In response to the inquiry from Richard Stibbons, it impossible to
determine with 100% accuracy whether an Ampico roll is coded in A format
or B format without looking at the roll coding.  But there are other
things to look for that will be about 90% accurate in identifying the
roll format.

Last year, at the AMICA Sundusky convention, I presented a tech session
devoted to this subject.  While I cannot give all the details here, I
can give the following general guidelines.

If the roll is numbered in the pop  series 2xxxxx-E (or some other
letter), the numbers 209161-E and above are B rolls.  209161-E, "Blue
River", is the first B-coded roll issued (Oct 1927).  It is fully
B-coded.  Many rolls in the pop series above 209161-E are not fully
B-coded, but do have parallel bass and treble crescendo coding
perforations producing satisfactory results.

In the classical series almost all rolls above 68283-H are B coded.
There are exceptions such as 68523-H.

In addition, many rolls below 68283-H exist in both formats.

If the roll box has "London" on it, or if it has a red or black star,
or If the roll leader has a green star, or if the roll box is in the
art deco block letters, the chances are it is a B roll.

There are three distinct types of B-coding and two more that are not
so distinct.  There are exceptions to some "box" identifiers, and of
course, over the years a particular roll may have been placed into a
box other than its original.  (I did that myself--putting the best
condition roll in the best condition box and selling the rest--
sometimes an A roll in a B box and so on)

Learn to read the roll coding.  It is the only way.  Parallel, identical
crescendo (bass and treble) coding, sub-intensity, and amplifier coding
are positive  B identifiers. It is not that hard to learn.

Bob Taylor