Earliest 1" Drivers ?

[Mirrophonic Sound System]

Is the 802-B the earliest 1" driver ?
What changes are there between the"B" & the"D"?(assuming both are 16 ohm)
Were the earliest diaphragms lower mass ? -that
is, did they change the thickness of the duraluminum to boost power handling at some point in time ?
What was the gauge (in mils) of the earliest
duraluminum diaphragms ?

[Jim D]

You are asking a lot of questions that I do not think you will be able to find answers to, the people who knew are probably long in the cemetery. The first of the 1" family of drivers could be presented as the WE 555. In the Lansing (pre ALTEC) family, the first would be the field coil 801. It had a roll compliance aluminum diaphragm. The permanent magnet version of it was the 901 (alnico 3), very few were made. The first of the 802s was the 802. Later it became the 802B then C and D. The old diaphragm books list the B,C,D all using the same 20275 16 ohm diaphragm. The 802 since it was very early, may have been some different. As for the differences in the drivers, these probably are changes in magnet construction. From what I know, there were no differences in material thickness, except for perhaps the 70s 23744 8 ohm unit which no one now seems to know what the differences were for it. Maybe some one else knows some of these answers, however I wouldn't know who. Jim

[Mirrophonic Sound System]

Thanks for the info Jim. The W.E. 594-A also has a 'roll compliance' diaphragm
of 1.5 mil gauge duralumin and a power rating of 25 watts - not bad for July 1936
when it was introduced.The early JBL copies the 594 but has a smaller (3.9")
voice coil on a 3 mil duralumin diaphragm. The higher mass diaphragm
giving it increased power handling (30 w).Interestingly, the
new JBL 435Be driver has to a lower mass 1.6 mil diaphragm.
Other specs I have found:
Electro Voice DH1 (duralumin) 2 mil
Fostex D232 2 mil

[RonSSS]

One could measure the thickness of these diaphragms, bt it would be difficult to do w/o hurting them.
I remember many years ago Jim, you told me not to blow up my 802-8G as the diaphragms were thinner than others and there were no exact replacements. I guess we don't know if they are or aren't thinner, but the good news is that I still have them and never blew them up!
Ron