collection and then hired me for some additional training,
but the bulk of the work was done by volunteers.
On 2012-10-28 2:56 PM, Derek J Jackson wrote:
> I am a long time listener, first time caller on this listserv. I am student
> looking for some help on research I am doing on the standard audio compact
> cassette. Specifically, I am looking for any information on the upper
> frequency limits a compact cassette could capture but in general I also
> wonder if there are some resources people may know of that explain some of
> the essential, but more technical, characteristics of cassettes and cassette
> recorders (e.g. alignment, tape bias, equalization, gap loss.) I seem to be
> at an intermediate stage where most of the resources I find are too general
> and donít give me any new information, or so technical that I have
> difficulty making sense out of them. I would really appreciate it if anyone
> could give me information about what factors limit the ability of cassette
> tape/recorders to record high frequencies, and some idea of what that limit
> might be for standard commercial equipment and tape? And/Or more generally
> point me to any resources that might help me understand some of the more
> technical aspects of cassette recording and tape characteristics.
> And while I am at it I may as well solicit your opinions on digitizing
> cassettes. I have read several case studies of institutions digitizing their
> own cassettes, but then I have also read the IASA TC reports, Sound
> Direction, ARSC TC guidelines, etc. and these reports would indicate that
> digital transfers should always be done by audio professionals. What do the
> folks here think? Is there some middle ground? On a format as ubiquitous as
> the compact cassette is it conceivable that an institution could responsibly
> do its own digitization work? Just trying to sort it all out.
> Any help is greatly and kindly appreciated.
> Derek Jackson
Richard L. Hess email: [log in to unmask]
Aurora, Ontario, Canada (905) 713 6733 1-877-TAPE-FIX
Quality tape transfers -- even from hard-to-play tapes.