Markings on DECCA "dead vinyl" areas
The off
groove or dead vinyl markings on old DECCA LP’s are an interesting detail that
gives a lot of information. You can improve your knowledge of the LP by
understanding
the meaning of the numbers and letters and this will help in identifying
the age and version of the LP. The markings are directly related to the
manufacturing process.
Before
going into more details, I’d like to take you through the manufacturing process
in the 60’s at DECCA Records Company.
Well, at least as I understand it. It is not easy to find detailed information
on the subject. So please correct me if you find any wrong information here.
Master tape
Everything starts from the master tape that is the ready mixed and produced set
of songs that should be on the final record.
To be able to get the sound from the tape and down to a disc we need a Laquer
Disc and a cutting (recording) machine called a Mastering Lathe.
Laquer disc
For LP’s this is a 12” disc made of aluminium coated with a thin layer of laquer. Other materials may also have been used for the disc and for the coating.
Laquer Matrix, Acetate, Master Laquer
Laquer
disc is put into the Mastering Lathe maching that cuts the grooves into the
surface of the Laquer disc. The ready cut disc is then called a Laquer Matrix.
In the 60’s this disc was also called Acetate. If the disc is approved in
quality control, then it will be called Master Laquer.
The matrix number is then added on the approved Master Laquer on the ”dead vax”
area.
Plated Laquer
The
Master Laquer is then sprayed with a silver solution. Then it is put in a bath
of a nickle solution. An electric current is passed through the solution
and the nickle particles in the bath are attracted to the surface of the
silver plated Laquer Disc. This process will create a rather hard mirror piece
of the Master Laquer.
Metal Master
The
Master Laquer is then removed form the new metal cover. This new piece is called
Metal Master.
Two or three metal masters are med from one Master Laquer. This disc is a so
called negative one
Metal mother
One Metal
Mother is then made from each Metal Master. This disc is a positive one, meaning
that it could be played.
The Metal Mother is numbered. This number will be visible at approximately 9 a
clock on the final vinyl.
Stamper
The
stamper is then made form the Metal Mother. This is the disc actually used for
pressing a piece of vinyl into one side of a record. Each Mother was used to do
10 stampers.
The stamper number was marked in the off groove area atapproximately 3 a
clok and a letters was used for stamper identification.
The word BUCKINGHAM was used so that the first stamper got the letter B, then
second one got letter U and so on.
You may somethimes find two letters at 3 a clock. The reason for this is not
known by me. There can be two reasons.
- Two old stampers were combined into one for pressing vinyls
- More than 10 stampers were made from one mother and the eleventh may have had a combination of two letters
Vinyl record
The
stampers are then used to press the vinyls. There is one stamper for side 1 and
another stamper for side 2.
One label paper is put on each stamper and a piece of vinyl is put in between
the stampers, then you press them together and the record is made.
The quality of the stampers did decrease fast as more vinyls were pressed and
approximately 500 copies was the limit.
The stampers were then retirde after 500 pressed vinyls and the next stamper was
taken into use.
When all
stampers were consumed they went back to the Laquer Disc stage and created again
a new Laquer Matrix.
This was also the phase of the production when the matrix numbers were changed.
On old DECCA records you will find three different markings resulting from the above described process:
Matrix number, Mother number and Stamper letter.
Matrix Number
This number can be found at 6 a clock on the vinyl. A typical number can looke
like this: XARL-6791-2A, this number is on a LK4725 Out Of Our Heads
export version.
The number can then be broken up in a few pieces that carry different
information like this:
XARL - This stands for a Mono recording. If you have a Stereo record, the the numbers would be ZAL
6791 - This is either the running number of the recording session or the master tape. I am not sure which one it is
2 - This is the running number oft the Matrix. Or in other words which Master Laquer was used for the manufacturing process. The higher number, the later Master Laquer is used.
A - this is the
code letter of the engeneer who created the Master Laquer and supervised the
whole process up to the stampers.
Some of the engeneers are known and the letters they used are as follows:
G = Ted Burkett
K = Tony Hawkins
W = Harry Fisher
In general we can say
that the lower Matrix number you have, the earlier pressing is in your hand.
This is not always 100% correct as DECCA used several plants for pressing the
records.
Some of the plants had a high number of produced LP's and then the
consumption of stampers was high. Another plant again could have a smaller
production capacity and
the same stampers may have been used for a number of years. Antoher factor
was also the number of copies sold. I have a copy of the Out Of Our Heads LK4725
export version
with a non grooved label that still has a -1A matrix number. The original
issue was in September of 1965 and the non grooved labels were produced during
end of 1968 and 1969.
So almost four years after the first issue they still used a stamper
originated from the first Matrix.
Mother Number
This number can be found approximately at 9 a clock on the vinyl. The number is somethimes difficult to se, but it is there. This is the number of the Metal Mother used to make the Stamper.
The highest number I have found to date is 5. Most of all LP's has either 1 or 2. You may also somethimes find combinations of two numbers.
The reason for double numbers is not known to me.
In general you it can be said that the lower number you find, the earlier Mother is used.
The number in this picture is 1
Stamper
The letter identifying the Stamber can be found at 3 a clock on th evinyl. The letter is sometimes difficult to se, but it is there. As mentioned earlier DECCA used the word
BUCKINGHAM for numbering of the Stamper. The first Stamper to be made from the Mother has the letter B, the next one has U and so on.
You may also somethimes find combinations of two letters. The reason for double letters is not known to me.
In general it can be said that the earlier letter in BUCKINGHAM you find, the earlier Stamper is used.
The letter in this picture is C
What to look for
From a sound quality point of view you should be looking for a Mother number as low as possible. The first Mother made with number one would have the best sound quality.
But more important is the Stamper number. The best sound quality is in a record that has B as the stamper number. As they took at least ten stampers from one Mother,
the quality of sound did
deteriorate as the numbers went up. The Matrix number is not important for the
sound as it is made directly from the master tape.
The next number in line is
then used when a new Matrix is made. Basically all Matrix numbers would
have the same sound quality if the Mother number is 1 and the Stamper number is
B.
One exeption to this statement would be this: If you have a Matrix number that is very high, like 10 or more, then the cutting of the disc probably took place during the mid or end 70's.
At this time they used smaller cutting tools with the result of more narrow grooves. You can see the difference if you compare an original LK4605 with a late one with boxed label from the end of the 70's.
You will find a lot more "dead vinyl" on the boxed one compared to the original non boxed disc just because there is less space in between the grooves.
Original with wide deep
grooves gives better sound than small narrow grooves.
So if you are looking for a good sound, then
look for an LP with 1 and B and preferably a so called "wide grooved" pressing.
The numbers should for example be:
XARL-6791-6A 1 B
If you are looking for a pressings made as early as possible, then you should look for a Matrix number as low as possible, at least for the high sales volume records.
As earlier explained, low sales volume records can be pressed during a long periode with stampers originated from the same Mother och Matrix.
You should more rely on other indications on the label and on the cover for confirming an early press. But in general the one to look for would have this number combination:
XARL-6791-1A 1 B
And.....
As earlier said, I cannot
guarantee that my description of the manufacturing process at DECCA was exactly
as I have written. I have a few doubts, especially on the
Metal Master and Metal
Mother relationship, mainly how many Masters and Mothers came out from one
Plated Laquer.
The process of making records today has slightly changed
from the 60's so a few steps in the process has been taken out.
Links
is a nice place, you can find just about anything over there. For example information on how records are made:)
Here is a link to video on how RCA manufactured records in the 40's
Part one: http://www.youtube.com/watch?v=ZxhiUgK5gzs&feature=related
Part two: http://www.youtube.com/watch?v=8xwe-Mt99Dw&feature=related
A tour of the todays United Records pressing plant
http://www.youtube.com/watch?v=43n5bVXAqzo&feature=related
EMI's old pressing plant in London
http://www.youtube.com/watch?v=3QV94t-u6Rs
Here are two nice ones from Discovery TV channel
http://www.youtube.com/watch?v=xUGRRUecBik
http://www.youtube.com/watch?v=IReDh9ec_rk&feature=related